fyp-solar-air-cooler.pdf

SOLAR AIR COOLING 1 | P a g e

Lovely School of Mechanical Engineering

COURSE CODE: MEC492

COURSE TITLE: Capstone Project 2

Submitted by: Maneesh Bhardwaj

Registration Number: 10805611

Roll Number: RM2R31B27

Section Number: RM2R31

Academic Year: 2012

Name and Signature of Project Mentor: _______________________________________


CERTIFICATE

This is to certify that Mr. Maneesh Bhardwaj, bearing Registration no 10805611, has

completed his capstone project titled, SOLAR AIR COOLING under my guidance and

supervision. To the best of my knowledge, the present work is the result of his original

investigation and study. No part of the report has ever been submitted for any other degree at any

University.

Signature and Name of the Research Supervisor

Designation

School

Lovely Professional University

Phagwara, Punjab.

Date :


DECLARATION

I, Mr. Maneesh Bhardwaj student of B.Tech(ME) of Lovely Professional University, Punjab,

hereby declare that all the information furnished in this capstone project report is based on my

own intensive research and is genuine.

This report does not to the best of my knowledge, contain part of my work which has been

submitted for the award of my degree either of this university or any other university without

proper citation.

Date: Signature and Name of the student

Registration No. 10805611


ACKNOWLEDGEMENT

The architecture of success stands on a strong foundation made up of strenuous hard work,

determination, presence of mind and above all, timely advice from the learned and experienced

people. This word of acknowledgement is to express our deep sense of gratitude to all those

luminaries and unseen hands without whose support the completion of this dissertation would

not have been materialized.

This pleasure would not have been ours without the firm support extended to us by our guide

Mr. Piyush Jain, his smile, his appreciation and continuous motivation not only made working

under him but also delectable.

We express our deep sense of gratitude to the Head of Mechanical Engineering Department, Mr.

Gurpreet Singh Phull who gave us inspiration to pursue this project and providing all facilities

needed

Finally we thank our director Mr. Ashok Mittal, for his encouragement and providing all

facilities needed in our project.


ABSTRACT

Solar air conditioning has great potential. Sunlight is most plentiful in the summer when cooling

loads are highest.

Unfortunately, currently available technologies have not been able to economically use this huge

resource. For example, photovoltaic (PV) cells are expensive and require a large portion of the

roof to provide sufficient electrical power to drive an air conditioner. The cost for these panels

can be ten times that of a conventional air conditioner.

The new solar air-conditioning system takes a much different approach. It is a thermally driven

system that differs from earlier thermal systems in that it is designed to work with low-

temperature solar collectors and includes low-cost energy storage. Energy is stored in the form of

a concentrated salt (desiccant, calcium chloride) solution that can be used to provide

dehumidification. A cooler with a special heat exchanger design combines the dehumidification

from the desiccant with cooling from evaporation of water to provide air conditioning.

The preferred salt is calcium chloride. It is inexpensive and is commonly used as road salt. The

solar collector can be a shallow pool in a black plastic liner, which allows the sun to evaporate

water from the salt solution. The concentrated salt solution is then stored in a tank until it is

needed for cooling. If sunlight is not sufficient to concentrate the desiccant, off-peak electricity

or natural gas can be used as a back-up heat source.

The overall objective of the project is to demonstrate a thermally driven solar air conditioner that

has the potential of being economically viable compared to conventional electrically driven

systems. The immediate objectives were to obtain component test data and modeling results that

can be used to support the overall objective.


Table of Contents

Introduction...................8

Literature Review10

2.1 Air Conditioning.10

2.2 Solar Cooling System..10

2.2.1 Vapour Compression System.10

2.2.2 Absorption Air Conditioning.11

2.3 Solar Air Conditioning...12

2.3.1 Solar A/C Using Dessicants.12

2.3.2 Passive Solar Cooling12

2.3.3 Solar Thermal Cooling12

2.3.4 Photovoltaic Solar Cooling13

2.4 Solar Power Benefits14

2.5 Solar Collector14

2.6 Heat Exchanger15

2.7 Desiccants.16

Methodology..19

3.1 Principle..19

Fabrication...22

4.1 Fabrication of heat exchanger.22

4.1.1 Liquid-liquid indirect contact type.22

4.1.2 Liquid-air indirect contact type..23

4.2 Fabrication of solar collector...24


4.3 Fabrication of pumping device, fan/ exhaust system..24

4.4 Water storage tank...25

4.5 Interconnection between components.25

Testing.26

Project Costing28

Advantage and Limitation...29

7.1 Advantage....29

7.2 Limitation31

Future scope of the project..33

Applications.34

Conclusion...35

References...36


INTRODUCTION

The use of solar energy for cooling can be either to provide refrigeration for food preservation or

to provide comfort cooling. There is less experience with solar cooling than solar heating.

