The simple air refrigeration cycle works on Reversed Brayton or Joule cycle. The four processes of the cycle are:
1. Isentropic compression process (1-2): Cold air from refrigerated space is drawn into the compressor and compressed to the cooler pressure. The air temperature increases from T1 to T2.
2. Constant pressure cooling process (2-3): The high pressure and high temperature air is now passed into the cooler where it is cooled at constant pressure.
3. Isentropic expansion process (3-4): Air from cooler is drawn into the expander where it is expanded isentropically from cooler pressure to refrigerator pressure which is equal to atmospheric pressure. The temperature of air also falls from T3 to T4 i.e. much below the cooling water temperature T3.
4. Constant pressure heating process (4-1): This cold air from expander is now sent to the refrigerated space where it absorbs the heat at constant pressure.