solar evaporative air cooler

1

Design Report

on

Cooling fan for Kiosk Stall

(Course: Design and Engineering for sustainability)

Submitted by Submitted to

Sheshadri Shekhar Rauth Dr. Bala Pesala

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Contents

SL. N. Contents Page No. 1 Introduction & Defining Need 3

2 Concept Generation 5

3 Concept Selection 7

4 Product Design & Features 8

5 Components Need for Hardware Implementation 10

6 Proposed Circuit Diagram and description 11

7 3D Design & Final Product 13

8 Analysis & Test Result 14

9 References 15


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CHAPTER 1

INTRODUCTION AND DEFINING NEED

1.1 Introduction:

Every day when we go through the roads, we see many of small shops. Every day in

those shops small business are continuing throughout the day. It might be vegetable

shop, tea shop or small food shop etc. This whole day’s work gives them some earning

through their livelihood. In our daily life path, we also find them according to our need.

But there is also some area in India, where electricity is not abundantly available. Then

in such situation they need to continue their work in warm sunny condition. Even due

to lack of much light, they cannot extend their small business after little darkness by

evening. Again also in urban area, the hot weather problem remain same. So to get rid

of those issues, one system is needed that gives cooling effect and also will give light.

There are different types of coolers available in the market. Currently available coolers

need external electricity supply and also not having lighting system along with it. So it

is very important to develop a cooler that will consume less or zero power from existing

power supply and also should have to be with a lighting option for both rural small

shops and urban kiosk stalls.

Fig.1 One small kiosk stall model and one small tea shop in Orissa [1]


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1.2 Defining Need

Cooling system with lighting option for small kiosk stall (such as tea, food, vegetable

etc.) holder who works inside, from 10 AM to 8 PM.

Need Priority:

Many cooling systems are available in market, its known that shop holders are not fully

satisfying with those existing system.

S. No Needs Specification which refers to Need Units

1 Cooling Temperature 0C

2 Enough lighting Luminosity Lux

3 Low cost Cost Rs

4 Portable Portable ---

5 Durable Life time Years

6 Less weight Mass Kg

7 Less maintenance Maintenance ---

8 Easy to operate Air flow control ---

Table.1: Needs Priority


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CHAPTER 2

CONCEPT GENERATION

The cooling process can be done by various processes. Some kind of process is given

bellow.

2.1 Different Concepts

Central Air Conditioners and Heat Pumps

Central air conditioners and heat pumps are

designed to cool the entire house. In each system, a

large compressor unit located outside drives the

process; an indoor coil filled with refrigerant cools

air that is then distributed throughout the house

via ducts. Heat pumps are like central air

conditioners, except that the cycle can be reversed

and used for heating during the winter month. Fig.2 Central air conditioners[2]

Room Air Conditioners

Room air conditioners are available for mounting in

windows or through walls, but in each case they work the

same way, with the compressor located outside. Room air

conditioners are sized to cool just one room, so a number

of them may be required for a whole house. Fig.3 Room AC[3]

Evaporative Coolers

Evaporative coolers, sometimes called swamp coolers, are

less common than vapor compression (refrigerant) air

conditioners, but they are a practical alternative in very dry

areas. They work by pulling fresh outside air through moist

pads where the air is cooled by evaporation. The cooler air

is then circulated. Fig.4 Evaporative Cooler[4]


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This process is very similar to the experience of feeling cold when you get out of a

swimming pool in the breeze. An evaporative cooler can lower the temperature of

outside air by as much as 30 degrees.

Ductless Mini-Split Air Conditioners

Mini-split systems, very popular in other countries, can be

an attractive retrofit option for room additions and for

houses without ductwork, such as those using hydroid heat.

Like conventional central air conditioners, mini-splits use an

outside compressor/condenser and indoor air handling

units. The difference is that each room or zone to be cooled

has its own air handler. Each indoor unit is connected to the

outdoor unit via a conduit carrying the power and the Fig.5 Ductless Mini-Split AC[3]

refrigerant lines. Indoor units are typically mounted on the wall or ceiling.