Several solar heated buildings have been designed, built, operated for extended periods but only

a few short time experiments have been reported on solar cooling. However, research work is

expected to close the gap between the two within few years.

Solar air conditioning systems have used two basic approaches in an attempt to capture the suns

energy for coolingthermal and photovoltaic. The photovoltaic systems use photovoltaic panels

to convert solar radiation directly into DC electricity. Photovoltaic systems have two major

advantageous attributes. First, they can use conventional electrically driven air-conditioning

equipment, which is widely available and inexpensive. Second, they can use the utility grid for

backup power during dark or cloudy periods.

Unfortunately other attributes: the high cost of manufacturing, the low conversion efficiencies,

and the need for a continual stream of photons to produce power, create three major

disadvantages. First electricity from solar cells is very expensive because of the high cost of the

solar panels. Second the space needed for powering the air conditioning units is large. And third

the panels provide no energy storage, which creates a need for use of grid-based electricity at

night and on cloudy days. In fact, the peak output from the solar panels occurs around solar

noon, while peak air-conditioning loads occurs several hours later, resulting in a significant

mismatch between supply of needed power and demand. This mismatch greatly reduces the

value of the system in reducing peak power demand to the utility. Recently deregulated markets

are demonstrating that these demands are much more expensive to meet than had been

previously apparent.


For off-grid locations, the only viable energy storage system to match the provision of power to

times when demand is high (later in afternoon and at night) is batteries. Batteries have a high

first cost, require periodic replacement, and normally use toxic and/or corrosive materials. These

problems have prevented the use of photovoltaic systems in other than a few high-cost

demonstration systems.

Thermally driven systems are another approach; they use heat from the sun to drive an air

conditioner. Typical approaches from the past used a high-temperature flat-plate collector to

supply heat to an absorption system. Systems with concentrating collectors and steam turbines

have also been proposed. Natural gas or other fuel is used for backup heat.

While thermal systems have the advantage of eliminating the need for expensive photovoltaic

panels, the existing systems have attributes that produce major disadvantages. As used in the

past, thermal systems are based on single-effect absorption chillers or other cooling systems that

are designed to use natural gas, steam or other high-temperature heat source. They require a very

high collector temperature to drive the cooling system. The high collector temperature and

relatively poor efficiency, greatly increases collector size and cost. In addition, there is no

economically viable way of storing solar energy with this approach. The result of these problems

is that thermal systems have been very expensive and have relied primarily on natural gas or

other fuel for their thermal energy. For this reason they have seen very little use.


LITERATURE REVIEW

2.1 AIR CONDITIONING: - The air conditioning is that branch of engineering science

which deals the study of conditioning of air i.e. supplying and maintaining desirable internal

atmospheric condition for human comfort, irrespective of external condition and the system

which effectively controls these conditions to produce the desired effects on the occupants of the

space is known as air conditioning system.

2.2 SOLAR COOLING SYSTEM:-Solar air cooling system works on two basic

principle:-

2.2.1 Vapour compression system

2.2.2 Absorption air conditioning

2.2.1 Vapour compression system:- A vapour compression system is an improved type

of air refrigeration system in which a suitable working substance, termed as refrigerant, is used.

It Condenses and evaporate at temp. & pressure close to atm. conditions.

Fig.1. Vapour Compression System


The refrigerant usually used for this purpose are NH3, CO2 and SO2.The refrigerant used does not

leave the system but it is circulated throughout the system alternatively condensing and

evaporating, the refrigerant absorbs its latent heat from the brine which is used for circulating

around the cold chamber while condensing, its gives out its latent heat to the circulating water of

the cooler.

