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, condensed, expanded, and evaporated to absorb heat before repeating the cycle. 3) The coefficient of performance (COP) of the system, which indicates efficiency, depends on factors like subcooling, superheating, evaporating and condensing pressures, and compressor volumetric efficiency.