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Faculty of Engineering Cairo University Mechanical Power Departement Cooling Tower Educational Stand B.Sc. Graduation Project 2008

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Page 1: Cooling Tower Educational Standcairouniversity

Faculty of Engineering Cairo University Mechanical Power Departement

Cooling Tower Educational Stand BSc Graduation Project

2008

I

Cairo University

Faculty of Engineering

Mechanical power department

BSc Graduation Project 2008

Cooling Tower Educational Stand

bull Prof Dr Adel Khalil

Project Supervisors

bull Prof Dr Hany Khater bull Dr Galal Mostafa

II

- Acknowledgement

Contents

- Project description - Nomenclatures

Page

Chapter One Introduction 1 Objective 2 Classification 3 Components 4 Water Treatment

Chapter Two Literature review

1 Gunt 2 Armfield 3 P A Hilton 4 Edibon

Chapter Three Cooling Tower Design Calculation 1 Column 2 Cooling tower performance 3 Tanks

i Water tank ii Air tank

iii Make up tank iv Drain tank

4 Piping System and pump 5 Blower and Butterfly Valve 6 Water Injection Nozzle 7 Stand

Chapter Four Measuring devices and auxiliaries 1 Temperature Measurements 2 Humidity Measurements 3 Flow Measurements 4 Displays 5 Data acquisition card 6 Calibration

Chapter Five Bill of Material and Cost Chapter Six Fabrication Procedure

1 Welding 2 Stand fabrication 3 Painting and coating 4 Pipes components and fittings 5 The column 6 Stand preparation 7 Control panel 8 Electronic and Electric devices installation 9 Electric Connections 10 Component assembly

1 1 2 6 7 8 8

10 12 14 16 20 21 21 23 23 24

25 29 30 31 32 32 34 34 37 38 46 48 51 51 55 56 57 59 61 62 62 63 64

III

Chapter Seven Tests and Results

1 Procedure 2 Results 3 Relations summery and conclusion

-Appendices -References

66 66 67 70 71

105

IV

First we would like to thank Allah the merciful and compassionate for making all this work possible and for granting us with the best professors family friends and colleagues that many people would wish and dream of having

Acknowledgment

We would like to thank our supervisors

bull Prof Dr Adel Khalil bull Prof Dr Hany Khater bull Dr Galal Mostafa

We are greatly indebted to them for their valuable supervision kind guidance and great help and effort to make this project possible Words cannot express our deep gratitude and sincere appreciation to them

Group Members

Eng Basel Amr Gouda

Eng Hebatallah Abdel Moniem Mohamed

Eng Mohamed El Sayed Rizk

Eng Al Hussain Mohamed Kamel

Eng Ismail Gamal El Din Ismail

Eng Ahmed Samir Abdallah

Special Thanks to

bull Eng Somya Mohamed Abdel Rehim - For Supplying us with materials and support bull Colleague Ahmed waheed - For his effort

V

- The students affiliating with the present project will be required to study design and fabricate a Water Cooling Tower Educational Stand

Project description

The Water Cooling Tower educational stand will eventually form a part of the undergraduate students ldquoHeat Transfer Laboratoryrdquo

In this step the following will be accomplished

Step 1 Water cooling tower fabrication

Study the different heat and mass transfer mechanisms

Cooling tower heat load estimation

Design calculations of the water cooling tower showing different geometrical parameters and dimensions

Material selection of the different components

Working drawing sheets for the different cooling tower components

Fabricating the different components and assembling the cooling tower

In this step the following will be accomplished

Step 2 Water cooling tower educational stand erection

Selecting and preparing the types of the measuring sensors devices and data acquisition system

Assembling the cooling tower together with the storage tank with heaters the make-up tank the air blower and air chamber the water circulating pump water injection nozzle the column valves and hoses and the different measuring devices on the stand

Finalizing all mechanical electrical and electronic works needed for the stand

In this step the following will be accomplished

Step 3 Performance test on the water cooling tower educational stand

Assuring the validity of all stand measuring devices

Studying the effect of different parameters on the cooling tower performance

Comparing the experimental results with those calculated

VI

-Nomenclatures

VII

Chapter 1

1 Cooling Tower Educational Stand BSc Project 2008

Chapter One Introduction

1 Objective Cooling towers (Fig 1) are heat removal devices used to transfer process waste heat to the atmosphere They may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or rely solely on air to cool the working fluid to near the dry-bulb air temperature The objective of cooling towers can be divided into two categories

HVAC An HVAC cooling tower is a subcategory rejecting heat from a chiller Water-cooled chillers

are normally more energy efficient than air-cooled chillers due to heat rejection to tower water at or near wet-bulb temperatures Air-cooled chillers must reject heat at the dry-bulb temperature and thus have a lower average reverse-Carnot cycle effectiveness Large office buildings hospitals and schools typically use one or more cooling towers as part of their air conditioning systems Generally industrial cooling towers are much larger than HVAC towers

Industrial Industrial cooling towers can be used to remove heat from various sources such as machinery

or heated process material The primary use of large industrial cooling towers is to remove the heat absorbed in the circulating cooling water systems used in power plants petroleum refineries petrochemical plants natural gas processing plants food processing plants semi-conductor plants and other industrial facilities The circulation rate of cooling water in a typical 700 MW coal-fired power plant with a cooling tower amounts to about 71600 cubic metres an hour (315000 US gallons per minute) and the circulating water requires a supply water make-up rate of perhaps 5 percent (ie 3600 cubic metres an hour)

Fig (11) cooling tower

Chapter 1

2 Cooling Tower Educational Stand BSc Project 2008

2 Classification Cooling towers can be classified into different categories as follows

Heat transfer mode bull Wet cooling towers or simply cooling towers operate on the principle of evaporation bull Dry coolers operate by heat transfer through a surface that separates the working fluid

from ambient air such as in a heat exchanger utilizing convective heat transfer bull Fluid coolers are hybrids that pass the working fluid through a tube bundle upon which

clean water is sprayed and a fan-induced draft applied The resulting heat transfer performance is much closer to that of a wet cooling tower with the advantage provided by a dry cooler of protecting the working fluid from environmental exposure

In a wet cooling tower the warm water can be cooled to a temperature lower than the ambient air dry-bulb temperature if the air is relatively dry As ambient air is drawn past a flow of water evaporation occurs Evaporation results in saturated air conditions lowering the temperature of the water to the wet bulb air temperature which is lower than the ambient dry bulb air temperature the difference determined by the humidity of the ambient air Air flow generation With respect to drawing air through the tower there are three types of cooling towers

bull Natural draft which utilizes buoyancy via a tall chimney Warm moist air naturally rises due to the density differential to the dry cooler outside air Warm moist air is less dense than drier air at the same pressure This moist air buoyancy produces a current of air through the tower (Fig 2)

Fig (12) Natural draft cooling tower

Chapter 1

3 Cooling Tower Educational Stand BSc Project 2008

bull Mechanical draft which uses power driven fan to force or draw air through the tower minus Induced draft A mechanical draft tower with a fan at the discharge which pulls

air through tower (Fig 3) The fan induces hot moist air out the discharge This produces low entering and high exiting air velocities reducing the possibility of recirculation in which discharged air flows back into the air intake This fanfill arrangement is also known as draw-through

Fig (13) Induced draft fan cooling tower minus Forced draft A mechanical draft tower with a blower type fan at the intake (Fig

4) The fan forces air into the tower creating high entering and low exiting air velocities The low exiting velocity is much more susceptible to recirculation With the fan on the air intake the fan is more susceptible to complications due to freezing conditions Another disadvantage is that a forced draft design typically requires more motor horsepower than an equivalent induced draft design The forced draft benefit is its ability to work with high static pressure They can be installed in more confined spaces and even in some indoor situations This fanfill geometry is also known as blow-through

Chapter 1

4 Cooling Tower Educational Stand BSc Project 2008

Fig (14) Forced draft fan cooling tower

Air-to-Water Flow

-Cross flow Is a design in which the air flow is directed perpendicular to the water flow

(Fig 5) Air flow enters one or more vertical faces of the cooling tower to meet the fill material Water flows (perpendicular to the air) through the fill by gravity The air continues through the fill and thus past the water flow into an open plenum area A distribution or hot water basin consisting of a deep pan with holes or nozzles in the bottom is utilized in a cross flow tower Gravity distributes the water through the nozzles uniformly across the fill material

-Counter Flow The air flow is directly opposite of the water flow (Fig 6) Air flow first enters an open area beneath the fill media and is then drawn up vertically The water is sprayed through pressurized nozzles and flows downward through the fill opposite to the air flow Common to both designs

bull The interaction of the air and water flow allow a partial equalization and evaporation of water

bull The air now saturated with water vapour is discharged from the cooling tower bull A collection or cold water basin is used to contain the water after its interaction with the

air flow Both cross flow and counter flow designs can be used in natural draft and mechanical draft cooling towers

Chapter 1

5 Cooling Tower Educational Stand BSc Project 2008

Fig (15) Cross Flow cooling tower

Fig (16) Counter Flow cooling tower

Chapter 1

6 Cooling Tower Educational Stand BSc Project 2008

3 Components

Inlet water distributors There are several types of water distributors among them

1 Gravity distributors applied mainly for cross flow cooling towers and consist of vertical water riser that feed water into an open concrete basin from which the water flows by gravity through orifices to the fill

2 Spray distributors used mainly with counter flow cooling towers and have cross pipe net with spray downward nozzles

3 Rotary distributors applied for cross flow cooling towers and consists of two slotted arms rotate about a central hub containing water supply pipe The slots in the tow arms are directed downward but make small angle with the vertical direction to one side The slots form a curtain angle and due to reaction force the arms rotate at a rotational speed of 25-to-30 revmin

Drift eliminators An assembly constructed of wood plastic cement board or other material that serves to

remove entrained moisture from the discharged air Circulating Pump

The circulating pump transports the cooling water between the cooling tower and the condenser The water is pumped from the cooling tower basin through to the condenser where it is used as cooling medium The water returns back for evaporative cooling in the cooling tower Fan A device for moving air in a mechanical draft tower The fan design may be either an axial flow propeller or centrifugal blower Also may be applied as induced draft or forced draft Noticing that the induced type requires less power for same result Fills

Is the heart of the cooling tower The fill must provide good water-air contact area high rates of heat and mass transfer and low air flow resistance The fill also must be strong and deterioration resistant The fill has mainly two forms

minus Splash fill breaks falling water into small drops This Type is made of bars stacked in desks and may be narrow-edged square bars rough bars and grids Different materials are used such as redwood high-impact polystyrene or polyethylene

minus Film fill is made of vertical sheets that have a rough adsorbent surface and good wetness of water that allows water to fall as a film over the vertical surface Film fill has different forms and materials redwood battens cellulose corrugated sheets asbestos cement and waveform plastic

Water Basin Is situated beneath the tower collects and strains the water before pumped back to the circulating system Large utility tower basins are generally made of concrete Water leaves the basin via sloped canal at the bottom and through screens that prevent dust and foreign materials from entering the pump

Chapter 1

7 Cooling Tower Educational Stand BSc Project 2008

4 Water Treatment

The large variety of alternative construction materials allows users to match unit construction to the water quality available for their systems while helping to protect the tower from temporary upsets

Water treatment programs must be designed for three requirements

1 Scale control 2 Protection of system components against corrosion and 3 Control of biological contaminants such as Legionella pneumophilia the bacterium that causes

Legionnaires disease

The first two requirements help to ensure energy efficiency and longevity of the cooling system while the third ensures safe operation

Biological control is relatively easy to accomplish and is essential to the safe operation of the tower

Cooling towers can collect and concentrate airborne dirt and debris over time To control this buildup the cooling tower should be located so as to minimize contaminant induction and a proper blowdown rate should be maintained Sidestream filters or separators have proven valuable in this regard by effectively removing dirt and debris from the tower water These devices are coupled with a basin-sweeping nozzle package which is available either as original equipment in the tower or as a field-installed aftermarket item Cleaner tower water makes water treatment regimens more effective while keeping the cooling loop cleaner saving energy reducing maintenance and improving reliability of the entire cooling system

Chapter 2

8 Cooling Tower Educational Stand BSc Project 2008

Chapter Two

Literature review

In this chapter we will introduce the specifications of the cooling tower educational stand that manufactured by different companies like Gunt Armfield PA Hilton Edibon

1 Gunt

Fig (2-1) Gunt cooling tower educational stand

Column

Dimensions 150x150x630 mm

Pacing density 110 m2m3

Orifice diameter 80 mm

Approx weight 5 Kg

Heaters

3 stages 05-1-15 KW Thermostat switches off at 50⁰c

Fan

Radial fan - Power consumption 025 KW -max Differential pressure 430 pa

-max Flow rate 13 m3min

Chapter 2

9 Cooling Tower Educational Stand BSc Project 2008

Pump

-Power consumption 07 KW

-max Head 34 m

-max Flow rate 34 Lmin

Instrumentation

-Temp Sensors at air inlet ampoutlet

-Temp Sensors at water inletamp outlet

-Water flow rate sensor

-Humidity sensors at air inletamp outlet

Dimensions

Height 1228 m

Length 111 m

Width 046 m

Weight approx 90 Kg

Service required

Electrical -230 v 5060 HZ 1 phase

or -230 v 60 HZ 3 phases

Computeramp Data acquisition

Data acquisition with lab view software h-w diagram and Windows X-P

Chapter 2

10 Cooling Tower Educational Stand BSc Project 2008

2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

Chapter 2

11 Cooling Tower Educational Stand BSc Project 2008

Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 2: Cooling Tower Educational Standcairouniversity

I

Cairo University

Faculty of Engineering

Mechanical power department

BSc Graduation Project 2008

Cooling Tower Educational Stand

bull Prof Dr Adel Khalil

Project Supervisors

bull Prof Dr Hany Khater bull Dr Galal Mostafa

II

- Acknowledgement

Contents

- Project description - Nomenclatures

Page

Chapter One Introduction 1 Objective 2 Classification 3 Components 4 Water Treatment

Chapter Two Literature review

1 Gunt 2 Armfield 3 P A Hilton 4 Edibon

Chapter Three Cooling Tower Design Calculation 1 Column 2 Cooling tower performance 3 Tanks

i Water tank ii Air tank

iii Make up tank iv Drain tank

4 Piping System and pump 5 Blower and Butterfly Valve 6 Water Injection Nozzle 7 Stand

Chapter Four Measuring devices and auxiliaries 1 Temperature Measurements 2 Humidity Measurements 3 Flow Measurements 4 Displays 5 Data acquisition card 6 Calibration

Chapter Five Bill of Material and Cost Chapter Six Fabrication Procedure

1 Welding 2 Stand fabrication 3 Painting and coating 4 Pipes components and fittings 5 The column 6 Stand preparation 7 Control panel 8 Electronic and Electric devices installation 9 Electric Connections 10 Component assembly

1 1 2 6 7 8 8

10 12 14 16 20 21 21 23 23 24

25 29 30 31 32 32 34 34 37 38 46 48 51 51 55 56 57 59 61 62 62 63 64

III

Chapter Seven Tests and Results

1 Procedure 2 Results 3 Relations summery and conclusion

-Appendices -References

66 66 67 70 71

105

IV

First we would like to thank Allah the merciful and compassionate for making all this work possible and for granting us with the best professors family friends and colleagues that many people would wish and dream of having

Acknowledgment

We would like to thank our supervisors

bull Prof Dr Adel Khalil bull Prof Dr Hany Khater bull Dr Galal Mostafa

We are greatly indebted to them for their valuable supervision kind guidance and great help and effort to make this project possible Words cannot express our deep gratitude and sincere appreciation to them

Group Members

Eng Basel Amr Gouda

Eng Hebatallah Abdel Moniem Mohamed

Eng Mohamed El Sayed Rizk

Eng Al Hussain Mohamed Kamel

Eng Ismail Gamal El Din Ismail

Eng Ahmed Samir Abdallah

Special Thanks to

bull Eng Somya Mohamed Abdel Rehim - For Supplying us with materials and support bull Colleague Ahmed waheed - For his effort

V

- The students affiliating with the present project will be required to study design and fabricate a Water Cooling Tower Educational Stand

Project description

The Water Cooling Tower educational stand will eventually form a part of the undergraduate students ldquoHeat Transfer Laboratoryrdquo

In this step the following will be accomplished

Step 1 Water cooling tower fabrication

Study the different heat and mass transfer mechanisms

Cooling tower heat load estimation

Design calculations of the water cooling tower showing different geometrical parameters and dimensions

Material selection of the different components

Working drawing sheets for the different cooling tower components

Fabricating the different components and assembling the cooling tower

In this step the following will be accomplished

Step 2 Water cooling tower educational stand erection

Selecting and preparing the types of the measuring sensors devices and data acquisition system

Assembling the cooling tower together with the storage tank with heaters the make-up tank the air blower and air chamber the water circulating pump water injection nozzle the column valves and hoses and the different measuring devices on the stand

Finalizing all mechanical electrical and electronic works needed for the stand

In this step the following will be accomplished

Step 3 Performance test on the water cooling tower educational stand

Assuring the validity of all stand measuring devices

Studying the effect of different parameters on the cooling tower performance

Comparing the experimental results with those calculated

VI

-Nomenclatures

VII

Chapter 1

1 Cooling Tower Educational Stand BSc Project 2008

Chapter One Introduction

1 Objective Cooling towers (Fig 1) are heat removal devices used to transfer process waste heat to the atmosphere They may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or rely solely on air to cool the working fluid to near the dry-bulb air temperature The objective of cooling towers can be divided into two categories

HVAC An HVAC cooling tower is a subcategory rejecting heat from a chiller Water-cooled chillers

are normally more energy efficient than air-cooled chillers due to heat rejection to tower water at or near wet-bulb temperatures Air-cooled chillers must reject heat at the dry-bulb temperature and thus have a lower average reverse-Carnot cycle effectiveness Large office buildings hospitals and schools typically use one or more cooling towers as part of their air conditioning systems Generally industrial cooling towers are much larger than HVAC towers

Industrial Industrial cooling towers can be used to remove heat from various sources such as machinery

or heated process material The primary use of large industrial cooling towers is to remove the heat absorbed in the circulating cooling water systems used in power plants petroleum refineries petrochemical plants natural gas processing plants food processing plants semi-conductor plants and other industrial facilities The circulation rate of cooling water in a typical 700 MW coal-fired power plant with a cooling tower amounts to about 71600 cubic metres an hour (315000 US gallons per minute) and the circulating water requires a supply water make-up rate of perhaps 5 percent (ie 3600 cubic metres an hour)

Fig (11) cooling tower

Chapter 1

2 Cooling Tower Educational Stand BSc Project 2008

2 Classification Cooling towers can be classified into different categories as follows

Heat transfer mode bull Wet cooling towers or simply cooling towers operate on the principle of evaporation bull Dry coolers operate by heat transfer through a surface that separates the working fluid

from ambient air such as in a heat exchanger utilizing convective heat transfer bull Fluid coolers are hybrids that pass the working fluid through a tube bundle upon which

clean water is sprayed and a fan-induced draft applied The resulting heat transfer performance is much closer to that of a wet cooling tower with the advantage provided by a dry cooler of protecting the working fluid from environmental exposure

In a wet cooling tower the warm water can be cooled to a temperature lower than the ambient air dry-bulb temperature if the air is relatively dry As ambient air is drawn past a flow of water evaporation occurs Evaporation results in saturated air conditions lowering the temperature of the water to the wet bulb air temperature which is lower than the ambient dry bulb air temperature the difference determined by the humidity of the ambient air Air flow generation With respect to drawing air through the tower there are three types of cooling towers

bull Natural draft which utilizes buoyancy via a tall chimney Warm moist air naturally rises due to the density differential to the dry cooler outside air Warm moist air is less dense than drier air at the same pressure This moist air buoyancy produces a current of air through the tower (Fig 2)

Fig (12) Natural draft cooling tower

Chapter 1

3 Cooling Tower Educational Stand BSc Project 2008

bull Mechanical draft which uses power driven fan to force or draw air through the tower minus Induced draft A mechanical draft tower with a fan at the discharge which pulls

air through tower (Fig 3) The fan induces hot moist air out the discharge This produces low entering and high exiting air velocities reducing the possibility of recirculation in which discharged air flows back into the air intake This fanfill arrangement is also known as draw-through

Fig (13) Induced draft fan cooling tower minus Forced draft A mechanical draft tower with a blower type fan at the intake (Fig

4) The fan forces air into the tower creating high entering and low exiting air velocities The low exiting velocity is much more susceptible to recirculation With the fan on the air intake the fan is more susceptible to complications due to freezing conditions Another disadvantage is that a forced draft design typically requires more motor horsepower than an equivalent induced draft design The forced draft benefit is its ability to work with high static pressure They can be installed in more confined spaces and even in some indoor situations This fanfill geometry is also known as blow-through

Chapter 1

4 Cooling Tower Educational Stand BSc Project 2008

Fig (14) Forced draft fan cooling tower

Air-to-Water Flow

-Cross flow Is a design in which the air flow is directed perpendicular to the water flow

(Fig 5) Air flow enters one or more vertical faces of the cooling tower to meet the fill material Water flows (perpendicular to the air) through the fill by gravity The air continues through the fill and thus past the water flow into an open plenum area A distribution or hot water basin consisting of a deep pan with holes or nozzles in the bottom is utilized in a cross flow tower Gravity distributes the water through the nozzles uniformly across the fill material

-Counter Flow The air flow is directly opposite of the water flow (Fig 6) Air flow first enters an open area beneath the fill media and is then drawn up vertically The water is sprayed through pressurized nozzles and flows downward through the fill opposite to the air flow Common to both designs

bull The interaction of the air and water flow allow a partial equalization and evaporation of water

bull The air now saturated with water vapour is discharged from the cooling tower bull A collection or cold water basin is used to contain the water after its interaction with the

air flow Both cross flow and counter flow designs can be used in natural draft and mechanical draft cooling towers

Chapter 1

5 Cooling Tower Educational Stand BSc Project 2008

Fig (15) Cross Flow cooling tower

Fig (16) Counter Flow cooling tower

Chapter 1

6 Cooling Tower Educational Stand BSc Project 2008

3 Components

Inlet water distributors There are several types of water distributors among them

1 Gravity distributors applied mainly for cross flow cooling towers and consist of vertical water riser that feed water into an open concrete basin from which the water flows by gravity through orifices to the fill

2 Spray distributors used mainly with counter flow cooling towers and have cross pipe net with spray downward nozzles

3 Rotary distributors applied for cross flow cooling towers and consists of two slotted arms rotate about a central hub containing water supply pipe The slots in the tow arms are directed downward but make small angle with the vertical direction to one side The slots form a curtain angle and due to reaction force the arms rotate at a rotational speed of 25-to-30 revmin

Drift eliminators An assembly constructed of wood plastic cement board or other material that serves to

remove entrained moisture from the discharged air Circulating Pump

The circulating pump transports the cooling water between the cooling tower and the condenser The water is pumped from the cooling tower basin through to the condenser where it is used as cooling medium The water returns back for evaporative cooling in the cooling tower Fan A device for moving air in a mechanical draft tower The fan design may be either an axial flow propeller or centrifugal blower Also may be applied as induced draft or forced draft Noticing that the induced type requires less power for same result Fills

Is the heart of the cooling tower The fill must provide good water-air contact area high rates of heat and mass transfer and low air flow resistance The fill also must be strong and deterioration resistant The fill has mainly two forms

minus Splash fill breaks falling water into small drops This Type is made of bars stacked in desks and may be narrow-edged square bars rough bars and grids Different materials are used such as redwood high-impact polystyrene or polyethylene

minus Film fill is made of vertical sheets that have a rough adsorbent surface and good wetness of water that allows water to fall as a film over the vertical surface Film fill has different forms and materials redwood battens cellulose corrugated sheets asbestos cement and waveform plastic

Water Basin Is situated beneath the tower collects and strains the water before pumped back to the circulating system Large utility tower basins are generally made of concrete Water leaves the basin via sloped canal at the bottom and through screens that prevent dust and foreign materials from entering the pump

Chapter 1

7 Cooling Tower Educational Stand BSc Project 2008

4 Water Treatment

The large variety of alternative construction materials allows users to match unit construction to the water quality available for their systems while helping to protect the tower from temporary upsets

Water treatment programs must be designed for three requirements

1 Scale control 2 Protection of system components against corrosion and 3 Control of biological contaminants such as Legionella pneumophilia the bacterium that causes

Legionnaires disease

The first two requirements help to ensure energy efficiency and longevity of the cooling system while the third ensures safe operation

Biological control is relatively easy to accomplish and is essential to the safe operation of the tower

Cooling towers can collect and concentrate airborne dirt and debris over time To control this buildup the cooling tower should be located so as to minimize contaminant induction and a proper blowdown rate should be maintained Sidestream filters or separators have proven valuable in this regard by effectively removing dirt and debris from the tower water These devices are coupled with a basin-sweeping nozzle package which is available either as original equipment in the tower or as a field-installed aftermarket item Cleaner tower water makes water treatment regimens more effective while keeping the cooling loop cleaner saving energy reducing maintenance and improving reliability of the entire cooling system