2.2.2 Absorption system:- Absorption system uses heat energy, instead of mechanical

energy as in the vapour compression system in order to change the conditions of the refrigerant

required for the operation of refrigeration cycle.

Fig.2. Vapour Absorption System

In the vapour absorption system, the compressor is replaced by an absorber, a pump, a generator

and a pressure reducing valve these component perform the same function as that of compressor

in vapour compression system. In this system, the vapour refrigerant from the evaporator is

drawn into an absorber where it is absorbed by the weak solution of the refrigerant forming a

strong solution. This strong solution is pumped to the generator where it is heated by some

external source. During the heating process, the vapour refrigerant is driven off by the solution


and enters into the condenser where it is liquefied. The liquid refrigerant then flows into

evaporator and thus cycle is completed.

2.3 Solar air conditioning: - It refers to any air conditioning (cooling) system that uses

solar power. It can be achieved by following four types: -

2.3.1 Solar A/C using desiccants

2.3.2 Passive solar cooling

2.3.3 Solar thermal cooling

2.3.4 Photovoltaic solar cooling

2.3.1 Solar A/C using desiccants: - Air can be passed over common, solid desiccants (like

silica gel or zeolite) to draw moisture from the air and make it more comfortable. (See

Desiccant Cooling and Dehumidification) The desiccant is then regenerated by using

solar thermal energy to dry it out, in a cost-effective, low-energy-consumption,

continuously repeating cycle. Active solar cooling wherein solar thermal collectors

provide input energy for a desiccant cooling system: A packed column air-liquid

contactor has been studied in application to air dehumidification and regeneration in

solar air conditioning with liquid desiccants. A theoretical model has been developed

to predict the performance of the device under various operating conditions.

2.3.2 Passive solar cooling: - In this type of cooling solar thermal energy is not used

directly to create a cold environment or drive any direct cooling processes. Instead,

passive solar building design aims at slowing the rate of heat transfer into a building

in the summer, and improving the removal of unwanted heat. It involves a good

understanding of the mechanisms of heat transfer: heat conduction, convective heat

transfer, and thermal radiation, the latter primarily from the sun.

2.3.3 Solar thermal cooling:- There are multiple alternatives to compressor-based chillers

that can reduce energy consumption, with less noise and vibration. Solar thermal

energy can be used to efficiently cool in the summer, and also heat domestic hot


water and buildings in the winter. Single, double or triple iterative absorption cooling

cycles are used in different solar-thermal-cooling system designs.

The more cycles, the more efficient they are. Efficient absorption chillers require

water of at least 190F (88 C). Common, inexpensive flat-plate solar thermal

collectors only produce about 160 F (71 C) water, but several successful

commercial projects in the US, Asia and Europe have shown that flat plate solar

collectors specially developed for temperatures over 200 F (featuring double glazing,

increased backside insulation, etc.) can be effective and cost efficient.

2.3.3 Photovoltaic solar cooling: - Photovoltaic (PV) cells are expensive and require a

large portion of the roof to provide sufficient electrical power to drive an air

conditioner. The cost for these panels can be ten times that of a conventional air

conditioner. Of course the electrical grid can be used to supplement the energy from

the PV panels, but this approach means that the generation and transmission capacity

must be available to handle the maximum cooling load, which negates much of the

benefits from solar air conditioning.

Till now, we have discussed four types of cooling methods. But due to inherent advantages of

solar cooling by desiccants over other methods we are adopting this method. Those advantages

are as follows: -

Low cost.

Low collector temperature.

Low collector size.

Can be used in in-favorable conditions ( night, cloudy cond.).


2.4 Solar Power benefits:-

Because of the high demand for energy it would make more sense to use solar

power air condition units. And because they would be solar power it would make

it more affordable. The reason for my title Solar power AC just make sense is

because in most cases the use of the air conditioning units is mostly during sunny

hot weather. . In 1991 Sanyo developed a solar powered conditioning unit but

mass production seems to never have started, so this tell me that the product is out

there, I think is time we stat putting it to god use.

There lots of prove that solar power is a lot more cost efficient to use.


2.5 Solar collector: - The test collectors are round plastic plates covered with 4-mil black

polyethylene that are filled with a shallow pool of liquid.

