cooling tower educational standcairouniversity
DESCRIPTION
cw towerTRANSCRIPT
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
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
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
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
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
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
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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
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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
Chapter 2
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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
Chapter 3
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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
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
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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
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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
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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
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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
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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
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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
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Fig (640) the final shape of cooling tower educational stand
Chapter 7
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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
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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
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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
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Appendices
Appendix
72 Cooling Tower Educational Stand BSc Project 2008
Appendix -1-
Physical Properties of Water
Appendix
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Appendix
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Appendix -2-
Orifice ASME Standards
Appendix
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Appendix
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Flow Coefficient Chart
Appendix
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Appendix -3-
Moody Chart
Appendix
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Appendix
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Appendix -4-
Physical properties of Air
Appendix
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Appendix
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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
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Loss coefficient for pipe fittings
Appendix
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Appendix -6-
Cooling Tower Design Charts
Appendix
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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
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Appendix
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Appendix
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Appendix
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Appendix
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Appendix
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Appendix
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Appendix
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Appendix
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Appendix -8-
Electric Circuit
Appendix
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Appendix
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Appendix -9-
Electric Loads
Appendix
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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
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Appendix -10-
AutoCAD Drawings
References
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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
VI
-Nomenclatures
VII
Chapter 1
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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
Chapter 1
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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
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
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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
Chapter 2
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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
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
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
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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
Chapter 2
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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
Chapter 3
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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
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
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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
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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
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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
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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
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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
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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
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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
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Fig (640) the final shape of cooling tower educational stand
Chapter 7
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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
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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
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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
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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
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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
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Appendices
Appendix
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Appendix -1-
Physical Properties of Water
Appendix
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Appendix
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Appendix -2-
Orifice ASME Standards
Appendix
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Appendix
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Flow Coefficient Chart
Appendix
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Appendix -3-
Moody Chart
Appendix
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Appendix
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Appendix -4-
Physical properties of Air
Appendix
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Appendix
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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
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Loss coefficient for pipe fittings
Appendix
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Appendix -6-
Cooling Tower Design Charts
Appendix
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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
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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
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Appendix -7-
Product Catalogues
Appendix
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Appendix
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Appendix
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Appendix
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Appendix
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Appendix
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Appendix
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Appendix
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Appendix
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Appendix -8-
Electric Circuit
Appendix
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Appendix
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Appendix -9-
Electric Loads
Appendix
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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
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Appendix -10-
AutoCAD Drawings
References
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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
Chapter 1
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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
Chapter 1
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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
Chapter 2
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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
Chapter 3
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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
Chapter 3
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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
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
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
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
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
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
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
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
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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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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Appendices
Appendix
72 Cooling Tower Educational Stand BSc Project 2008
Appendix -1-
Physical Properties of Water
Appendix
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Appendix
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Appendix -2-
Orifice ASME Standards
Appendix
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Appendix
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Flow Coefficient Chart
Appendix
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Appendix -3-
Moody Chart
Appendix
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Appendix
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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
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Loss coefficient for pipe fittings
Appendix
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Appendix -6-
Cooling Tower Design Charts
Appendix
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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
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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
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Appendix
99 Cooling Tower Educational Stand BSc Project 2008
Appendix
100 Cooling Tower Educational Stand BSc Project 2008
Appendix -8-
Electric Circuit
Appendix
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Appendix
102 Cooling Tower Educational Stand BSc Project 2008
Appendix -9-
Electric Loads
Appendix
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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
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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
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
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Appendices
Appendix
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Appendix -1-
Physical Properties of Water
Appendix
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Appendix
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Appendix -2-
Orifice ASME Standards
Appendix
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Appendix
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Flow Coefficient Chart
Appendix
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Appendix -3-
Moody Chart
Appendix
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Appendix
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Appendix -4-
Physical properties of Air
Appendix
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Appendix
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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
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Loss coefficient for pipe fittings
Appendix
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Appendix -6-
Cooling Tower Design Charts
Appendix
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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
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Appendix -7-
Product Catalogues
Appendix
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Appendix
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Appendix
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Appendix
95 Cooling Tower Educational Stand BSc Project 2008
Appendix
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Appendix
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Appendix
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Appendix
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Appendix
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Appendix -8-
Electric Circuit
Appendix
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Appendix
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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
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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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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