Chapter 2

8 Cooling Tower Educational Stand BSc Project 2008

Chapter Two

Literature review

In this chapter we will introduce the specifications of the cooling tower educational stand that manufactured by different companies like Gunt Armfield PA Hilton Edibon

1 Gunt

Fig (2-1) Gunt cooling tower educational stand

Column

Dimensions 150x150x630 mm

Pacing density 110 m2m3

Orifice diameter 80 mm

Approx weight 5 Kg

Heaters

3 stages 05-1-15 KW Thermostat switches off at 50⁰c

Fan

Radial fan - Power consumption 025 KW -max Differential pressure 430 pa

-max Flow rate 13 m3min

Chapter 2

9 Cooling Tower Educational Stand BSc Project 2008

Pump

-Power consumption 07 KW

-max Head 34 m

-max Flow rate 34 Lmin

Instrumentation

-Temp Sensors at air inlet ampoutlet

-Temp Sensors at water inletamp outlet

-Water flow rate sensor

-Humidity sensors at air inletamp outlet

Dimensions

Height 1228 m

Length 111 m

Width 046 m

Weight approx 90 Kg

Service required

Electrical -230 v 5060 HZ 1 phase

or -230 v 60 HZ 3 phases

Computeramp Data acquisition

Data acquisition with lab view software h-w diagram and Windows X-P

Chapter 2

10 Cooling Tower Educational Stand BSc Project 2008

2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

Chapter 2

11 Cooling Tower Educational Stand BSc Project 2008

Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 3: Cooling Tower Educational Standcairouniversity

II

- Acknowledgement

Contents

- Project description - Nomenclatures

Page

Chapter One Introduction 1 Objective 2 Classification 3 Components 4 Water Treatment

Chapter Two Literature review

1 Gunt 2 Armfield 3 P A Hilton 4 Edibon

Chapter Three Cooling Tower Design Calculation 1 Column 2 Cooling tower performance 3 Tanks

i Water tank ii Air tank

iii Make up tank iv Drain tank

4 Piping System and pump 5 Blower and Butterfly Valve 6 Water Injection Nozzle 7 Stand

Chapter Four Measuring devices and auxiliaries 1 Temperature Measurements 2 Humidity Measurements 3 Flow Measurements 4 Displays 5 Data acquisition card 6 Calibration

Chapter Five Bill of Material and Cost Chapter Six Fabrication Procedure

1 Welding 2 Stand fabrication 3 Painting and coating 4 Pipes components and fittings 5 The column 6 Stand preparation 7 Control panel 8 Electronic and Electric devices installation 9 Electric Connections 10 Component assembly

1 1 2 6 7 8 8

10 12 14 16 20 21 21 23 23 24

25 29 30 31 32 32 34 34 37 38 46 48 51 51 55 56 57 59 61 62 62 63 64

III

Chapter Seven Tests and Results

1 Procedure 2 Results 3 Relations summery and conclusion

-Appendices -References

66 66 67 70 71

105

IV

First we would like to thank Allah the merciful and compassionate for making all this work possible and for granting us with the best professors family friends and colleagues that many people would wish and dream of having

Acknowledgment

We would like to thank our supervisors

bull Prof Dr Adel Khalil bull Prof Dr Hany Khater bull Dr Galal Mostafa

We are greatly indebted to them for their valuable supervision kind guidance and great help and effort to make this project possible Words cannot express our deep gratitude and sincere appreciation to them

Group Members

Eng Basel Amr Gouda

Eng Hebatallah Abdel Moniem Mohamed

Eng Mohamed El Sayed Rizk

Eng Al Hussain Mohamed Kamel

Eng Ismail Gamal El Din Ismail

Eng Ahmed Samir Abdallah

Special Thanks to

bull Eng Somya Mohamed Abdel Rehim - For Supplying us with materials and support bull Colleague Ahmed waheed - For his effort

V

- The students affiliating with the present project will be required to study design and fabricate a Water Cooling Tower Educational Stand

Project description

The Water Cooling Tower educational stand will eventually form a part of the undergraduate students ldquoHeat Transfer Laboratoryrdquo

In this step the following will be accomplished

Step 1 Water cooling tower fabrication

Study the different heat and mass transfer mechanisms

Cooling tower heat load estimation

Design calculations of the water cooling tower showing different geometrical parameters and dimensions

Material selection of the different components

Working drawing sheets for the different cooling tower components

Fabricating the different components and assembling the cooling tower

In this step the following will be accomplished

Step 2 Water cooling tower educational stand erection

Selecting and preparing the types of the measuring sensors devices and data acquisition system

Assembling the cooling tower together with the storage tank with heaters the make-up tank the air blower and air chamber the water circulating pump water injection nozzle the column valves and hoses and the different measuring devices on the stand

Finalizing all mechanical electrical and electronic works needed for the stand

In this step the following will be accomplished

Step 3 Performance test on the water cooling tower educational stand

Assuring the validity of all stand measuring devices

Studying the effect of different parameters on the cooling tower performance

Comparing the experimental results with those calculated

VI

-Nomenclatures

VII

Chapter 1

1 Cooling Tower Educational Stand BSc Project 2008

Chapter One Introduction

1 Objective Cooling towers (Fig 1) are heat removal devices used to transfer process waste heat to the atmosphere They may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or rely solely on air to cool the working fluid to near the dry-bulb air temperature The objective of cooling towers can be divided into two categories

HVAC An HVAC cooling tower is a subcategory rejecting heat from a chiller Water-cooled chillers

are normally more energy efficient than air-cooled chillers due to heat rejection to tower water at or near wet-bulb temperatures Air-cooled chillers must reject heat at the dry-bulb temperature and thus have a lower average reverse-Carnot cycle effectiveness Large office buildings hospitals and schools typically use one or more cooling towers as part of their air conditioning systems Generally industrial cooling towers are much larger than HVAC towers

Industrial Industrial cooling towers can be used to remove heat from various sources such as machinery

or heated process material The primary use of large industrial cooling towers is to remove the heat absorbed in the circulating cooling water systems used in power plants petroleum refineries petrochemical plants natural gas processing plants food processing plants semi-conductor plants and other industrial facilities The circulation rate of cooling water in a typical 700 MW coal-fired power plant with a cooling tower amounts to about 71600 cubic metres an hour (315000 US gallons per minute) and the circulating water requires a supply water make-up rate of perhaps 5 percent (ie 3600 cubic metres an hour)

Fig (11) cooling tower

Chapter 1

2 Cooling Tower Educational Stand BSc Project 2008

2 Classification Cooling towers can be classified into different categories as follows

Heat transfer mode bull Wet cooling towers or simply cooling towers operate on the principle of evaporation bull Dry coolers operate by heat transfer through a surface that separates the working fluid

from ambient air such as in a heat exchanger utilizing convective heat transfer bull Fluid coolers are hybrids that pass the working fluid through a tube bundle upon which

clean water is sprayed and a fan-induced draft applied The resulting heat transfer performance is much closer to that of a wet cooling tower with the advantage provided by a dry cooler of protecting the working fluid from environmental exposure

In a wet cooling tower the warm water can be cooled to a temperature lower than the ambient air dry-bulb temperature if the air is relatively dry As ambient air is drawn past a flow of water evaporation occurs Evaporation results in saturated air conditions lowering the temperature of the water to the wet bulb air temperature which is lower than the ambient dry bulb air temperature the difference determined by the humidity of the ambient air Air flow generation With respect to drawing air through the tower there are three types of cooling towers

bull Natural draft which utilizes buoyancy via a tall chimney Warm moist air naturally rises due to the density differential to the dry cooler outside air Warm moist air is less dense than drier air at the same pressure This moist air buoyancy produces a current of air through the tower (Fig 2)

Fig (12) Natural draft cooling tower

Chapter 1

3 Cooling Tower Educational Stand BSc Project 2008

bull Mechanical draft which uses power driven fan to force or draw air through the tower minus Induced draft A mechanical draft tower with a fan at the discharge which pulls

air through tower (Fig 3) The fan induces hot moist air out the discharge This produces low entering and high exiting air velocities reducing the possibility of recirculation in which discharged air flows back into the air intake This fanfill arrangement is also known as draw-through

Fig (13) Induced draft fan cooling tower minus Forced draft A mechanical draft tower with a blower type fan at the intake (Fig

4) The fan forces air into the tower creating high entering and low exiting air velocities The low exiting velocity is much more susceptible to recirculation With the fan on the air intake the fan is more susceptible to complications due to freezing conditions Another disadvantage is that a forced draft design typically requires more motor horsepower than an equivalent induced draft design The forced draft benefit is its ability to work with high static pressure They can be installed in more confined spaces and even in some indoor situations This fanfill geometry is also known as blow-through

Chapter 1

4 Cooling Tower Educational Stand BSc Project 2008

Fig (14) Forced draft fan cooling tower

Air-to-Water Flow

-Cross flow Is a design in which the air flow is directed perpendicular to the water flow

(Fig 5) Air flow enters one or more vertical faces of the cooling tower to meet the fill material Water flows (perpendicular to the air) through the fill by gravity The air continues through the fill and thus past the water flow into an open plenum area A distribution or hot water basin consisting of a deep pan with holes or nozzles in the bottom is utilized in a cross flow tower Gravity distributes the water through the nozzles uniformly across the fill material

-Counter Flow The air flow is directly opposite of the water flow (Fig 6) Air flow first enters an open area beneath the fill media and is then drawn up vertically The water is sprayed through pressurized nozzles and flows downward through the fill opposite to the air flow Common to both designs

bull The interaction of the air and water flow allow a partial equalization and evaporation of water

bull The air now saturated with water vapour is discharged from the cooling tower bull A collection or cold water basin is used to contain the water after its interaction with the

air flow Both cross flow and counter flow designs can be used in natural draft and mechanical draft cooling towers

Chapter 1

5 Cooling Tower Educational Stand BSc Project 2008

Fig (15) Cross Flow cooling tower

Fig (16) Counter Flow cooling tower

Chapter 1

6 Cooling Tower Educational Stand BSc Project 2008

3 Components

Inlet water distributors There are several types of water distributors among them

1 Gravity distributors applied mainly for cross flow cooling towers and consist of vertical water riser that feed water into an open concrete basin from which the water flows by gravity through orifices to the fill

2 Spray distributors used mainly with counter flow cooling towers and have cross pipe net with spray downward nozzles

3 Rotary distributors applied for cross flow cooling towers and consists of two slotted arms rotate about a central hub containing water supply pipe The slots in the tow arms are directed downward but make small angle with the vertical direction to one side The slots form a curtain angle and due to reaction force the arms rotate at a rotational speed of 25-to-30 revmin

Drift eliminators An assembly constructed of wood plastic cement board or other material that serves to

remove entrained moisture from the discharged air Circulating Pump

The circulating pump transports the cooling water between the cooling tower and the condenser The water is pumped from the cooling tower basin through to the condenser where it is used as cooling medium The water returns back for evaporative cooling in the cooling tower Fan A device for moving air in a mechanical draft tower The fan design may be either an axial flow propeller or centrifugal blower Also may be applied as induced draft or forced draft Noticing that the induced type requires less power for same result Fills

Is the heart of the cooling tower The fill must provide good water-air contact area high rates of heat and mass transfer and low air flow resistance The fill also must be strong and deterioration resistant The fill has mainly two forms

minus Splash fill breaks falling water into small drops This Type is made of bars stacked in desks and may be narrow-edged square bars rough bars and grids Different materials are used such as redwood high-impact polystyrene or polyethylene

minus Film fill is made of vertical sheets that have a rough adsorbent surface and good wetness of water that allows water to fall as a film over the vertical surface Film fill has different forms and materials redwood battens cellulose corrugated sheets asbestos cement and waveform plastic

Water Basin Is situated beneath the tower collects and strains the water before pumped back to the circulating system Large utility tower basins are generally made of concrete Water leaves the basin via sloped canal at the bottom and through screens that prevent dust and foreign materials from entering the pump

Chapter 1

7 Cooling Tower Educational Stand BSc Project 2008

4 Water Treatment

The large variety of alternative construction materials allows users to match unit construction to the water quality available for their systems while helping to protect the tower from temporary upsets

Water treatment programs must be designed for three requirements

1 Scale control 2 Protection of system components against corrosion and 3 Control of biological contaminants such as Legionella pneumophilia the bacterium that causes

Legionnaires disease

The first two requirements help to ensure energy efficiency and longevity of the cooling system while the third ensures safe operation

Biological control is relatively easy to accomplish and is essential to the safe operation of the tower

Cooling towers can collect and concentrate airborne dirt and debris over time To control this buildup the cooling tower should be located so as to minimize contaminant induction and a proper blowdown rate should be maintained Sidestream filters or separators have proven valuable in this regard by effectively removing dirt and debris from the tower water These devices are coupled with a basin-sweeping nozzle package which is available either as original equipment in the tower or as a field-installed aftermarket item Cleaner tower water makes water treatment regimens more effective while keeping the cooling loop cleaner saving energy reducing maintenance and improving reliability of the entire cooling system

Chapter 2

8 Cooling Tower Educational Stand BSc Project 2008

Chapter Two

Literature review

In this chapter we will introduce the specifications of the cooling tower educational stand that manufactured by different companies like Gunt Armfield PA Hilton Edibon

1 Gunt

Fig (2-1) Gunt cooling tower educational stand

Column

Dimensions 150x150x630 mm

Pacing density 110 m2m3

Orifice diameter 80 mm

Approx weight 5 Kg

Heaters

3 stages 05-1-15 KW Thermostat switches off at 50⁰c

Fan

Radial fan - Power consumption 025 KW -max Differential pressure 430 pa

-max Flow rate 13 m3min

Chapter 2

9 Cooling Tower Educational Stand BSc Project 2008

Pump

-Power consumption 07 KW

-max Head 34 m

-max Flow rate 34 Lmin

Instrumentation

-Temp Sensors at air inlet ampoutlet

-Temp Sensors at water inletamp outlet

-Water flow rate sensor

-Humidity sensors at air inletamp outlet

Dimensions

Height 1228 m

Length 111 m

Width 046 m

Weight approx 90 Kg

Service required

Electrical -230 v 5060 HZ 1 phase

or -230 v 60 HZ 3 phases

Computeramp Data acquisition

Data acquisition with lab view software h-w diagram and Windows X-P

Chapter 2

10 Cooling Tower Educational Stand BSc Project 2008

2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

Chapter 2

11 Cooling Tower Educational Stand BSc Project 2008

Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 4: Cooling Tower Educational Standcairouniversity

III

Chapter Seven Tests and Results

1 Procedure 2 Results 3 Relations summery and conclusion

-Appendices -References

66 66 67 70 71

105

IV

First we would like to thank Allah the merciful and compassionate for making all this work possible and for granting us with the best professors family friends and colleagues that many people would wish and dream of having

Acknowledgment

We would like to thank our supervisors

bull Prof Dr Adel Khalil bull Prof Dr Hany Khater bull Dr Galal Mostafa

We are greatly indebted to them for their valuable supervision kind guidance and great help and effort to make this project possible Words cannot express our deep gratitude and sincere appreciation to them

Group Members

Eng Basel Amr Gouda

Eng Hebatallah Abdel Moniem Mohamed

Eng Mohamed El Sayed Rizk

Eng Al Hussain Mohamed Kamel

Eng Ismail Gamal El Din Ismail

Eng Ahmed Samir Abdallah

Special Thanks to

bull Eng Somya Mohamed Abdel Rehim - For Supplying us with materials and support bull Colleague Ahmed waheed - For his effort

V

- The students affiliating with the present project will be required to study design and fabricate a Water Cooling Tower Educational Stand

Project description

The Water Cooling Tower educational stand will eventually form a part of the undergraduate students ldquoHeat Transfer Laboratoryrdquo

In this step the following will be accomplished

Step 1 Water cooling tower fabrication

Study the different heat and mass transfer mechanisms

Cooling tower heat load estimation

Design calculations of the water cooling tower showing different geometrical parameters and dimensions

Material selection of the different components

Working drawing sheets for the different cooling tower components

Fabricating the different components and assembling the cooling tower

In this step the following will be accomplished

Step 2 Water cooling tower educational stand erection

Selecting and preparing the types of the measuring sensors devices and data acquisition system

Assembling the cooling tower together with the storage tank with heaters the make-up tank the air blower and air chamber the water circulating pump water injection nozzle the column valves and hoses and the different measuring devices on the stand

Finalizing all mechanical electrical and electronic works needed for the stand

In this step the following will be accomplished

Step 3 Performance test on the water cooling tower educational stand

Assuring the validity of all stand measuring devices

Studying the effect of different parameters on the cooling tower performance

Comparing the experimental results with those calculated

VI

-Nomenclatures

VII

Chapter 1

1 Cooling Tower Educational Stand BSc Project 2008

Chapter One Introduction

1 Objective Cooling towers (Fig 1) are heat removal devices used to transfer process waste heat to the atmosphere They may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or rely solely on air to cool the working fluid to near the dry-bulb air temperature The objective of cooling towers can be divided into two categories

HVAC An HVAC cooling tower is a subcategory rejecting heat from a chiller Water-cooled chillers

are normally more energy efficient than air-cooled chillers due to heat rejection to tower water at or near wet-bulb temperatures Air-cooled chillers must reject heat at the dry-bulb temperature and thus have a lower average reverse-Carnot cycle effectiveness Large office buildings hospitals and schools typically use one or more cooling towers as part of their air conditioning systems Generally industrial cooling towers are much larger than HVAC towers

Industrial Industrial cooling towers can be used to remove heat from various sources such as machinery

or heated process material The primary use of large industrial cooling towers is to remove the heat absorbed in the circulating cooling water systems used in power plants petroleum refineries petrochemical plants natural gas processing plants food processing plants semi-conductor plants and other industrial facilities The circulation rate of cooling water in a typical 700 MW coal-fired power plant with a cooling tower amounts to about 71600 cubic metres an hour (315000 US gallons per minute) and the circulating water requires a supply water make-up rate of perhaps 5 percent (ie 3600 cubic metres an hour)

Fig (11) cooling tower

Chapter 1

2 Cooling Tower Educational Stand BSc Project 2008

2 Classification Cooling towers can be classified into different categories as follows

Heat transfer mode bull Wet cooling towers or simply cooling towers operate on the principle of evaporation bull Dry coolers operate by heat transfer through a surface that separates the working fluid

from ambient air such as in a heat exchanger utilizing convective heat transfer bull Fluid coolers are hybrids that pass the working fluid through a tube bundle upon which

clean water is sprayed and a fan-induced draft applied The resulting heat transfer performance is much closer to that of a wet cooling tower with the advantage provided by a dry cooler of protecting the working fluid from environmental exposure

In a wet cooling tower the warm water can be cooled to a temperature lower than the ambient air dry-bulb temperature if the air is relatively dry As ambient air is drawn past a flow of water evaporation occurs Evaporation results in saturated air conditions lowering the temperature of the water to the wet bulb air temperature which is lower than the ambient dry bulb air temperature the difference determined by the humidity of the ambient air Air flow generation With respect to drawing air through the tower there are three types of cooling towers

bull Natural draft which utilizes buoyancy via a tall chimney Warm moist air naturally rises due to the density differential to the dry cooler outside air Warm moist air is less dense than drier air at the same pressure This moist air buoyancy produces a current of air through the tower (Fig 2)

Fig (12) Natural draft cooling tower

Chapter 1

3 Cooling Tower Educational Stand BSc Project 2008

bull Mechanical draft which uses power driven fan to force or draw air through the tower minus Induced draft A mechanical draft tower with a fan at the discharge which pulls

air through tower (Fig 3) The fan induces hot moist air out the discharge This produces low entering and high exiting air velocities reducing the possibility of recirculation in which discharged air flows back into the air intake This fanfill arrangement is also known as draw-through

Fig (13) Induced draft fan cooling tower minus Forced draft A mechanical draft tower with a blower type fan at the intake (Fig

4) The fan forces air into the tower creating high entering and low exiting air velocities The low exiting velocity is much more susceptible to recirculation With the fan on the air intake the fan is more susceptible to complications due to freezing conditions Another disadvantage is that a forced draft design typically requires more motor horsepower than an equivalent induced draft design The forced draft benefit is its ability to work with high static pressure They can be installed in more confined spaces and even in some indoor situations This fanfill geometry is also known as blow-through

Chapter 1

4 Cooling Tower Educational Stand BSc Project 2008

Fig (14) Forced draft fan cooling tower

Air-to-Water Flow

-Cross flow Is a design in which the air flow is directed perpendicular to the water flow

(Fig 5) Air flow enters one or more vertical faces of the cooling tower to meet the fill material Water flows (perpendicular to the air) through the fill by gravity The air continues through the fill and thus past the water flow into an open plenum area A distribution or hot water basin consisting of a deep pan with holes or nozzles in the bottom is utilized in a cross flow tower Gravity distributes the water through the nozzles uniformly across the fill material

-Counter Flow The air flow is directly opposite of the water flow (Fig 6) Air flow first enters an open area beneath the fill media and is then drawn up vertically The water is sprayed through pressurized nozzles and flows downward through the fill opposite to the air flow Common to both designs

bull The interaction of the air and water flow allow a partial equalization and evaporation of water

bull The air now saturated with water vapour is discharged from the cooling tower bull A collection or cold water basin is used to contain the water after its interaction with the

air flow Both cross flow and counter flow designs can be used in natural draft and mechanical draft cooling towers

Chapter 1

5 Cooling Tower Educational Stand BSc Project 2008

Fig (15) Cross Flow cooling tower

Fig (16) Counter Flow cooling tower

Chapter 1

6 Cooling Tower Educational Stand BSc Project 2008

3 Components

Inlet water distributors There are several types of water distributors among them

1 Gravity distributors applied mainly for cross flow cooling towers and consist of vertical water riser that feed water into an open concrete basin from which the water flows by gravity through orifices to the fill

2 Spray distributors used mainly with counter flow cooling towers and have cross pipe net with spray downward nozzles

3 Rotary distributors applied for cross flow cooling towers and consists of two slotted arms rotate about a central hub containing water supply pipe The slots in the tow arms are directed downward but make small angle with the vertical direction to one side The slots form a curtain angle and due to reaction force the arms rotate at a rotational speed of 25-to-30 revmin

Drift eliminators An assembly constructed of wood plastic cement board or other material that serves to

remove entrained moisture from the discharged air Circulating Pump

The circulating pump transports the cooling water between the cooling tower and the condenser The water is pumped from the cooling tower basin through to the condenser where it is used as cooling medium The water returns back for evaporative cooling in the cooling tower Fan A device for moving air in a mechanical draft tower The fan design may be either an axial flow propeller or centrifugal blower Also may be applied as induced draft or forced draft Noticing that the induced type requires less power for same result Fills

Is the heart of the cooling tower The fill must provide good water-air contact area high rates of heat and mass transfer and low air flow resistance The fill also must be strong and deterioration resistant The fill has mainly two forms

minus Splash fill breaks falling water into small drops This Type is made of bars stacked in desks and may be narrow-edged square bars rough bars and grids Different materials are used such as redwood high-impact polystyrene or polyethylene

minus Film fill is made of vertical sheets that have a rough adsorbent surface and good wetness of water that allows water to fall as a film over the vertical surface Film fill has different forms and materials redwood battens cellulose corrugated sheets asbestos cement and waveform plastic

Water Basin Is situated beneath the tower collects and strains the water before pumped back to the circulating system Large utility tower basins are generally made of concrete Water leaves the basin via sloped canal at the bottom and through screens that prevent dust and foreign materials from entering the pump

Chapter 1

7 Cooling Tower Educational Stand BSc Project 2008

4 Water Treatment

The large variety of alternative construction materials allows users to match unit construction to the water quality available for their systems while helping to protect the tower from temporary upsets

Water treatment programs must be designed for three requirements

1 Scale control 2 Protection of system components against corrosion and 3 Control of biological contaminants such as Legionella pneumophilia the bacterium that causes

Legionnaires disease

The first two requirements help to ensure energy efficiency and longevity of the cooling system while the third ensures safe operation

Biological control is relatively easy to accomplish and is essential to the safe operation of the tower

Cooling towers can collect and concentrate airborne dirt and debris over time To control this buildup the cooling tower should be located so as to minimize contaminant induction and a proper blowdown rate should be maintained Sidestream filters or separators have proven valuable in this regard by effectively removing dirt and debris from the tower water These devices are coupled with a basin-sweeping nozzle package which is available either as original equipment in the tower or as a field-installed aftermarket item Cleaner tower water makes water treatment regimens more effective while keeping the cooling loop cleaner saving energy reducing maintenance and improving reliability of the entire cooling system

Chapter 2

8 Cooling Tower Educational Stand BSc Project 2008

Chapter Two

Literature review

In this chapter we will introduce the specifications of the cooling tower educational stand that manufactured by different companies like Gunt Armfield PA Hilton Edibon

