Water Cooler.docx

CHAPTER I 1INTRODUCTION: In tropical countries such as India, small split type air conditioners are generally used in residential and commercial buildings. In such establishments, electric water heaters are often used to generate hot water and water coolers to generate cold water. Air conditioner, electric water heater and electric water cooler are generally the major energy consuming devices in the buildings. The number of air conditioners, electric water heaters and water coolers has been increasing over the years, and this poses a serious problem to the country that largely depends on non renewable energy. Wasteheat from air conditioners may be used to produce hot water. The benefits of doing this are twofold. One is elimination of the need to install an electric water heater, and the other is saving of electrical energy otherwise used in the electric water heater and water cooler. These may be accomplished while the usefulness of the air conditioner for cooling is maintained. At present, water heaters using waste heat from small split type air conditioners are commercially available in India and are generally mechanically made to the specific requirements of the users. Even though split type air conditioners with water heaters are successfully used, their performance and system design for application in India have not been fully investigated, especially when both cooling and heating effects are desirable. Studies of heat pump hot water heaters operating in subtropical and cold countries have appeared in the literature. The need for the development of an integrated air conditioning cum water dispenser system at low cost was overcome by using a common compressor for both the systems. The use of common compressor eliminates the use of a separate electrical energy for the operation of water heaters and water coolers. A parallel connection can be bypassed from the compressor of a normal air conditioner in order to make the system suitable for all the three purposes i.e. water heating, water cooling and space conditioning. In such a system there are two cycles involved: air cycle and water cycle. In evaporator of air cycle, the air is cooled. In condenser of air cycle, the air is heated. In evaporating coil of water cycle, the water is cooled and in condensing coil of water cycle, the water is heated. An attractive point is that this air conditioner cum water dispenser system can produce hot & cold water as well as hot & cold air. The system can be operated in five modes: water heating only, space cooling and water heating, space heating and water heating, space cooling, space heating with three cycles of operations: air cycle(in which air conditioner operates), water cycle(in which water dispenser operates) and air/water cycle(in which air conditioner cum water dispenser operates). These cycles can be controlled by means of valves. 1.2.Rerigeration System

Any substance capable of absorbing heat from another required substance can be used as refrigerant i.e. ice, water, air or brine. A mechanical refrigerant is a refrigerant which will absorb the heat from the source and dissipate the same to the sink or in the form of latent heat. The physical properties will enable them to repeat continuously a liquid to gas and gas to liquid transformation. Air was used as a refrigerant in many refrigerant system in olden days considering as safest refrigerant. Ammonia, carbon dioxide and sulphur dioxide were used for domestic and commercial purposes until ferons were available. The refrigerants are classified in to two groups: 1. Primary refrigerants 2. Secondary refrigerants Primary refrigerants directly take the part in the refrigerants system where secondary refrigerants are first cooled with the help of the primary refrigerants and are further used for cooling purpose. Vapor-compression refrigeration is one of from many refrigeration cycles available for use . It is the most widely used method for air-conditioning of offices, private residences, hotels, large public buildings, restaurants ,automobiles, hospitals and theaters,. It is also used in private and economic refrigerators, large-scale warehouses for chilled or frozen storage of foods. Oil refineries, petrochemical and chemical processing plants, and natural gas processing plants are many types of industrial plants that often use large vapor-compression refrigeration systems. A household refrigerator is a common household gadget that consists of a thermally insulated Compartment and which when works, transfers heat from the inside of the chamber to its external environment so that the inside of the thermally isolated compartment is cooled to a temperature below the surroundings temperature of the room. Heat rejection may occur directly to the air in the case of a traditional household refrigerator having air-cooled condenser. The utilization of waste heat is profitable when heating and refrigeration are needed at the same time, or where waste heat can be stored: In air conditioning systems to reheat exhaust air In butcheries, dairies, hotels, etc., where, on the one hand, cold storage rooms are supervised and where there is always a great demand for domestic hot water In shops, where in addition to cooling foodstuff, need of heat also occurs In cold storage facilities, for heating and domestic hot water. Waste heat rejected from refrigeration and air conditioning systems can be used by Intercepting it before it is vented to atmosphere by passing refrigerant gas through water cooled

Condenser to deliver heated water. Heat can be recovered by using the water-cooled condenser and the system can work like a waste heat recovery unit. The recovered heat from the condenser can be used for domestic use. This idea is selected keeping its scope in mind for various applications along with the overall cost. The thought process was to modify the refrigerator in such a way, enabling it to produce cold and hot water without consuming extra electric power, while improving the efficiency of there figuration system. Saving heat energy which is usually lost to the surrounding in domestic refrigerators and utilizing it in a useful way. Manifesting this model in desired form, at expense of cost comparable with the cost of available refrigerators is our aim. The same concept can be applied to a water cooler working on refrigerant cycle, thus modifying it into hot and cold water dispenser. This concept has numerous applications which can save large amount of energy and money 1.3. WATER COOLING SYSTEM : A water cooler or water dispenser is a device that cools and dispenses water. Water coolers come in a variety of form factors, ranging from wall-mounted to bottle filler water cooler combination units, to bi-level units and other formats. They are generally broken up in two categories: point-of use (POU) water coolers and bottled water coolers. POU Water coolers are connected to a water supply, while bottled water coolers require delivery (or self-pick-up) of water in large bottles from vendors. Bottled water coolers can be top-mounted or bottomloaded, depending on the design of the model. Bottled water coolers typically use 5 or 10-gallon dispensers commonly found on top of the unit. Pressure coolers are a subcategory of water coolers encompassing water fountains and direct-piping water dispensers. Water cooler may also refer to a primitive device for keeping water cool Water coolers are a common metonym referring to workplace socialization. DISPENSER TYPES Wall-mounted / recessed The wall-mounted type is connected to the building's water supply for a continuous supply of water and electricity to run a refrigeration unit to cool the incoming water, and to the building's waste disposal system to dispose of unused water. Wall-mounted water coolers are frequently used in commercial buildings like hospitals, schools, businesses, and other facilities.

