Design of a Solar assisted Liquid Desiccant based evaporative Cooler

TABLE OF CONTENTS

ABSTRACT

LIST OF FIGURES

LIST OF TABLES

LIST OF SYMBOLS and ABBREVIATIONS

CHAPTER 1 - INTRODUCTION
1.1. Detailed definition of the project
1.1.1 Conventional Evaporative Cooling Systems
1.1.2 Desiccant Material
1.1.3 Different Type of Desiccants
1.1.4 Desiccant Cooling System
1.1.5 Desiccant Dehumidification
1.1.6 Desiccant Based Evaporative Cooling
1.2. Significance of the project
1.3. Detailed project objectives
1.4. Detailed project constraints
1.5. Report Organization

CHAPTER 2 - LITERATURE REVIEW
2.1. Background information
2.1.1 Liquid Desiccant Dehumidification for Solar Cooling
2.1.2 Hybrid Solar Liquid desiccant and Evaporative Cooling Systems
2.2. Concurrent solutions
2.3. Comparisons of the concurrent solutions
2.4. Engineering standards of the concurrent solutions

CHAPTER 3 -DESIGN and ANALYSIS
3.1. Proposed/Selected design
3.2. Engineering standards
3.3. Design calculations
3.3.1 Solar Collector
3.3.2 Desiccant Dehumidifier
3.3.3 Pump Calculations
3.3.4 Evaporative Cooler
3.4. Cost analysis

CHAPTER 4 – MANUFACTURING PLAN
4.1. Manufacturing process selection
4.1.1 Material Selection
4.1.2 Cost of the Manufacturing Process
4.1.3 Properties and characteristics of product
4.2. Detailed manufacturing process

CHAPTER 5 - PRODUCT TESTING PLAN
5.1. Verification plan of the objectives of the project

REFERENCES

APPENDIX A: Electronic Media

APPENDIX B: Constraints

APPENDIX C: Standards

APPENDIX D: Logbook

APPENDIX E: Project Timeline

APPENDIX F: Engineering Drawings

LIST OF FIGURES

Fig 1: Indirect evaporative cooling system

Fig 2: Direct evaporative cooling system

Fig 3: Scheme of working principle and simplified scheme of direct evaporative cooler (DEC)

Fig 4: Psychrometric processes of Liquid Desiccant Evaporative system

Fig 5: Psychometric variations of different desiccant salts

Fig 6: (a) Specific Gravity vs. % 7 (b) Boiling Points of

Fig 7: Surface Tension of Pure Solutions

Fig 8: Specific Heat of Aqueous

Fig 9: Phase Diagram of Solution

Fig 10: Viscosity of Pure Solution

Fig 11: Vapor Pressure of Hydrates and Solutions

Fig 12: Desiccant dehumidifier processes

Fig 13: evaporative desiccant cooling systems working principle

Fig 14: Fabricated dehumidifier

Fig 15: Water Pump

Fig 16: Fan

Fig 17: Spray chamber

Fig 18: Three main employed flow configuration for dehumidifier

Fig 19: Methods of regeneration

Fig 20: Desiccant cooling system incorporated with an evaporative cooler and a solar collector (schematic diagram)

Fig 21: Schematic diagram of solar air pre-treatment collector/regenerator

Fig 22: Simplified diagram of direct and indirect evaporative cooling mechanisms

Fig 23: Psychrometric process of direct and indirect evaporative cooling systems

Fig 24: Principle behind liquid desiccant evaporative coolers

Fig 25: Simplified design of the solar liquid desiccant air conditioning unit

Fig 26: Design of solar LDAC apparatus in Queensland, Australia

Fig 27: shows the components of Desicool system

Fig 28: General principle of DEVap process

Fig 29: System configuration of solar based desiccant evaporative cooler

Fig 30: Evaporative Cooler

Fig 31: Rate of energy trasnfer vs temperature difference across evaporative cooler