Fig.3. Flat Plate Solar Collector

Most of the test data is from one collector that is filled with calcium chloride solution. A second

collector is filled with water for one day. A balance provided a measurement of mass of the

collector at various times throughout the day. Calcium chloride concentration is determined by

measured liquid density at the end of the first day and is calculated based on the mass of the

liquid at the other points. Air flow over the collector is by natural convection; wind speeds are

generally less than 10 mph. At the beginning of the third day of measurements, a measured

quantity of distilled water is added to the calcium chloride solution to prevent crystallization.

2.6 Heat-exchanger: - Several different designs were evaluated for a low-cost liquid-to-

liquid heat exchanger. The exchanger uses separate plastic bags for each fluid. The bags are


constructed of polyethylene or other plastic. Spacers were used inside bags to create a thin

channel, typically about .010 to .050 inches.

Several tests were made using variations of this design. The basic idea is to keep the liquid layers

thin so that thermal resistance is small even with low-velocity laminar flow. Sealing the heat

exchanger and maintaining the proper distribution of liquid through the heat exchanger was

difficult. Air gaps between the bags can also introduce significant thermal resistance.

Fig.4.Counter Flow Heat Exchanger

Figure shows an alternate configuration of heat exchanger. This design is formed with flexible

plastic sheets that are welded together to form two, counter-flow channels. The heat exchanger is

open to the atmosphere at the top so that the only pressure is the static head of the liquids that fill

the heat exchanger. Heat exchanger testing was conducted using a simple, once-through test

apparatus. Warm city water was supplied to one side of the heat exchanger, and cool water was

supplied to the other side. The flow rate was determined by measuring the time for water to fill a

container and then weighing the mass of water collected using a balance. Temperature

measurements used thermister probes with a digital readout.

2.7 Desiccants: - Desiccants are materials with a high tendency to adsorb water. If a dry

desiccant is exposed to the air, it will dehumidify the air, while the desiccant becomes warm.

Eventually the desiccant will become saturated with water, but it can be "regenerated" by

heating. The most common desiccants are silica gel, calcium chloride (CaCl2), activated carbon,

zeolites, lithium chloride (LiCl) and lithium bromide (LiBr).


Some desiccants can adsorb other liquids than water. Of interest are liquids which boil at

temperatures somewhat below water's freezing point: methanol, ammonia, ethanol, and

methylene chloride. Calcium chloride is by far the best choice for a desiccant system because of

its cheapness, strong affinity for water, and relative ease of regeneration. In contact with metals

(even copper), it causes the metals to react with carbon dioxide and corrode, so anything in

contact with the wet calcium chloride needs to be made of glass or plastic. Concentrated calcium

chloride solutions don't freeze as easily, unlike magnesium chloride brines (another possible

desiccant available in vast natural deposits).If you need a solid desiccant, there is a possibility

that desiccant materials like calcium chloride might be integrated into cements. I don't know if

anyone has tried this, but it should get a look. Cements are, in some cases, pretty porous.

Imagine a honeycomb of cement and calcium chloride, extruded through a forming process to

form a high surface area material like a honeycomb. Ever hear of desiccant wheels? They are

basically this same concept: a ceramic binder with an absorptive material integrated into it. I

think the current desiccant wheels are made with titania and cement somehow. The desiccant

wheels out there now have very high surface areas, and are quite a piece of technology. But

here, I'm talking about a lower-cost, bulk material that would do the job. A little appreciated fact

about boiling heat transfer in all liquids: the heat transfer coefficient depends on the partial

pressure of the boiling fluid!! Systems using lithium bromide/water vapor must work with very

low pressures (substantially below atmospheric). The result: heat exchanger surfaces must be

made very large (that's part of the reason these systems are so expensive).

Liquid desiccant systems have certain advantages over dry desiccants. One of the biggest is the

fact that as the desiccant is heated up to drive off the moisture, significant heat may remain in the

hot, dried solution. In the case of solid desiccant systems, such as systems employing solid

desiccant wheels, it is hard to recover this heat. With liquid desiccants, the hot, dried solution

may be circulated into a counter-flow heat exchanger, using the heat of the hot and dried solution

to pre-heat the incoming moisture loaded solution.