In the standard wall-mounted cooler, also commonly referred to as a water fountain or drinking fountain, a small tank in the machine holds chilled water so the user does not have to wait for chilled water. Water is delivered by turning or pressing a button on a springloaded valve located on the top of the unit that turns off the water when released. Some devices also offer a large button on the front or side. Newer machines may not have a button at all; instead, a sensor that detects when someone is near and activates the water. Water is delivered in a stream that arches up, allowing the user to drink directly from the top of the stream of water. These devices usually dispense water directly from the municipal water supply, without treatment or filtering. Wall mount water coolers come in a wide variety of styles, from recessed models to splash resistant, contoured basins protruding out from the wall, traditional rounded square edge designs, bottle filler and water cooler combination units, bi-level designs, and other features and options Bottom-load water dispenser Water dispensers commonly have the water supply vessel mounted at the top of the unit. Bottom-load water dispensers have the vessel mounted at the bottom of the unit to make loading easier. Tabletop water dispenser There are also smaller versions of the water dispensers where the dispenser can be placed directly on top of a table. Direct-piping water dispenser (POU) Water dispensers can be directly connected to the in-house water source for continuous dispensing of hot and cold drinking water. This type is commonly referred to as POU (Point of Use) water dispensers. These are more hygienic than bottled water coolers.

Freestanding water cooler with bottle Freestanding A freestanding design generally involves bottles of water placed spout-down into the dispensing machine. Tabletop or kitchen worktop versions are available which utilize readily available five-liter water bottles from supermarkets. These coolers use air pumps to push the water into the cooling chamber and Peltier devices to chill the water. A new development within the water cooler market is the advent of countertop appliances which are connected to the mains and provide an instant supply of not only chilled water but also hot and boiling water. This is often visible in the horeca industry. Water will flow faster when the handle is in the upright position. The water is aerated which allows the water to come through the spout at a faster rate

WATER SOURCE AND PURIFICATION Bottle To install the bottle, the bottle is tipped upside down and set onto the dispenser; a probe punctures the cap of the bottle and allows the water to flow into the machine's internal reservoir. These gravity-powered systems have a device to dispense water in a controlled manner. These machines come in different sizes and vary from table units, intended for occasional use to floor-mounted units intended for heavier use. Bottled water normally is delivered to the household or business on a regular basis, where empty bottles are exchanged for full ones. The bottle size varies with the size of the unit, with the larger versions in the US using 5-USgallon (19 L) bottles. This is also the most common size elsewhere, labelled as 18.9 litres in

countries that use the metric system. These units usually do not have a place to dump excess water, only offering a small basin to catch minor spills. On the front, a lever or pushbutton dispenses the water into a cup held beneath the spigot. When the water container is empty, it is lifted off the top of the dispenser, and automatically seals to prevent any excess water still in the bottle from leaking. Plumbed with purification Plumbed water coolers use tap water and therefore do not need bottles due to their use of the main water supply. Usually some method of purification is used. Filtration Filtration methods include reverse osmosis, ion exchange, and activated carbon. Disinfection UVGI (Ultraviolet Germicidal Irradiation) is a commonly used disinfection method to kill or inactivate micro-organisms and leaving them unable to perform vital cellular functions. Log reduction (i.e. 6-log reduction or 99.9999% effective) is used as a measure on the effectiveness of disinfection. COOLING AND HEATING METHODS

A modern water cooler dispensing cold water, hot water and boiling water Cooling Most modern units offer a refrigeration function to chill the water, using Vapor compression refrigeration or Thermoelectric cooling. Vapor compression refrigeration Water coolers using vapor compression refrigeration come in one of the following systems:



Reservoir System - A tank where water is held, to be used for cooling or heating and is fitted with a float mechanism to prevent overflowing. 

RR technology - a removable reservoir is an open-end tank with cooling coils that come into contact with the external tank surface. It operates on the basis of a modular system, allowing one to easily detach and refill water instead of keeping it in a closed system. One of the advantages in using a removable reservoir is the ease of sanitization. This allows end users to replace the reservoir completely rather than sending an entire water cooler back for servicing. A similar technology can be found in many modern water dispensers and coffee machines.



Stainless Steel - open end tank with cooling coils that come into contact with the external tank surface



Pressure Vessel Direct Chill System - The combination of a pressure vessel, which protects the water in the tank from air-borne contamination, and a direct chill system which cools water coming from the mains quickly. 