Fig 32: COP vs change in temperature across the evaporative cooler

Fig 33: Material selection flow chart

Fig 34: Manufacturing Processes Flow Chart

Fig 35: Sequence Detailed Manufacturing Process

Fig 36: Product Testing plan

LIST OF TABLES

Table 1: Properties of hydrates

Table 2: list of all standards of concurrent solutions along with their descriptions

Table 3: List of all engineering standards used in our design

Table 4: list of parameters depending on the various types of solar collectors

Table 5: Solar collector Analysis

Table 6: Psychrometric analysis of desiccant dehumidifier

Table 7: Psychrometric analysis of the Evaporative Cooler

Table 8: Relationship between the inlet and exit temperature of evaporative cooler with the amount of energy trasnfered and COP (Coefficient of Performance)

Table 9: A general cost analysis approach

LIST OF SYMBOLS and ABBREVIATIONS

3D: Three Dimensional

: is the average amount of heat energy produced by a solar collector during the day, kWh m2.

Ec: average amount of heat energy received by 1m2 of solar collector during day kWh m-2

: efficiency of the collector.

a, b – experimentally determined coefficients.

K- parameter, oC.

Tin – heat carrier inlet temperature into collector oC;

T0 – surrounding air temperature oC;

L - average monthly value of atmospheric lucidity.

E - average daily amount of global solar energy received during a month by 1 m2 of horizontal surface area, kWh m2;

Eout – average daily amount of global solar energy received during a month by 1 m2 of horizontal surface outside the atmosphere, kWh m2.

N – duration of the day measured in hours;

Pmax – maximal power of solar insolation on the collector surface during the day, kW m2 .

Cs – solar constant (Cs = 1355 W m-2.);

ϕ – latitude angle of the place (for Latvia φ = 57˚);

ω – angle of solar hours (in the middle of a day ω = 0);

δ – declination angle of the sun, degree.

n - number of year day counted from January 1.

: rate of moisture evaporating inside the solar collector measured in kg/s.

V: Velocity measured in m/s.

: Density measured in kg/m3.

: mass flow rate of air measured in kg/s.

: specific humidity measured in (kg moisture/ kg dry air)

L: total length measured in m.

D: Diameter measured in m.

µ: Viscosity measured in kg/m.s.

r: radius measured in m.

A: Area measured in m2.

: volumetric flow rate measured in m3/s.

Re: Reynolds Number

f: Darcy friction factor

: equivalent roughness measured in mm

Pressure difference measured in Pa

W pump: Power of the pump measured in W.

g: Gravitational acceleration = 9.81 m/s2

KL: Loss factors

are the minor losses in the pipe due to ducts, tees, elbows etc.

hL: head loss measured in m.

x: Specific humidity of moisture removal from air across dehumidifier, measured in (kg moisture/ kg dry air).

y: Specific humidity of moisture addition across evaporative cooler, measured in (kg moisture/ kg dry air).

P: Power consumed by the system measured in W.

: T2 – T3 (temperature difference across evaporative cooler measured in oC.

COP: Coefficient of Performance.

: Amount of energy transfer across evaporative cooler measured in kW.

c: specific heat capacity of water measured in kJ/kg. oC.

Subscripts:

1: Inlet of dehumidifier.

2: Exit of dehumidifier or Inlet of evaporative unit.

3: Exit of evaporative cooler.

evap: Evaporation.

air: air

w: water

CHAPTER 1 INTRODUCTION

1.1 Detailed Definition of The Project

1.1.1 Conventional Evaporative Cooling Systems

The accomplishment of evaporative cooling can be achieved by indirect or direct cooling system or by the combination of these both types on different stages.

Indirect evaporative cooling systems

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This system employments the outside air on cool an internal environment, without permitting outer and inner airstreams to directly mix. Cool outer air will be drawn through a heat recuperation unit that point instantly exhausted, same time inner air will be drawn from the room and flowed through the recuperation unit preceding being re-introduced of the room. The outside air’s cool thermal energy is consequently exchanged of the internal air by means of those heat recuperation unit without the two streams specifically mixing.

