Subject:- Refrigeration and Air Conditioning

Topic:- Duct Design, Controls & Applications

Difficulty:- Medium

The household refrigerator commonly used, works on vapour compression refrigeration cycle because of its compactness and more electrical efficiency compared to absorption system.

Refrigerants generally used are R-12 or R-22.

The compressor used in household refrigeration system is hermetic compressor.

Compressor is mounted at bottom of refrigerator frame and its power depends on the size of refrigerator i.e. 75 W, 180 W, etc.

The condenser which may be either chassis type or tube and wire type is mounted at back of cabinet. Both types of condensers have fins to increase heat transfer rate.

The capillary tube is kept in contact with evaporator inlet pipe and a drier is connected between receiver and evaporator to eliminate any moisture.

The refrigerant vapour is compressed to a pressure at which temperature will be greater than atmosphere so that vapour rejects heat to atmosphere and gets condensed.

The condensate then passes through capillary so that by throttling its pressure and temperature are lowered.

The pressure of refrigerant leaving capillary is maintained above atmosphere whereas temperature is corresponding to the saturation temperature to be maintained in the cabinet, so that when vapour flows through evaporator it is capable of heat absorption.

The refrigerant evaporates and leaves the evaporator as dry and saturated or super heated vapour which is then sucked by compressor and cycle is repeated.

There is also an accumulator whose function is to not allow any liquid refrigerant to pass to the compressor.