Pressure Vessel - A sealed pressure vessel is filled at a lower pressure within the water cooler. As such, the water does not come into contact with the atmosphere, allowing a larger amount of cold water (depending on the size of the tank) to be dispensed at the expense of a slower cooling system.



Direct Chill - In a standard direct chill system, water is passed through a stainless steel coil that is in contact with a copper evaporator that circulates refrigerant gas. The refrigeration system is attached outside of the coil and the cold transfers through the pipe walls to chill the water in the coil through conduction. When the taps are operated, the chilled water is dispensed at mains pressure. The water never comes into contact with the atmosphere as the cold temperature emitted by the refrigerant gas is transferred through the copper coil which transfers the cold temperatures to water passing through the stainless steel coil without touching each other. This allows the water to get cold more quickly again at the expense of having a lower volume of cold water available.



Ice-bank Cooling System - A pressurized stainless steel coil and a copper coil is immersed in a reservoir full of pre-chilled water. The copper coil containing the refrigerant gas freezes the water contained within the reservoir producing a cold supply, which in turns cools the drinking water flowing through stainless steel coil.

Thermoelectric cooling Thermoelectric cooling is a green alternative to HFC refrigerant that uses a solid state device that acts as a heat pump to transfer heat from one side of the device to another using the Peltier effect. It is made up of numerous pairs of semiconductors enclosed by ceramic wafers. Thermoelectric coolers use direct current power rather than refrigerant gas and a compressor and have no moving parts or complex assemblies.

Heating Some versions also have a second dispenser that delivers room-temperature water or even heated water that can be used for tea, hot chocolate or other uses. The water in the alternate hot tap is generally heated with a heating element and stored in a hot tank (much like the traditional hot water heaters used in residential homes). Additionally, the hot tap is usually equipped with a push-in safety valve to prevent burns from an accidental or inadvertent pressing of the lever.

CHAPTER II LITERATURE SURVEY: Scientists all over the world are in search of new and renewable energy sources. One of the options is to develop energy storage devices, which are as important as developing new

sources of energy. The air conditioning along with water dispenser can operate in various modes which are water heating, water cooling, space heating, etc.

According to Q. P. Ha [1] they have performed the vapor-absorption cooling plant fully powered by a renewable energy source with solar radiation, in which no water storage and auxiliary heat exchanger are used. They have proposed system in meeting the airconditioning demand while addressing directly critical issues of electricity consumption and greenhouse gas emissions. With the results they come up as the new fully solar driven single effect hot water absorption chiller of 6kW cooling capacity to ultimately achieve high energy efficiency and greenhouse gas emission reductions in buildings. Here they produce hot water without the use of additional heat exchanger. The influence of condenser-water temperature, hot-water temperature and chilled-water temperature on the system cooling capacity investigated.

Zhang Jie[2] had done the theoretical study and proposed that in the cooling conditions the low-temperature condensed water of indoor unit on the evaporator drainage to outdoor unit on the condenser fins, thereby reducing the condensing temperature to improve the cooling of the condenser , and enhance the air-conditioning refrigeration coefficient. Theywere focused on to solve the “Air- conditioning drip water” problem. Emissions of condensed water of air conditioners in the run-time give rise to inconvenience and affect the environment, and the condensed water discharge to the outdoor is a waste of water resource. Thus the treatment of condensed water is very practical problem [3]. Mecler[4] proposed a two-stage solid desiccant air conditioning system, integrated with an HVAC system. An energy ex-change was employed to precool and predehumidify the process air by exchanging sensible and latent heat with return air from conditioned space without the addition of external heat or regeneration. Much research was carried out on the solar air heater.

Alvarez et al.[5] described the development and testing of an efficient, single-glass air solar collector with an absorber plate made of recyclable aluminum cans(RAC). The maximum efficiency reached was 74%, which was very satisfactory for an air solar collector with an absorber plate made of recyclable aluminum cans. The advantages of using recyclable materials to build the absorber plate of the air solar collector imply that the absorbers are cheaper with a cleaner environment.

To overcome all these problems we offer an air conditioner coupled with heat pump water heater with the main components such as heat exchanger, compressor, and valves. The air to water heat pumps water heater offers an energy saving alternatives. Heat pump water

heater can provide hot water two or three times more energy efficient than electric resistance heater. So the primary cost will be reduced and it can realize multifunction easily. Here we can demonstrate an air conditioning water heater (ACWH) and the performance analysis. 2.1.The Refrigeration systems: It changes according to the objective and the type of refrigerant used. They are the means by which we can actually perform the refrigeration process. A better understanding of them is thus, very essential .Methods of Refrigeration systems can be classified as: 2.1.1. Cyclic refrigeration - Vapor-Compression Refrigeration, Vapor-Absorption Refrigeration, Gas cycle. 2.1.2 Vapor-Compression Refrigeration System Vapor-Compression Refrigeration System (VCRS) is the most widely used method for airconditioning of buildings and automobiles. Vapor compression cycle is an improved type of air refrigeration cycle in which a suitable working termed as refrigerant, is used. The refrigerants generally used for this objective are ammonia (NH3), carbon dioxide (CO2) and sulphurdioxide (SO2). The refrigerant used, does not assent the system, but is circulated throughout the system alternately condensing and evaporating.

