The Refrigeration Loop: How it Works

The first known artificial refrigeration system was demonstrated by William Cullen in 1748. But relax, it’s not completely necessary understand the Physics of the basic refrigeration loop to enjoy the benefits of cold beer and ice cream aboard your boat! But for the scientifically inclined it sure is “cool” (that’s a science nerd joke I couldn’t resist).

The below flow chart represents the basic CoolBlue refrigeration system.
Starting with the pressurized liquid refrigerant ahead of the fin/tube holding plate evaporator at Point A, the introduction of liquid refrigerant is regulated by a thermally adjusting expansion valve (TXV) that is controlled by temperature and pressure. The pressurized refrigerant is reduced in pressure across the expansion valve from high pressure (Point A) to the fin/tube evaporator holding plate pressure (Point B). The expansion valve acts as a boundary between the high and low-pressure sides of the system and uses the holding plate exit refrigerant gas temperature to throttle in more or less liquid refrigerant.

Once inside the holding plate, the low-pressure refrigerant evaporates and absorbs heat from the eutectic solution. The refrigerant liquid and vapor passing through the fin/tube holding plate evaporator coil continues to absorb heat until it is completely evaporated and turns into gas (Point C). The now heated gas is drawn through the suction line to the compressor suction (Point D). The increased pressure produced in the compressor causes the gas to compress and heat and flow into the condenser (Point E). In the condenser heat is removed causing the refrigerant gas to condense back to a liquid refrigerant form. The liquid refrigerant is collected and stored in the filter/drier (Point F) and is available to begin the cycle again. The thermostat (G) is monitoring the temperature of the holding plate and turning the compressor on/off to ensure that the eutectic solution is never allowed to defrost and undergo a phase change from solid back to liquid.