The vapor compression refrigeration cycle transfers heat from a low-temperature cooled space to a higher-temperature ambient sink. Circulating refrigerant evaporates at low pressure and temperature, absorbing latent heat of vaporization (4→1). An electrically driven compressor raises the vapor to high pressure (1→2), followed by isobaric heat rejection in the condenser (2→3). An expansion valve isenthalpically throttles the fluid back to the evaporator pressure (3→4).