2.1.3 Vapor-Absorption Refrigeration – The Vapor Absorption Refrigeration is heat operated system. In the absorption system the compressor of the vapor compression system is reintegrated by the combination of absorber and generator. A solution known as the absorbent, which has an affinity for the refrigerant used, is circulated between the absorber and the generator by a pump. The absorbent in the absorber draws (or sucks) the refrigerant vapor formed in the evaporator thus maintaining a low pressure in the evaporator to enable the refrigerant to evaporate at low temperature. In the generator the absorbent is heated. There by releasing the refrigerant vapor (absorbed in the absorber) as high pressure vapor, to be condensed in the condenser. Thus the suction function is performed by absorbent in the absorberand the generator performs the function of the

compression and discharge. The absorbent solution carries the refrigerant vapor from the low side (evaporator absorber) to the high side (generator condenser). Thus establishing circulation of the refrigerant through the system. 2.1.4. Gas Refrigeration Cycle – Just as the vapors are used for cooling in the vapor compression cycle and vapor absorption cycle, the gas is used for cooling in gas refrigeration cycle. When the gas is throttled from very high pressure to low pressure in the throttling valve, its temperature reduces suddenly while its enthalpy remains constant. This principle is used in gas refrigeration system.

2. 2.Non-cyclic refrigeration: Ice Refrigeration and Dry Ice Refrigeration. 2.2.1 Ice Refrigeration – In this method the ordinary ice is used for keeping the space at temperature below the surrounding temperature. The temperature of ice is considered to be zero degree Celsius hence it can be used to maintain the temperatures of about 5 to 10 degree Celsius. To use the ice for refrigerating effect a closed and insulated chamber is required. On one side of the chamber ice is kept while on the other side there is a space which is to be cooled where some material to be cooled can be placed. If the temperature below 0 degree Celsius is required, then the mixture of ice and salt is used. This method of cooling is still being used for cooling the cold drinks, keeping the water chilled in thermos, etc.

2.2 Dry ice refrigeration – Dry ice is the solid carbon dioxide having the temperature of -78 degree Celsius. Dry ice disciple directly from solid state to gaseous; this process is called as sublimation. Dry ice can be pressed into various sizes and shapes as blocks or slabs. Dry ice is usually packed in the frozen food cartons along with the food that has to be kept frozen for long time. When the dry ice gets converted into vapor state it keeps the food frozen. The process of dry ice refrigeration is now-a-days being used for freezing the food in aircraft transportation

CHAPTER III 3FABRICATION COMPONENTS COMPRESSOR:

A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor. Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas. Liquids are relatively incompressible; while some can be compressed, the main action of a pump is to pressurize and transport liquids.  

Working Pressure (minimum) 9 Kg. / Sq. Cm.



No. of stages One (or more)



Motor Power 200 KW (or more)



Operating Voltage 3 Phase, 415 V

CONDENSER In systems involving heat transfer, a condenser is a device or unit used to condense a substance from its gaseous to its liquid state, by cooling it. In so doing, the latent heat is given up by the substance and transferred to the surrounding environment. Condensers can be made according to numerous designs, and come in many sizes ranging from rather small (hand-held) to very large (industrial-scale units used in plant processes). For example, a refrigerator uses a condenser to get rid of heat extracted from the interior of the unit to the outside air. Condensers are used in air conditioning, industrial chemical processes such as distillation, steam power plants and other heat-exchange systems. Use of cooling water or surrounding air as the coolant is common in many condensers

 Expansion valve A thermal expansion valve (often abbreviated as TEV, TXV, or TX valve) is a component in refrigeration and air conditioningsystems that controls the amount of refrigerant released into the evaporator thereby keeping superheat, that is, the difference between the current refrigerant temperature and its saturation temperature at the current pressure, at a stable value, ensuring that the only phase in which the refrigerant leaves the evaporator is vapor, and, at the same time, supplying the evaporator's coils with the optimal amount of liquid refrigerant to achieve the optimal heat exchange rate allowed by that evaporator. Thermal expansion valves are often referred to generically as "metering devices".

EVAPORATOR : An evaporator is a device in a process used to turn the liquid form of a chemical substance such as water into its gaseous-form/vapor. The liquid is evaporated, or vaporized, into a gas form of the targeted substance in that process

One kind of evaporator is a kind of radiator coil used in a closed compressor driven circulation of a liquid coolant. That is called an air-conditioning system (A/C) or refrigeration system to allow a compressed cooling chemical, such as R-22 (Freon) or R-410A, to evaporate/vaporize from liquid to gas within the system while absorbing heat from the enclosed cooled area, for example a refrigerator or rooms indoors, in the process. This works in the closed A/C or refrigeration system with a condenser radiator coil that exchanges the heat from the coolant, such as into the ambient environment STORAGE TANK: Storage tanks are containers that hold liquids, compressed gases (gas tank; or in U.S.A "pressure vessel", which is not typically labeled or regulated as a storage tank) or mediums used for the short- or long-term storage of heat or cold. The term can be used for reservoirs (artificial lakes and ponds), and for manufactured containers. The usage of the word tank for reservoirs is uncommon in American English but is moderately common in British English. In other countries, the term tends to refer only to artificial containers. In the USA, storage tanks operate under no (or very little) pressure, distinguishing them

from pressure vessels. Storage tanks are

often

cylindrical in shape, perpendicular to the

ground with

flat bottoms, and a fixed flangible or

floating roof.