Fig 1: Indirect evaporative cooling system [1]

By humidifying the outside air former to it entering the high temperature recuperation unit, its temperature may be economically diminished Furthermore actually more low-cost cooling might be associated of the internal atmosphere. This enhances those limit of the system, also makes it convincing Indeed going Throughout periods when the outside temperature will be more sizzling or warming over the desired internal room condition.

There will be a decreased credibility of inner atmosphere continually traded off by outer pollutants so this might be a prefect plan for critical environment or incredulous situations, if the inner air never mixes with the outer air. It additionally allows the velocity of the outside air stream through the heat recuperation unit to be much greater than the internally circulating air, Therefore “scavenging” even magnificent levels of cooling from the system.

Direct evaporative cooling systems

Direct air evaporative cooling can be an extremely efficient and achievable approach to decrease the temperature, for different types of building, areas and regions that don't have a central air conditioning system. Shower humidifiers convey moisture to an atmosphere utilizing either high pressure or compacted air to guarantee evaporation. Deliberately situated all through the space, shower spouts convey cooling at a small amount of the cost of conventional air conditioning.

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Fig 2: Direct evaporative cooling system [1]

Similarly, as with in-channel or duct direct evaporative cooling, the amount of cooling accomplished is dependent on the humidity levels of the area, as a high humidity will avert(stop) more moisture being absorbed and its resultant cooling impact. This technique is best utilized inside areas that has exceptionally dynamic ventilation and a great state of air exchange to keep the ambient humidity sufficiently low to constantly absorb moisture.

It can be utilized inside or remotely, just like the situation when Condair made the world's biggest evaporative cooling system around the Prophet's Mosque in Medina, Saudi Arabia. Over the 15-hectare site, showers discharge up to 50,000 liters of moisture for each hour, giving 34,000 kW of evaporative cooling to the desert air and diminishing its temperature by up to 10 °C.

Principle of direct evaporative cooling systems

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Fig 3: Scheme of working principle and simplified scheme of direct evaporative cooler (DEC)

In the above figure 3. The working principle of a direct evaporative cooling(DEC) with its equipment and gears are shown. The hot air entering inside (1) in a cooling pad which is splashed with water at the wet blub temperature of the inner air. From the hot air the heat is transfer to the cold water. by the air stream as the heat is transfer as sensible heat also, is consumed as latent heat by the water. If the value of latent heat is compared, the portion of water is vanished or eliminated which is being implanted by the diffusion into the flowing air and the moisture content of this air is increasing. As the sensible heat transfer by the air, the existing air temperature (2) is diminished, both the enthalpy of entering and existing air will be the same as impact of the latent heat recuperated as moisture into the air as moisture. The direct evaporative cooling (DEC) working procedure is exhibited in the psychrometric chart in fig 4 by the green line joining the points 2 and 3.

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Fig 4: Psychrometric processes of Liquid Desiccant Evaporative system

As it can be seen on the diagram the working procedure from stage1 to stage 2 (1-2) is acknowledged at constant enthalpy. The cooling operation could proceed until the condition of saturation (2'), at limit. By the simple construction of the equipment the primary benefit of direct evaporative cooling is. The major drawback of the direct evaporative cooling is shown by the rising of the air moisture content which might be unfortunate for incontrovertible applications.

1.1.2 Desiccant Material

There are two basic necessities for healthy and agreeable indoor conditions i.e.: enough exposure to fresh air and proper control over humid environment. Many areas in the world which are rich in population have unfortunately humid climate, so a lot of electricity is needed to fulfill both these conditions otherwise it will be hard.

