1) A simple vapor compression refrigeration system consists of a compressor, condenser, expansion valve, and evaporator connected in a closed loop. 2) Refrigerant is compressed from a low pressure vapor to a high pressure vapor in the compressor, condensed in the condenser, expanded through the expansion valve, and evaporated in the evaporator, absorbing heat from its surroundings. 3) The coefficient of performance (COP) of the system, which indicates its efficiency, depends on factors like subcooling of the refrigerant liquid, superheating of the refrigerant vapor, evaporating and condensing pressures, and the volumetric efficiency of the compressor.