There are usually many environmental

regulations

applied to the design and operation of

storage

tanks, often depending on the nature of

the

fluid

contained

within. Above-ground

storage

tanks (ASTs)

differ

from underground storage tanks (USTs) in the kinds of regulations that are applied. Above ground storage tanks can be used to hold materials such as petroleum, waste matter, water, chemicals, and other hazardous materials, all while meeting strict industry standards and regulations

Thermostat:

A thermostat is a component which senses the temperature of a physical system and performs actions so that the system's temperature is maintained near a desired setpoint. Thermostats are used in any device or system that heats or cools to a setpoint temperature, examples include building heating, central heating, air conditioners, HVAC systems, water heaters, as well as kitchen equipment including ovens and refrigerators and medical and scientific incubators. In scientific literature, these devices are often broadly classified as thermostatically controlled loads (TCLs). Thermostatically controlled loads comprise roughly 50% of the overall electricity demand in the United States.[1] A thermostat operates as a "closed loop" control device, as it seeks to reduce the error between the desired and measured temperatures. Sometimes a thermostat combines both the sensing and control action elements of a controlled system, such as in an automotive thermostat.

INSULATOR An electrical insulator is a material whose internal electric charges do not flow freely; very little electric current will flow through it under the influence of an electric field. This contrasts with other materials, semiconductors and conductors, which conduct electric current more easily. The property that distinguishes an insulator is its resistivity; insulators have higher resistivity than semiconductors or conductors.

A perfect insulator does not exist, because even insulators contain small numbers of mobile charges

(charge

carriers) which can carry current.

In addition, all

insulators

become electrically conductive when a sufficiently large voltage is applied that the electric field tears electrons away from the atoms. This is known as the breakdown voltage of an insulator. Some materials such as glass, paper and Teflon, which have high resistivity, are very good electrical insulators. A much larger class of materials, even though they may have lower bulk resistivity, are still good enough to prevent significant current from flowing at normally used voltages, and thus are employed as insulation for electrical wiring and cables. Examples

include

rubber-like polymers and

most plastics which

can

be thermoset or thermoplastic in nature evaporator coil

An evaporator coil is the part of an air conditioner or heat pump that absorbs the heat from the air in your house. It is located inside the air handler or attached to the furnace. Located inside the blower compartment or air handler, the evaporator coil holds the chilled refrigerant that the compressor moves into it. As the air from the blower fan moves over the coil, the cold refrigerant removes the heat from your home’s air. The refrigerant becomes warmer and travels to the condenser coil outdoors.

With a heat pump, the process reverses in the winter and the evaporator coil expels heat from the refrigerant into your home, instead of absorbing it and taking it outdoors. Most heat pumps have auxiliary heating elements that are part of the evaporator coil components to supply heat when temperatures fall below a certain point

CHAPTER IV 4. SYSTEM DESIGN

A. Introduction Air-Conditioning cum Water dispenser system is a unique combination of air-cycle and water-cycle into a single unit. “Air-conditioning” is the simultaneous control of temperature, humidity, motion and purity of the atmosphere in confined space. The important factors which control the air-conditioning are i.

Temperature control

ii.

Humidity control

iii.

Air movement and circulation

iv.

Air filtering, cleaning and purification

Complete conditioning provides simultaneous control of these factors. In addition to comfort phases of air conditioning, many industries have found that this process has made possible more complete control of manufacturing processes and materials and improve the quality of finished products. “Water-dispenser system” is sequential process of controlling the temperature, motion and purity of water which is being circulated in the closed system. Factors controlled by water dispenser are  Temperature control  Water motion and circulation  Water filtering, cleaning and purification Thus in an “Air-conditioning cum Water-dispenser system” controlled, cleaned, purified, filtered air and water with better efficiency.

B. Components The basic elements of an air-conditioning system are Fans – for moving air Filters – for cleaning air, either fresh, recirculated or both. Condenser – for exchanging heat with the surrounding atmosphere and provides hot air Compressor–for compressing the refrigerant at high pressure and temperature Evaporator–for exchanging heat with the atmosphere and provides cold air Control system– for automatic regulation of amount of heating and cooling

C. Working of Air-Conditioning System Air conditioning comprises of the following steps A

The fan forces air into the duct work which is connected to the openings in the room called as terminals.

B

The duct work directs the air into the room through the outlets.

C

The air enters the room and either heats or cools as required. Dust particles from the room enter the air stream and are carried along with it.

D

The compressor initially is filled with the refrigerant in the form of gas.

E

On switching on the system the compressor compresses the gas to high temperature and pressure and then sends the super-heated gas to the condenser.

