Marine Refrigeration System Vapour Compression System: The vapour compression cycle takes place in a closed system, comprising a compressor, a condenser, a liquid receiver, an evaporator, and a flow control or expansion valve, interconnected by discharge, liquid and suction lines. Principle of refrigeration: 1) Absorption of heat by the evaporation of a liquid refrigerant in the evaporator at a low pressure; 2) Raising the pressure ( to raise the condensing temperature ) of low pressure vapour coming from the evaporator by the compressor; 3) Removal of heat from the high pressure vapour in the condenser so as to liquefy or condense the vapour; 4) By the use of the throttling device, reducing the pressure of the high pressure liquid ( from the condenser ) to the level of pressure needed in the evaporator. Expansion valve ( flow control ): The liquid refrigerant is stored at high pressure in the receiver. The liquid flows from the receiver through the