Though the refrigerant used in the refrigeration and the air conditioning systems is also a gas, the refrigeration compressors are different from the compressors used for compressing other gases and air. Let us see these differences:
1) Other gas and air compressors are independent entities: The compressors used for compressing the other gases and air are independent entities. This means they merely compress the gas or air and supply it for the suitable applications. They have no direct connection with any other type of machine, though lots of machines and equipments depend on the compressed air or gas. The refrigeration and the air conditioning compressors are a part of the complete vapor compression cycle that comprises of additional components like the condenser, expansion valve and the evaporator. If the compressor is removed from this cycle, the refrigeration process will cease to exist.
2) Main function of the compressor: The main function of the other compressors is to merely compress the gas or air. The refrigerant compressor compresses the refrigerant to the pressure corresponding to the saturation pressure higher than the temperature of the naturally available air or water. This enables the cooling of the refrigerant in the condenser by the available atmospheric air or water.
Further, the refrigerant compressor also circulates the refrigerant through the whole cycle. The refrigerant after leaving the compressor is forced to the condenser, the expansion valve, and the evaporator and then it is sucked by the compressor for compression and recirculation though the whole cycle.
3) Capacity Determination: The capacity of the refrigerating compressor determines the capacity of the whole refrigerating or air conditioning plant. The capacity of the air or gas compressor doesn't determine the capacity of the other plants. For instance, though the pneumatic tool depends on the compressed air for its operation, it has its own capacity.
4) Relation to the other equipments: The refrigerating compressor is integral part of the cycle that includes other components of the cycle like condenser, expansion valve, and the evaporator. The working and proper functioning of each of these components depend on the working of other components. If the refrigeration compressor breaks down the whole system will collapse. There is no such dependency in case of the other compressors. If the air or gas compressor breaks down, the standby compressor can be started easily.