Figure Air- Conditioning System

Figure p-h graph

4.2METHODOLOGY The modification of domestic refrigerator into hot and cold water dispenser is explained below. It is achieved by replacing the air cooled condenser with water cooled condenser. It includes construction and fabrication of tank which will act as structure for water cooled condenser. Construction of Hot and Cold Water Dispenser

Domestic refrigerator has air cooled condenser as shown in below figure. We are going to replace it with a Tank & Coil condenser. A. Air Cooled Condenser

Figure 1.1: Domestic Refrigerator

The above figure shows the system for cooling found in domestic refrigerator. It has air cooled condenser, in which coils is exposed to air and it releases the heat directly into the atmosphere. B. Water Cooled Condenser Tank and Coil condenser is fabricated from Galvanized Iron sheet with dimensions as Length: 17 inches, Width: 6 inches, Height: 10 inches, Thickness: 5mm, Capacity: 10 liters

Figure 1.2: Working Diagram of Water Cooled Condenser

The tank and coil condenser will be having following sub-components:

1.

Condenser Coil: Condenser coil made of copper tube having size of ¼th inch and thickness 18 mm. It is bend using tube bender and fit into the tank.

2.

Supply Valve: It will act as inlet for water supply to the tank. Water from purifier or tap will enter through this valve.

3.

Float Valve: Float valve will keep the water level in check. If the level of water is to fall below the set level, it opens and water is filled in the tank.

4.

Outlet Valve: It will act as outlet for warm water.

C. Refrigerant A refrigerant is a fluid that is used in air conditioners and refrigerators, to take heat from the contents of refrigerator or the room (like ACs) and throw the heat out in the atmosphere. A refrigerant undergoes phase changes from a liquid to gas (while absorbing heat) and back to liquid (when a compressor compresses it). The choice of ideal refrigerant is made based on: its fa-vorable thermodynamic properties, non-corrosive nature and safety.

Although many fluids can be used to act as refrigerant, CFCs are the most popular refrigerants. Taking energy efficiency, global warming and safety, going for an Air Conditioner with R-410A and Refrigerator with R-134A is the best bet as of today. So the refrigerant we are going to use is R-134A .

D. Process A Galvanized Iron Tank is fabricated and assembled with the valves, condenser coil. It is welded onto the back of Refrigerator in place of air cooled condenser it had. Provisions are made to supply water into the tank either from tap (if not for drinking) or manually. The discharge line from compressor is joined with the copper condenser coil in tank. And the outlet of condenser coil goes to evaporator through expansion valve/capillary tube. The working of cycle will be same as before except that the heat energy is not lost to the atmosphere but used to heat water. In brief, Refrigerant will be compressed to high pressure and high temperature by compressor. It enters the tank and coil condenser in form of vapor. Tank is filled with water supplied through inlet from water source. Float valve keeps check on level of water. Water-cooled condenser acts as a heat exchanger that removes heat from refrigerant vapor and transfers it to the water in it. In doing so, the vapor condenses and gives up heat to the water. This warm water is supplied through outlet/tap so that it can be used for different chores.

Figure 1.4: Working of Water Cooled Refrigeration System At the inlet of the condenser the refrigerant is in the gaseous form as well as at high temperature. When a flow of air at room temperature is flown over the condenser at that time a heat exchange takes place between the air and the refrigerant causing the air to heated up and also leads condensation of the refrigerant that liquefies after condensation, slight difference in temperature occurs between the inlet and outlet of the condenser in practical scenario as it is a constant temperature process.

From the condenser outlet the liquid refrigerant is passed through the capillary tubes that act as an expansion valve where the drop in temperature of the refrigerant occurs due to expansion as it is a constant enthalpy process. The cooled refrigerant is now passed to the evaporator where in when air at room-temperature is passed over a heat exchange takes place leading to evaporation of the refrigerant and thus the air is cooled which is passed to the outlet terminals. The refrigerant is again directed back to compressor where the compression takes place at constant entropy. Finally the cycle of air- conditioning is completed.

D. Design of Air-Conditioning cum Water Dispenser System

Here, P1- compressor inlet pressure P2- compressor outlet pressure T1- condenser inlet temperature T2- condenser outlet temperature T3- evaporator inlet temperature T4- evaporator outlet temperature T5- hot water temperature T6- cold water temperature Valves- for regulation of refrigerant into the water-cycle

E. Working of Air-Conditioning cum Water Dispenser System

i.

Working of air-conditioning cum water dispenser system is similar to that of the air-conditioning system with an additional water cycle associated with it.

Initially R22 refrigerant of 1.75 kg is inserted into the compressor pin valve. iii.

Copper coils of 40 turns are made and inserted in the drum that acts as an condenser for the water cycle and copper coils of 20 turns are made for the evaporator in order to get maximum efficiency.

iv.

The condenser and evaporator of the water cycle are connected to the outlet and the inlet of the compressor.

v.

A filter is placed between condenser and capillary tube in order to prevent clogging of impurities in the setup.

vi.

Capillary tubes are used in order to enable expansion under constant enthalpy process

vii.

Valves are here used in order to regulate and control the air and water cycles independently

viii.

When the system is started the refrigerant flows to both air cycle and the water cycle

ix.

The compressed refrigerant flows through the condenser coils where condensation of the refrigerant occurs causing heating of the water in the hot water chamber and then it is passed through the expansion valve leading to a drop of temperature of the refrigerant and then it is passed to the evaporator in the form of liquid at a very low temperature where heat exchange occurs between water at room temperature and the refrigerant leading to cooling of the water and heating of the refrigerant thus cold water is obtained from cold water chamber.

x.