From ventilation and the days of extreme humidity a typical cooling coil (when direct expansion refrigerant or deep-freeze water has to be used) cannot fulfill the requirement of load (latent loads). Every single regular chiller and air conditioner systems is a crucially rational cooling device that brings down the temperature of the air below its saturation point to concentrate the moisture in order to humidify it. Only by the help of a wet cooling coil these systems can run, and the air will be very close or near the saturation. When it leaves or exit the coil. Utilizing the constraint of traditional chillers and air conditioners becomes evident when tires them in an advance Air Conditioning system. low level-energy air conditioning system is the one that takes out the fan energy which is utilized as a part of a regular typical systems that diffuses great extent of air, But Technologies, for example chilled beams, displacement ventilation, also, beaming boards can be a component of low level energy cooling systems for this operation, But these progressed and Advanced system won’t work with a regular chiller or Direct air conditioner system which have an outcome of comparatively chilled air (e.g., 50 to 55 ) which is condensed with humidity (i.e., 100 % Rh).

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Fig 5: Psychometric variations of different desiccant salts [3]

There is a need of a cooling system that gives drier, but hotter air (chart1). For displacement ventilation regular supply of air requirements might be 65 and 50 % relative humidity. Absolute humidity of 45.5 grains moisture is contain by this supply air for every pound of dry air (which is proportionate to a humidity proportion of 65 g/kg and a dew purpose of 46 ).

The air conditioners that uses the phenomenon of lowering the temperature of the air in order to condense the moisture so it can be dehumidifies first have 46 below temperature to cool the air and then increase the air temperature to 65 to heat it again.

10.8 tons of rewarmed and 54.0 tons of chilled is produced by the air conditioners that uses 6,000 cfm of hot, moisturized outdoor air. The chillers are processing 25 % more chilling than that which is necessary to fulfill the conditions of load. Besides this percent’s extra cooling turns out to be considerable bigger during cooler, foggy environment e.g. 42 % extra cooling can be produced than the required percentage if it were 70 and drizzling [2]

There is a property for water vapor that liquid desiccants are solutions that have a high empathy, due to this the dehumidify air is generated by the cooling system without over cooling. In dehumidify air the liquid desiccants have been used from 1930s.

1.1.3 Different Type of Desiccants

For these types of systems lithium chloride and calcium chloride are the most commonly ionic salts used as a liquid desiccant which are basically strong solutions. In the air which is supplied by the liquid desiccant air conditioning the condensation of desiccant will not arrive because of the engaging characteristic of the iconic salts themselves have imperative zero vapor pressure. But there is a price from to have this zero-vapor Pressure such as: with salt water, solution of calcium chloride and lithium chloride are very corrosive. This corrosiveness conditions are that no small drops of this desiccant are entrained by the supply air and protection must be given to all wellet parts within the solution desiccant air conditioning.

Properties and characteristics of calcium chloride () as a liquid desiccant

The moisture from the air is absorbed by different type of desiccant materials at distinct quantities. There are solid and Liquid(solution) desiccant martials. lithium chloride, calcium chloride, lithium bromide, Silica gel, and natural zeolite and activated ammonia, are the most frequently utilized desiccants. But we will be using calcium chloride in our system.

The most common characteristics conditions in any of the liquid desiccant are the following:

- High affinity with water vapor.
- Chemical and physical stability over many cycles.
- Ability to hold large weight fractions of water.
- Ability to separate water vapor from other constituents.
- Ability to attract water vapor at desired partial pressures.

The manufacturing of Liquid calcium chloride in general range conc. Of 28% - 45% and 45% for the use in HVAC applications. Other trace elements and compounds manufactured within the limits defined by The American Society for Testing and Materials (ASTM) Standards which is contain by the commercial grades of calcium chloride. However, for the theory points of view the, properties of pure calcium chloride & calcium chloride –water solution has been given below

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Fig 6: (a) Specific Gravity vs. % , (b) Boiling Points of [4]

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Table 1: Properties of hydrates [4]

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Fig 7: Surface Tension of Pure Solutions [4]

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Fig 8: Specific Heat of Aqueous [4]

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Fig 9: Phase Diagram of Solution [4]

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Fig 10: Viscosity of Pure Solution [4]

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Fig 11: Vapor Pressure of Hydrates and Solutions [4]

Advantages of desiccant system

1. Low-pressure drops.

2. Less regeneration temperature.

3. Huge energy storage.

4. Have the possibly to eliminate pollutants.

5. The adaptability and capacity of a pump for pumping the desiccant solution makes the whole unit little and conservative.