Calcium chloride is a cheap, non-toxic, widely available material that has certain properties that

make it a good candidate for this application.


First, we'll take a few points off of the twelfth edition's Table 10-20, "Composition of Aqueous

Antifreeze Solutions", which is based on Dow Chemical's 1929 data sheet. The (%CaCl2) is

percent anhydrous Calcium Chloride. Bags typically don't contain pure anhydrous, so keep this

in mind.

Table.1

Freezing Point(C) % CaCl2

0 (32F) 0

-4.8 (23.4F) 9.2

-9.9 (14.4F) 14.6

-15.6(4.1F) 18.6

-21 (-5.8F) 21.5

-30.8(-34.9F) 26.9

-41.8(-41F) 30.5

The above table shows that the calcium chloride solutions will not freeze, and this is important.

Next, here is some excerpts from Lange's Table 10-25, which shows the humidity level above

various concentrations of calcium chloride solutions. Data is for 25 0C.

Table.2

Humidity %CaCl2

100% 44.36

95% 39.62

90% 35.64

80% 31.73


At very high concentrations, you end up with basically a pure Calcium Chloride Hex hydrate

tank. Calcium Chloride Hex hydrate melts at almost room temperature, 29.9 0C. So, in effect, it

could act as its own phase change storage material.

METHODOLOGY

70% 27.4

60% 22.25

50% 14.95

40% 9.33

30% 7.2


3.1 Principle: - Figure 5 is a schematic diagram of a proposed thermally driven solar air

conditioner that addresses the problems of the earlier systems. The basic idea is to use a

desiccant liquid (preferably calcium chloride, CaCl2) for cooling and dehumidifying. The cooler

uses the calcium chloride to dehumidify the air. Water is evapouratively cooled with exhaust air.

Approximate air dry-bulb/wet-bulb temperatures in degrees F are included in the figure for

illustration purposes. This schematic shows the configuration of cooler evaluated in this project;

other configurations are possible and are discussed in the copy of the patent in the appendix.

Fig.5. Solar Air Cooling

The operation of cooler requires further explanation. The driving force behind this cooler is a

temperature difference between a water surface and a desiccant surface in contact with an air

stream. The temperature of a water surface is close to the wet-bulb temperature of the air, while

the temperature of a desiccant surface corresponds to a higher temperature. For a concentrated

solution of calcium chloride, the temperature difference between the wet-bulb and the desiccant

equilibrium temperature is approximately 15 to 20 F. The cooler provides a way of using a

relatively weak desiccant to efficiently provide cooling.

The cooler uses three counter flow heat exchangers to move thermal energy from incoming

outside air to the exhaust air. Starting at the top of the figure, the first heat exchanger is a direct-


contact device that evaporates water into the exhaust air stream. The temperature of water

leaving this heat exchanger approaches the wet-bulb temperature of the exhaust stream leaving

the conditioned space.

The second heat exchanger is a liquid-to-liquid heat exchanger that uses the cooled water to cool

a calcium chloride solution. The third heat exchanger is a direct-contact device that cools and

dehumidifies the incoming outside air using the cooled calcium chloride solution.

The cooler is able to work because the equilibrium temperature of the desiccant with the

incoming air is higher than the wet-bulb temperature of the exhaust air stream. This temperature

difference allows the cooler to lower the enthalpy of the incoming air below that of the exhaust

air leaving the occupied space. An optional direct evaporative cooler can provide a low supply-

air temperature for applications where the cooling load is primarily sensible.

A solar collector uses thermal energy from the sun to drive out water absorbed by the desiccant.

The collector temperatures are relatively low because the equilibrium relative humidity of the

desiccant is relatively high.

Note that if the ambient temperature is above the equilibrium temperature for the desiccant it is

possible to evaporate water into the air without any solar input.

The concentrated desiccant solution also serves as a storage medium to provide cooling at night

or during cloudy periods, when sufficient sunlight is not available. The preferred desiccant

material is calcium chloride because of its low cost and low toxicity. (It is commonly used for

road salt and as a food additive. These features mean that calcium chloride can serve as a safe,

compact, inexpensive storage medium.