1 Gunt

Fig (2-1) Gunt cooling tower educational stand

Column

Dimensions 150x150x630 mm

Pacing density 110 m2m3

Orifice diameter 80 mm

Approx weight 5 Kg

Heaters

3 stages 05-1-15 KW Thermostat switches off at 50⁰c

Fan

Radial fan - Power consumption 025 KW -max Differential pressure 430 pa

-max Flow rate 13 m3min

Chapter 2

9 Cooling Tower Educational Stand BSc Project 2008

Pump

-Power consumption 07 KW

-max Head 34 m

-max Flow rate 34 Lmin

Instrumentation

-Temp Sensors at air inlet ampoutlet

-Temp Sensors at water inletamp outlet

-Water flow rate sensor

-Humidity sensors at air inletamp outlet

Dimensions

Height 1228 m

Length 111 m

Width 046 m

Weight approx 90 Kg

Service required

Electrical -230 v 5060 HZ 1 phase

or -230 v 60 HZ 3 phases

Computeramp Data acquisition

Data acquisition with lab view software h-w diagram and Windows X-P

Chapter 2

10 Cooling Tower Educational Stand BSc Project 2008

2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

Chapter 2

11 Cooling Tower Educational Stand BSc Project 2008

Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 5: Cooling Tower Educational Standcairouniversity

IV

First we would like to thank Allah the merciful and compassionate for making all this work possible and for granting us with the best professors family friends and colleagues that many people would wish and dream of having

Acknowledgment

We would like to thank our supervisors

bull Prof Dr Adel Khalil bull Prof Dr Hany Khater bull Dr Galal Mostafa

We are greatly indebted to them for their valuable supervision kind guidance and great help and effort to make this project possible Words cannot express our deep gratitude and sincere appreciation to them

Group Members

Eng Basel Amr Gouda

Eng Hebatallah Abdel Moniem Mohamed

Eng Mohamed El Sayed Rizk

Eng Al Hussain Mohamed Kamel

Eng Ismail Gamal El Din Ismail

Eng Ahmed Samir Abdallah

Special Thanks to

bull Eng Somya Mohamed Abdel Rehim - For Supplying us with materials and support bull Colleague Ahmed waheed - For his effort

V

- The students affiliating with the present project will be required to study design and fabricate a Water Cooling Tower Educational Stand

Project description

The Water Cooling Tower educational stand will eventually form a part of the undergraduate students ldquoHeat Transfer Laboratoryrdquo

In this step the following will be accomplished

Step 1 Water cooling tower fabrication

Study the different heat and mass transfer mechanisms

Cooling tower heat load estimation

Design calculations of the water cooling tower showing different geometrical parameters and dimensions

Material selection of the different components

Working drawing sheets for the different cooling tower components

Fabricating the different components and assembling the cooling tower

In this step the following will be accomplished

Step 2 Water cooling tower educational stand erection

Selecting and preparing the types of the measuring sensors devices and data acquisition system

Assembling the cooling tower together with the storage tank with heaters the make-up tank the air blower and air chamber the water circulating pump water injection nozzle the column valves and hoses and the different measuring devices on the stand

Finalizing all mechanical electrical and electronic works needed for the stand

In this step the following will be accomplished

Step 3 Performance test on the water cooling tower educational stand

Assuring the validity of all stand measuring devices

Studying the effect of different parameters on the cooling tower performance

Comparing the experimental results with those calculated

VI

-Nomenclatures

VII

Chapter 1

1 Cooling Tower Educational Stand BSc Project 2008

Chapter One Introduction

1 Objective Cooling towers (Fig 1) are heat removal devices used to transfer process waste heat to the atmosphere They may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or rely solely on air to cool the working fluid to near the dry-bulb air temperature The objective of cooling towers can be divided into two categories

HVAC An HVAC cooling tower is a subcategory rejecting heat from a chiller Water-cooled chillers

are normally more energy efficient than air-cooled chillers due to heat rejection to tower water at or near wet-bulb temperatures Air-cooled chillers must reject heat at the dry-bulb temperature and thus have a lower average reverse-Carnot cycle effectiveness Large office buildings hospitals and schools typically use one or more cooling towers as part of their air conditioning systems Generally industrial cooling towers are much larger than HVAC towers

Industrial Industrial cooling towers can be used to remove heat from various sources such as machinery

or heated process material The primary use of large industrial cooling towers is to remove the heat absorbed in the circulating cooling water systems used in power plants petroleum refineries petrochemical plants natural gas processing plants food processing plants semi-conductor plants and other industrial facilities The circulation rate of cooling water in a typical 700 MW coal-fired power plant with a cooling tower amounts to about 71600 cubic metres an hour (315000 US gallons per minute) and the circulating water requires a supply water make-up rate of perhaps 5 percent (ie 3600 cubic metres an hour)

Fig (11) cooling tower

Chapter 1

2 Cooling Tower Educational Stand BSc Project 2008

2 Classification Cooling towers can be classified into different categories as follows

Heat transfer mode bull Wet cooling towers or simply cooling towers operate on the principle of evaporation bull Dry coolers operate by heat transfer through a surface that separates the working fluid

from ambient air such as in a heat exchanger utilizing convective heat transfer bull Fluid coolers are hybrids that pass the working fluid through a tube bundle upon which

clean water is sprayed and a fan-induced draft applied The resulting heat transfer performance is much closer to that of a wet cooling tower with the advantage provided by a dry cooler of protecting the working fluid from environmental exposure

In a wet cooling tower the warm water can be cooled to a temperature lower than the ambient air dry-bulb temperature if the air is relatively dry As ambient air is drawn past a flow of water evaporation occurs Evaporation results in saturated air conditions lowering the temperature of the water to the wet bulb air temperature which is lower than the ambient dry bulb air temperature the difference determined by the humidity of the ambient air Air flow generation With respect to drawing air through the tower there are three types of cooling towers

bull Natural draft which utilizes buoyancy via a tall chimney Warm moist air naturally rises due to the density differential to the dry cooler outside air Warm moist air is less dense than drier air at the same pressure This moist air buoyancy produces a current of air through the tower (Fig 2)

Fig (12) Natural draft cooling tower

Chapter 1

3 Cooling Tower Educational Stand BSc Project 2008

bull Mechanical draft which uses power driven fan to force or draw air through the tower minus Induced draft A mechanical draft tower with a fan at the discharge which pulls

air through tower (Fig 3) The fan induces hot moist air out the discharge This produces low entering and high exiting air velocities reducing the possibility of recirculation in which discharged air flows back into the air intake This fanfill arrangement is also known as draw-through

Fig (13) Induced draft fan cooling tower minus Forced draft A mechanical draft tower with a blower type fan at the intake (Fig

4) The fan forces air into the tower creating high entering and low exiting air velocities The low exiting velocity is much more susceptible to recirculation With the fan on the air intake the fan is more susceptible to complications due to freezing conditions Another disadvantage is that a forced draft design typically requires more motor horsepower than an equivalent induced draft design The forced draft benefit is its ability to work with high static pressure They can be installed in more confined spaces and even in some indoor situations This fanfill geometry is also known as blow-through

Chapter 1

4 Cooling Tower Educational Stand BSc Project 2008

Fig (14) Forced draft fan cooling tower

Air-to-Water Flow

-Cross flow Is a design in which the air flow is directed perpendicular to the water flow

(Fig 5) Air flow enters one or more vertical faces of the cooling tower to meet the fill material Water flows (perpendicular to the air) through the fill by gravity The air continues through the fill and thus past the water flow into an open plenum area A distribution or hot water basin consisting of a deep pan with holes or nozzles in the bottom is utilized in a cross flow tower Gravity distributes the water through the nozzles uniformly across the fill material

-Counter Flow The air flow is directly opposite of the water flow (Fig 6) Air flow first enters an open area beneath the fill media and is then drawn up vertically The water is sprayed through pressurized nozzles and flows downward through the fill opposite to the air flow Common to both designs

bull The interaction of the air and water flow allow a partial equalization and evaporation of water

bull The air now saturated with water vapour is discharged from the cooling tower bull A collection or cold water basin is used to contain the water after its interaction with the

air flow Both cross flow and counter flow designs can be used in natural draft and mechanical draft cooling towers

Chapter 1

5 Cooling Tower Educational Stand BSc Project 2008

Fig (15) Cross Flow cooling tower

Fig (16) Counter Flow cooling tower

Chapter 1

6 Cooling Tower Educational Stand BSc Project 2008

3 Components

Inlet water distributors There are several types of water distributors among them

1 Gravity distributors applied mainly for cross flow cooling towers and consist of vertical water riser that feed water into an open concrete basin from which the water flows by gravity through orifices to the fill

2 Spray distributors used mainly with counter flow cooling towers and have cross pipe net with spray downward nozzles

3 Rotary distributors applied for cross flow cooling towers and consists of two slotted arms rotate about a central hub containing water supply pipe The slots in the tow arms are directed downward but make small angle with the vertical direction to one side The slots form a curtain angle and due to reaction force the arms rotate at a rotational speed of 25-to-30 revmin

Drift eliminators An assembly constructed of wood plastic cement board or other material that serves to

remove entrained moisture from the discharged air Circulating Pump

The circulating pump transports the cooling water between the cooling tower and the condenser The water is pumped from the cooling tower basin through to the condenser where it is used as cooling medium The water returns back for evaporative cooling in the cooling tower Fan A device for moving air in a mechanical draft tower The fan design may be either an axial flow propeller or centrifugal blower Also may be applied as induced draft or forced draft Noticing that the induced type requires less power for same result Fills

Is the heart of the cooling tower The fill must provide good water-air contact area high rates of heat and mass transfer and low air flow resistance The fill also must be strong and deterioration resistant The fill has mainly two forms

minus Splash fill breaks falling water into small drops This Type is made of bars stacked in desks and may be narrow-edged square bars rough bars and grids Different materials are used such as redwood high-impact polystyrene or polyethylene

minus Film fill is made of vertical sheets that have a rough adsorbent surface and good wetness of water that allows water to fall as a film over the vertical surface Film fill has different forms and materials redwood battens cellulose corrugated sheets asbestos cement and waveform plastic

Water Basin Is situated beneath the tower collects and strains the water before pumped back to the circulating system Large utility tower basins are generally made of concrete Water leaves the basin via sloped canal at the bottom and through screens that prevent dust and foreign materials from entering the pump

Chapter 1

7 Cooling Tower Educational Stand BSc Project 2008

4 Water Treatment

The large variety of alternative construction materials allows users to match unit construction to the water quality available for their systems while helping to protect the tower from temporary upsets

Water treatment programs must be designed for three requirements

1 Scale control 2 Protection of system components against corrosion and 3 Control of biological contaminants such as Legionella pneumophilia the bacterium that causes

Legionnaires disease

The first two requirements help to ensure energy efficiency and longevity of the cooling system while the third ensures safe operation

Biological control is relatively easy to accomplish and is essential to the safe operation of the tower

Cooling towers can collect and concentrate airborne dirt and debris over time To control this buildup the cooling tower should be located so as to minimize contaminant induction and a proper blowdown rate should be maintained Sidestream filters or separators have proven valuable in this regard by effectively removing dirt and debris from the tower water These devices are coupled with a basin-sweeping nozzle package which is available either as original equipment in the tower or as a field-installed aftermarket item Cleaner tower water makes water treatment regimens more effective while keeping the cooling loop cleaner saving energy reducing maintenance and improving reliability of the entire cooling system

Chapter 2

8 Cooling Tower Educational Stand BSc Project 2008

Chapter Two

Literature review

In this chapter we will introduce the specifications of the cooling tower educational stand that manufactured by different companies like Gunt Armfield PA Hilton Edibon

1 Gunt

Fig (2-1) Gunt cooling tower educational stand

Column

Dimensions 150x150x630 mm

Pacing density 110 m2m3

Orifice diameter 80 mm

Approx weight 5 Kg

Heaters

3 stages 05-1-15 KW Thermostat switches off at 50⁰c

Fan

Radial fan - Power consumption 025 KW -max Differential pressure 430 pa

-max Flow rate 13 m3min

Chapter 2

9 Cooling Tower Educational Stand BSc Project 2008

Pump

-Power consumption 07 KW

-max Head 34 m

-max Flow rate 34 Lmin

Instrumentation

-Temp Sensors at air inlet ampoutlet

-Temp Sensors at water inletamp outlet

-Water flow rate sensor

-Humidity sensors at air inletamp outlet

Dimensions

Height 1228 m

Length 111 m

Width 046 m

Weight approx 90 Kg

Service required

Electrical -230 v 5060 HZ 1 phase

or -230 v 60 HZ 3 phases

Computeramp Data acquisition

Data acquisition with lab view software h-w diagram and Windows X-P

Chapter 2

10 Cooling Tower Educational Stand BSc Project 2008

2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

Chapter 2

11 Cooling Tower Educational Stand BSc Project 2008

Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 6: Cooling Tower Educational Standcairouniversity

V

- The students affiliating with the present project will be required to study design and fabricate a Water Cooling Tower Educational Stand

Project description

The Water Cooling Tower educational stand will eventually form a part of the undergraduate students ldquoHeat Transfer Laboratoryrdquo

In this step the following will be accomplished

Step 1 Water cooling tower fabrication

Study the different heat and mass transfer mechanisms

Cooling tower heat load estimation

Design calculations of the water cooling tower showing different geometrical parameters and dimensions

Material selection of the different components

Working drawing sheets for the different cooling tower components

Fabricating the different components and assembling the cooling tower

In this step the following will be accomplished

Step 2 Water cooling tower educational stand erection

Selecting and preparing the types of the measuring sensors devices and data acquisition system

Assembling the cooling tower together with the storage tank with heaters the make-up tank the air blower and air chamber the water circulating pump water injection nozzle the column valves and hoses and the different measuring devices on the stand

Finalizing all mechanical electrical and electronic works needed for the stand

In this step the following will be accomplished

Step 3 Performance test on the water cooling tower educational stand

Assuring the validity of all stand measuring devices

Studying the effect of different parameters on the cooling tower performance

Comparing the experimental results with those calculated

VI

-Nomenclatures

VII

Chapter 1

1 Cooling Tower Educational Stand BSc Project 2008

Chapter One Introduction

1 Objective Cooling towers (Fig 1) are heat removal devices used to transfer process waste heat to the atmosphere They may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or rely solely on air to cool the working fluid to near the dry-bulb air temperature The objective of cooling towers can be divided into two categories

HVAC An HVAC cooling tower is a subcategory rejecting heat from a chiller Water-cooled chillers

are normally more energy efficient than air-cooled chillers due to heat rejection to tower water at or near wet-bulb temperatures Air-cooled chillers must reject heat at the dry-bulb temperature and thus have a lower average reverse-Carnot cycle effectiveness Large office buildings hospitals and schools typically use one or more cooling towers as part of their air conditioning systems Generally industrial cooling towers are much larger than HVAC towers

Industrial Industrial cooling towers can be used to remove heat from various sources such as machinery

or heated process material The primary use of large industrial cooling towers is to remove the heat absorbed in the circulating cooling water systems used in power plants petroleum refineries petrochemical plants natural gas processing plants food processing plants semi-conductor plants and other industrial facilities The circulation rate of cooling water in a typical 700 MW coal-fired power plant with a cooling tower amounts to about 71600 cubic metres an hour (315000 US gallons per minute) and the circulating water requires a supply water make-up rate of perhaps 5 percent (ie 3600 cubic metres an hour)

Fig (11) cooling tower

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2 Classification Cooling towers can be classified into different categories as follows

Heat transfer mode bull Wet cooling towers or simply cooling towers operate on the principle of evaporation bull Dry coolers operate by heat transfer through a surface that separates the working fluid

from ambient air such as in a heat exchanger utilizing convective heat transfer bull Fluid coolers are hybrids that pass the working fluid through a tube bundle upon which

clean water is sprayed and a fan-induced draft applied The resulting heat transfer performance is much closer to that of a wet cooling tower with the advantage provided by a dry cooler of protecting the working fluid from environmental exposure

In a wet cooling tower the warm water can be cooled to a temperature lower than the ambient air dry-bulb temperature if the air is relatively dry As ambient air is drawn past a flow of water evaporation occurs Evaporation results in saturated air conditions lowering the temperature of the water to the wet bulb air temperature which is lower than the ambient dry bulb air temperature the difference determined by the humidity of the ambient air Air flow generation With respect to drawing air through the tower there are three types of cooling towers

bull Natural draft which utilizes buoyancy via a tall chimney Warm moist air naturally rises due to the density differential to the dry cooler outside air Warm moist air is less dense than drier air at the same pressure This moist air buoyancy produces a current of air through the tower (Fig 2)

Fig (12) Natural draft cooling tower

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bull Mechanical draft which uses power driven fan to force or draw air through the tower minus Induced draft A mechanical draft tower with a fan at the discharge which pulls

air through tower (Fig 3) The fan induces hot moist air out the discharge This produces low entering and high exiting air velocities reducing the possibility of recirculation in which discharged air flows back into the air intake This fanfill arrangement is also known as draw-through

Fig (13) Induced draft fan cooling tower minus Forced draft A mechanical draft tower with a blower type fan at the intake (Fig

4) The fan forces air into the tower creating high entering and low exiting air velocities The low exiting velocity is much more susceptible to recirculation With the fan on the air intake the fan is more susceptible to complications due to freezing conditions Another disadvantage is that a forced draft design typically requires more motor horsepower than an equivalent induced draft design The forced draft benefit is its ability to work with high static pressure They can be installed in more confined spaces and even in some indoor situations This fanfill geometry is also known as blow-through

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Fig (14) Forced draft fan cooling tower

Air-to-Water Flow

-Cross flow Is a design in which the air flow is directed perpendicular to the water flow

(Fig 5) Air flow enters one or more vertical faces of the cooling tower to meet the fill material Water flows (perpendicular to the air) through the fill by gravity The air continues through the fill and thus past the water flow into an open plenum area A distribution or hot water basin consisting of a deep pan with holes or nozzles in the bottom is utilized in a cross flow tower Gravity distributes the water through the nozzles uniformly across the fill material

-Counter Flow The air flow is directly opposite of the water flow (Fig 6) Air flow first enters an open area beneath the fill media and is then drawn up vertically The water is sprayed through pressurized nozzles and flows downward through the fill opposite to the air flow Common to both designs

bull The interaction of the air and water flow allow a partial equalization and evaporation of water

bull The air now saturated with water vapour is discharged from the cooling tower bull A collection or cold water basin is used to contain the water after its interaction with the

air flow Both cross flow and counter flow designs can be used in natural draft and mechanical draft cooling towers

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Fig (15) Cross Flow cooling tower

Fig (16) Counter Flow cooling tower

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3 Components

Inlet water distributors There are several types of water distributors among them

1 Gravity distributors applied mainly for cross flow cooling towers and consist of vertical water riser that feed water into an open concrete basin from which the water flows by gravity through orifices to the fill

2 Spray distributors used mainly with counter flow cooling towers and have cross pipe net with spray downward nozzles

3 Rotary distributors applied for cross flow cooling towers and consists of two slotted arms rotate about a central hub containing water supply pipe The slots in the tow arms are directed downward but make small angle with the vertical direction to one side The slots form a curtain angle and due to reaction force the arms rotate at a rotational speed of 25-to-30 revmin

Drift eliminators An assembly constructed of wood plastic cement board or other material that serves to

remove entrained moisture from the discharged air Circulating Pump

The circulating pump transports the cooling water between the cooling tower and the condenser The water is pumped from the cooling tower basin through to the condenser where it is used as cooling medium The water returns back for evaporative cooling in the cooling tower Fan A device for moving air in a mechanical draft tower The fan design may be either an axial flow propeller or centrifugal blower Also may be applied as induced draft or forced draft Noticing that the induced type requires less power for same result Fills

Is the heart of the cooling tower The fill must provide good water-air contact area high rates of heat and mass transfer and low air flow resistance The fill also must be strong and deterioration resistant The fill has mainly two forms

minus Splash fill breaks falling water into small drops This Type is made of bars stacked in desks and may be narrow-edged square bars rough bars and grids Different materials are used such as redwood high-impact polystyrene or polyethylene

minus Film fill is made of vertical sheets that have a rough adsorbent surface and good wetness of water that allows water to fall as a film over the vertical surface Film fill has different forms and materials redwood battens cellulose corrugated sheets asbestos cement and waveform plastic

Water Basin Is situated beneath the tower collects and strains the water before pumped back to the circulating system Large utility tower basins are generally made of concrete Water leaves the basin via sloped canal at the bottom and through screens that prevent dust and foreign materials from entering the pump

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4 Water Treatment

The large variety of alternative construction materials allows users to match unit construction to the water quality available for their systems while helping to protect the tower from temporary upsets

Water treatment programs must be designed for three requirements

1 Scale control 2 Protection of system components against corrosion and 3 Control of biological contaminants such as Legionella pneumophilia the bacterium that causes

Legionnaires disease

The first two requirements help to ensure energy efficiency and longevity of the cooling system while the third ensures safe operation

Biological control is relatively easy to accomplish and is essential to the safe operation of the tower

Cooling towers can collect and concentrate airborne dirt and debris over time To control this buildup the cooling tower should be located so as to minimize contaminant induction and a proper blowdown rate should be maintained Sidestream filters or separators have proven valuable in this regard by effectively removing dirt and debris from the tower water These devices are coupled with a basin-sweeping nozzle package which is available either as original equipment in the tower or as a field-installed aftermarket item Cleaner tower water makes water treatment regimens more effective while keeping the cooling loop cleaner saving energy reducing maintenance and improving reliability of the entire cooling system

Chapter 2

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Chapter Two

Literature review

In this chapter we will introduce the specifications of the cooling tower educational stand that manufactured by different companies like Gunt Armfield PA Hilton Edibon

1 Gunt

Fig (2-1) Gunt cooling tower educational stand

Column

Dimensions 150x150x630 mm

Pacing density 110 m2m3

Orifice diameter 80 mm

Approx weight 5 Kg

Heaters

3 stages 05-1-15 KW Thermostat switches off at 50⁰c

Fan

Radial fan - Power consumption 025 KW -max Differential pressure 430 pa

-max Flow rate 13 m3min

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Pump

-Power consumption 07 KW

-max Head 34 m

-max Flow rate 34 Lmin

Instrumentation

-Temp Sensors at air inlet ampoutlet

-Temp Sensors at water inletamp outlet

-Water flow rate sensor

-Humidity sensors at air inletamp outlet

Dimensions

Height 1228 m

Length 111 m

Width 046 m

Weight approx 90 Kg

Service required

Electrical -230 v 5060 HZ 1 phase

or -230 v 60 HZ 3 phases

Computeramp Data acquisition

Data acquisition with lab view software h-w diagram and Windows X-P

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2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

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Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

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3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

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Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

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4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

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Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

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Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

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mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

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Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

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-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

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2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

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3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

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Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

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ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

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Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

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4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

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Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

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Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

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Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

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Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

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Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

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Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

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90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

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Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 7: Cooling Tower Educational Standcairouniversity

VI

-Nomenclatures

VII

Chapter 1

1 Cooling Tower Educational Stand BSc Project 2008

Chapter One Introduction

1 Objective Cooling towers (Fig 1) are heat removal devices used to transfer process waste heat to the atmosphere They may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or rely solely on air to cool the working fluid to near the dry-bulb air temperature The objective of cooling towers can be divided into two categories

HVAC An HVAC cooling tower is a subcategory rejecting heat from a chiller Water-cooled chillers

are normally more energy efficient than air-cooled chillers due to heat rejection to tower water at or near wet-bulb temperatures Air-cooled chillers must reject heat at the dry-bulb temperature and thus have a lower average reverse-Carnot cycle effectiveness Large office buildings hospitals and schools typically use one or more cooling towers as part of their air conditioning systems Generally industrial cooling towers are much larger than HVAC towers

Industrial Industrial cooling towers can be used to remove heat from various sources such as machinery

or heated process material The primary use of large industrial cooling towers is to remove the heat absorbed in the circulating cooling water systems used in power plants petroleum refineries petrochemical plants natural gas processing plants food processing plants semi-conductor plants and other industrial facilities The circulation rate of cooling water in a typical 700 MW coal-fired power plant with a cooling tower amounts to about 71600 cubic metres an hour (315000 US gallons per minute) and the circulating water requires a supply water make-up rate of perhaps 5 percent (ie 3600 cubic metres an hour)

Fig (11) cooling tower

Chapter 1

2 Cooling Tower Educational Stand BSc Project 2008

2 Classification Cooling towers can be classified into different categories as follows

Heat transfer mode bull Wet cooling towers or simply cooling towers operate on the principle of evaporation bull Dry coolers operate by heat transfer through a surface that separates the working fluid

from ambient air such as in a heat exchanger utilizing convective heat transfer bull Fluid coolers are hybrids that pass the working fluid through a tube bundle upon which

clean water is sprayed and a fan-induced draft applied The resulting heat transfer performance is much closer to that of a wet cooling tower with the advantage provided by a dry cooler of protecting the working fluid from environmental exposure

