Refrigerant Cycle

Compression

By the action of the compressor, the vapor resulting from the vaporization is drawn from the evaporator through the suction line into the suction inlet of the compressor. In the compressor, the temperature and pressure of the vapor are rised by compression and the high-temperature, high-pressure vapor is discharged from the compressor into the discharge line.

Condensation

The vapor flows through the discharge line to the condenser where it gives off heat to the relatively cool or being drawn across the condenser by the condenser fan. As the hot vapor gives off heat to the cooler air, its temperature is reduced to the new saturation temperature corresponding to its new pressure, and the vapor condenses back into the liquid state as additional heat is removed. By the time the refrigerant reaches the bottom of the condenser, all of the vapor is condensed and further sub cooled. Then the sub cooled liquid passes into the receiver and ready to be recirculated.

Expansion

Starting at the receiver, high-temperature, high-pressure liquid refrigerant flows from the receiver through the liquid line to the refrigerant flow control. The pressure of the liquid is reduced to the evaporator pressure as the liquid passes through the refrigerant flow control so that the saturation temperature of the refrigerant entering the evaporator will be below the temperature of the refrigerated space. A part of the liquid vaporizes as it passes through the refrigerant control in order to reduce the temperature of the liquid to the evaporating temperature.

Vaporization

In the evaporator, the liquid vaporizes at a constant pressure and temperature as heat to supply the latent heat of vaporization passes from the refrigerated space through the walls of the evaporator to the vaporizing liquid. All the refrigerant is completely vaporized within the evaporator, and super heated by the end of the evaporator. Although the temperature of the vapor increases somewhat by the end of the evaporator as the result of super heating, the pressure of the vapor does not change.  Although the vapor absorbs heat from the air surrounding the suction line, raising its temperature and also decreases its pressure slightly because of the friction loss in the suction line, those changes are neglected in the explanation of a simple refrigeration cycle.