Refrigeration It is defined as the method of reducing the temperature of a system below surrounding temperature and maintains it at the lower temperature by continuously abstracting the heat from it. Ton of Refrigeration It is defined as the rate of heat transfer that results in the freezing or melting of 1 short ton of pure ice at 0 °C (32 °F) in 24 hours. Coefficient of Performance It is defined as the ratio of refrigerating effect to work required compressing the refrigerant in the compressor.