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CHAPTER 3

CONCEPT SELECTION

Concept selection is the selection of concept from the generation of concepts. Those

have to be filtered according to needs and different aspect of concepts. After the first

filtration, the concept should be compared and filtered based on the Need priority and

weightage matrix.

From the previous generated concepts selected concepts are compared to choose the

concept for designing.

S. No Need

Priority

Weightage Central ACs

and Heat

Pumps

Room

AC

Evaporative

Coolers

Units

1. Cooling 1 4 3 2 OC

2. Portability 0.8 1 1 4 ---

3. Initial cost 0.8 1 2 4 Rs

4. Weight 0.7 1 2 4 Kg

5. Running

cost

0.8 2 3 4 Rs

6. Maintenance 0.5 3 3 3 ---

7. Life time 0.5 4 4 3 Year

8. Air flow

control

0.7 4 4 4 ---

Total 20 22 28 18

Table.2: Technical parameters of product

After the comparison of concepts from the filtered concept it is cleared that evaporative

cooling is best suit for that purpose. So, now evaporative cooler is chosen for

development.


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CHAPTER 4

PRODUCT DESIGN AND FEATURES

Based on the previous table I can see that it is good to go for evaporative cooling. It has

to be designed for shop holders. So there should be included lighting option too.

4.1 Product Features:

Solar based charging

Evaporative cooling

Led lighting

Air flow control

Switch

Battery

AC & DC charging option

Battery charge and Water level indicator

Solar based charging

A solar charger employs solar energy to supply electricity to

devices or charge batteries. Here I am using this to charge the

battery, which will run the water pump, cooling fan and the LED

light. Charging circuit is used here. It can charge the battery

without available electricity. Only sun irradiance is needed. Fig.6 Solar panel

Evaporative cooling fan

They work by pulling fresh outside air through moist pads where

the air is cooled by evaporation. The cooler air is then circulated

through a house. This process is very similar to the experience of

feeling cold when you get out of a swimming pool in the breeze. Fig.7 Cooler diagram[5]

Here in the fan part, DC fan I have used.

Led lighting

There are led strips which will give light with switching from the top

of the cooler. Fig.8 LEDs[6]


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Air flow control

There is a switching control option to control the air flow speed.

Switch

Various switches are there to on or off the pump, on or off the fan,

speed control, light, ac/dc charging etc. Fig.9 Switch[6]

Battery

Battery is the dc storage device. Here I can charge it by both ac and dc

supply. The ac supply we are getting from the solar panel. From that

battery I am able to run pump, fan and led. Fig.10 Battery

AC & DC charging option

There are two options, where we can change the mode of charging by ac or dc.


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CHAPTER 5

COMPONENTS NEEDED FOR HARDWARE IMPLEMENTATIO

SL.N. NAME SPECIFICATIONS PICS.

1 DC pump 12V, 10W 1

2 DC fan 12V, 12W 1

3 Mosquito net --- 1

4 Grass wool 250 g ---

5 Plastic sheet 0.20 m2 6

6 Pipes 2 m 1

7 Battery 12V, 7.5 Ah 1

8 Wire 2 m 1

9 Switches 20V, 3A 4

10 Solar panel 16V, 8W 1

11 Rectifier --- 1

12 Charge controller --- 1

13 LED 0.5W 4

Table.3: List of Hardware required

Fig. 11 Making of cooling pad from grass wool and mosquito net

Fig. 12 Sheets to make the structure, DC fan, Battery, DC pump


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CHAPTER 6

CIRCUIT DIAGRAM AND DESCRIPTION

Fig.13 Circuit block diagram of the cooling system

As water is evaporated, energy is lost from the air, reducing the temperature. Two

temperatures are important when dealing with evaporative cooling systems.

Dry Bulb Temperature

This is the temperature that we usually think of as air temperature, measured by

a regular thermometer exposed to the air stream.

Wet Bulb Temperature

This is the lowest temperature that can be reached by the evaporation of water

only.

