12 Mechanical Vapor Compression Heat Pumps
Mechanical vapor compression systems operating in a subcritical cycle represent the vast majority of heat pump, air-conditioning, and refrigeration applications today. The cycle operates by transfer of heat through a closed-loop cycle by compressing, condensing, expanding, and evaporating a refrigerant fluid. The term ‘subcritical’ means that the cycle operates well below the critical point of the refrigerant. Heat pump manufacturers install controls to monitor refrigerant temperature and pressure, and heat pumps will shut off when the refrigerant pressure approaches the critical pressure.