On the other hand, the desiccant properties of calcium chloride impose some limitations. At 25

C (77 F) calcium chloride solution crystallizes at a concentration above about 50%. This

concentration corresponds to a relative humidity of about 30%; operation of the system requires


that the solution be kept safely above this concentration. In contrast, more-conventional

desiccants, such as lithium chloride, crystallize at much higher concentrations and can achieve a

much lower relative humidity. Unfortunately, lithium chloride costs over 20 times as much as

calcium chloride and has some toxicity issues, which makes it undesirable for use as a thermal

storage medium. Designing for a higher relative humidity that is available with calcium chloride

also allows for much lower solar collector temperatures, which can greatly reduce collector cost.

An important feature for making the system work is to develop very low-cost, high-performance

heat exchangers. In order to make calcium chloride work effectively, the heat exchangers must

handle large transfer large amounts of thermal energy at a small temperature difference.

As will be discussed in more detail later, the design approach used in this project was make use

of low-cost materials, such as plastic, as much as possible in the design of the heat exchangers.

Plastics have the advantage of being resistant to the corrosive effects of salt solutions and water.

The disadvantage is that plastic has a much lower thermal conductivity and lower strength

compared to metals. The design approach was to use large areas of primary surface with very

small pressure differences.

At very high concentrations, you end up with basically a pure Calcium Chloride Hex hydrate

tank. Calcium Chloride Hex hydrate melts at almost room temperature, 29.9 0C. So, in effect, it

could act as its own phase change storage material.

FABRICATION


4.1 Fabrication of Heat Exchanger: -

In the project, mainly two types of heat exchanger are used. The fabrication of both type are

shown below.

4.1.1 Liquid-Liquid Indirect Contact Type: -

In this heat exchanger heat transfer takes place between CaCl2 brine solution and cold water. The

heat flows from high temp. brine solution to cold water, resulting brine solution becomes cooler

and it is ready for further circulation.

In this type of heat exchanger, copper coils are used in which CaCl2 solution flows. Because of

high coefficient of thermal conductivity of copper, effectiveness of heat exchanger would

improve. These copper tubes are in shape of helix and are fitted in closed hollow cylindrical

drum. This cylindrical drum is filled with the cold water; hence heat transfer takes place in the

drum.

Fig.6. liquid-liquid indirect contact type

4.2.2 Liquid-Air Direct Contact Type: -


In this heat exchanger heat transfer takes place between cold CaCl2 brine solution and warm and

humid atmospheric air. The heat flows from high temp. atmospheric air to cold CaCl2 solution,

resulting hot and humid atmospheric air becomes cold and dehumidified.

In this arrangement plastic tubes are fitted at the top of cubical box through which CaCl2 solution

flows and made to fall in form of droplets at the bottom of box due to holes provided in the

plastic tubes. Now, the air present inside the box becomes cooler and dehumidified due to

moisture absorbing property of CaCl2. This cooled and dehumidified air is sucked by the fan to

the space to be cooled. The size of heat exchanger is (1*1*1) feet.

Fig.7. Air-liquid indirect contact type

4.2 Fabrication of Solar Collector: -

Dehumidified air Surrounding air


Solar collector is used to evaporate the moisture contained in the CaCl2 brine solution. It is in the

shape of cuboids that is open at the top and made of steel sheet. Solar collector is also work as a

CaCl2 storage tank.

To increase the effectiveness of flat plat solar collector, whole body is being painted black color

and covered by the glass plate from the top. The heat energy coming from sun is trapped inside

the solar collector and the rays are not able to get back due to glass plate covered at the top.

Hence the temperature of inside the collector is sufficient to evaporate the moisture. The size of

solar collector is (3*1*1) feet.

4.3 Fabrication Of Pumping Device, Fan/ Exhaust System: -

In this project two pumps are used, one of which is used to circulate CaCl2 brine solution from

the storage tank. And other is used to circulate water from water storage tank to liquid- liquid

heat exchanger. The pump used in the project has 5.6 ft. discharge head.

Fan is used to supply dehumidified and cooled air from liquid-air heat exchanger to the space to

be cooled.

4.4 Water Storage Tank: -


It is used to collect the water coming out from the heat exchanger. It has certain amount of

capacity to store water that is used for liquid-liquid indirect type of heat exchanger.