Disadvantages of desiccant system

1. Desiccant system can be damaged by the corrosive nature of the different liquid desiccants such as , Lithium chloride and lithium bromide.

2. These solutions such as , Lithium chloride, lithium bromide re corrosive in nature and can harm or damage the desiccant system

3. Any carry over of fluid desiccant along with supply air flow ca harm the strength of the inhabitants.

4. There is a need of hug and large pumps which draw a lot of energy to deal with the huge volume desiccant solutions.

5. Desiccants of liquid salts likewise confront the issue of crystallization.

1.1.4 Desiccant Cooling System

Nowadays living a life with satisfying condition is a famous tendency, which leads to air conditioner. Vapor compression cooling system is the most commonly used air conditioner nowadays, and it is operated by an electric power. This system is an innovative cooling system with great energy sparing potential. The solution desiccant system has pulled in to an ever-increasing extent consideration lately because of its environmentally friendly innovation as contrasted with the vapor pressure cooling system because of its encouraging use of less thermal energy. The regeneration procedure of the desiccant solution is the part on which the energy utilization of liquid desiccant system depends. Generally, the working of desiccant system is run by the thermal energy and this energy can be obtain from heat sources of low-temperature and it’s a renewable type of energy and in a liquid desiccant system this solar energy can be purpose to regenerate the desiccant solution. Numerous researches are shared with inspection of the working performance of the liquid desiccant system or air conditioning with solar energy. In any case, there will be one issue for the solar energy regeneration system is that this energy will always be depended on climate conditions, so it means that the dehumidification and solar energy regeneration system can't meet most of the time. In this manner, it is important for the liquid desiccant system to locate another regeneration system under the condition without enough of solar energy.

1.1.5 Desiccant Dehumidification

The desiccant dehumidifier contains of a desiccant material, the purpose of that material is to take in the moist by the mechanism of dehumidification from the air.

At different capacities there are various types of desiccant materials which absorb the moist from the air at. There are solid and Liquid(solution) desiccant martials. lithium chloride, calcium chloride, lithium bromide, Silica gel, and natural zeolite and activated ammonia, are the most frequently utilized desiccants, by using the heat energy to evaporate the excessive moisture from the desiccant solution, the desiccant dehumidifier can be regenerated. Mostly by different researchers, for regeneration of the desiccant dehumidifier the solar energy is used as an input source.

In the case in which the desiccant is in solid state, the dehumidifier is mostly a rotating wheel which is slow or a periodically regenerated adsorbent bed. In the case where desiccant is a solution the dehumidifier is the apparatus.

Surrounded by which the desiccant is contact with the process air stream. Its design includes finned-tube surface, coil-type absorber, spray tower, and packed tower. The dehumidifier and the regenerator are generally referred to as contactors

The process of dehumidification and regeneration of desiccant dehumidifier is shown in the Fig 12.

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Fig 12: Desiccant dehumidifier processes [5]

1-2 → From the air the humidity is eliminated by the desiccant

2-3 → By discharging the humidity the desiccant is regenerated from it by using warm air.

3-1 →the desiccant is cooled down.

1.1.6 Desiccant Based Evaporative Cooling

In general, evaporative cooling systems are used when the wet blub temperature does not rise beyond 25 ˚C usually. In dry climatic conditions the high coefficient of performance (COP) and evaporative cooling units can operate and because of the air saturation of the surrounding air in moisture climates the effectiveness of these cooling units decreases. On the basis of this we can say that the partnership of evaporative cooler with desiccant dehumidifier is best and by this the elimination of moisture is possible from the air steam and so the function of these cooling units can be proven very effective. The dehumidifier contains desiccant material, the purpose of that material is to absorb or remove moisture from the moist air. These materials have the ability to absorb or adsorb so these materials absorb or adsorb and hold water vapor from the humid air. The evaporative desiccant system is the combination of the following units:

- desiccant dehumidifier unit
- regenerator unit
- cooling unit

The basic operation of a desiccant evaporative system with a solar collector or thermal collector is shown in Fig 13.

