As far as the energy field is concerned, the term ‘refrigeration unit’ can be defined as refrigeration unit: reduces temperature by means of a mechanical process. Electricity The engine is powered by a typical refrigeration unit, which operates a pump to compress the refrigerant in order to maintain proper pressure. (A ‘refrigerant’ is a material that varies between liquid and gaseous states under appropriate temperature and pressure conditions.) The heat from the compressed liquid is collected and discharged from the device, and the refrigerant evaporates when the pressure is reduced. The coolant absorbs heat as it evaporates and repeats the cycle by returning to the compressor.