When considering water evaporating into air, the wet-bulb temperature, as compared to

the air's dry-bulb temperature is a measure of the potential for evaporative cooling. The

dry and wet bulb temperature can be used to calculate the relative humidity.


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Evaporation will take place when the humidity is below 100% and the air begins to

absorb water. Any given volume of air can hold a certain amount of water vapor and

the degree of absorption will depend on the amount it is already holding. The term

humidity describes how much water is already in the air; relative to the amount it is

capable of holding. Air is saturated when it cannot hold any more water. Imagine it as a

sponge, if the sponge held half as much water as it was capable of holding, it would be

50% saturated. In the case of air, we would describe the Relative Humidity as being

50%.Energy is required to change water from liquid to vapor. This energy is obtained in

an adiabatic process from the air itself. Air entering an evaporative air cooler gives up

heat energy to evaporate water. During this process, the dry bulb temperature of the air

passing through the cooler is lowered.

In this direct evaporative cooling system designed by me, there is a switch that can on

and off the water pump inside. Firstly we have to on that to make the cooling pads

weight. Than we have to on the fan, which will force to come the air through the

weighted cooling pads. As it passes through the pad the air is cooled by evaporation.

The key to effective evaporative cooling is ensuring that each of the cooling pads are

completely saturated at all times during operation and that the systems fan & motor are

sized and designed to deliver the appropriate airflow for the home. There a speed

control option is also there, where we can control the flow of air. There is an option with

LED lighting system. The system can be charge both solar panel and ac existing source.

Calculations:

Here load voltage is 12V and the total wattage is (10+12+2) W = 22 W.

Minimum run time needed = 4 hours

Ah required by load = ((22*4)/12) Ah = 7.33 Ah

Battery capacity is 12V, 7.5 Ah

Time need to charge only by solar ((7.5*16)/8) = 15 hours.

Combination of external sources and solar panel will reduce the charging time.

(All assumptions are made neglecting all losses)


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CHAPTER 7

3D DESIGN AND FINAL PRODUCT

Fig.14 3D design of the cooler

Fig.15 Solar evaporative cooler with LED


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CHAPTER 8

TEST RESULT AND ANALYSIS

Measuring instrument used:

Fig.16 Thermocouple based thermometer and Digital anemometer[7]

There are two options for the dc fan speed is given bellow.

Options Speed of air (m/s)

High button 3.90

Low button 3.00

Table.4: Air speed measurement

As I have tested it, I got those results given bellow in the high speed option in

between 2:00 PM to 2:30 PM on 19/05/2016 in Chennai.

S. No. Actual

RH

(%)

Increased

RH

(%)

RH

Increment

(%)

Actual

Temperature

(0C)

Reduced

temperature

(0C)

Temperature

reduction

(0C)

1 48.00 58.50 10.50 33.50 29.60 3.90

2 49.50 57.50 8.00 33.00 29.40 3.60

3 50.00 59.00 9.00 33.10 29.30 3.80

4 51.00 59.50 8.50 32.70 29.10 3.60

5 51.50 58.00 6.50 32.80 29.40 3.40

Total

avg.

8.50 3.66

Table.5: Temperature and Humidity measurement


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Conclusion:

So finally the product that I have made will run by both solar and existing power

supply which will resolve the power issue and it can give both light and cooling effect

to those persons. As I have tested this in Chennai, having higher humidity, it will work

more efficiently in low humidity areas.

References:

[1] http://www.alamy.com/stock-photo/orissa.html

[2] http://www.westcountyheatandcool.com

[3] http://www.nairaland.com/1508281/lg-introduces-new-mosquito-combating-air

[4] http://www.portacool.com/en/us/home

[5] http://evaporative-cooling24.co.uk/evaporative-coolers

[6] http://www.switch-lighting.co.nz

[7] http://www.amprobe.com/amprobe/usen/hvac-tools

[8] http://www.sciencedirect.com/science/article/pii/S1359431102000698
