Fig.8.1 Content Of post

8.1 Working and Types of water Cooler
Water Cooler is generally used in schools, college, hospitals, factories, offices, stores etc.Basically, there are two types of Water Cooler as follows: 
1. Storage type water cooler. 
2. Instantaneous type water cooler. 

1. Storage type cooler: 
1. Figure shows simple water cooler structure diagram, basic cycle is vapour compression cycle consisting of compressor, condenser, fan with motor, expansion device, filter or strainer, thermostatic switch and evaporator coil as shown above figure. 
2. Temperature is control by thermostatic switch as per our desired temperature. 
3. Compressor compresses the Refrigerant R12 vapour to high temperature high pressure vapour is then condensed in condenser by fan motor unit. High pressure high temperature vapour converted into High pressure high temperature liquid in condenser. 
4. Liquid refrigerant passes through strainer or filter which removes moisture and impurities if any. 
5. The liquid refrigerant is throttled through expansion device (generally capillary tube). In throttling pressure and temperature of liquid drops down. This low-pressure low temperature refrigerant then extracts heat of water from the evaporator tank. By taking heat from water refrigerant evaporates and this vapour refrigerant sucked by compressor and process continues.

Fig 8.2 Storage Type Water Cooler
2. Instantaneous type water cooler:
1. The only difference in instantaneous and storage type is in construction of evaporate as shown below. The storage type cooler has evaporated coils solders on the wall of storage tank. The tank is either of stainless steel or galvanized steel and water level is maintained by float valve. 
2. The Evaporator in instantaneous type consist of two separate coils made of either copper or stainless steel. Copper pipe carries R12 while stainless steel pipe carries water. The two pipe or coils are bound together by soldering. 
3. Thermostatic filler bulb is clamped on the water coil just at outlet end in case of instantaneous type, while in storage type it is emerged in the water in the tank.

Fig.8.3 Instantaneous Type Water Cooler 


3. Difference between Storage and instantaneous type water cooler:
Fig 8.4 Difference between Instantaneous and storage type water cooler

8.2 Domestic Refrigerator:
The household refrigerator commonly used in our day to day life.
Fig 8.5 Domestic Refrigerator
1.It works on vapour compression Refrigeration cycle as shown in figure. It uses R12 (freon 12) as a refrigerant unemployed with hermetically sealed compressor.(compressor and motor together). This compressors are generally manufactured by Kirloskar,copeland,Shri Ram,Godrej etc.
2. The refrigerant vapour is compressed by means of compressor to a pressure and temperature more than atmosphere. The high temperature vapour refrigerant will reject the heat to the atmosphere and will get condensed in in air cooled condenser.
3. The liquid refrigerant then passes through a capillary tube where the pressure and temperature are are lowered. Capillary tube acts as throttling device for expansion expansion valve.
4. The pressure of the refrigerant even though lowered when it leaves the capillary tube, it maintain above atmosphere.
5. The temperature of refrigerant will be e corresponding to saturation temperature to be maintained in cabinet of refrigerator.
6. So that when this liquid flows through evaporator (placed in the cabinet of refrigerator) will absorb the heat from the evaporator and gets converted into vapour this will give cooling effect in the evaporator. 
7. The refrigerant after absorbing the heat will be either dry and saturated or superheated which will be sucked by compressor and cycle is completed and same is repeated. 
8. Strainer, dryer or filter is used to remove moisture to avoid freezing of moisture in the capillary tube. 
9. The accumulator accumulates or collects the liquid refrigerant and will not allow liquid to pass compressor. 
10. Generally the domestic refrigerator are available in 165 litre, 180 litre, 220 litre, 300 litre etc. 
11. The cabinet of refrigerator is insulated with puff(polyurethane foam). 
12. Solenoid valve or controller is used to control the temperature and pressure of the entire service.