In a wet cooling tower the warm water can be cooled to a temperature lower than the ambient air dry-bulb temperature if the air is relatively dry As ambient air is drawn past a flow of water evaporation occurs Evaporation results in saturated air conditions lowering the temperature of the water to the wet bulb air temperature which is lower than the ambient dry bulb air temperature the difference determined by the humidity of the ambient air Air flow generation With respect to drawing air through the tower there are three types of cooling towers

bull Natural draft which utilizes buoyancy via a tall chimney Warm moist air naturally rises due to the density differential to the dry cooler outside air Warm moist air is less dense than drier air at the same pressure This moist air buoyancy produces a current of air through the tower (Fig 2)

Fig (12) Natural draft cooling tower

Chapter 1

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bull Mechanical draft which uses power driven fan to force or draw air through the tower minus Induced draft A mechanical draft tower with a fan at the discharge which pulls

air through tower (Fig 3) The fan induces hot moist air out the discharge This produces low entering and high exiting air velocities reducing the possibility of recirculation in which discharged air flows back into the air intake This fanfill arrangement is also known as draw-through

Fig (13) Induced draft fan cooling tower minus Forced draft A mechanical draft tower with a blower type fan at the intake (Fig

4) The fan forces air into the tower creating high entering and low exiting air velocities The low exiting velocity is much more susceptible to recirculation With the fan on the air intake the fan is more susceptible to complications due to freezing conditions Another disadvantage is that a forced draft design typically requires more motor horsepower than an equivalent induced draft design The forced draft benefit is its ability to work with high static pressure They can be installed in more confined spaces and even in some indoor situations This fanfill geometry is also known as blow-through

Chapter 1

4 Cooling Tower Educational Stand BSc Project 2008

Fig (14) Forced draft fan cooling tower

Air-to-Water Flow

-Cross flow Is a design in which the air flow is directed perpendicular to the water flow

(Fig 5) Air flow enters one or more vertical faces of the cooling tower to meet the fill material Water flows (perpendicular to the air) through the fill by gravity The air continues through the fill and thus past the water flow into an open plenum area A distribution or hot water basin consisting of a deep pan with holes or nozzles in the bottom is utilized in a cross flow tower Gravity distributes the water through the nozzles uniformly across the fill material

-Counter Flow The air flow is directly opposite of the water flow (Fig 6) Air flow first enters an open area beneath the fill media and is then drawn up vertically The water is sprayed through pressurized nozzles and flows downward through the fill opposite to the air flow Common to both designs

bull The interaction of the air and water flow allow a partial equalization and evaporation of water

bull The air now saturated with water vapour is discharged from the cooling tower bull A collection or cold water basin is used to contain the water after its interaction with the

air flow Both cross flow and counter flow designs can be used in natural draft and mechanical draft cooling towers

Chapter 1

5 Cooling Tower Educational Stand BSc Project 2008

Fig (15) Cross Flow cooling tower

Fig (16) Counter Flow cooling tower

Chapter 1

6 Cooling Tower Educational Stand BSc Project 2008

3 Components

Inlet water distributors There are several types of water distributors among them

1 Gravity distributors applied mainly for cross flow cooling towers and consist of vertical water riser that feed water into an open concrete basin from which the water flows by gravity through orifices to the fill

2 Spray distributors used mainly with counter flow cooling towers and have cross pipe net with spray downward nozzles

3 Rotary distributors applied for cross flow cooling towers and consists of two slotted arms rotate about a central hub containing water supply pipe The slots in the tow arms are directed downward but make small angle with the vertical direction to one side The slots form a curtain angle and due to reaction force the arms rotate at a rotational speed of 25-to-30 revmin

Drift eliminators An assembly constructed of wood plastic cement board or other material that serves to

remove entrained moisture from the discharged air Circulating Pump

The circulating pump transports the cooling water between the cooling tower and the condenser The water is pumped from the cooling tower basin through to the condenser where it is used as cooling medium The water returns back for evaporative cooling in the cooling tower Fan A device for moving air in a mechanical draft tower The fan design may be either an axial flow propeller or centrifugal blower Also may be applied as induced draft or forced draft Noticing that the induced type requires less power for same result Fills

Is the heart of the cooling tower The fill must provide good water-air contact area high rates of heat and mass transfer and low air flow resistance The fill also must be strong and deterioration resistant The fill has mainly two forms

minus Splash fill breaks falling water into small drops This Type is made of bars stacked in desks and may be narrow-edged square bars rough bars and grids Different materials are used such as redwood high-impact polystyrene or polyethylene

minus Film fill is made of vertical sheets that have a rough adsorbent surface and good wetness of water that allows water to fall as a film over the vertical surface Film fill has different forms and materials redwood battens cellulose corrugated sheets asbestos cement and waveform plastic

Water Basin Is situated beneath the tower collects and strains the water before pumped back to the circulating system Large utility tower basins are generally made of concrete Water leaves the basin via sloped canal at the bottom and through screens that prevent dust and foreign materials from entering the pump

Chapter 1

7 Cooling Tower Educational Stand BSc Project 2008

4 Water Treatment

The large variety of alternative construction materials allows users to match unit construction to the water quality available for their systems while helping to protect the tower from temporary upsets

Water treatment programs must be designed for three requirements

1 Scale control 2 Protection of system components against corrosion and 3 Control of biological contaminants such as Legionella pneumophilia the bacterium that causes

Legionnaires disease

The first two requirements help to ensure energy efficiency and longevity of the cooling system while the third ensures safe operation

Biological control is relatively easy to accomplish and is essential to the safe operation of the tower

Cooling towers can collect and concentrate airborne dirt and debris over time To control this buildup the cooling tower should be located so as to minimize contaminant induction and a proper blowdown rate should be maintained Sidestream filters or separators have proven valuable in this regard by effectively removing dirt and debris from the tower water These devices are coupled with a basin-sweeping nozzle package which is available either as original equipment in the tower or as a field-installed aftermarket item Cleaner tower water makes water treatment regimens more effective while keeping the cooling loop cleaner saving energy reducing maintenance and improving reliability of the entire cooling system

Chapter 2

8 Cooling Tower Educational Stand BSc Project 2008

Chapter Two

Literature review

In this chapter we will introduce the specifications of the cooling tower educational stand that manufactured by different companies like Gunt Armfield PA Hilton Edibon

1 Gunt

Fig (2-1) Gunt cooling tower educational stand

Column

Dimensions 150x150x630 mm

Pacing density 110 m2m3

Orifice diameter 80 mm

Approx weight 5 Kg

Heaters

3 stages 05-1-15 KW Thermostat switches off at 50⁰c

Fan

Radial fan - Power consumption 025 KW -max Differential pressure 430 pa

-max Flow rate 13 m3min

Chapter 2

9 Cooling Tower Educational Stand BSc Project 2008

Pump

-Power consumption 07 KW

-max Head 34 m

-max Flow rate 34 Lmin

Instrumentation

-Temp Sensors at air inlet ampoutlet

-Temp Sensors at water inletamp outlet

-Water flow rate sensor

-Humidity sensors at air inletamp outlet

Dimensions

Height 1228 m

Length 111 m

Width 046 m

Weight approx 90 Kg

Service required

Electrical -230 v 5060 HZ 1 phase

or -230 v 60 HZ 3 phases

Computeramp Data acquisition

Data acquisition with lab view software h-w diagram and Windows X-P

Chapter 2

10 Cooling Tower Educational Stand BSc Project 2008

2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

Chapter 2

11 Cooling Tower Educational Stand BSc Project 2008

Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 8: Cooling Tower Educational Standcairouniversity

VII

Chapter 1

1 Cooling Tower Educational Stand BSc Project 2008

Chapter One Introduction

1 Objective Cooling towers (Fig 1) are heat removal devices used to transfer process waste heat to the atmosphere They may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or rely solely on air to cool the working fluid to near the dry-bulb air temperature The objective of cooling towers can be divided into two categories

HVAC An HVAC cooling tower is a subcategory rejecting heat from a chiller Water-cooled chillers

are normally more energy efficient than air-cooled chillers due to heat rejection to tower water at or near wet-bulb temperatures Air-cooled chillers must reject heat at the dry-bulb temperature and thus have a lower average reverse-Carnot cycle effectiveness Large office buildings hospitals and schools typically use one or more cooling towers as part of their air conditioning systems Generally industrial cooling towers are much larger than HVAC towers

Industrial Industrial cooling towers can be used to remove heat from various sources such as machinery

or heated process material The primary use of large industrial cooling towers is to remove the heat absorbed in the circulating cooling water systems used in power plants petroleum refineries petrochemical plants natural gas processing plants food processing plants semi-conductor plants and other industrial facilities The circulation rate of cooling water in a typical 700 MW coal-fired power plant with a cooling tower amounts to about 71600 cubic metres an hour (315000 US gallons per minute) and the circulating water requires a supply water make-up rate of perhaps 5 percent (ie 3600 cubic metres an hour)

Fig (11) cooling tower

Chapter 1

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2 Classification Cooling towers can be classified into different categories as follows

Heat transfer mode bull Wet cooling towers or simply cooling towers operate on the principle of evaporation bull Dry coolers operate by heat transfer through a surface that separates the working fluid

from ambient air such as in a heat exchanger utilizing convective heat transfer bull Fluid coolers are hybrids that pass the working fluid through a tube bundle upon which

clean water is sprayed and a fan-induced draft applied The resulting heat transfer performance is much closer to that of a wet cooling tower with the advantage provided by a dry cooler of protecting the working fluid from environmental exposure

In a wet cooling tower the warm water can be cooled to a temperature lower than the ambient air dry-bulb temperature if the air is relatively dry As ambient air is drawn past a flow of water evaporation occurs Evaporation results in saturated air conditions lowering the temperature of the water to the wet bulb air temperature which is lower than the ambient dry bulb air temperature the difference determined by the humidity of the ambient air Air flow generation With respect to drawing air through the tower there are three types of cooling towers

bull Natural draft which utilizes buoyancy via a tall chimney Warm moist air naturally rises due to the density differential to the dry cooler outside air Warm moist air is less dense than drier air at the same pressure This moist air buoyancy produces a current of air through the tower (Fig 2)

Fig (12) Natural draft cooling tower

Chapter 1

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bull Mechanical draft which uses power driven fan to force or draw air through the tower minus Induced draft A mechanical draft tower with a fan at the discharge which pulls

air through tower (Fig 3) The fan induces hot moist air out the discharge This produces low entering and high exiting air velocities reducing the possibility of recirculation in which discharged air flows back into the air intake This fanfill arrangement is also known as draw-through

Fig (13) Induced draft fan cooling tower minus Forced draft A mechanical draft tower with a blower type fan at the intake (Fig

4) The fan forces air into the tower creating high entering and low exiting air velocities The low exiting velocity is much more susceptible to recirculation With the fan on the air intake the fan is more susceptible to complications due to freezing conditions Another disadvantage is that a forced draft design typically requires more motor horsepower than an equivalent induced draft design The forced draft benefit is its ability to work with high static pressure They can be installed in more confined spaces and even in some indoor situations This fanfill geometry is also known as blow-through

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Fig (14) Forced draft fan cooling tower

Air-to-Water Flow

-Cross flow Is a design in which the air flow is directed perpendicular to the water flow

(Fig 5) Air flow enters one or more vertical faces of the cooling tower to meet the fill material Water flows (perpendicular to the air) through the fill by gravity The air continues through the fill and thus past the water flow into an open plenum area A distribution or hot water basin consisting of a deep pan with holes or nozzles in the bottom is utilized in a cross flow tower Gravity distributes the water through the nozzles uniformly across the fill material

-Counter Flow The air flow is directly opposite of the water flow (Fig 6) Air flow first enters an open area beneath the fill media and is then drawn up vertically The water is sprayed through pressurized nozzles and flows downward through the fill opposite to the air flow Common to both designs

bull The interaction of the air and water flow allow a partial equalization and evaporation of water

bull The air now saturated with water vapour is discharged from the cooling tower bull A collection or cold water basin is used to contain the water after its interaction with the

air flow Both cross flow and counter flow designs can be used in natural draft and mechanical draft cooling towers

Chapter 1

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Fig (15) Cross Flow cooling tower

Fig (16) Counter Flow cooling tower

Chapter 1

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3 Components

Inlet water distributors There are several types of water distributors among them

1 Gravity distributors applied mainly for cross flow cooling towers and consist of vertical water riser that feed water into an open concrete basin from which the water flows by gravity through orifices to the fill

2 Spray distributors used mainly with counter flow cooling towers and have cross pipe net with spray downward nozzles

3 Rotary distributors applied for cross flow cooling towers and consists of two slotted arms rotate about a central hub containing water supply pipe The slots in the tow arms are directed downward but make small angle with the vertical direction to one side The slots form a curtain angle and due to reaction force the arms rotate at a rotational speed of 25-to-30 revmin

Drift eliminators An assembly constructed of wood plastic cement board or other material that serves to

remove entrained moisture from the discharged air Circulating Pump

The circulating pump transports the cooling water between the cooling tower and the condenser The water is pumped from the cooling tower basin through to the condenser where it is used as cooling medium The water returns back for evaporative cooling in the cooling tower Fan A device for moving air in a mechanical draft tower The fan design may be either an axial flow propeller or centrifugal blower Also may be applied as induced draft or forced draft Noticing that the induced type requires less power for same result Fills

Is the heart of the cooling tower The fill must provide good water-air contact area high rates of heat and mass transfer and low air flow resistance The fill also must be strong and deterioration resistant The fill has mainly two forms

minus Splash fill breaks falling water into small drops This Type is made of bars stacked in desks and may be narrow-edged square bars rough bars and grids Different materials are used such as redwood high-impact polystyrene or polyethylene

minus Film fill is made of vertical sheets that have a rough adsorbent surface and good wetness of water that allows water to fall as a film over the vertical surface Film fill has different forms and materials redwood battens cellulose corrugated sheets asbestos cement and waveform plastic

Water Basin Is situated beneath the tower collects and strains the water before pumped back to the circulating system Large utility tower basins are generally made of concrete Water leaves the basin via sloped canal at the bottom and through screens that prevent dust and foreign materials from entering the pump

Chapter 1

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4 Water Treatment

The large variety of alternative construction materials allows users to match unit construction to the water quality available for their systems while helping to protect the tower from temporary upsets

Water treatment programs must be designed for three requirements

1 Scale control 2 Protection of system components against corrosion and 3 Control of biological contaminants such as Legionella pneumophilia the bacterium that causes

Legionnaires disease

The first two requirements help to ensure energy efficiency and longevity of the cooling system while the third ensures safe operation

Biological control is relatively easy to accomplish and is essential to the safe operation of the tower

Cooling towers can collect and concentrate airborne dirt and debris over time To control this buildup the cooling tower should be located so as to minimize contaminant induction and a proper blowdown rate should be maintained Sidestream filters or separators have proven valuable in this regard by effectively removing dirt and debris from the tower water These devices are coupled with a basin-sweeping nozzle package which is available either as original equipment in the tower or as a field-installed aftermarket item Cleaner tower water makes water treatment regimens more effective while keeping the cooling loop cleaner saving energy reducing maintenance and improving reliability of the entire cooling system

Chapter 2

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Chapter Two

Literature review

In this chapter we will introduce the specifications of the cooling tower educational stand that manufactured by different companies like Gunt Armfield PA Hilton Edibon

1 Gunt

Fig (2-1) Gunt cooling tower educational stand

Column

Dimensions 150x150x630 mm

Pacing density 110 m2m3

Orifice diameter 80 mm

Approx weight 5 Kg

Heaters

3 stages 05-1-15 KW Thermostat switches off at 50⁰c

Fan

Radial fan - Power consumption 025 KW -max Differential pressure 430 pa

-max Flow rate 13 m3min

Chapter 2

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Pump

-Power consumption 07 KW

-max Head 34 m

-max Flow rate 34 Lmin

Instrumentation

-Temp Sensors at air inlet ampoutlet

-Temp Sensors at water inletamp outlet

-Water flow rate sensor

-Humidity sensors at air inletamp outlet

Dimensions

Height 1228 m

Length 111 m

Width 046 m

Weight approx 90 Kg

Service required

Electrical -230 v 5060 HZ 1 phase

or -230 v 60 HZ 3 phases

Computeramp Data acquisition

Data acquisition with lab view software h-w diagram and Windows X-P

Chapter 2

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2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

Chapter 2

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Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

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3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

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Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

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4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

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Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

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Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

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mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

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Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

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-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

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Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

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26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

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Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

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Appendix

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Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 9: Cooling Tower Educational Standcairouniversity

Chapter 1

1 Cooling Tower Educational Stand BSc Project 2008

Chapter One Introduction

1 Objective Cooling towers (Fig 1) are heat removal devices used to transfer process waste heat to the atmosphere They may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or rely solely on air to cool the working fluid to near the dry-bulb air temperature The objective of cooling towers can be divided into two categories

HVAC An HVAC cooling tower is a subcategory rejecting heat from a chiller Water-cooled chillers

are normally more energy efficient than air-cooled chillers due to heat rejection to tower water at or near wet-bulb temperatures Air-cooled chillers must reject heat at the dry-bulb temperature and thus have a lower average reverse-Carnot cycle effectiveness Large office buildings hospitals and schools typically use one or more cooling towers as part of their air conditioning systems Generally industrial cooling towers are much larger than HVAC towers

Industrial Industrial cooling towers can be used to remove heat from various sources such as machinery

or heated process material The primary use of large industrial cooling towers is to remove the heat absorbed in the circulating cooling water systems used in power plants petroleum refineries petrochemical plants natural gas processing plants food processing plants semi-conductor plants and other industrial facilities The circulation rate of cooling water in a typical 700 MW coal-fired power plant with a cooling tower amounts to about 71600 cubic metres an hour (315000 US gallons per minute) and the circulating water requires a supply water make-up rate of perhaps 5 percent (ie 3600 cubic metres an hour)

Fig (11) cooling tower

Chapter 1

2 Cooling Tower Educational Stand BSc Project 2008

2 Classification Cooling towers can be classified into different categories as follows

Heat transfer mode bull Wet cooling towers or simply cooling towers operate on the principle of evaporation bull Dry coolers operate by heat transfer through a surface that separates the working fluid

from ambient air such as in a heat exchanger utilizing convective heat transfer bull Fluid coolers are hybrids that pass the working fluid through a tube bundle upon which

clean water is sprayed and a fan-induced draft applied The resulting heat transfer performance is much closer to that of a wet cooling tower with the advantage provided by a dry cooler of protecting the working fluid from environmental exposure

In a wet cooling tower the warm water can be cooled to a temperature lower than the ambient air dry-bulb temperature if the air is relatively dry As ambient air is drawn past a flow of water evaporation occurs Evaporation results in saturated air conditions lowering the temperature of the water to the wet bulb air temperature which is lower than the ambient dry bulb air temperature the difference determined by the humidity of the ambient air Air flow generation With respect to drawing air through the tower there are three types of cooling towers

bull Natural draft which utilizes buoyancy via a tall chimney Warm moist air naturally rises due to the density differential to the dry cooler outside air Warm moist air is less dense than drier air at the same pressure This moist air buoyancy produces a current of air through the tower (Fig 2)

Fig (12) Natural draft cooling tower

Chapter 1

3 Cooling Tower Educational Stand BSc Project 2008

bull Mechanical draft which uses power driven fan to force or draw air through the tower minus Induced draft A mechanical draft tower with a fan at the discharge which pulls

air through tower (Fig 3) The fan induces hot moist air out the discharge This produces low entering and high exiting air velocities reducing the possibility of recirculation in which discharged air flows back into the air intake This fanfill arrangement is also known as draw-through

Fig (13) Induced draft fan cooling tower minus Forced draft A mechanical draft tower with a blower type fan at the intake (Fig

4) The fan forces air into the tower creating high entering and low exiting air velocities The low exiting velocity is much more susceptible to recirculation With the fan on the air intake the fan is more susceptible to complications due to freezing conditions Another disadvantage is that a forced draft design typically requires more motor horsepower than an equivalent induced draft design The forced draft benefit is its ability to work with high static pressure They can be installed in more confined spaces and even in some indoor situations This fanfill geometry is also known as blow-through

Chapter 1

4 Cooling Tower Educational Stand BSc Project 2008

Fig (14) Forced draft fan cooling tower

Air-to-Water Flow

-Cross flow Is a design in which the air flow is directed perpendicular to the water flow

(Fig 5) Air flow enters one or more vertical faces of the cooling tower to meet the fill material Water flows (perpendicular to the air) through the fill by gravity The air continues through the fill and thus past the water flow into an open plenum area A distribution or hot water basin consisting of a deep pan with holes or nozzles in the bottom is utilized in a cross flow tower Gravity distributes the water through the nozzles uniformly across the fill material

-Counter Flow The air flow is directly opposite of the water flow (Fig 6) Air flow first enters an open area beneath the fill media and is then drawn up vertically The water is sprayed through pressurized nozzles and flows downward through the fill opposite to the air flow Common to both designs

bull The interaction of the air and water flow allow a partial equalization and evaporation of water

bull The air now saturated with water vapour is discharged from the cooling tower bull A collection or cold water basin is used to contain the water after its interaction with the

air flow Both cross flow and counter flow designs can be used in natural draft and mechanical draft cooling towers

Chapter 1

5 Cooling Tower Educational Stand BSc Project 2008

Fig (15) Cross Flow cooling tower

Fig (16) Counter Flow cooling tower

Chapter 1

6 Cooling Tower Educational Stand BSc Project 2008

3 Components

Inlet water distributors There are several types of water distributors among them

1 Gravity distributors applied mainly for cross flow cooling towers and consist of vertical water riser that feed water into an open concrete basin from which the water flows by gravity through orifices to the fill

2 Spray distributors used mainly with counter flow cooling towers and have cross pipe net with spray downward nozzles

3 Rotary distributors applied for cross flow cooling towers and consists of two slotted arms rotate about a central hub containing water supply pipe The slots in the tow arms are directed downward but make small angle with the vertical direction to one side The slots form a curtain angle and due to reaction force the arms rotate at a rotational speed of 25-to-30 revmin

Drift eliminators An assembly constructed of wood plastic cement board or other material that serves to

remove entrained moisture from the discharged air Circulating Pump

The circulating pump transports the cooling water between the cooling tower and the condenser The water is pumped from the cooling tower basin through to the condenser where it is used as cooling medium The water returns back for evaporative cooling in the cooling tower Fan A device for moving air in a mechanical draft tower The fan design may be either an axial flow propeller or centrifugal blower Also may be applied as induced draft or forced draft Noticing that the induced type requires less power for same result Fills

Is the heart of the cooling tower The fill must provide good water-air contact area high rates of heat and mass transfer and low air flow resistance The fill also must be strong and deterioration resistant The fill has mainly two forms

minus Splash fill breaks falling water into small drops This Type is made of bars stacked in desks and may be narrow-edged square bars rough bars and grids Different materials are used such as redwood high-impact polystyrene or polyethylene

minus Film fill is made of vertical sheets that have a rough adsorbent surface and good wetness of water that allows water to fall as a film over the vertical surface Film fill has different forms and materials redwood battens cellulose corrugated sheets asbestos cement and waveform plastic

Water Basin Is situated beneath the tower collects and strains the water before pumped back to the circulating system Large utility tower basins are generally made of concrete Water leaves the basin via sloped canal at the bottom and through screens that prevent dust and foreign materials from entering the pump

Chapter 1

7 Cooling Tower Educational Stand BSc Project 2008

4 Water Treatment

The large variety of alternative construction materials allows users to match unit construction to the water quality available for their systems while helping to protect the tower from temporary upsets

Water treatment programs must be designed for three requirements

1 Scale control 2 Protection of system components against corrosion and 3 Control of biological contaminants such as Legionella pneumophilia the bacterium that causes

Legionnaires disease

The first two requirements help to ensure energy efficiency and longevity of the cooling system while the third ensures safe operation

Biological control is relatively easy to accomplish and is essential to the safe operation of the tower

Cooling towers can collect and concentrate airborne dirt and debris over time To control this buildup the cooling tower should be located so as to minimize contaminant induction and a proper blowdown rate should be maintained Sidestream filters or separators have proven valuable in this regard by effectively removing dirt and debris from the tower water These devices are coupled with a basin-sweeping nozzle package which is available either as original equipment in the tower or as a field-installed aftermarket item Cleaner tower water makes water treatment regimens more effective while keeping the cooling loop cleaner saving energy reducing maintenance and improving reliability of the entire cooling system

Chapter 2

8 Cooling Tower Educational Stand BSc Project 2008

Chapter Two

Literature review

In this chapter we will introduce the specifications of the cooling tower educational stand that manufactured by different companies like Gunt Armfield PA Hilton Edibon