The refrigerant from the evaporator enters the compressor and thus the cycle continues.

xi.

Temperatures at the inlet and outlet of the condenser, inlet outlet temperatures of evaporator , pressures at the inlet and outlet of compressor is noted down and calculations related to COP , mass-flow rates, efficiencies are determined.

xii.

Finally a combined system of air cycle and water cycle is obtained with increased efficiency is thus obtained

Figure Air conditioning cum Water Dispenser System

CALCULATIONS

For Water Cycle

Design of Hot Chamber The refrigerant flows from the compressor in a chamber consisting of 40 turns which acts as a condenser. The chamber acts as Shell and tube heat exchanger wherein the condensation of the refrigerant takes place. The calculations are done taking the hot chamber as a heat exchanger.

i. Heat transferred by condenser Q = K x πd x (Thi-Tho)

where, Q= heat transferred by condenser in W K= Thermal conductivity of copper = 386W/m2k D = Diameter of tube= 6.35 x 10-3m

Thi= Condenser inlet temperature = 79.3 0C Tho= Condenser outlet temperature = 36.7 0C

Q= 386 x π x 6.35 x 10-3x (79.3-36.7)

Q= 328.035 W

ii. Mass flow rate of refrigerant Q= m x Cp x (Thi-Tho)

where, Q= heat transferred by condenser in W m= mass flow rate in Kg/sec Cp= Specific heat at constant pressure = 1.022KJ/KgK Thi= Condenser inlet temperature in 0c Tho= Condenser outlet temperature in 0c

m= 328.035/ (1022 x (79.3-36.7))

m= 7.35 x 10-3 Kg/sec

iii. Velocity of refrigerant m=ρxAxv

where, m= mass flow rate in Kg/sec ρ = density of Refrigerant = 1216Kg/m3 A = Area of tube, m2

v = velocity of refrigerant, m/s A= π x d x L

where, L= length of condenser tube= 10.884 m

A= 3.14 x 6.35 x10-3 x 10.884

A = 0.2171 m2

V = (7.35 x 10-3)/(1216 x 0.2171) V = 2.8523 x 10-5 m/s

iv. Logarithmic mean temperature difference (LMTD) LMTD= ((Thi-Tsat)-(Tsat-Tho))/ln((Thi-Tsat)/(Tsat-Thi))

where, Thi= Condenser inlet temperature in 0c Tho= Condenser outlet temperature in 0c

Tsat = Saturation temperature = 500c

LMTD= ((79.3-50)-(50-36.7))/ln((29.3/13.3))

LMTD = 20.250C

v. Effectiveness of condenser (ε): ε= ((m x cp x (Thi-Tho))/(m x cp x (Thi-Tw))

where, m= mass flow rate of refrigerant in kg/sec Thi= Condenser inlet temperature in 0C

Tho= Condenser outlet temperature in 0C Tw = Temperature of water = 31.80C

Cp = Specific heat at constant pressure =1.022KJ/KgK

ε = ((79.3-36.7)/(79.3-31.8)) ε = 0.8968= 89.68%

Design of Evaporator The refrigerant now passes through a receiver drier and then goes into the cold chamber which acts as an evaporator. This chamber also acts as a Shell and tube heat exchanger and the calculations are done taking this consideration. In the evaporator, the refrigerant changes its state from liquid to gaseous form and the heat transfer takes place through conduction to the water.

i. Heat transferred by evaporator Q = K x πd x (Tco-Tci) where, Q= heat transferred by condenser in W K= Thermal conductivity of copper = 386W/m2k d= Diameter of tube= 6.35 x 10-3m Tci= Evaporator inlet temperature = 36.7 0c Tco= Evaporator outlet temperature = 27.1 0c

Q= 386 x π x 6.35 x 10-3x (36.7-27.1) Q= 73.923W

ii. Mass flow rate of refrigerant Q= m x Cp x (Thi-Tho)

where, Q= heat transferred by condenser in W m= mass flow rate in Kg/sec Cp= Specific heat at constant pressure = 0.966KJ/KgK Tci= Evaporator inlet temperature = 36.7 0c

Tco= Evaporator outlet temperature = 27.1 0c

m= 73.923/ (966 x (36.7-27.1)

m= 7.971 x 10-3 Kg/sec

iii. Velocity of refrigerant

m=ρxAxv

where m= mass flow rate in Kg/sec ρ = density of Refrigerant R22 = 1330Kg/m3 A = area of tube, m2 v = velocity of refrigerant, m/s

A= π x d x L where L= length of evaporator tube= 5.422 m A= 3.14 x 6.35 x10-3 x 5.422 A= 0.1081 m2

v = (7.35 x 10-3)/(1330 x 0.1081) v= 5.524 x 10-5 m/s

iv. Logarithmic mean temperature difference (LMTD)

LMTD = ((Tci-Tsat)-(Tco-Tsat))/ln((Tci-Tsat)/(Tco-Tsat))

where Tci= Evaporator inlet temperature = 36.7 0C Tco= Evaporator outlet temperature = 27.1 0C Tsat = Saturation temperature = 23.10C

LMTD= ((36.7-23.1)-(27.1-23.1))/ln((13.6/4))