By the help of a desiccant dehumidifier the moisture from the air can be removed and the desired temperature is obtained by using evaporative cooler. For constant operation of the cooling system, by using a heat energy the desiccant dehumidifier is regenerated, which is taken from a solar collector or some other source of energy as shown in figure 5. In this system the latent and sensible loads are removed by the usage of desiccant dehumidification System and the cooling unit. The objective of the cooling unit is to handle the both factors of the load. The cooling depends on the humidity and temperature of the air. There are following parts of the desiccant dehumidifier are discussed below.

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Fig 13: evaporative desiccant cooling systems working principle [5]

Dehumidifier

In a chamber the dehumidifier process is done, where from bottom to top and through the counter flowing solution the airflow of ambient air is forced. To decrease the vapor pressure the solution is cooled, may be before entering the chamber in a liquid heat exchanger, inner side of the chamber by cooling coils or evaporative with wetted air mediums which is going from the chamber. Water vapor is absorbed by the solution when the solution encounters the air. By utilizing few methods for leading the solution in contact with air. A basic technique to splash the solution over packing. Another possibility, on the soaked area it can be splashed by wicks or let wet areas using overflowing mediums above the areas. As a failing firm the solution flow downward the soaked surface (Fig 14).

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Fig 14: Fabricated dehumidifier [3]

Pump

Energy can be change over to another type of energy form by an appliance called pump. A pump can be of kinds, which are the following:

- centrifugal pump

- reciprocating pump

Water from a low level can be pumps or drag to a high level and this process is done by centrifugal water pumps. From the outside energy source work is done to function the pump and the sources may be electric engine or motor. The dragging of water from the tank can be by dipping the pump in it or the pressurized air is used to intake the water from the tank. Dipped pump is used which have the working limits up to 230 V which can fetch water up to 8 feet.

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Fig 15: Water Pump [6]

Fan

The main function of fans is to rotate air through chillers, condensers and dehydrators. There are two types of fans which are the following:

- Centrifugal Fans

- Axial Fans

Axial fans make their best to reach the highest effectiveness by producing aeronautic boost. Noise can be produced when turbulence causes fall in the performance in the divert area. Air is rotated through the whole channel with the help of fans. It is present at the opening of the chillers. A stopped part called as housing surrounds a circulating wheel which is the main part of a fan. Flow of air is produced by transmitting energy between the difference in pressure and power-driven wheels. In order to eliminate air, low or high atmospheric pressure can be produced. These two conditions can be produced by every fan. Low atmospheric pressure air is present at the opening of a fan and high atmospheric pressure is at the exit part. Induced draft is the air which enters a fan and forced air is the one which exits a fan. Blowers and exhausters are the two types which a fan can act like disregarding its construction. Exhausters eliminate gases by fusion while blowers remove air against a pressure at their exit part. In this case we used axial flow propeller fans.

On a mounted brand, a rotor is present which uses blades that is the main part of a fan. The most important thing is the design of the blades which are around the wheel because it stops the air elimination from getting back into the wheel around its boundary. The propeller fans are used only when the resistance of air movement is small. They are used for the radiator fans, air ducts, etc.

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Fig 16: Fan [7]

Spray chamber

In this unit, by means of high pressure nozzles the liquid is atomized into the air stream. to improve furthermore the mass transfer rate. The large surface area of the dispersed liquid serves and the outcome in good dehumidifying effectiveness.

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Fig 17: Spray chamber [8]

the low air pressure drop is the benefit of a spray chamber, but this is counterbalance by the condition for high pressure at the spray nozzles for good atomization. Other drawback are compared to the packed tower its greater bulk and it’s hard to arrange for isothermal operation although by a heat exchanger in the sump or in the liquid circulation line a certain quantity of cooling can be given .