1 Gunt

Fig (2-1) Gunt cooling tower educational stand

Column

Dimensions 150x150x630 mm

Pacing density 110 m2m3

Orifice diameter 80 mm

Approx weight 5 Kg

Heaters

3 stages 05-1-15 KW Thermostat switches off at 50⁰c

Fan

Radial fan - Power consumption 025 KW -max Differential pressure 430 pa

-max Flow rate 13 m3min

Chapter 2

9 Cooling Tower Educational Stand BSc Project 2008

Pump

-Power consumption 07 KW

-max Head 34 m

-max Flow rate 34 Lmin

Instrumentation

-Temp Sensors at air inlet ampoutlet

-Temp Sensors at water inletamp outlet

-Water flow rate sensor

-Humidity sensors at air inletamp outlet

Dimensions

Height 1228 m

Length 111 m

Width 046 m

Weight approx 90 Kg

Service required

Electrical -230 v 5060 HZ 1 phase

or -230 v 60 HZ 3 phases

Computeramp Data acquisition

Data acquisition with lab view software h-w diagram and Windows X-P

Chapter 2

10 Cooling Tower Educational Stand BSc Project 2008

2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

Chapter 2

11 Cooling Tower Educational Stand BSc Project 2008

Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 10: Cooling Tower Educational Standcairouniversity

Chapter 1

2 Cooling Tower Educational Stand BSc Project 2008

2 Classification Cooling towers can be classified into different categories as follows

Heat transfer mode bull Wet cooling towers or simply cooling towers operate on the principle of evaporation bull Dry coolers operate by heat transfer through a surface that separates the working fluid

from ambient air such as in a heat exchanger utilizing convective heat transfer bull Fluid coolers are hybrids that pass the working fluid through a tube bundle upon which

clean water is sprayed and a fan-induced draft applied The resulting heat transfer performance is much closer to that of a wet cooling tower with the advantage provided by a dry cooler of protecting the working fluid from environmental exposure

In a wet cooling tower the warm water can be cooled to a temperature lower than the ambient air dry-bulb temperature if the air is relatively dry As ambient air is drawn past a flow of water evaporation occurs Evaporation results in saturated air conditions lowering the temperature of the water to the wet bulb air temperature which is lower than the ambient dry bulb air temperature the difference determined by the humidity of the ambient air Air flow generation With respect to drawing air through the tower there are three types of cooling towers

bull Natural draft which utilizes buoyancy via a tall chimney Warm moist air naturally rises due to the density differential to the dry cooler outside air Warm moist air is less dense than drier air at the same pressure This moist air buoyancy produces a current of air through the tower (Fig 2)

Fig (12) Natural draft cooling tower

Chapter 1

3 Cooling Tower Educational Stand BSc Project 2008

bull Mechanical draft which uses power driven fan to force or draw air through the tower minus Induced draft A mechanical draft tower with a fan at the discharge which pulls

air through tower (Fig 3) The fan induces hot moist air out the discharge This produces low entering and high exiting air velocities reducing the possibility of recirculation in which discharged air flows back into the air intake This fanfill arrangement is also known as draw-through

Fig (13) Induced draft fan cooling tower minus Forced draft A mechanical draft tower with a blower type fan at the intake (Fig

4) The fan forces air into the tower creating high entering and low exiting air velocities The low exiting velocity is much more susceptible to recirculation With the fan on the air intake the fan is more susceptible to complications due to freezing conditions Another disadvantage is that a forced draft design typically requires more motor horsepower than an equivalent induced draft design The forced draft benefit is its ability to work with high static pressure They can be installed in more confined spaces and even in some indoor situations This fanfill geometry is also known as blow-through

Chapter 1

4 Cooling Tower Educational Stand BSc Project 2008

Fig (14) Forced draft fan cooling tower

Air-to-Water Flow

-Cross flow Is a design in which the air flow is directed perpendicular to the water flow

(Fig 5) Air flow enters one or more vertical faces of the cooling tower to meet the fill material Water flows (perpendicular to the air) through the fill by gravity The air continues through the fill and thus past the water flow into an open plenum area A distribution or hot water basin consisting of a deep pan with holes or nozzles in the bottom is utilized in a cross flow tower Gravity distributes the water through the nozzles uniformly across the fill material

-Counter Flow The air flow is directly opposite of the water flow (Fig 6) Air flow first enters an open area beneath the fill media and is then drawn up vertically The water is sprayed through pressurized nozzles and flows downward through the fill opposite to the air flow Common to both designs

bull The interaction of the air and water flow allow a partial equalization and evaporation of water

bull The air now saturated with water vapour is discharged from the cooling tower bull A collection or cold water basin is used to contain the water after its interaction with the

air flow Both cross flow and counter flow designs can be used in natural draft and mechanical draft cooling towers

Chapter 1

5 Cooling Tower Educational Stand BSc Project 2008

Fig (15) Cross Flow cooling tower

Fig (16) Counter Flow cooling tower

Chapter 1

6 Cooling Tower Educational Stand BSc Project 2008

3 Components

Inlet water distributors There are several types of water distributors among them

1 Gravity distributors applied mainly for cross flow cooling towers and consist of vertical water riser that feed water into an open concrete basin from which the water flows by gravity through orifices to the fill

2 Spray distributors used mainly with counter flow cooling towers and have cross pipe net with spray downward nozzles

3 Rotary distributors applied for cross flow cooling towers and consists of two slotted arms rotate about a central hub containing water supply pipe The slots in the tow arms are directed downward but make small angle with the vertical direction to one side The slots form a curtain angle and due to reaction force the arms rotate at a rotational speed of 25-to-30 revmin

Drift eliminators An assembly constructed of wood plastic cement board or other material that serves to

remove entrained moisture from the discharged air Circulating Pump

The circulating pump transports the cooling water between the cooling tower and the condenser The water is pumped from the cooling tower basin through to the condenser where it is used as cooling medium The water returns back for evaporative cooling in the cooling tower Fan A device for moving air in a mechanical draft tower The fan design may be either an axial flow propeller or centrifugal blower Also may be applied as induced draft or forced draft Noticing that the induced type requires less power for same result Fills

Is the heart of the cooling tower The fill must provide good water-air contact area high rates of heat and mass transfer and low air flow resistance The fill also must be strong and deterioration resistant The fill has mainly two forms

minus Splash fill breaks falling water into small drops This Type is made of bars stacked in desks and may be narrow-edged square bars rough bars and grids Different materials are used such as redwood high-impact polystyrene or polyethylene

minus Film fill is made of vertical sheets that have a rough adsorbent surface and good wetness of water that allows water to fall as a film over the vertical surface Film fill has different forms and materials redwood battens cellulose corrugated sheets asbestos cement and waveform plastic

Water Basin Is situated beneath the tower collects and strains the water before pumped back to the circulating system Large utility tower basins are generally made of concrete Water leaves the basin via sloped canal at the bottom and through screens that prevent dust and foreign materials from entering the pump

Chapter 1

7 Cooling Tower Educational Stand BSc Project 2008

4 Water Treatment

The large variety of alternative construction materials allows users to match unit construction to the water quality available for their systems while helping to protect the tower from temporary upsets

Water treatment programs must be designed for three requirements

1 Scale control 2 Protection of system components against corrosion and 3 Control of biological contaminants such as Legionella pneumophilia the bacterium that causes

Legionnaires disease

The first two requirements help to ensure energy efficiency and longevity of the cooling system while the third ensures safe operation

Biological control is relatively easy to accomplish and is essential to the safe operation of the tower

Cooling towers can collect and concentrate airborne dirt and debris over time To control this buildup the cooling tower should be located so as to minimize contaminant induction and a proper blowdown rate should be maintained Sidestream filters or separators have proven valuable in this regard by effectively removing dirt and debris from the tower water These devices are coupled with a basin-sweeping nozzle package which is available either as original equipment in the tower or as a field-installed aftermarket item Cleaner tower water makes water treatment regimens more effective while keeping the cooling loop cleaner saving energy reducing maintenance and improving reliability of the entire cooling system

Chapter 2

8 Cooling Tower Educational Stand BSc Project 2008

Chapter Two

Literature review

In this chapter we will introduce the specifications of the cooling tower educational stand that manufactured by different companies like Gunt Armfield PA Hilton Edibon

1 Gunt

Fig (2-1) Gunt cooling tower educational stand

Column

Dimensions 150x150x630 mm

Pacing density 110 m2m3

Orifice diameter 80 mm

Approx weight 5 Kg

Heaters

3 stages 05-1-15 KW Thermostat switches off at 50⁰c

Fan

Radial fan - Power consumption 025 KW -max Differential pressure 430 pa

-max Flow rate 13 m3min

Chapter 2

9 Cooling Tower Educational Stand BSc Project 2008

Pump

-Power consumption 07 KW

-max Head 34 m

-max Flow rate 34 Lmin

Instrumentation

-Temp Sensors at air inlet ampoutlet

-Temp Sensors at water inletamp outlet

-Water flow rate sensor

-Humidity sensors at air inletamp outlet

Dimensions

Height 1228 m

Length 111 m

Width 046 m

Weight approx 90 Kg

Service required

Electrical -230 v 5060 HZ 1 phase

or -230 v 60 HZ 3 phases

Computeramp Data acquisition

Data acquisition with lab view software h-w diagram and Windows X-P

Chapter 2

10 Cooling Tower Educational Stand BSc Project 2008

2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

Chapter 2

11 Cooling Tower Educational Stand BSc Project 2008

Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 11: Cooling Tower Educational Standcairouniversity

Chapter 1

3 Cooling Tower Educational Stand BSc Project 2008

bull Mechanical draft which uses power driven fan to force or draw air through the tower minus Induced draft A mechanical draft tower with a fan at the discharge which pulls

air through tower (Fig 3) The fan induces hot moist air out the discharge This produces low entering and high exiting air velocities reducing the possibility of recirculation in which discharged air flows back into the air intake This fanfill arrangement is also known as draw-through

Fig (13) Induced draft fan cooling tower minus Forced draft A mechanical draft tower with a blower type fan at the intake (Fig

4) The fan forces air into the tower creating high entering and low exiting air velocities The low exiting velocity is much more susceptible to recirculation With the fan on the air intake the fan is more susceptible to complications due to freezing conditions Another disadvantage is that a forced draft design typically requires more motor horsepower than an equivalent induced draft design The forced draft benefit is its ability to work with high static pressure They can be installed in more confined spaces and even in some indoor situations This fanfill geometry is also known as blow-through

Chapter 1

4 Cooling Tower Educational Stand BSc Project 2008

Fig (14) Forced draft fan cooling tower

Air-to-Water Flow

-Cross flow Is a design in which the air flow is directed perpendicular to the water flow

(Fig 5) Air flow enters one or more vertical faces of the cooling tower to meet the fill material Water flows (perpendicular to the air) through the fill by gravity The air continues through the fill and thus past the water flow into an open plenum area A distribution or hot water basin consisting of a deep pan with holes or nozzles in the bottom is utilized in a cross flow tower Gravity distributes the water through the nozzles uniformly across the fill material

-Counter Flow The air flow is directly opposite of the water flow (Fig 6) Air flow first enters an open area beneath the fill media and is then drawn up vertically The water is sprayed through pressurized nozzles and flows downward through the fill opposite to the air flow Common to both designs

bull The interaction of the air and water flow allow a partial equalization and evaporation of water

bull The air now saturated with water vapour is discharged from the cooling tower bull A collection or cold water basin is used to contain the water after its interaction with the

air flow Both cross flow and counter flow designs can be used in natural draft and mechanical draft cooling towers

Chapter 1

5 Cooling Tower Educational Stand BSc Project 2008

Fig (15) Cross Flow cooling tower

Fig (16) Counter Flow cooling tower

Chapter 1

6 Cooling Tower Educational Stand BSc Project 2008

3 Components

Inlet water distributors There are several types of water distributors among them

1 Gravity distributors applied mainly for cross flow cooling towers and consist of vertical water riser that feed water into an open concrete basin from which the water flows by gravity through orifices to the fill

2 Spray distributors used mainly with counter flow cooling towers and have cross pipe net with spray downward nozzles

3 Rotary distributors applied for cross flow cooling towers and consists of two slotted arms rotate about a central hub containing water supply pipe The slots in the tow arms are directed downward but make small angle with the vertical direction to one side The slots form a curtain angle and due to reaction force the arms rotate at a rotational speed of 25-to-30 revmin

Drift eliminators An assembly constructed of wood plastic cement board or other material that serves to

remove entrained moisture from the discharged air Circulating Pump

The circulating pump transports the cooling water between the cooling tower and the condenser The water is pumped from the cooling tower basin through to the condenser where it is used as cooling medium The water returns back for evaporative cooling in the cooling tower Fan A device for moving air in a mechanical draft tower The fan design may be either an axial flow propeller or centrifugal blower Also may be applied as induced draft or forced draft Noticing that the induced type requires less power for same result Fills

Is the heart of the cooling tower The fill must provide good water-air contact area high rates of heat and mass transfer and low air flow resistance The fill also must be strong and deterioration resistant The fill has mainly two forms

minus Splash fill breaks falling water into small drops This Type is made of bars stacked in desks and may be narrow-edged square bars rough bars and grids Different materials are used such as redwood high-impact polystyrene or polyethylene

minus Film fill is made of vertical sheets that have a rough adsorbent surface and good wetness of water that allows water to fall as a film over the vertical surface Film fill has different forms and materials redwood battens cellulose corrugated sheets asbestos cement and waveform plastic

Water Basin Is situated beneath the tower collects and strains the water before pumped back to the circulating system Large utility tower basins are generally made of concrete Water leaves the basin via sloped canal at the bottom and through screens that prevent dust and foreign materials from entering the pump

Chapter 1

7 Cooling Tower Educational Stand BSc Project 2008

4 Water Treatment

The large variety of alternative construction materials allows users to match unit construction to the water quality available for their systems while helping to protect the tower from temporary upsets

Water treatment programs must be designed for three requirements

1 Scale control 2 Protection of system components against corrosion and 3 Control of biological contaminants such as Legionella pneumophilia the bacterium that causes

Legionnaires disease

The first two requirements help to ensure energy efficiency and longevity of the cooling system while the third ensures safe operation

Biological control is relatively easy to accomplish and is essential to the safe operation of the tower

Cooling towers can collect and concentrate airborne dirt and debris over time To control this buildup the cooling tower should be located so as to minimize contaminant induction and a proper blowdown rate should be maintained Sidestream filters or separators have proven valuable in this regard by effectively removing dirt and debris from the tower water These devices are coupled with a basin-sweeping nozzle package which is available either as original equipment in the tower or as a field-installed aftermarket item Cleaner tower water makes water treatment regimens more effective while keeping the cooling loop cleaner saving energy reducing maintenance and improving reliability of the entire cooling system

Chapter 2

8 Cooling Tower Educational Stand BSc Project 2008

Chapter Two

Literature review

In this chapter we will introduce the specifications of the cooling tower educational stand that manufactured by different companies like Gunt Armfield PA Hilton Edibon

1 Gunt

Fig (2-1) Gunt cooling tower educational stand

Column

Dimensions 150x150x630 mm

Pacing density 110 m2m3

Orifice diameter 80 mm

Approx weight 5 Kg

Heaters

3 stages 05-1-15 KW Thermostat switches off at 50⁰c

Fan

Radial fan - Power consumption 025 KW -max Differential pressure 430 pa

-max Flow rate 13 m3min

Chapter 2

9 Cooling Tower Educational Stand BSc Project 2008

Pump

-Power consumption 07 KW

-max Head 34 m

-max Flow rate 34 Lmin

Instrumentation

-Temp Sensors at air inlet ampoutlet

-Temp Sensors at water inletamp outlet

-Water flow rate sensor

-Humidity sensors at air inletamp outlet

Dimensions

Height 1228 m

Length 111 m

Width 046 m

Weight approx 90 Kg

Service required

Electrical -230 v 5060 HZ 1 phase

or -230 v 60 HZ 3 phases

Computeramp Data acquisition

Data acquisition with lab view software h-w diagram and Windows X-P

Chapter 2

10 Cooling Tower Educational Stand BSc Project 2008

2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

Chapter 2

11 Cooling Tower Educational Stand BSc Project 2008

Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 12: Cooling Tower Educational Standcairouniversity

Chapter 1

4 Cooling Tower Educational Stand BSc Project 2008

Fig (14) Forced draft fan cooling tower

Air-to-Water Flow

-Cross flow Is a design in which the air flow is directed perpendicular to the water flow

(Fig 5) Air flow enters one or more vertical faces of the cooling tower to meet the fill material Water flows (perpendicular to the air) through the fill by gravity The air continues through the fill and thus past the water flow into an open plenum area A distribution or hot water basin consisting of a deep pan with holes or nozzles in the bottom is utilized in a cross flow tower Gravity distributes the water through the nozzles uniformly across the fill material

-Counter Flow The air flow is directly opposite of the water flow (Fig 6) Air flow first enters an open area beneath the fill media and is then drawn up vertically The water is sprayed through pressurized nozzles and flows downward through the fill opposite to the air flow Common to both designs

bull The interaction of the air and water flow allow a partial equalization and evaporation of water

bull The air now saturated with water vapour is discharged from the cooling tower bull A collection or cold water basin is used to contain the water after its interaction with the

air flow Both cross flow and counter flow designs can be used in natural draft and mechanical draft cooling towers

Chapter 1

5 Cooling Tower Educational Stand BSc Project 2008

Fig (15) Cross Flow cooling tower

Fig (16) Counter Flow cooling tower

Chapter 1

6 Cooling Tower Educational Stand BSc Project 2008

3 Components

Inlet water distributors There are several types of water distributors among them

1 Gravity distributors applied mainly for cross flow cooling towers and consist of vertical water riser that feed water into an open concrete basin from which the water flows by gravity through orifices to the fill

2 Spray distributors used mainly with counter flow cooling towers and have cross pipe net with spray downward nozzles

3 Rotary distributors applied for cross flow cooling towers and consists of two slotted arms rotate about a central hub containing water supply pipe The slots in the tow arms are directed downward but make small angle with the vertical direction to one side The slots form a curtain angle and due to reaction force the arms rotate at a rotational speed of 25-to-30 revmin

Drift eliminators An assembly constructed of wood plastic cement board or other material that serves to

remove entrained moisture from the discharged air Circulating Pump

The circulating pump transports the cooling water between the cooling tower and the condenser The water is pumped from the cooling tower basin through to the condenser where it is used as cooling medium The water returns back for evaporative cooling in the cooling tower Fan A device for moving air in a mechanical draft tower The fan design may be either an axial flow propeller or centrifugal blower Also may be applied as induced draft or forced draft Noticing that the induced type requires less power for same result Fills

Is the heart of the cooling tower The fill must provide good water-air contact area high rates of heat and mass transfer and low air flow resistance The fill also must be strong and deterioration resistant The fill has mainly two forms

minus Splash fill breaks falling water into small drops This Type is made of bars stacked in desks and may be narrow-edged square bars rough bars and grids Different materials are used such as redwood high-impact polystyrene or polyethylene

minus Film fill is made of vertical sheets that have a rough adsorbent surface and good wetness of water that allows water to fall as a film over the vertical surface Film fill has different forms and materials redwood battens cellulose corrugated sheets asbestos cement and waveform plastic

Water Basin Is situated beneath the tower collects and strains the water before pumped back to the circulating system Large utility tower basins are generally made of concrete Water leaves the basin via sloped canal at the bottom and through screens that prevent dust and foreign materials from entering the pump

Chapter 1

7 Cooling Tower Educational Stand BSc Project 2008

4 Water Treatment

The large variety of alternative construction materials allows users to match unit construction to the water quality available for their systems while helping to protect the tower from temporary upsets

Water treatment programs must be designed for three requirements

1 Scale control 2 Protection of system components against corrosion and 3 Control of biological contaminants such as Legionella pneumophilia the bacterium that causes

Legionnaires disease

The first two requirements help to ensure energy efficiency and longevity of the cooling system while the third ensures safe operation

Biological control is relatively easy to accomplish and is essential to the safe operation of the tower

Cooling towers can collect and concentrate airborne dirt and debris over time To control this buildup the cooling tower should be located so as to minimize contaminant induction and a proper blowdown rate should be maintained Sidestream filters or separators have proven valuable in this regard by effectively removing dirt and debris from the tower water These devices are coupled with a basin-sweeping nozzle package which is available either as original equipment in the tower or as a field-installed aftermarket item Cleaner tower water makes water treatment regimens more effective while keeping the cooling loop cleaner saving energy reducing maintenance and improving reliability of the entire cooling system

Chapter 2

8 Cooling Tower Educational Stand BSc Project 2008

Chapter Two

Literature review

In this chapter we will introduce the specifications of the cooling tower educational stand that manufactured by different companies like Gunt Armfield PA Hilton Edibon

1 Gunt

Fig (2-1) Gunt cooling tower educational stand

Column

Dimensions 150x150x630 mm

Pacing density 110 m2m3

Orifice diameter 80 mm

Approx weight 5 Kg

Heaters

3 stages 05-1-15 KW Thermostat switches off at 50⁰c

Fan

Radial fan - Power consumption 025 KW -max Differential pressure 430 pa

-max Flow rate 13 m3min

Chapter 2

9 Cooling Tower Educational Stand BSc Project 2008

Pump

-Power consumption 07 KW

-max Head 34 m

-max Flow rate 34 Lmin

Instrumentation

-Temp Sensors at air inlet ampoutlet

-Temp Sensors at water inletamp outlet

-Water flow rate sensor

-Humidity sensors at air inletamp outlet

Dimensions

Height 1228 m

Length 111 m

Width 046 m

Weight approx 90 Kg

Service required

Electrical -230 v 5060 HZ 1 phase

or -230 v 60 HZ 3 phases

Computeramp Data acquisition

Data acquisition with lab view software h-w diagram and Windows X-P

Chapter 2

10 Cooling Tower Educational Stand BSc Project 2008

2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

Chapter 2

11 Cooling Tower Educational Stand BSc Project 2008

Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 13: Cooling Tower Educational Standcairouniversity

Chapter 1

5 Cooling Tower Educational Stand BSc Project 2008

Fig (15) Cross Flow cooling tower

Fig (16) Counter Flow cooling tower

Chapter 1

6 Cooling Tower Educational Stand BSc Project 2008

3 Components

Inlet water distributors There are several types of water distributors among them

1 Gravity distributors applied mainly for cross flow cooling towers and consist of vertical water riser that feed water into an open concrete basin from which the water flows by gravity through orifices to the fill

2 Spray distributors used mainly with counter flow cooling towers and have cross pipe net with spray downward nozzles

3 Rotary distributors applied for cross flow cooling towers and consists of two slotted arms rotate about a central hub containing water supply pipe The slots in the tow arms are directed downward but make small angle with the vertical direction to one side The slots form a curtain angle and due to reaction force the arms rotate at a rotational speed of 25-to-30 revmin

Drift eliminators An assembly constructed of wood plastic cement board or other material that serves to

remove entrained moisture from the discharged air Circulating Pump

The circulating pump transports the cooling water between the cooling tower and the condenser The water is pumped from the cooling tower basin through to the condenser where it is used as cooling medium The water returns back for evaporative cooling in the cooling tower Fan A device for moving air in a mechanical draft tower The fan design may be either an axial flow propeller or centrifugal blower Also may be applied as induced draft or forced draft Noticing that the induced type requires less power for same result Fills

Is the heart of the cooling tower The fill must provide good water-air contact area high rates of heat and mass transfer and low air flow resistance The fill also must be strong and deterioration resistant The fill has mainly two forms

minus Splash fill breaks falling water into small drops This Type is made of bars stacked in desks and may be narrow-edged square bars rough bars and grids Different materials are used such as redwood high-impact polystyrene or polyethylene

minus Film fill is made of vertical sheets that have a rough adsorbent surface and good wetness of water that allows water to fall as a film over the vertical surface Film fill has different forms and materials redwood battens cellulose corrugated sheets asbestos cement and waveform plastic

Water Basin Is situated beneath the tower collects and strains the water before pumped back to the circulating system Large utility tower basins are generally made of concrete Water leaves the basin via sloped canal at the bottom and through screens that prevent dust and foreign materials from entering the pump

Chapter 1

7 Cooling Tower Educational Stand BSc Project 2008

4 Water Treatment

The large variety of alternative construction materials allows users to match unit construction to the water quality available for their systems while helping to protect the tower from temporary upsets

Water treatment programs must be designed for three requirements

1 Scale control 2 Protection of system components against corrosion and 3 Control of biological contaminants such as Legionella pneumophilia the bacterium that causes

Legionnaires disease

The first two requirements help to ensure energy efficiency and longevity of the cooling system while the third ensures safe operation

Biological control is relatively easy to accomplish and is essential to the safe operation of the tower

Cooling towers can collect and concentrate airborne dirt and debris over time To control this buildup the cooling tower should be located so as to minimize contaminant induction and a proper blowdown rate should be maintained Sidestream filters or separators have proven valuable in this regard by effectively removing dirt and debris from the tower water These devices are coupled with a basin-sweeping nozzle package which is available either as original equipment in the tower or as a field-installed aftermarket item Cleaner tower water makes water treatment regimens more effective while keeping the cooling loop cleaner saving energy reducing maintenance and improving reliability of the entire cooling system

Chapter 2

8 Cooling Tower Educational Stand BSc Project 2008

Chapter Two

Literature review

In this chapter we will introduce the specifications of the cooling tower educational stand that manufactured by different companies like Gunt Armfield PA Hilton Edibon