4.5 Interconnection Between Components: -

The different components are arranged as per the working principle of the project. These

connections are as follows: -

The solar collector, which also works as desiccant storage tank, is connected to the

inlet pipe of the pump and the outlet of pump is connected with the inlet of liquid-liquid

heat exchanger with the help of connectors.

The outlet pipe of liquid-liquid heat exchanger is connected with the inlet of liquid-

air heat exchanger, inside which the desiccant falls in the form of droplet and hence

collected at the base of heat exchanger.

The collected desiccant at the base again supplied to the solar collector by using the

phenomenon of gravity with the help of pipes.

The water storage tank supplies the water inside the liquid-liquid heat exchanger. The

water from heat exchanger again transferred to the storage tank by using pump.

The exhaust fan is provided on the face of the liquid-air heat exchanger, which suck the

dehumidified air from heat exchanger and supply it to the region to be cooled.

TESTING


Testing compromise to find out the relative humidity as well as temperature of air which is being

stored in thermion box-

Step 1:-First we find out the wet bulb temperature as well as dry bulb temperature of surrounding

air with the help of sling thermometer.

Step 2: Then after we measured both the temperatures of air which is collected in thermion box.

Step 3:-Now we plot the conditions of atmospheric air and collected air on psychometric chart.

Step 4:-After plotting both the condition on psychometric chart, we find out the change in

specific humidity of air.

Step 5:-This change in specific humidity shows the dehumidification process.

Now, during the testing of project we observe following reading-

Dry bulb temperature of surrounding air (tdbs) = 41oc

Wet bulb temperature of surrounding air (twbs) = 28 oc

Dry bulb temperature of collected air (tdbc) = 22 oc

Wet bulb temperature of collected air (twbc) = 17 oc


Fig.8. Psychometric chart


PROJECT COSTING

The project consists of so many different components that are enlisted below with their

respective cost. The cost of the components is given as per the market analysis and availability of

that component in market.

Quantity Units Retail Cost per Unit (Rs.) Total Cost (Rs.)

Heat Exchangers

1.Liquid-Liquid HX 1 400.00 400.00

2. Liquid-Air HX 1 460.00 460.00

Collector 1 620.00 620.00

Storage (Water) 1 220.00 220.00

CaCl2 (kg) 5 55.00 275.00

Fan 1 180.00 180.00

Pumps 2 150.00 300.00

Piping, controls, structure 672.00

Overhead

120.00

Grand Total (Rs.)

3247.00


ADVANTAGE AND LIMITATION

7.1 Advantages Of Project

The demand for AC is likely to increase because worldwide temperature increases.

While using soaring demand in energy, count on costs in order to continually

advance.

Any a lot more feasible, long-term solution lies in harnessing solar energy to cool our

own atmosphere through any solar air conditioning solar panel array. Whenever you

think about the idea, the days when you need air-cooling most are generally those

days when the solar reaches its best.

The solar air conditioning can work precisely. Solar air conditioning makes use of

the solar panel that soaks up and traps heat from the sun within the form of thermal

power simply by warming normal water.

This power can be delivered to the solar air conditioner along with heats up the solution

causing it to steam. Since it cools it creates a cooling effect that's taken into an additional

water loop

.

Solar air conditioning provides a great package involving benefits. Installation

expenses can be reduced through tax credits, deductions and also refunds.


Solar AC is a wise method to help save the particular atmosphere and also satisfy the

electrical power requirements each at the same time. Using solar energy solutions

displays a company's commitment to environmental stewardship and that

responsibility is actually observed through probable along with existing clients.

Solar air conditioning does not use any Freon or other hazardous chemicals.

Solar energy may be the best way to obtain replenishes able power.

Desiccant cooling systems are energy efficient and environmentally benign.

In humid regions, desiccant dehumidification can reduce electricity demand

considerably by providing a drier, more comfortable, and clean indoor environment

with a lower energy bill. Desiccant systems allow more fresh air into buildings, thus

improving indoor air quality without using more energy.

Desiccant systems also displace chlorofluorocarbon-based cooling equipment, the

emissions from which contribute to the depletion of the Earth's ozone layer.

