The vapor compression cycle is most commonly used for refrigeration and air-conditioning systems for the domestic and industrial applications. Let us see the comparison of vapor compression and gas compression refrigerating cycles based on following parameters:
1) Type of refrigerant used: In vapor compression cycle liquids like Freon and ammonia are used as the refrigerant. In the gas cycle the gas like air is used as the refrigerant.
2) Heat exchangers: In the vapor compression refrigeration cycle condenser and evaporator are the two heat exchangers where the refrigerant gives up and absorbs heat respectively. The refrigerant undergoes change in phase in both the heat exchangers. In the gas cycle the refrigerant exchanges heat in the heat exchangers, but there is no phase change of the gas.
3) Efficiency of the cycle: The efficiency of the vapor compression cycle is more than that of the gas cycle. For producing the same amount of refrigerating effect in the gas cycle, large volume of gas is required; hence the systems tend to become very large, bulky and expensive, which are not affordable for the domestic applications.
4) Cycle used: The vapor compression cycle works on the reverse Brayton cycle, while the gas compression cycle works on reverse Rankine cycle.
5) Applications: The vapor compression cycle is most widely used for the refrigeration purposes. It is used in household refrigerators, air-conditioners, water cooler, ice and ice cream makers, deep freezers, large industrial refrigeration and air-conditioning systems, etc. Since the size of the gas compression systems is very large, they are not used for the domestic and industrial purposes. They are used widely in the aircraft air-conditioning systems since in aircrafts air at very high pressures is available readily and there won’t be the need of air compressors. This makes the air-conditioning system in the aircraft light weight and less power consuming. The use of air as the refrigerant in aircraft prevents the dangers of fire of from the flammable refrigerants.