1 Gunt

Fig (2-1) Gunt cooling tower educational stand

Column

Dimensions 150x150x630 mm

Pacing density 110 m2m3

Orifice diameter 80 mm

Approx weight 5 Kg

Heaters

3 stages 05-1-15 KW Thermostat switches off at 50⁰c

Fan

Radial fan - Power consumption 025 KW -max Differential pressure 430 pa

-max Flow rate 13 m3min

Chapter 2

9 Cooling Tower Educational Stand BSc Project 2008

Pump

-Power consumption 07 KW

-max Head 34 m

-max Flow rate 34 Lmin

Instrumentation

-Temp Sensors at air inlet ampoutlet

-Temp Sensors at water inletamp outlet

-Water flow rate sensor

-Humidity sensors at air inletamp outlet

Dimensions

Height 1228 m

Length 111 m

Width 046 m

Weight approx 90 Kg

Service required

Electrical -230 v 5060 HZ 1 phase

or -230 v 60 HZ 3 phases

Computeramp Data acquisition

Data acquisition with lab view software h-w diagram and Windows X-P

Chapter 2

10 Cooling Tower Educational Stand BSc Project 2008

2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

Chapter 2

11 Cooling Tower Educational Stand BSc Project 2008

Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 14: Cooling Tower Educational Standcairouniversity

Chapter 1

6 Cooling Tower Educational Stand BSc Project 2008

3 Components

Inlet water distributors There are several types of water distributors among them

1 Gravity distributors applied mainly for cross flow cooling towers and consist of vertical water riser that feed water into an open concrete basin from which the water flows by gravity through orifices to the fill

2 Spray distributors used mainly with counter flow cooling towers and have cross pipe net with spray downward nozzles

3 Rotary distributors applied for cross flow cooling towers and consists of two slotted arms rotate about a central hub containing water supply pipe The slots in the tow arms are directed downward but make small angle with the vertical direction to one side The slots form a curtain angle and due to reaction force the arms rotate at a rotational speed of 25-to-30 revmin

Drift eliminators An assembly constructed of wood plastic cement board or other material that serves to

remove entrained moisture from the discharged air Circulating Pump

The circulating pump transports the cooling water between the cooling tower and the condenser The water is pumped from the cooling tower basin through to the condenser where it is used as cooling medium The water returns back for evaporative cooling in the cooling tower Fan A device for moving air in a mechanical draft tower The fan design may be either an axial flow propeller or centrifugal blower Also may be applied as induced draft or forced draft Noticing that the induced type requires less power for same result Fills

Is the heart of the cooling tower The fill must provide good water-air contact area high rates of heat and mass transfer and low air flow resistance The fill also must be strong and deterioration resistant The fill has mainly two forms

minus Splash fill breaks falling water into small drops This Type is made of bars stacked in desks and may be narrow-edged square bars rough bars and grids Different materials are used such as redwood high-impact polystyrene or polyethylene

minus Film fill is made of vertical sheets that have a rough adsorbent surface and good wetness of water that allows water to fall as a film over the vertical surface Film fill has different forms and materials redwood battens cellulose corrugated sheets asbestos cement and waveform plastic

Water Basin Is situated beneath the tower collects and strains the water before pumped back to the circulating system Large utility tower basins are generally made of concrete Water leaves the basin via sloped canal at the bottom and through screens that prevent dust and foreign materials from entering the pump

Chapter 1

7 Cooling Tower Educational Stand BSc Project 2008

4 Water Treatment

The large variety of alternative construction materials allows users to match unit construction to the water quality available for their systems while helping to protect the tower from temporary upsets

Water treatment programs must be designed for three requirements

1 Scale control 2 Protection of system components against corrosion and 3 Control of biological contaminants such as Legionella pneumophilia the bacterium that causes

Legionnaires disease

The first two requirements help to ensure energy efficiency and longevity of the cooling system while the third ensures safe operation

Biological control is relatively easy to accomplish and is essential to the safe operation of the tower

Cooling towers can collect and concentrate airborne dirt and debris over time To control this buildup the cooling tower should be located so as to minimize contaminant induction and a proper blowdown rate should be maintained Sidestream filters or separators have proven valuable in this regard by effectively removing dirt and debris from the tower water These devices are coupled with a basin-sweeping nozzle package which is available either as original equipment in the tower or as a field-installed aftermarket item Cleaner tower water makes water treatment regimens more effective while keeping the cooling loop cleaner saving energy reducing maintenance and improving reliability of the entire cooling system

Chapter 2

8 Cooling Tower Educational Stand BSc Project 2008

Chapter Two

Literature review

In this chapter we will introduce the specifications of the cooling tower educational stand that manufactured by different companies like Gunt Armfield PA Hilton Edibon

1 Gunt

Fig (2-1) Gunt cooling tower educational stand

Column

Dimensions 150x150x630 mm

Pacing density 110 m2m3

Orifice diameter 80 mm

Approx weight 5 Kg

Heaters

3 stages 05-1-15 KW Thermostat switches off at 50⁰c

Fan

Radial fan - Power consumption 025 KW -max Differential pressure 430 pa

-max Flow rate 13 m3min

Chapter 2

9 Cooling Tower Educational Stand BSc Project 2008

Pump

-Power consumption 07 KW

-max Head 34 m

-max Flow rate 34 Lmin

Instrumentation

-Temp Sensors at air inlet ampoutlet

-Temp Sensors at water inletamp outlet

-Water flow rate sensor

-Humidity sensors at air inletamp outlet

Dimensions

Height 1228 m

Length 111 m

Width 046 m

Weight approx 90 Kg

Service required

Electrical -230 v 5060 HZ 1 phase

or -230 v 60 HZ 3 phases

Computeramp Data acquisition

Data acquisition with lab view software h-w diagram and Windows X-P

Chapter 2

10 Cooling Tower Educational Stand BSc Project 2008

2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

Chapter 2

11 Cooling Tower Educational Stand BSc Project 2008

Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 15: Cooling Tower Educational Standcairouniversity

Chapter 1

7 Cooling Tower Educational Stand BSc Project 2008

4 Water Treatment

The large variety of alternative construction materials allows users to match unit construction to the water quality available for their systems while helping to protect the tower from temporary upsets

Water treatment programs must be designed for three requirements

1 Scale control 2 Protection of system components against corrosion and 3 Control of biological contaminants such as Legionella pneumophilia the bacterium that causes

Legionnaires disease

The first two requirements help to ensure energy efficiency and longevity of the cooling system while the third ensures safe operation

Biological control is relatively easy to accomplish and is essential to the safe operation of the tower

Cooling towers can collect and concentrate airborne dirt and debris over time To control this buildup the cooling tower should be located so as to minimize contaminant induction and a proper blowdown rate should be maintained Sidestream filters or separators have proven valuable in this regard by effectively removing dirt and debris from the tower water These devices are coupled with a basin-sweeping nozzle package which is available either as original equipment in the tower or as a field-installed aftermarket item Cleaner tower water makes water treatment regimens more effective while keeping the cooling loop cleaner saving energy reducing maintenance and improving reliability of the entire cooling system

Chapter 2

8 Cooling Tower Educational Stand BSc Project 2008

Chapter Two

Literature review

In this chapter we will introduce the specifications of the cooling tower educational stand that manufactured by different companies like Gunt Armfield PA Hilton Edibon

1 Gunt

Fig (2-1) Gunt cooling tower educational stand

Column

Dimensions 150x150x630 mm

Pacing density 110 m2m3

Orifice diameter 80 mm

Approx weight 5 Kg

Heaters

3 stages 05-1-15 KW Thermostat switches off at 50⁰c

Fan

Radial fan - Power consumption 025 KW -max Differential pressure 430 pa

-max Flow rate 13 m3min

Chapter 2

9 Cooling Tower Educational Stand BSc Project 2008

Pump

-Power consumption 07 KW

-max Head 34 m

-max Flow rate 34 Lmin

Instrumentation

-Temp Sensors at air inlet ampoutlet

-Temp Sensors at water inletamp outlet

-Water flow rate sensor

-Humidity sensors at air inletamp outlet

Dimensions

Height 1228 m

Length 111 m

Width 046 m

Weight approx 90 Kg

Service required

Electrical -230 v 5060 HZ 1 phase

or -230 v 60 HZ 3 phases

Computeramp Data acquisition

Data acquisition with lab view software h-w diagram and Windows X-P

Chapter 2

10 Cooling Tower Educational Stand BSc Project 2008

2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

Chapter 2

11 Cooling Tower Educational Stand BSc Project 2008

Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 16: Cooling Tower Educational Standcairouniversity

Chapter 2

8 Cooling Tower Educational Stand BSc Project 2008

Chapter Two

Literature review

In this chapter we will introduce the specifications of the cooling tower educational stand that manufactured by different companies like Gunt Armfield PA Hilton Edibon

1 Gunt

Fig (2-1) Gunt cooling tower educational stand

Column

Dimensions 150x150x630 mm

Pacing density 110 m2m3

Orifice diameter 80 mm

Approx weight 5 Kg

Heaters

3 stages 05-1-15 KW Thermostat switches off at 50⁰c

Fan

Radial fan - Power consumption 025 KW -max Differential pressure 430 pa

-max Flow rate 13 m3min

Chapter 2

9 Cooling Tower Educational Stand BSc Project 2008

Pump

-Power consumption 07 KW

-max Head 34 m

-max Flow rate 34 Lmin

Instrumentation

-Temp Sensors at air inlet ampoutlet

-Temp Sensors at water inletamp outlet

-Water flow rate sensor

-Humidity sensors at air inletamp outlet

Dimensions

Height 1228 m

Length 111 m

Width 046 m

Weight approx 90 Kg

Service required

Electrical -230 v 5060 HZ 1 phase

or -230 v 60 HZ 3 phases

Computeramp Data acquisition

Data acquisition with lab view software h-w diagram and Windows X-P

Chapter 2

10 Cooling Tower Educational Stand BSc Project 2008

2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

Chapter 2

11 Cooling Tower Educational Stand BSc Project 2008

Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 17: Cooling Tower Educational Standcairouniversity

Chapter 2

9 Cooling Tower Educational Stand BSc Project 2008

Pump

-Power consumption 07 KW

-max Head 34 m

-max Flow rate 34 Lmin

Instrumentation

-Temp Sensors at air inlet ampoutlet

-Temp Sensors at water inletamp outlet

-Water flow rate sensor

-Humidity sensors at air inletamp outlet

Dimensions

Height 1228 m

Length 111 m

Width 046 m

Weight approx 90 Kg

Service required

Electrical -230 v 5060 HZ 1 phase

or -230 v 60 HZ 3 phases

Computeramp Data acquisition

Data acquisition with lab view software h-w diagram and Windows X-P

Chapter 2

10 Cooling Tower Educational Stand BSc Project 2008

2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

Chapter 2

11 Cooling Tower Educational Stand BSc Project 2008

Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 18: Cooling Tower Educational Standcairouniversity

Chapter 2

10 Cooling Tower Educational Stand BSc Project 2008

2 Armfield

Fig (2-2) Armfield cooling tower educational stand

Column

Dimensions150x150x600 mm

Pacing density110 m2m3 (10 plates)

Heaters

Maximum working temperature 50⁰c

Chapter 2

11 Cooling Tower Educational Stand BSc Project 2008

Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 19: Cooling Tower Educational Standcairouniversity

Chapter 2

11 Cooling Tower Educational Stand BSc Project 2008

Fan

Centrifugal fan Maximum air flows 006 Kgs-1

Instrumentation

-thermocouple with digital read out

-Variable area flow meter with control valve

-Inclined manometer for orifice differential pressure measurement

Dimensions

Height 12 m

Length 095 m

Width 06 m

Weight approx 130 Kg

Volume 07 m3

Service required

Electrical -220-240 v1 ph50 HZ

or -120 v1 ph60 HZ

Water 2 Lhr distilled

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 20: Cooling Tower Educational Standcairouniversity

Chapter 2

12 Cooling Tower Educational Stand BSc Project 2008

3 P A Hilton

Fig (2-3) PAHilton cooling tower educational stand

Column

Dimensions 150x150x60 mm

Pacing density 110 m2m3 transparent PVC

Orifice diameter 80 mm

Heaters

05 amp1 KW

Instrumentation

-digital temp indicator with channel selector switch for all wet bulb dry bulb amp water temp variable area water temp flow meter amp manometer air flow

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 21: Cooling Tower Educational Standcairouniversity

Chapter 2

13 Cooling Tower Educational Stand BSc Project 2008

Dimensions

Height 112 m

Length 082 m

Width 073m

Weight approx 56 Kg

Gross weight app 96 Kg

Volume 076 m3

Service required

Electrical -16 KW 220-240 v 1 ph 50 HZ (with earth ground)

or -16 KW 110-220 v 1 ph 60 HZ (with earth ground)

Water demineralised or distilled approx 2 Kghr

Computeramp Data acquisition

An optional Data Acquisition Upgrade HC892A comprising of an electronic data logger menu driven software and all necessary transducers allow all relevant parameters to be simultaneously displayed and recorded on a suitable PC

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 22: Cooling Tower Educational Standcairouniversity

Chapter 2

14 Cooling Tower Educational Stand BSc Project 2008

4 Edibon

Fig (2-4) Edibon cooling tower educational stand

Column

Dimensions Total surface 1915 m2 Height of packaging 650 mm Pacing density 58 m2m3 (10 plates)

Dimensions

Height 14m

Length 1 m

Width 045 m

Weight approx 100 Kg

Service required

Electrical -220V50 Hz or 110 V 60 Hz directly from the mains

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 23: Cooling Tower Educational Standcairouniversity

Chapter 2

15 Cooling Tower Educational Stand BSc Project 2008

Computeramp Data acquisition

PCI Data acquisition board (National Instruments) to be placed in a computer slot Bus PCI

Analog input Number of channels= 16 single-ended or 8 differential

Resolution=16 bits 1 in 65536

Sampling rate up to 250 KSs (Kilo samples per second)

Input range (V)= 10V

Data transfers=DMA interrupts programmed I0 Number of DMA channels=6

Analog output Number of channels=2

Resolution=16 bits 1 in 65536

Maximum output rate up to 833 KSs

Output range(V)= 10V

Data transfers=DMA interrupts programmed I0

Digital InputOutput

Number of channels=24 inputsoutputs

D0 or DI Sample Clock frequency 0 to 1 MHz

Timing Countertimers=2

Resolution Countertimers 32 bits

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 24: Cooling Tower Educational Standcairouniversity

Chapter 3

16 Cooling Tower Educational Stand BSc Project 2008

Chapter Three

Cooling Tower Design Calculation

1 Column The column is divided into two parts as follows -The column body

The column body Fig (31) is an important component of the cooling tower at which the water and air interface where heat and mass exchange occur The column material was manufactured from transparent plastic to allow viewing of water through the system It is oppened from endes to allow the water and air movement inside it also to insert and renise fill from it eassly

Column dimension estimation

The inlet air conditions Tai=35⁰C=308 K Pai=1013 kPa RHi=40

Fig(31) columnbody

ρai =Pai

R times Tai

Where ρai Air inlet densitykgm3 Pai Air inlet pressurekPa

Tai Air inlet temperatureK R universal constant

ρai =1013 times 103

287 times 308yields⎯⎯ ρai = 115 kgm3

Assume air flow rate to berarr Vblower = 13 m3min

mblower = Vblower times ρai

mblower =1360

times 115yields⎯⎯ mblower = 024 kgs

From psychrometric chart at 35⁰c dry bulb temperature and 40 relative humiditythe humidity ratio ψai=001414 kgkgda and wet bulb temperature wbtai=239⁰C

mda = mblower

1 + ψai

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 25: Cooling Tower Educational Standcairouniversity

Chapter 3

17 Cooling Tower Educational Stand BSc Project 2008

mda =024

1 + 001414

mda = 0238 kgs

Where mda Dray air mass flow rate kgs

The cooling tower characteristics (KaVL) specifies the size of the tower necessary to achevie the maximum possible effectiveness

The cooling tower characteristicsas a whole are function of cooling range tower approach ambient wet bulb temperature and fluid flow ratiothese cooling tower characteristics represents also at the same time the fill characteristics required for a spacified jobthe fill characteristics should be equal to the fill performance which is a function of fluid flow ratio for a given matrix

As the evaluation of the cooling tower characteristics is time consuming procudure in practice this is avoided by using the charts available by the Cooling Tower institute in Houston In these charts the tower characteristic are expressed in terms of the cooling rangetower approach ambient wet bulb temperature and the flow ratio

Design conditions

- Twi=50⁰C - Two=45⁰C - Wbtai=239⁰C

- Vw=2 lmin - ρw=1000 kgm3

mw = Vw times ρw =2 times 10minus3

60times 1000

mw = 00333 kgs Where Vw Water volumetric flow rate m3s ρw Water density kgm3 there4 L=00333 kgs ldquototal water mass flow raterdquo G=0238 kgs ldquototal air mass flow raterdquo

LG

=Lprime

Gprime =003330238

= 014

Where Lprime Water loading kgm2 s Gprime Air loading kgm2 s

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 26: Cooling Tower Educational Standcairouniversity

Chapter 3

18 Cooling Tower Educational Stand BSc Project 2008

Note The cross section area at which the air pass equal to that thwe water pass in counter flow

cooling tower so rarrLG

= L prime

G prime Approach= Two-Wbtai Approach=35-239 Approach=211⁰C=3816 ⁰F Cooloing Range (CR)=Twi-Two=50-45 CR=5 ⁰C=9 ⁰F From the characteristic curves Appendix (6) the required cooling range doesnrsquot exist Hence make interpolation

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=18 ⁰F=10 ⁰C rarrKaVL

= 024

From Appendix (6) at L prime

G prime = 014 Approach=3816 ⁰F and CR=22 ⁰F=122⁰C rarrKaVL

= 027

From Appendix (6) at L prime

G prime=014 Approach=3816 ⁰F and CR=26 ⁰F=144 ⁰C rarrKaVL

= 036

By interpolation using Appendix (6) at CR=9 ⁰F=5 ⁰C KaV

L= 017 rarr(1)

By using table (31) and assuming Height (Y)=3 ft=09144m we get Constants C=05 m=009 n=091 Substituting in the following equation K a = c (L)m (G)n

K a =05 (00333)009 (0238)091

K a =00997 rarr(2) By substituiting (2) in (1) we get

KaVL

= 017

00997 times V

00333= 017

yields⎯⎯ V = 00568 m3

V = A times Y

A =0056809144

= 0062 m2

A cong 025 times 025 m2 So the column dimensions will be 250times250times 900 mm3

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 27: Cooling Tower Educational Standcairouniversity

Chapter 3

19 Cooling Tower Educational Stand BSc Project 2008

-The column cap Itrsquos the upper component of the column The spray nozzle drift eliminator and the humidity and exit air tempreature sensors are located in the cap Hence the cap hieght mustnrsquot be long and itrsquos cross section equal to that of the column body The cap dimensions=250times250times200 mm3

Fig (32) column cap -The packingfill and drift elimenator The packing(Fig 33) used to increase the area of content between the air and water The packing surface is corecated of PVC material The fill spacing shown inFig (34) The drift elimenator Fig(35) is placed in the air exit way to decrease the water droplets carried by air

Fig (34) Fill spacing

Fig (33) Packing

Fig (35) Drift eliminator

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 28: Cooling Tower Educational Standcairouniversity

Chapter 3

20 Cooling Tower Educational Stand BSc Project 2008

2 Cooling tower performance Water Twi=50⁰C Two=45⁰C mw = 00333 kgs Cpw=418 kJkg C Air in Tai=35⁰C RHai=40 mda = 0238 kgs

From psychrometric chart Wbtai=239⁰C Ψai=001414 kgkgda hai=7149 kJkg

Cooling range and approach obtained

CR=Twi-Two=50-45=5⁰C

Approach= Two-Wbtai=35-239=211⁰C

QCT = mw times Cpw times CR Where

QCT Cooling tower load mw Water flow rate Cpw specific heat at constant pressure

QCT = 0033 times 418 times 5

QCT = 07 kW

QCT = mda times (hao minus hai )

07 = 0238 times (hao minus 7149)

hao = 7442 kJkgda From psychrometric at hao = 7442 kJkgda and RHao=100

Tao=239⁰C Ψao=001877 kgkgda

mevap = mda (ψao minus ψai )

mevap = 0238(001877 minus 001414)

mevap = 110194 times 10minus3kgs

ϵ =Twi minus Two

Twi minus Wbtai

ϵ =50 minus 45

45 minus 239times 100

ϵ = 23697

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 29: Cooling Tower Educational Standcairouniversity

Chapter 3

21 Cooling Tower Educational Stand BSc Project 2008

3 Tanks i Water tank

In the educational stand cooling tower the water tank considered as the heat load component (condenser) water is heated by an immersion heaters fitted from the back of tank The heaters are metal tubes containing an insulated electric resistance heater which provide heat load about 15 kilowatts

The water return pipe contains twelve holes to provide good mixing of cold and hot water

The tank was attached with eye glass to determine the level of water in the tank

There is a baffle inside the tank to make good mixing of the hot water and cold water coming from the column

Tank capacity estimation

119876119876 = 119898 times 119862119862119862119862 times ∆119879119879

119898 = 120588120588 times119881119881119905119905

Where

Q Heaters power kW 119898 Mass flow rate kgs CP water specific heat kJkg K ΔT Temperature difference ⁰C

ρ Water density kgm3 V Water volume m3 t time need to heat the water sec

Q=15 kW

∆119879119879 = 119891119891119891119891119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905 119905119905119905119905119903119903119905119905119891119891119905119905119905119905119903119903 minus 119891119891119891119891119905119905119891119891119905119905119891119891119891119891119891119891 119905119905119905119905119898119898119862119862119905119905119905119905119891119891119905119905119905119905119905119905119905119905

∆119879119879 = 50 minus 25 = 25deg119862119862

Cp=418 kJkg K

t=25 min

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 30: Cooling Tower Educational Standcairouniversity

Chapter 3

22 Cooling Tower Educational Stand BSc Project 2008

Q = 120588120588 times119881119881119905119905

times 119862119862119862119862 times ∆119879119879

15 = 1000 times119881119881

25 times 60times 418 times 25

119910119910119891119891119905119905119891119891119903119903119910119910⎯⎯⎯ 119881119881 = 00215 1198981198983

V cong 025 times 025 times 035 m3

The tank dimension = 250 times 250 times 450 mm3

Fig (31) Water tank main dimensions(dimensions in cm)

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

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Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

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Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 31: Cooling Tower Educational Standcairouniversity

Chapter 3

23 Cooling Tower Educational Stand BSc Project 2008

ii Air Tank

Air tank is designed to deliver the air from the blower also to hold the column and allow air to be introduced into the column

So its dimensions must be suitable for carrying the column and also not large to force air to accelerate in the column (ie velocity is inversely proportional with area)

Design requirements-

bull Air velocity inside the tank doesnrsquot exceed 4ms to reduce the friction losses inside the tank

bull Take in consideration that the drain tank dimensions (2525) bull Air flow upward around drain to the column and the area must be sufficient to the

velocity not exceed 4 ms bull The air tank must be higher than the water tank to give the chance to support the drain

inside to let the water flow the drain to the water tank bull When the water tank have the water at level 40 cm from the ground and the drain must

have at least 7 cm to let air flow from the air tank to the column bull Hence the air tank will be 50 cm height and then the area around the drain as flow

Q = Av

1360

= A lowast 4

A = 054167m2

Aaround drain + Adrai n = 0341 lowast 0341

Let the air tank dimensions to be 04 lowast 04 lowast 05 m

And at this condition

v =13

60042 minus 0352 = 2222 m sfrasl

Acceptable velocity

iii Make up tank

Is used to supply the system by the water loosest due to evaporation drift and blow down The makeup water is piped to the water tank and at the end of the pipe a float valve exists to keep water level in the water tank constant

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

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Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

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Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

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Appendix -3-

Moody Chart

Appendix

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Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

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Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

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Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

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90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

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Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 32: Cooling Tower Educational Standcairouniversity

Chapter 3

24 Cooling Tower Educational Stand BSc Project 2008

Assume that the makeup tank support the system with makeup water for 15 hour so the tank capacity can be calculated as follows

mevap =ρ times Vmakeup

t

11662 times 10minus3 =1000 times Vmakeup

15 times 60 times 60

yields⎯⎯ Vmakeup = 63 times 10minus3m3

Vmakeup = 185 times 185 times 185 cm3

So let the makeup tank dimensions to be 20times20times20 cm3

iv Drain tank

A tank that located in the air chamber under the column to collect the cooled water from the column and return it back to the water tank

The tank is designed to be with inclined base to accelerate the water over it to return quickly to the water tank to be heated and recirculated

Assume that the recirculated water to be stored in the drain tank for 25 minute so the drain tank capacity can be calculated as follows

mcirculated =ρ times Vdrain

t

00322 =1000 times Vdrain

25 times 60

yields⎯⎯ Vdrain = 0005 m3

The drain tank dimensions are shown in figure (32) the base inclination is to force the water to be discharged from the pipe