LMTD = 7.8440C

v. Effectiveness of evaporator (ε) ε= ((m x cp x (Tci-Tco))/(m x cp x (Tci-Tw))

where m= mass flow rate of refrigerant in kg/sec Tci= Evaporator inlet temperature in 36.70C Tco= Evaporator outlet temperature in 27.10C Tw = Temperature of water = 23.10C Cp = Specific heat at constant pressure =0.966KJ/KgK

ε = ((36.7-27.1)/(36.7-23.1)) ε = 0.7058 = 70.58%

Design of Capillary Tube The capillary tube has been taken into consideration according to the capacity of the heat exchanger and the volume of the chambers respectively. F=L/D

where F= friction factor of capillary tube L= length of capillary tube=304.8mm D= diameter of capillary tube = 0.6mm

F= 304.8/0.6= 508

Theoretical C.O.P The theoretical C.O.P is the coefficient of performance which is calculated from the pyscometric chart and the respective temperatures and pressures. C.O.P = (h1-h4)/(h2-h1)

where h1 = Enthalpy at inlet of compressor in KJ/Kg h2 = Enthalpy at outlet of compressor in KJ/Kg h4 = Enthalpy at outlet of evaporator in KJ/Kg

From Psychometric chart of R-22, p1= pressure at compressor inlet = 3.2psi p1= (3.2 x 0.06894) + 1.013= 1.2336 bar p2 = pressure at compressor outlet = 15.8psi p2= (15.8 x 0.06894) + 1.013= 2.1 bar h1 = Enthalpy at p=1.2336 bar and T=27.10c = 320 KJ/Kg h2 = Enthalpy at p=2.1 bar and T=79.30c = 360 KJ/Kg h3= Enthalpy at p=1.2336 bar and T=23.10c = 260KJ/Kg C.O.P= (320-260)/(360-320)

C.O.P = 60/40

C.O.P = 1.5

Actual C.O.P The actual C.O.P is defined as the ratio of refrigeration effect to the compressor work. This C.O.P is the actual coefficient of performance which corresponds to the experimental value. C.O.P = Refrigeration Effect / Compressor Work Refrigeration Effect: For 1 ton A/C, refrigeration effect = 3.5 KW For 1.5 ton A/C, refrigeration effect = 3.5 x 1.5= 5.25 KW Compressor work: I = current input to compressor = 20A V = Voltage across the compressor = 240v Compressor work = V x I = 20 x 240 = 4800W = 4.8KW C.O.P = 5.25/4.8

C.O.P = 1.1

For Air-Cycle

Theoretical C.O.P This C.O.P is the coefficient of performance that is calculated for the air cycle

C.O.P = (h1-h4)/(h2-h1)

h1 = Enthalpy at inlet of compressor in KJ/Kg h2 = Enthalpy at outlet of compressor in KJ/Kg

From Psychometric chart of R-22,

p1= pressure at compressor inlet = 3.2psi p1= (3.2 x 0.06894) + 1.013= 1.2336 bar p2 = pressure at compressor outlet = 15.8psi p2= (15.8 x 0.06894) + 1.013= 2.1 bar h1 = Enthalpy at p=1.2336 bar and T=27.10c = 320 KJ/Kg h2 = Enthalpy at p=2.1 bar and T=79.30c = 360 KJ/Kg h4= Enthalpy at outlet of evaporator = 180KJ/Kg C.O.P = (320-180)/(360-320)

C.O.P= 140/40= 3.5

Actual C.O.P C.O.P = Refrigeration effect/energy input

Refrigeration effect produced by 1.5 ton A/C:

1 ton of refrigeration = (2000lb/day)(144BTU/lb)/(24h/day)(60min/h)

=300BTU/min

where 2000lb/day



144BTU/lb

1ton of ice



Enthalpy of solidification at 320

F So for 1.5 ton, it is 300BTU/min In S.I units 1ton= 210KJ/min 1.5 ton=210*1.5=315KJ/min. Energy input for 1.5ton A/C = 1.5KW = 1500Watts C.O.P = Refrigeration effect/energy input

C.O.P = (315*1000/60)/(1500)

C.O.P = 3.5

. TESTING The testing of the equipment has been carried out under certain crucial conditions where in the values are tabulated and the corresponding data is tabulated and the graphs are plotted as per calculations. These values are then matched with that of the theoretical values and the corresponding data are calculated. The graphs are drawn according to the respective values in the table for cold chamber, hot chamber, pressure and comparison of C.O.P of air and water.

Tabulation Evaporator

S.

Condenser

Time

temperature in

temperature in

(t) in

(0c)

(0c)

Compressor

Cold

Hot

pressure in (psi)

water

water

tempera

tempera

ture (0c)

ture (0c)

no

min

Inlet

Outlet

Inlet

Outlet

Inlet

Outlet

(Tci)

(Tco)

(Thi)

(Tho)

(p1)

(p2)

1

0

29

29

32

29

1.7

12

31

31

2

30

31

28

35

31

2.1

13

28

33

3

60

33

27

38

33

2.5

14

24

36

4

90

34

27

50

34

2.7

14

24

42

The graphs are drawn according to the respective values in the table for cold chamber, hot chamber, pressure and comparison of C.O.P of air and water.