Based on direction of interaction between air and liquid desiccant used in practice for liquid desiccant based air dehumidifier are:

Parallel flow

In parallel stream design, air and desiccant solution stream or flow parallel with each other in descending direction. Initially at the entry point, the vapor pressure difference is substantial amongst air and desiccant solution which at that point continue diminishing as stream continues to downward, which influences the effectiveness and thus economy of the dehumidification procedure. It is one of the simple’s technique to have simple and efficient setup. Since, the stream direction is same and descending, so there is no real issue identified with extend of desiccant solution with airflow.

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Fig 18: Three main employed flow configuration for dehumidifier [9]

Counter flow

In counter flow or stream, air and desiccant stream in opposite direction. Best air upward way and desiccant solution descending way with the assistance of gravity. In this design, there is general extensive vapor pressure contrast amongst air and desiccant solution compared with some other method and subsequently it is one of the most effective, efficient and smaller plan for dehumidification of air. In any case, slight carryover of desiccant may occur in this design because of upward motion of air.

Cross flow

In cross stream or flow configuration, air and desiccant stream opposite direction with respect to each other. For the most part, desiccant in descending direction and air in perpendicular horizontal direction as for desiccant. There is issue of carryover of desiccant with air due to cross flow or stream between them. Be that as it may, advantage is that there is great interaction and more surface contact between them to have better effectiveness. Our system will have cross flow.

Energy Source

There is requirement and need of electricity to work pumps, fans and other equipment’s in desiccant cooling system and for regeneration there is also a need of heat energy to per heat the liquid desiccant. The desiccant system can work or can operate on low level of heat, from solar thermal systems or any waste heat source such as smokestacks, control plants and power plants etc., the acquirement of heat energy can be done.

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Fig 19: Methods of regeneration

In two ways the solar energy can be used. firstly, a photovoltaic system in which pumps and fans are driven by the electricity which is in the form of solar energy. Secondly, From the sun the heat energy can be obtain to use and to revive the unstable liquid desiccant [9]. Figure demonstrates the simplified diagram of an evaporative cooler incorporated with a desiccant cooling system and a solar collector. Before recommending or introducing in the regenerator the desiccant solution is directly pre-heat by the solar collector and regenerator. amongst collector and liquid desiccant another sort of collector(solar) utilizes water as a medium of heat exchange. Former kind of solar collector equipment is very much effective as by the collector all the heat energy is consumed and is specifically conveyed to the liquid desiccant. However, as desiccant solution is corrosive in nature, the collector must be deigned to be corrosion resistant or there should be a way to prevent the corrosion.

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Fig 20: Desiccant cooling system incorporated with an evaporative cooler and a solar collector (schematic diagram) [10]

1.2 Significance of the Project

The evaporative cooling system (desiccant based) is a unique and promising invention that is mostly used in hot and moist conditions. In this system the process stream air come in explicit contact with the cooling water as the moisture is included to the cooled air stream. While In the indirect evaporative system, the cooling liquid stream and the procedure air stream not specifically meet and is just cooled practically. By utilizing salt solution for dehumidification, the Evaporative cooling is made more effective. One of the imperative favorable advantage of liquid desiccant is that by using free energy it can eliminate the latent heat of the air and recover it with low temperature such as, solar or waste energy. Even though the amount of solar energy technology can be expensive similar to most newly concepts, but it can lead to profitable saving in long run. From the return air of the conditioned space the heat energy is recovered, utilized to cool the entering air this helps in decreasing the cooling energy demands. A we know it is environment friendly, needs less input, and enhances indoor air quality the solar driven liquid desiccant evaporative cooling the most encouraging air-conditioning alternative. At last, this project demonstrates that liquid desiccant dehumidification which is a basic innovation that can be enhanced by combining the evaporative cooling advances.

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