Fig (32) drain tank main dimensions(dimensions in cm)

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 33: Cooling Tower Educational Standcairouniversity

Chapter 3

25 Cooling Tower Educational Stand BSc Project 2008

4 Piping system and pump

-piping system

Piping system conveys water between tanks to complete circulation

Piping system includes

bull Pipe bull Fittings

- Three elbows - One nibble - Two boshes - Two screwed union - One T joint

bull Orifice plate with flanges bull Valves

- Check valve - Gate valve - Float valve

Drain line -

Design requirements-

bull Water velocity doesnrsquot exceed 007 msec bull Water flow rate 2litmin

Hence when V=007msec amp 119898119898119908=(130)Kgsec

A=119898119898119908120588120588 119881119881

= (130)1000lowast007

Where 119898119898119908 is the water flow rate amp A is the inner area of the pipe

119860119860 = 47619 lowast 10minus4 1198981198982

119863119863 = 47619 lowast 10minus4 lowast 4120587120587

= 00246 119898119898

The nearest standard diameter 119863119863 = 1 119891119891119891119891 = 00254119898119898

Then 119898119908119908 = 120588120588 119860119860 119881119881 V= 006578 msec

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 34: Cooling Tower Educational Standcairouniversity

Chapter 3

26 Cooling Tower Educational Stand BSc Project 2008

Losses WRT the velocity

ℎ119891119891 = ℎ119891119891119905119905119891119891119890119890119890119890119908119908 + ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 = 119865119865 119871119871 1198811198812

2 119892119892 119863119863

Where L is the pipe length amp 119865119865 = 1

2 log 37119877119877

2

Also 119877119877 = 119870119870119863119863

= 10254

F = 026405

119910119910119905119905119905119905119891119891119891119891119892119892ℎ119905119905 119891119891119891119891119891119891119905119905 119891119891119890119890119910119910119910119910119905119905119910119910 = 20634 lowast 10minus3

For the orifice with 119891119891 = 12 ℎ119890119890119891119891119905119905119910119910

Design requirements- Orifice total area gt pipe area For holes exit velocity lt in pipe velocity

Let (125) pipe area = sum holes area

119860119860ℎ119890119890119891119891119905119905119910119910 = (125)1205871205874

002542

119860119860_ℎ119890119890119891119891119905119905119910119910 = 6334810minus41198981198982

119905119905ℎ119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905 119890119890119891119891 119905119905119891119891119900119900ℎ ℎ119890119890119891119891119905119905 = 82 lowast 102119898119898

Which gives a velocity 119860119860ℎ119890119890119891119891119905119905 lowast 119907119907 = 119876119876ℎ119890119890119891119891119905119905 = 119903119903119905119905119890119890119905119905119891119891

Check the velocity through each hole

119907119907 =

119876119876119905119905119890119890119905119905 119891119891

119860119860ℎ119890119890119891119891119905119905= 00525 lt 119907119907119862119862119891119891119862119862119905119905 119898119898 119910119910frasl

ℎ119891119891 =1198961198961199071199072

2119892119892+1198911198911198911198911199071199072

2119892119892119863119863+119891119891119896119896(119907119907 ℎ119890119890119891119891119905119905frasl )2 lowast 2

2119892119892

029 lowast (006968)2

2 lowast 981+ 20634 lowast 10minus3 +

12 lowast 1 lowast (00525)2 lowast 22119892119892

ℎ119905119905119890119890119905119905 = 61717 lowast 10minus3 119898119898

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 35: Cooling Tower Educational Standcairouniversity

Chapter 3

27 Cooling Tower Educational Stand BSc Project 2008

Losses in make up tank-

119898119898119905119905119907119907 = 119898119898119898119898119905119905119862119862

= 4635 lowast 10minus4 119870119870119892119892 119910119910frasl 2

119891119891119890119890119905119905 12 119907119907119862119862119891119891119862119862119905119905 119903119903119891119891119891119891119898119898119905119905119905119905119905119905119905119905

119907119907 =4 lowast 4635 lowast 10minus4

1000 lowast 1205871205874 12 lowast 00254

2

119907119907 = 3659 lowast 10minus3 119898119898 119910119910frasl

119891119891119890119890119905119905 119905119905ℎ119905119905 119862119862119891119891119862119862119905119905 119891119891119905119905119891119891119892119892119905119905ℎ = 05 119898119898

119877119877 =01 lowast 200254

= 7864

119891119891 =1

2 log 37119877119877

2 = 0554

ℎ119891119891 =119891119891 lowast 119891119891 lowast 1199071199072

2119892119892119863119863 =

0554 lowast 05 lowast 36592 lowast 10minus6

2 lowast 981 lowast 05 lowast 00254= 1487 lowast 10minus5 119898119898

ℎ119907119907119891119891119891119891119891119891119907119907119905119905119910119910 =012 lowast (3659 lowast 10minus3)2

2 lowast 981= 818855 lowast 10minus8 119898119898

ℎ119891119891119905119905119890119890119905119905 = ℎ119891119891119862119862 + ℎ119891119891119907119907 = 14952 lowast 10minus5 119898119898

Pump discharge pipe head loss

Total head losses

119867119867119891119891 = ℎ119891119891119862119862119891119891119862119862119905119905 + ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 + ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 + ℎ119891119891119879119879 + ℎ119891119891119905119905119905119905119890119890119890119890119905119905119905119905 ℎ119890119890119910119910119905119905 + ℎ119891119891119891119891119890119890119899119899119899119899119891119891119905119905

ℎ119891119891119862119862119891119891119862119862119905119905 =1198911198911198911198911199071199072

2119892119892119863119863

119891119891 =1

2 log 37119877119877

2 = 026405 119908119908ℎ119905119905119905119905119905119905 119877119877 =01

00254

ℎ119891119891119862119862119891119891119862119862119905119905 =026405 lowast 18 lowast 006572

2 lowast 981 lowast 00254= 41167 lowast 10minus3 119898119898

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 36: Cooling Tower Educational Standcairouniversity

Chapter 3

28 Cooling Tower Educational Stand BSc Project 2008

ℎ119891119891119900119900ℎ119905119905119900119900119896119896119907119907119891119891119891119891119907119907119905119905 =119896119896 lowast 1199071199072

2119892119892=

25 lowast 006572

2 lowast 981= 55 lowast 10minus4 119898119898

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =1198961198961199071199072

2119892119892 119908119908ℎ119905119905119905119905119905119905 119896119896 119891119891119905119905 119890119890119891119891119905119905 119903119903119905119905119891119891119905119905119905119905119905119905119905119905 119890119890119862119862119905119905119891119891119903119903

ℎ119891119891119892119892119905119905119905119905119907119907119891119891119891119891119907119907119905119905 =24 lowast 006572

2 lowast 981= 528 lowast 10minus3 119898119898

ℎ119891119891119890119890119905119905119891119891119891119891119891119891119900119900119905119905 =82(00659)2

2 lowast 981= 18 lowast 10minus3 119898119898

ℎ119891119891119879119879 =09(026287)2

2 lowast 981= 316975 lowast 10minus3

Head losses across the nozzle by using of hand pump and measuring the pressure in the nozzle line we find that ΔP=2 bar

Using BE

1198621198621

120588120588119892119892+ 1198991198991 +

11990711990712

2119892119892=1198621198622

120588120588119892119892+ 1198991198992 +

11990711990722

2119892119892+ ℎ119891119891

(1198621198621 minus 1198621198622)120588120588119892119892

+ (1198991198991 minus 1198991198992) +1199071199071

2 minus 11990711990722

2119892119892= 119867119867119891119891

119908119908ℎ119905119905119905119905119905119905 1199071199071 = 0657119898119898 119910119910frasl

1199071199072 = 1883672119898119898 119910119910frasl

1198631198631 = 254 119900119900119898119898

1198631198632 = 015 119900119900119898119898

119867119867119891119891 = 1763 119898119898

119867119867119891119891119905119905119890119890119905119905 = (41167 + 055 + 528 + 18 + 316975) lowast 10minus3 + 1763

119867119867119891119891119905119905119890119890119905119905 = 177791645 119898119898

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 37: Cooling Tower Educational Standcairouniversity

Chapter 3

29 Cooling Tower Educational Stand BSc Project 2008

-pump

Used to circulate the water through the system and also to overcome the losses in the pipes and valves

the suitable Pump specifications are

bull Power 05 HP bull Max Flow 216 m3hr bull Min Flow 06 m3hr bull Max delivery head 325 m bull Min delivery head 5 m bull Power supply 230v 50Hz

4 Blower and Butter fly valve

-Blower

The Blower has to overcome the system resistance which is defined as the pressure loss to move the air The Blower output or work done by the Blower is the product of air flow and the pressure loss

Specifications Power supplies 230 V-50 HZ bull Power 100 W bull Flow rate 740 m3hr bull Pressure 473 Pa

Fig (33) Blower main dimensions

Blower dimensions

Type of ventilator Size mm Mass Kg Φ d DΦ C A B L E

VKMZ 160 200 344 240 25 25 350 40 66

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 38: Cooling Tower Educational Standcairouniversity

Chapter 3

30 Cooling Tower Educational Stand BSc Project 2008

-Butterfly valve

A butterfly valve figure (34) is from a family of valves called quarter-turn valves The butterfly is a metal disc mounted on a rod When the valve is closed the disc is turned so that it completely blocks off the passageway When the valve is fully open the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the process fluid The valve may also be opened incrementally to regulate flow

The butter fly used was fabricated to suit the blower suction diameter

Fig (34) butterfly valve

5 Water Injection Nozzles

Two spray nozzles attached to sprinkler pipe The nozzle atomizes water to increase the heat exchange and mass transfer between air and water also the nozzle must provide good water distribution over the column fill Fig(35) spray nozzles

The nozzle spray shape is cone 30⁰ angles with vertical

Fig(36) testing angle of nozzle spray

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 39: Cooling Tower Educational Standcairouniversity

Chapter 3

31 Cooling Tower Educational Stand BSc Project 2008

6 Stand

The table which will carry all cooling tower components

Length(cm) Width(cm) Height(cm) Air Tank 40 40 50

Water Tank

25 25 45

Fits and Tolerance

10 10 -

Display and Screen

100 - -

Column 25 25 150 Connection

Pipe 10 - -

Stand 200 50 182

sumLength= 175 Cm (Length of air tank) lt Length of Stand

Max Width = 40 Cm (width of air tank) lt width of Stand

Max Height = 150 Cm (height of column) lt Height of Stand

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 119908119908119905119905119891119891119891119891119896119896119910119910 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119862119862119905119905119898119898119862119862 + 119908119908119903119903119891119891119910119910119862119862119891119891119891119891119910119910 + 119908119908119908119908119890119890119890119890119903119903 + 119908119908119910119910119905119905119891119891119891119891119903119903

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 = 5 + 7 + 335 + 5 + 30 + 40 = 1205119870119870119892119892

Max Weight for wheel=200Kg

119879119879119890119890119905119905119891119891119891119891 119882119882119905119905119891119891119892119892ℎ119905119905 lt Max Weight for wheel

119878119878119891119891119891119891119905119905 119863119863119905119905119910119910119891119891119892119892119891119891

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 40: Cooling Tower Educational Standcairouniversity

Chapter 4

32 Cooling Tower Educational Stand BSc Project 2008

Chapter 4

Measurement devices and data acquisition system

1 Temperature measurements Three basic types of temperature measuring sensors

bull Thermocouples ndash Self Generating - Two metals joined together at a junction which generate a very small voltage (millivolts) which is a function of temperature Voltage goes up as temperature goes up

bull Resistance Temperature Devices (RTDs) ndash Resistive - Measuring the change of resistance in a piece of metal due to temperature Resistance goes up as temperature goes up

bull Thermistors ndash Resistive - Measuring the change in resistance in a semiconductor material due to temperature Resistance goes down as temperature goes up

bull Other methods exist ndash such as infrared detection and bimetallic strips

Characteristic Thermocouple RTD Thermistor

Excitation Self-Generating External Required External Required

Output Signal millivolts Typically volts for coarse measurements Can be millivolts for high accuracy

Typically Volts Can be millivolts for high accuracy

GroundNoiseError Floating susceptibility to noise

Grounded susceptible to lead wire resistance

Grounded susceptible to lead wire resistance

Signal Increase with temperature

Increases with temperature

Decreases with temperature if NTC Increases with PTC

Range - 200 deg c to +1200 deg C depending on type

-200 to +800 DegC for platinum

-100 to + 200 DegC

Prorsquos Inexpensive and rugged

Stability and linearity High Sensitivity

Conrsquos Floating measurement requires careful attention

Expense Slow Response Time Low Sensitivity Self Heating

Smaller Temperature Range NonLinear Self Heating

Table (41) Comparison Of Sensing Methods

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 41: Cooling Tower Educational Standcairouniversity

Chapter 4

33 Cooling Tower Educational Stand BSc Project 2008

Resistance Temperature Detectors (RTDs) ndash a device used to relate change in resistance to change in temperature Typically made from platinum the controlling equation for an RTD is given by

119877119877119879119879 = 119877119877119900119900[1 + 120572120572 (119879119879 minus 119879119879119900119900)]

RT is the resistance of the RTD at temperature T (measured in degC) R0 is the resistance of the RTD at the reference temperature T0 (usually 0degC)

120572120572 s the temperature coefficient of the RTD

Platinum wire-wound detectors comprise a pure platinum wire wound into a miniature spiral and located within axial holes in a high purity alumina rod The freedom of movement of the platinum wire gives good long term stability Specifications Ro 100 Ohms Temperature range -200 to +800degC

PT100

Fig (41) Resistance Temperature curve for PT 100

Table (42) Resistance VS temperature and tolerance for PT100

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 42: Cooling Tower Educational Standcairouniversity

Chapter 4

34 Cooling Tower Educational Stand BSc Project 2008

2 Humidity sensors Is composed of a resistance where its ohm varies with the humidity of air General Description The EWHS 280 humidity sensor is a probe designed to be connected to a humidity measuring device Output signal is a current signal (420 mA) Specifications

Power input 9 ndash 28 Volt DC Measurement range 15 ndash 100 Maximum Load 250 Ohm Accuracy +- 5

3 Flow Measurements

31 Pipe Flow rate Meters

Fig (42) orifice plate

Three of the most common devices used to measure the instantaneous flow rate in pipes are The orifice meter the nozzle meter and the Venturi meter Each of these meters operates on the principle that a decrease in flow area in a pipe causes an increase in velocity that is accompanied by a decrease in pressure Correlation of the pressure difference with the velocity provides a means of measuring the flowrate In the absence of viscous effects and under the assumption of a horizontal pipe application of both the Continuity and Bernoulli equations between points (1) and (2) shown in the following figure gave

Fig(43) Typical pipe flow meter geometry

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 43: Cooling Tower Educational Standcairouniversity

Chapter 4

35 Cooling Tower Educational Stand BSc Project 2008

Qideal = A2V2 = A22∆Pρ

A typical orifice meter is constructed by inserting between two flanges of a pipe a flat plate with a hole The pressure at point (2) within the vena contracta is less than that at point (1) Nonideal effects occur for two reasons First the vena contracta area (A2) is less than the area of the hole (A0) by an unknown amount Thus A2=KA0 where Cc is the contraction coefficient (Cclt1) Second the swirling flow and turbulent motion near the orifice plate introduce a head loss that cannot be calculated theoretically Thus an orifice discharge coefficient K is used to take these effects into account That is

119876119876 = 119870119870119876119876119894119894119894119894119894119894119894119894119894119894 = 11987011987011986011986002∆119875119875120588120588

Where 1198601198600 = 12058712058711989411989424 is the area of the hole in the orifice plate The value of C0 is a function of 120573120573 = 119894119894119863119863 and the Reynolds number = 120588120588120588120588119863119863120583120583 where 120588120588 = 1198761198761198601198601 Typical values of C0

Fig (44) Typical pipe flow meter geometry

Fig (45) Typical orifice meter construction

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 44: Cooling Tower Educational Standcairouniversity

Chapter 4

36 Cooling Tower Educational Stand BSc Project 2008

are given in Appendix(3) Note that the value of K depends on the specific construction of the orifice meter (ie the placement of the pressure taps whether the orifice plate edge is square or beveled etc) Very precise conditions governing the construction of standard orifice meters have been established to provide the greatest accuracy possible Orifice Design Operating flow rate 120588 = 2 119894119894119898119898119894119894119898119898

= 3333 lowast 10minus5 1198981198983119904119904119894119894119904119904 119863119863 = 254 119898119898119898119898

120573120573 = 02 =119894119894119863119863

We assumed β a small value in order to obtain a large pressure drop over the orifice giving a more clearer reading by the differential pressure transmitter

119860119860119875119875119894119894119875119875119894119894 =1205871205874

(119863119863)2 = 50671 lowast 10minus4 1198981198982

120588120588119875119875119894119894119875119875119894119894 = 120588120588119860119860

= 006578 119898119898119904119904119894119894119904119904

119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 =1205871205874

(119894119894)2 = 202683 lowast 10minus5 1198981198982

120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 = 1645 119898119898119904119904

1198771198771198941198940 =120588120588120588120588119900119900119900119900119894119894119900119900119894119894119904119904119894119894 119894119894

120583120583=

988 lowast 1645 lowast 000508547 lowast 10minus4 = 1509004

From chart (according to ASME standard) 120573120573 = 02 119877119877119894119894 = 1509004 Therefore 119870119870 = 0605

119876119876 = 119870119870119860119860119900119900119900119900119894119894119900119900119894119894119904119904119894119894 2∆119875119875120588120588

120588 = 0605 lowast 20268 lowast 10minus5 lowast 2∆119875119875988

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 45: Cooling Tower Educational Standcairouniversity

Chapter 4

37 Cooling Tower Educational Stand BSc Project 2008

120588 = 55169976 lowast 10minus7radic∆119875119875

333 lowast 10minus5 = 55169979 lowast 10minus7radic∆119875119875

there4 ∆119875119875 = 36432 119875119875119894119894 = 36432 119870119870119875119875119894119894

Theoretical reading = 053 psi Error plusmn 2 Error = 5 002 = 01 Actual reading = 053 plusmn 01 = 063 = 043 (for 2 lmin water)

Error analysis = 01

053 = 188

4- Displays

Microprocessor based and fully programmable process controllers for single setpoint applications the output provides ON-OFF and analog output 4-20 mA

Fig(46) Display connection diagram

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 46: Cooling Tower Educational Standcairouniversity

Chapter 4

38 Cooling Tower Educational Stand BSc Project 2008

5-Data Acquisition

Fig(47) schematic diagram for DAQ card connection

It is a basic AD converter that allows a personal computer to control its actions also computer acquires the

values of the Analog or digital signals being processed A data acquisition card plugs directly into a PC bus like PCI or USBhellipetc

Analog Signal ndash any value

continuously within the range

continuous over time

Digital Signal ndash Maps to one of eight discrete values at only

has those values at discrete times that it was sampled and

converted

Elements of an End to End Data Acquisition System bull TransducerSensor

ndash May generate their own electrical signal (thermocouple or piezoelectric) or require external excitation (power)

ndash Converts one physical Quantity Under Measurement (QUM) into another ndash Typical output is in volts to microvolts

bull Data Acquisition Unit (DAU) ndash Samples and holds ndash Digitizes ndash Multiplexes (combines with other measurements) ndash Converts for transmission ndash Transmits ndash Typical output is in binary digits (bits)

bull Recording Storage and Display

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 47: Cooling Tower Educational Standcairouniversity

Chapter 4

39 Cooling Tower Educational Stand BSc Project 2008

Example Temperature Measurement fig (48) bull TransducerSensor is Platinum Resistance Temperature Detector (RTD) bull Signal Conditioning is power supply for excitation (power) and resistor to complete the circuit bull Data Acquisition fig (49)Unit is the NI 6008 bull It communicates over a Universal Serial Bus (USB) to the laptop computer bull The laptop Computer is running a LabVIEW Virtual Instrument (VI) bull Example is RTD Acq One Sample w loop and waveform chartvi

Fig (48) Example for temperature measurement Unit installation

Fig(49) DAQ Unit installation

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 48: Cooling Tower Educational Standcairouniversity

Chapter 4

40 Cooling Tower Educational Stand BSc Project 2008

51 Data acquisition system software (LAB VIEW)

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text-based programming languages where instructions determine the order of program execution LabVIEW uses dataflow programming where the flow of data through the nodes on the block diagram determines the execution order of the VIs and functions VIs or virtual instruments are LabVIEW programs that imitate physical instruments

In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects This graphical source code is also known as G code or block diagram code The block diagram contains this code In some ways the block diagram resembles a flowchart

Fig (410) Illustration for interface of LABVIEW

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 49: Cooling Tower Educational Standcairouniversity

Chapter 4

41 Cooling Tower Educational Stand BSc Project 2008

52 Electronic connections

In figure (411) the sensor sends signals to the display unit in turn the display transmits an analog output signal 4 ~ 20 mA a resistance is needed since the DAQ only accepts Voltage analog signal of range -10 ~ 10 Volt

Preferring a range from 1 ~ 5 Volt a resistance is required to be put in parallel

Returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

Also assuming minimum values for both V and I

1 = 4 times 10minus3 times 119877119877

Therefore the required resistance will be

119877119877 = 250 Ω

Due to there is no standard resistance 250 Ω we selected the nearest available resistance 270 Ω By recalculating the voltage range it varied to become 108 ~ 54 Volt

We programmed the display unit to transmit a minimum signal of 4 mA corresponding to 10 degC and a

maximum signal of 20 mA corresponding to 70degC

Fig(411) wiring diagram for temperature measurements

For the humidity sensor there was no display with analog output available in the market and the available

sensor had one terminal wire therefore we added a resistance in series with joining the resistance terminals with the sensorrsquos output wires and the display creating a voltage variation across the resistance terminals transmitted to the DAQ Figure (412 ) illustrates the previous operation

Fig (412) wiring diagram for Humidity measurements

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 50: Cooling Tower Educational Standcairouniversity

Chapter 4

42 Cooling Tower Educational Stand BSc Project 2008

Fig (413) solving the analog output problem for the humidity sensors

Fig(414) rear view of the temperature display showing ampere to volt conversion

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 51: Cooling Tower Educational Standcairouniversity

Chapter 4

43 Cooling Tower Educational Stand BSc Project 2008

53 Data Acquisition programming

1 For programming temperature values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119879119879 = 119894119894120588120588 + 119887119887

abconstants Ttemperature (degC) Vvoltage

Initial conditions I V=108 Volt at T=10degC

II V=54 Volt at T=70degC

10 = 108119894119894 + 119887119887 (1)

70 = 54119894119894 + 119887119887 (2) By solving equations (1) and (2)

a=138889 b= -5 Therefore the final equation is

119879119879 = 138889120588120588 minus 5

Fig(415) snapshot from LABVIEW

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 52: Cooling Tower Educational Standcairouniversity

Chapter 4

44 Cooling Tower Educational Stand BSc Project 2008

2 For humidity sensor its maximum load = 250 Ω therefore the required resistance should be higher than 250 Ω In order to avoid producing high ampere causing damage to sensor So the resistance added is 300Ω

Determining the maximum and minimum voltages and returning to Ohmrsquos law

120588120588 = 119868119868 times 119877119877

120588120588119898119898119894119894119898119898 = 119868119868119898119898119894119894119898119898 times 119877119877 120588120588119898119898119894119894119898119898 = 3 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 09 120588120588119900119900119894119894119881119881 120588120588119898119898119894119894119898119898 = 18 times 10minus3 times 300

120588120588119898119898119894119894119898119898 = 54 120588120588119900119900119894119894119881119881 Due to signal splitting there are some errors in the two signals one for display and other for data acquisition card So calibration must be done for both of them by an accurate device

For programming humidity values on LABVIEW we programmed the DAQ card to translate the voltage signal to temperature values having a linear relation between voltage and temperature

119877119877119877119877 = 119894119894120588120588 + 119887119887

abconstants RHRelative humidity () Vvoltage

Initial conditions III V=09 Volt at RH=15 IV V=54 Volt at RH=90

15 = 09119894119894 + 119887119887 (1)

90 = 54119894119894 + 119887119887 (2)

By solving equations (1) and (2)

a=1666667 b= 0 Therefore the final equation is

119877119877119877119877 = 1666667119894119894

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 53: Cooling Tower Educational Standcairouniversity

Chapter 4

45 Cooling Tower Educational Stand BSc Project 2008

Fig (416) snapshot from LABVIEW illustrating variation of humidity signal with voltage

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 54: Cooling Tower Educational Standcairouniversity

Chapter 4

46 Cooling Tower Educational Stand BSc Project 2008

6- Calibration

1 Humidity sensor 11 Inlet humidity sensor

Humidity sensor without

analog output Humidity sensor with

analog output DAQ reading Hygrometer

57 53 3266 587 65 61 4101 665 70 66 45834 72 76 72 51334 785 83 79 58765 843 90 85 64789 918 100 95 76122 100

