What is the superheat of a system if the refrigerant temperature in the suction line is 58°F and its temperature in the evaporator is 34°F with pressure in the evaporator at 60 psig?

To determine the superheat of a refrigeration system, you need to compare the temperature of the refrigerant in the suction line to the saturation temperature of the refrigerant at the corresponding pressure in the evaporator.

In this case, the refrigerant temperature in the suction line is 58°F. The pressure in the evaporator is 60 psig. To find the saturation temperature, you would typically refer to a saturation temperature-pressure chart for the specific refrigerant being used. For many refrigerants, a pressure of 60 psig corresponds to a saturation temperature of about 34°F.

Superheat is calculated as the difference between the suction line temperature and the saturation temperature. Therefore, you would subtract the saturation temperature from the suction line temperature:

Superheat = Suction Line Temperature - Saturation Temperature

Superheat = 58°F - 34°F

Superheat = 24°F

This means the superheat of the system is 24°F, which corresponds to the correct answer. Understanding superheat is crucial because it indicates how much heat has been added to the refrigerant after it has fully evaporated, ensuring that the compressor does not process liquid refrigerant, which could cause damage.