Desiccant dehumidification technology provides a method of drying air before it

enters a conditioned space. When combined with conventional vapour compression

systems, desiccant dehumidification systems are a cost-effective means of supplying

cool, dry, filtered air.


In the last decade, desiccant dehumidification technology has emerged as an

alternative or as a supplement to conventional vapour compression systems for

cooling and conditioning air in commercial and institutional buildings. A typical

hybrid system combines a desiccant system with a conventional vapour compression

cooling system.

Desiccant-based systems are cost-effective because they use low-grade thermal

sources to remove moisture from the air. In general, the benefits of desiccant-based

systems are greater where the thermal energy required for regenerating the desiccant

is readily available, the electricity price is high, and the latent load fraction is high

(>25%).

7.2 Limitation: -

In cloudy conditions solar collector cannot work properly as sun rays are not uniform.

CaCl2 is mainly for dehumidifying the humid air but in dry conditions it cannot

dehumidify the air as no moisture is present.

Prolong use of CaCl2 may result in scale formation.

Slow working process as less moving parts.


Less efficient due to intermittent supply of suns radiation.

CaCl2 results in corrosion of heat exchanger parts.

Process totally dependent on supply of suns radiation.

CaCl2 have salty odour.

Precaution is to be taken while handling of CaCl2 as it harms to skin and while making

solution it generates loads of heat.


FUTURE SCOPE OF SOLAR COOLING

Researchers, designers and manufacturers of refrigeration and air-conditioning

systems and equipment today are focusing on new and alternative technologies in

view of the phasing out of CFCs.

Desiccant-based and desiccant assisted air-conditioning systems are currently emerging

from a 60- year industrial heritage and expanding into commercial applications. Today,

both the user and the consultant opt to adopt non-conventional approach case by case

rather than sticking to conventional method of designing systems.

Effort at all levels is being made to identify new slots / areas where desiccant cooling

system provides immediate applicability i.e. stand alone as well as provides economical

and efficient alternative, by way of lowering TR (Reduce impact of CFCs).

Energy shortage is something which we live with day in and day out. This energy

shortage is expected to increase as more and more population shifts to air conditioned

buildings.

This presents the air conditioning industry with several challenges. Among these are demands for

increased energy efficiency and improved indoor air quality, growing concern for improved

comfort and environmental control, increased ventilation requirements, phase-out of

chlorofluorocarbons (CFCs), and rising peak demand charges.


APPLICATIONS

Desiccant technology has become an important alternative amongst the options

available to the industry for space-conditioning. In many cooling applications,

desiccant cooling units provide advantages over the more common vapour-

compression and absorption units. For example, desiccant systems do not need ozone-

depleting refrigerants and are very effective at treating the large humidity loads

resulting from ventilation air. Also, they use natural gas, solar thermal energy, or

waste heat, thus lowering peak electric demand.

As a result, the use of desiccant cooling and dehumidification systems for building

comfort conditioning has increased steadily during the past several years in the West.

Recent advances in adsorptive materials, in conjunction with dehumidifier design

innovations, are making the technology increasingly attractive.


CONCLUSION

As per the proposed plan of the project we have successfully constructed the solar air

conditioner which works on the desiccant (CaCl2) property of dehumidifying the humid air and

of producing cooling effect with the help of solar radiation.

Following conclusions observed are:-

It dehumidifies the atmospheric humid air present in our surroundings successfully. It

also provides cooling effect by absorbing the heat of air.

It is cost effective as the whole cost of the project comes around Rs 3247.00 only which

is very less and cheap as compared to other traditional electric air conditioner and it is

less bulky too.


REFERENCES

Books

1. By R.S. Khurmi Refrigeration And Air Conditioning (2010) Page 87, 165, 210

S.Chand .& Pub.

Websites:

1. http://rredc.nrel.gov/solar/old_data/nsrdb/bluebook/atlas/

2. NREL desiccant cooling page

http://www.nrel.gov/desiccantcool/

3. EREC brief: zeolites in solar energy applications

http://www.eren.doe.gov/consumerinfo/refbriefs/ba3.html


4. Solar Adsorption Refrigeration Using Zeolite and Water

http://www.fh-luebeck.de/an/pt/solar/publish/euros-00.pdf

Documents

fyp-solar-air-cooler.pdf