Deviations in Subcooling & Superheating

q  Deviations in Subcooling & Superheating

•To insure that the refrigerant entering the compressor is vapor, it is necessary to be at temperature higher than the saturation one. This can be done by superheating with different methods.

•To improve the expansion process in the expansion valve (EV), the entering refrigerant  must be absolute liquid.  Therefore, liquid must be  cooled  to temperature lower than the saturation one.

 Superheating

•It can be carried within the evaporator, allowing refrigerant to continue its heat   transfer

process after complete evaporation.

•         Outside   the   evaporator  can  be   done   using               electric               heater,   atmospheric               air   at                high temperature, or by heat exchange with the hot liquid refrigerant leaving the condenser.

• Allow refrigerant to be in contact with the electric motor, the refrigerant will be super- heated and motor will be cooled.

 Superheating

• When refrigerant enters to the compressor crank case, before entering the compressor

it will be super-heated and the oil will be cooled.

• The superheating must be limited as it increases the required compressor power.

 Subcooling

•       Can be done using secondary condenser, or by adding additional coil to it.

•       Performing a heat exchange process with the cold vapor refrigerant leaving the evaporator.

•       Using atmospheric air, if it has lower temperature than the hot liquid refrigerant leaving the

condenser, to be a cooling media for the condenser.

•       The sub-cooling can be increased as it increases the required compressor power.

Share This Article !

Sign up here with your email