Fig(417) inlet Humidity sensor calibration table

After updating the humidity sensor to give an output signal to the DAQ card there is a zero error = -4 so we calibrated the display to increase the displayed value about 4 to give the actual reading Ex Measured value = 50 so the display will indicate 54 In the DAQ reading there is a zero error = -25 therefore calibrated to increase the indicated value a 25 to give actual reading

12 Outlet humidity sensor

Humidity sensor without analog output

Humidity sensor with analog output

DAQ reading Hygrometer

57 52 293453 587 65 60 39014 672 70 65 44134 733 76 71 50334 779 83 72 56765 831 90 85 62789 924 100 95 74724 100

Fig(418) outlet Humidity sensor calibration table

For the displays the calculated error = -5 while the DAQ reading has a zero error = -265

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 55: Cooling Tower Educational Standcairouniversity

Chapter 4

47 Cooling Tower Educational Stand BSc Project 2008

2 Temperature sensor

Thermocouple K-Type degC PT 100 class B sensor degC DAQ Reading degC 30 302 299 40 405 402 50 507 506 60 605 601 70 702 70002 80 803 8007 90 907 904 100 100 10004

Fig(419) PT 100 sensor calibration table We see that the DAQ reading is less than the PT 100 sensor for about 03 degC and this is more accurate than the sensor display because Sensor display has a sampling rate for about 10 samples per sec but the DAQ card has sampling rate 1000 samples per sec

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 56: Cooling Tower Educational Standcairouniversity

Chapter 5

48 Cooling Tower Educational Stand BSc Project 2008

Chapter Five

Bill of Materials and Cost

SERIAL NO

Item no Item name

Quantity

Make or Buy

Description amp Specifications

Material price per each(LE)

total price (LE)

1 100 Stand 1 make

steel 7905 7905 11 101 Frame 1 make

steel 5455 5455

12 103 wheels 4

buy 4 wheels carry up to 200 Kg

55 220

13 105 Bords 2 buy 122x244 (m) Formica 350 700 14 109 Al edges 1 buy

Aluminum 30 30

15 Staneless steel 1 buy 60x60 cm stst 1584 1584 16 Cutting cup set 1 buy

715 715

2 200 Tanks

make

steel 0 21 203 Metal sheets 1 make

steel 1865 1865

22 Gaskets 1 buy

495 495 23 Teflon 4 buy

2 8

24 Silicon 2 buy

45 90 3 300 Heaters

3 buy 05 KWlength=

flange diameter= 2905 8715

4 400 Column 1 make

PVC 720 720 41 401 Column body 1 make dimensions 25x25x113 cm PVC 0 0 5 406 cap 1 make dimensions 25x25x20 cm PVC 0 0

51 500 Metal connections 6

buy

0

52 501 Butter fly valve 1 buy 3 60 60 53 502 Drain valve 1 buy

0

54 Gate valve 1

buy D=34 Oriffice Dia=20mm

copper 33 33

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 57: Cooling Tower Educational Standcairouniversity

Chapter 5

49 Cooling Tower Educational Stand BSc Project 2008

55 Check valve 1 buy

copper 26 26 56 Float valve 1 buy

plastic 15 15

57 Gelb 3 buy 125 iron 26125 78375 58 Gelb 2 buy 15 iron 33 66 59 Gelb 1 buy 05 20 20

511 screws+nuts 20 buy

iron 4 80 511 screws+nuts 1 buy no of units=52 stst 9835 9835 57 nozzles 2 make

copper 60 120

58 Welding rods 2 buy

27 54 511 Sight glass 1 buy

copper 122 122

512 Elbow 1 buy 1 90 deg 44 44 513 Copper rod 1 buy 19mm Hexagonal copper 45 45

6 Copper rod 1 buy 3mm dia copper 7 7 7

Blower 1 buy flow rate max=740

(m^3hr) 7107 7107

71 pumping system

make

0 72 pump 1 buy P=05 hp Hmax=35 m Qmax=35 Lmin 230 230 73 pipes 1 buy 15 m length steel 35 35 74 Hose 1 buy 6 m length 10 Bar PVC 5635 5635 8 Nozzle 1 make

copper 120 120

81 Electronics

buy

0 81-1 Displays 6 buy

0

81-2 Temp display for air 2

buy

880 1760

81-3 Temp display for water 2

buy

880 1760

82 Humidity display+Sensors 2

buy

2200 4400

82-2 sensors

buy

0 82-3 Air temp sensor 2 buy PT 100 platinum 2057 4114

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 58: Cooling Tower Educational Standcairouniversity

Chapter 5

50 Cooling Tower Educational Stand BSc Project 2008

82-4 Water temp sensor 2

buy PT 100

platinum 2057 4114

82-5 Orifice Meter 1 buy

stainless 1100 1100 84 Tempreature

Controller 3 buy

PT 100 2002 6006

85 Circuit components 7

buy

0

85-1 Main CB 1 buy

16 16 85-2 Blower CB 1 buy

12 12

85-3 Pump CB 1 buy

12 12 85-4 Heaters CB 1 buy

12 12

85-4 Displays CB 1 buy

12 12 Diff pressure

sensor CB 1 buy

12 12

85-5 Contactor 1 buy

462 462 85-6 Bridge 1 buy 6 Amperes 55 55 85-7 Leds 13 buy

11 143

85-8 Resistors 50

01 5 86 Switches 5 buy

11 55

87 Data acquisation card 2

buy

1540 3080

88 Cables

buy

0 88-1 Cables ducts 1 buy

15 15

88-2 Cable 6x022 1 buy

5875 5875 88-2 wiring 1 buy 6mm dia 45 45

9 Computer

buy

0 91 LCD screen 1 buy

1155 1155

92 Desktop 1 buy

0 Project Total Cost 20871375

LE

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 59: Cooling Tower Educational Standcairouniversity

Chapter 6

51 Cooling Tower Educational Stand BSc Project 2008

Chapter Six Fabrication procedure

1 Welding

Water tank

Fig (61) Pipe with twelve nozzles attached to elbow both of 1 inch diameters welded to the left side of the water tank

Fig (62) Section of water tank showing inner baffle attached by welding with hole of 1 inch for pump suction pipe (left side in picture)

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 60: Cooling Tower Educational Standcairouniversity

Chapter 6

52 Cooling Tower Educational Stand BSc Project 2008

Fig (63) Attaching the final side containing the positions through which the heaters will be inserted into tank

Fig (64) Top view of the tank after completing the welding process

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 61: Cooling Tower Educational Standcairouniversity

Chapter 6

53 Cooling Tower Educational Stand BSc Project 2008

Make up tank

Fig (65) the sides of the makeup tank being welded except the top cover for later internal painting

Fig (66) Make up tank after painting the internal with epoxy resin and completing welding appearing in the figure an eye sight glass four adjustable legs and a lid with air passage through its center

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 62: Cooling Tower Educational Standcairouniversity

Chapter 6

54 Cooling Tower Educational Stand BSc Project 2008

Air tank and its attached components

Fig (67) Air tank after complete welding appearing (on the right) the exit pipe of drain and (on the left) the opening through which the blower is attached as shown

Fig (68) Water drain basin receives the water falling from the column and delivers it to the water tank the basin is placed inside the air tank

Fig (69) butterfly handmade with various degrees of opening attached to the blower suction side all attached to the left side of air tank

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 63: Cooling Tower Educational Standcairouniversity

Chapter 6

55 Cooling Tower Educational Stand BSc Project 2008

2 Stand fabrication

Fig (610) The stands structure is constructed of bars welded together with four wheels attached which is capable of carrying the stand holding components weight

Fig (611) wood boards after being cut to designed dimensions and the exterior frames which will be attached to the edges to protect the wood

Fig (612) stand after installation of wooden boards

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 64: Cooling Tower Educational Standcairouniversity

Chapter 6

56 Cooling Tower Educational Stand BSc Project 2008

3 Painting and coating

Fig (613) tanks after painting the first layer (all tanks needed to be coated inside and outside with a primary layer of epoxy to protect it from corrosion)

Fig (614) after the epoxy had dried we painted a secondary layer of green paint To enhance its color

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 65: Cooling Tower Educational Standcairouniversity

Chapter 6

57 Cooling Tower Educational Stand BSc Project 2008

4 Pipe components and fittings Referring to the designs of the pipe line we cut the pipes with the required lengths (and screwing its ends) then connecting the elbows screwed union orifice meter throttle and check valves Fig (615) T joint screwed union elbow nibbles Fig(616) swing check valve

Fig (618) Gate valve

Fig (617) Orifice plate flanges and pipe

Fig (619) Float valve

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 66: Cooling Tower Educational Standcairouniversity

Chapter 6

58 Cooling Tower Educational Stand BSc Project 2008

Fig (620) T joint (one branch is attached by the bush showing in the figure the other branch by the pipe discharge line and the main branch by the Hose

Fig (621) pump after fixation on the stand and attaching the suction and delivery pipes with their fittings

Fig (622) The pump delivery line after attaching the fittings and valves

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 67: Cooling Tower Educational Standcairouniversity

Chapter 6

59 Cooling Tower Educational Stand BSc Project 2008

5 The Column The column consists of two main parts the lower part which holds the fills and the upper part (the cap) which holds the water distributers and drift eliminator The column body (lower part)

bull The body material is transparent PVC to provide clear view of the actions occurring inside the tower for the students there are small holders attached on the inner surface of the column to hang the fill on Also the column bottom is bending with 45⁰ to affirm that all water falls into drain basin The column appears in Figure (623)

bull The fill (Fig 624) was cut to calculated size and required number of layers and penetrated with two bars horizontally near the top and one at the bottom to settle down on the holders inside the column Also to confirm uniform distribution of fill layers stainless strips were added to constrain the fill Figure (625) show the final shape of column body

Fig (622) column body Fig (624) The Fill

Fig (625) the column body after attaching the fill

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 68: Cooling Tower Educational Standcairouniversity

Chapter 6

60 Cooling Tower Educational Stand BSc Project 2008

The column Cap (upper part) bull The column cap Fig (626) was fabricated similar to the column body also with adding two

opposite holders to carry the eliminator with adding two opposite holes to install the water spray line

bull The drift eliminator was also fabricated from the same material of the fill penetrated with three bars to confirm alignment of layers Fig (627)

bull The water spray nozzles were attached to a hexagonal pipe of copper vertically with an external connection to hose supplying income water from main pipe line and then installed in the cap Fig (628)

Fig (626) The Cap Fig (627) The drift eliminators attached to the cap

Fig (628) The hexagonal sprinkle attached to the cap

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 69: Cooling Tower Educational Standcairouniversity

Chapter 6

61 Cooling Tower Educational Stand BSc Project 2008

6 Stand preparation Mark the areas required to be cut on the stand to be opened for the following requirements

1 Pump Suction and delivery pipes holes and drain pipes holes Fig (629) 2 Digital displays openings Fig (630) 3 LCD screen opening Fig (631) 4 Control panel switches and indication light holes Fig (632)

Fig (629) pipes holes Fig (630) digital displays openings

Fig (632) Control panel holes Fig (631) LCD opening with circle holes around the opening circumference for ventilation

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 70: Cooling Tower Educational Standcairouniversity

Chapter 6

62 Cooling Tower Educational Stand BSc Project 2008

7 Control panel Since the project is an educational cooling tower it was preferred to show the switches on a schematic drawing of the cycle with apparent indication lights A stainless steel sheet being drilled to pass the switches and indication lights Fig (633) then the schematic drawing was attached to the stainless sheet finally the switches and lights where installed and fixed on the stand as shown in figure (634)

Fig (633) preparing the stainless steel sheet Fig (634) control panel final shape

8 Electronic and Electric devices installation After preparing the stand install the electronic devices (digital displays pressure deffrance transmitter temperature controller) the electric devices (LCD screen PC) and control panel fig (635)

Fig (635) electric and electronic devices after installation

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 71: Cooling Tower Educational Standcairouniversity

Chapter 6

63 Cooling Tower Educational Stand BSc Project 2008

9 Electric connections Before connecting any device to electricity we classified them according to their operating voltage All devices operate at 220 volt except for the differential pressure transmitter which works at 24 volt Therefore we used one adapter to convert 220 volt to 24 volt We designed the circuit loop by adding a main circuit breaker of maximum load of 40 Ampere at the beginning of the line Then we branched the main line into five lines each passing through a suitable circuit breaker each device-

bull Pump blower displays and differential pressure transmitter required circuit breakers of 10 ampere

bull Heaters required a circuit breaker of 16 ampere Finally we added a switch and indication light in series on the five sub-lines appearing on the control panel

(a) (b)

(c) (d)

Fig (636a b c d) electric connections

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 72: Cooling Tower Educational Standcairouniversity

Chapter 6

64 Cooling Tower Educational Stand BSc Project 2008

10 Components assembly After preparing all cooling tower educational stand components as shown in previous sections assembly the components together figures (637) (638) (639) and (640)

Fig (637) assemble the air tank with water tank by means of screwed union and pipes

Fig (639) assemble water tank with makeup tank and insert

the water tank sight glass

Fig (638) assemble air tank with column

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 73: Cooling Tower Educational Standcairouniversity

Chapter 6

65 Cooling Tower Educational Stand BSc Project 2008

Fig (640) the final shape of cooling tower educational stand

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 74: Cooling Tower Educational Standcairouniversity

Chapter 7

66 Cooling Tower Educational Stand BSc Project 2008

Chapter seven

Tests and results

After installing the educational stand cooling tower take some readings

Procedure

1 Turn on the main switch then the main circuit breaker (orange key) 2 Turn the CPU and LCD on 3 Turn the heaters and displays switches on and wait until reaching the required heating

temperature ie when the heaters disconnected by the temperature controller 4 Turn the blower differential pressure and pump switches on 5 Adjust the pump (water) flow rate and blower (air) flow rate 6 Wait until steady state the take the readings 7 Repeat the procedure by changing water and air flow rates 8 Turn off the CPU and all switches 9 Tabulate the results and calculate the cooling tower performance parameters

Results

1- Fix the air flow rate and change water flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 04 281 413 281 288 88 57 0 012 271 414 285 284 79 57 0 003 271 416 286 281 78 57

2-Fix the water flow rate and changes the air flow rate

θ ∆P (psi) Two Twi Tai Tao RHo RHi 0 022 268 429 296 283 79 57 30 022 275 438 29 289 79 57 60 022 283 435 297 302 82 57

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 75: Cooling Tower Educational Standcairouniversity

Chapter 7

67 Cooling Tower Educational Stand BSc Project 2008

Relations

To get the water mass flow rate using orifice equation

119876119876 = 119870119870119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 2∆119875119875120588120588

Where 119860119860119900119900119900119900119900119900119900119900119900119900119900119900119900119900 = 19625 lowast 10minus5 1198981198982

119870119870 = 0605

119876119876 = 0605 lowast 19625 lowast 10minus5

2 lowast 105147 lowast ∆119875119875

1000

119876119876(1198981198983sec) = 55172 ∆119875119875(119875119875119875119875119900119900) lowast 10minus7

NOTE There is no available measurement device installed for the air flow rate

So calibrations are made for the air flow rate using hot wire as follows

1 Divide the column exit cross section area into nine equal parts as shown in figure

2 Measure the air velocity at the center of each grid 3 Repeat the measuring at different butter fly angles of

opening 4 Then get the average velocity of the air and get the air

volumetric flow rate 5 Plot the relation between the butter fly opening (Ө) and the

air volumetric flow rate

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 76: Cooling Tower Educational Standcairouniversity

Chapter 7

68 Cooling Tower Educational Stand BSc Project 2008

Air velocity gradient through the matrix over the column cross-section with Average velocity and volumetric flow rate

04 38 04 Ө=20 07 51 07 v=27 ms 51 51 3 119881=016875 m3sec

04 34 04 Ө=30 06 45 05 v=25 ms 48 47 29 119881=015625 m3sec

05 32 04 Ө=40 07 41 07 v=235 ms 45 44 27 119881=0146875 m3sec

04 3 04 Ө=50 07 39 07 v=226 ms 44 41 28 119881= 014125 m3sec

04 25 04 Ө=60 07 35 07 v=201 ms 4 35 24 119881= 0125625 m3sec

08 22 03 Ө=70 2 24 04 v=1644 ms 28 35 04 119881= 010275 m3sec

04 55 04 Ө=0 07 56 07 v=331 ms 58 58 49 119881=0206875 m3sec

04 42 05 Ө=10 15 53 06 v=298 ms 52 51 4 119881= 018625 m3sec

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 77: Cooling Tower Educational Standcairouniversity

Chapter 7

69 Cooling Tower Educational Stand BSc Project 2008

Table between Air flow discharge (V) versus butterfly opening angle (Ө)

Ө 0 10 20 30 40 50 60 70

V 020688 018625 016875 015625 014688 014125 012563 01027

0

005

01

015

02

025

0 10 20 30 40 50 60 70 80

air

flow

rat

e m

^3s

Butterfly angle ⁰

Air Flow chart

Linear (Air Flow chart)

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 78: Cooling Tower Educational Standcairouniversity

Chapter 7

70 Cooling Tower Educational Stand BSc Project 2008

1 We designed the cooling tower with a cooling range 5⁰C but in the actual running for the experiment the cooling range goes up to 15⁰C and this is due to the high atomization happened for the water from the nozzle which in turns increased the exposed surface area of the water to that of the air

Summery and conclusion

2 Differential Pressure transmitter reading is unstable at high flow rates because the nozzles makes a back pressure on the downstream of the orifice plate which makes the downstream pressure nearly equal the upstream one

3 While preparing the experiment we noticed that the water present in its upper part of tank is higher than the lower on due to almost negligible mixing of water when the pump is not operating

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 79: Cooling Tower Educational Standcairouniversity

Appendix

71 Cooling Tower Educational Stand BSc Project 2008

Appendices

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 80: Cooling Tower Educational Standcairouniversity

Appendix

72 Cooling Tower Educational Stand BSc Project 2008

Appendix -1-

Physical Properties of Water

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 81: Cooling Tower Educational Standcairouniversity

Appendix

73 Cooling Tower Educational Stand BSc Project 2008

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 82: Cooling Tower Educational Standcairouniversity

Appendix

74 Cooling Tower Educational Stand BSc Project 2008

Appendix -2-

Orifice ASME Standards

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 83: Cooling Tower Educational Standcairouniversity

Appendix

75 Cooling Tower Educational Stand BSc Project 2008

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 84: Cooling Tower Educational Standcairouniversity

Appendix

76 Cooling Tower Educational Stand BSc Project 2008

Flow Coefficient Chart

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 85: Cooling Tower Educational Standcairouniversity

Appendix

77 Cooling Tower Educational Stand BSc Project 2008

Appendix -3-

Moody Chart

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 86: Cooling Tower Educational Standcairouniversity

Appendix

78 Cooling Tower Educational Stand BSc Project 2008

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 87: Cooling Tower Educational Standcairouniversity

Appendix

79 Cooling Tower Educational Stand BSc Project 2008

Appendix -4-

Physical properties of Air

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 88: Cooling Tower Educational Standcairouniversity

Appendix

80 Cooling Tower Educational Stand BSc Project 2008

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 89: Cooling Tower Educational Standcairouniversity

Appendix

81 Cooling Tower Educational Stand BSc Project 2008

Appendix -5-

Piping minor head losses

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 90: Cooling Tower Educational Standcairouniversity

Appendix

82 Cooling Tower Educational Stand BSc Project 2008

Entrance loss coefficient

Sudden contraction loss coefficient

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 91: Cooling Tower Educational Standcairouniversity

Appendix

83 Cooling Tower Educational Stand BSc Project 2008

Sudden expansion loss coefficient

Conical diffuser loss coefficient

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 92: Cooling Tower Educational Standcairouniversity

Appendix

84 Cooling Tower Educational Stand BSc Project 2008

90deg Bend loss coefficient

90 Mitered bend loss coefficient

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 93: Cooling Tower Educational Standcairouniversity

Appendix

85 Cooling Tower Educational Stand BSc Project 2008

Loss coefficient for pipe fittings

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 94: Cooling Tower Educational Standcairouniversity

Appendix

86 Cooling Tower Educational Stand BSc Project 2008

Appendix -6-

Cooling Tower Design Charts

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 95: Cooling Tower Educational Standcairouniversity

Appendix

87 Cooling Tower Educational Stand BSc Project 2008

Table ( 1 ) Film tower fill performance correlation constants Fill

Fill Size

Constants for Ka Equation Eq (8-21)

Constants for DP Equation Eq (8-25)

Source Type (Height X Depth in Feet) Ca ma laquoa

A

b

d

Munters Crossflow

5

X

2

061

023

077

816

E-09

0433

1665

XF1256015

5

X

3

060

020

080

1410

E-09

0210

1849

75

X

2

061

020

080

731

E-09

0428

1705

75

X

3

054

022

078

709

E-09

0371

1757

75

X

4

051

023

077

1710

E-09

0358

1665

Crossflow

75

X

3

019

054

046

020

E-09

0739

1682

XF19060

75

X

4

023

051

049

054

E-09

0622

1701

(Height)

hunters Counterflow

1

108

025

075

4410

E-12

0305

2545

CF12060

2

093

014

086

415

E-12

0175

2944

3

080

012

088

132

E-12

0148

3103

4

071

013

087

229

E-12

0148

3019

Counterflow

2

050

016

084

101

E-09

0272

2065

CF19060

3

050

009

091

067

E-09

0209

2180

4

049

004

096

076

E-09

0257

2120

5

045

008

092

128

E-09

0240

2070

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 96: Cooling Tower Educational Standcairouniversity

Appendix

88 Cooling Tower Educational Stand BSc Project 2008

Cooling Tower Performance Curves and Tower Fill Data

69 W E T BULB (degF)

26 RANGE (degF)

KaVL

Figure (1) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 26 F)

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 97: Cooling Tower Educational Standcairouniversity

Appendix

89 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (degF)

22 RANGE (degF)

119923119923119918119918

Figure (2) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 22 F)

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 98: Cooling Tower Educational Standcairouniversity

Appendix

90 Cooling Tower Educational Stand BSc Project 2008

69 W E T B U L B (F)

18 RANGE (F)

Figure (3) Counterflow tower charachteristic curves (wet-bulb temperature 69 F and cooling range 18 F)

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 99: Cooling Tower Educational Standcairouniversity

Appendix

91 Cooling Tower Educational Stand BSc Project 2008

Appendix -7-

Product Catalogues

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 100: Cooling Tower Educational Standcairouniversity

Appendix

92 Cooling Tower Educational Stand BSc Project 2008

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 101: Cooling Tower Educational Standcairouniversity

Appendix

93 Cooling Tower Educational Stand BSc Project 2008

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 102: Cooling Tower Educational Standcairouniversity

Appendix

94 Cooling Tower Educational Stand BSc Project 2008

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 103: Cooling Tower Educational Standcairouniversity

Appendix

95 Cooling Tower Educational Stand BSc Project 2008

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 104: Cooling Tower Educational Standcairouniversity

Appendix

96 Cooling Tower Educational Stand BSc Project 2008

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 105: Cooling Tower Educational Standcairouniversity

Appendix

97 Cooling Tower Educational Stand BSc Project 2008

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 106: Cooling Tower Educational Standcairouniversity

Appendix

98 Cooling Tower Educational Stand BSc Project 2008

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 107: Cooling Tower Educational Standcairouniversity

Appendix

99 Cooling Tower Educational Stand BSc Project 2008

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 108: Cooling Tower Educational Standcairouniversity

Appendix

100 Cooling Tower Educational Stand BSc Project 2008

Appendix -8-

Electric Circuit

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 109: Cooling Tower Educational Standcairouniversity

Appendix

101 Cooling Tower Educational Stand BSc Project 2008

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 110: Cooling Tower Educational Standcairouniversity

Appendix

102 Cooling Tower Educational Stand BSc Project 2008

Appendix -9-

Electric Loads

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 111: Cooling Tower Educational Standcairouniversity

Appendix

103 Cooling Tower Educational Stand BSc Project 2008

Electric loads

Voltage Ampere Pump 220 183 A Blower 220 04545 A Heaters 220 69 A Displays 220 0021 A

Differential pressure gauge 24 0003 A Computer 220

We choose Switches can withstand over 10 A for safety and circuit breakers over 20 A

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 112: Cooling Tower Educational Standcairouniversity

Appendix

104 Cooling Tower Educational Stand BSc Project 2008

Appendix -10-

AutoCAD Drawings

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 113: Cooling Tower Educational Standcairouniversity

References

105 Cooling Tower Educational Stand BSc Project 2008

ndash ASME Fluid Meters6th Ed ASME 1967

References-

ndash Lewitt Hydraulics Pullman 1980 ndash Clayton T crowe Elger Engineering Fluid Mechanics 8th Ed Wiley 2005 ndash Okishi Fundamentals of Fluid Mechanics 4th EdWiley ndash wwwCTIorg (Cooling Technology Institute) ndash wwwomegacom ndash ASHRAE Magazine

Page 114: Cooling Tower Educational Standcairouniversity