What does a Thermal Expansion Valve (TEV) maintain constant?

A Thermal Expansion Valve (TEV) plays a vital role in refrigeration and air conditioning systems by managing the flow of refrigerant into the evaporator. The main function of a TEV is to maintain a constant evaporator superheat. Superheat is the temperature differential between the refrigerant vapor in the evaporator and the refrigerant's saturation temperature at a corresponding pressure.

By controlling the amount of refrigerant that enters the evaporator, the TEV ensures that the refrigerant absorbs enough heat to vaporize completely before it exits the evaporator. This prevents liquid refrigerant from returning to the compressor, which can cause damage or inefficiency. By maintaining constant evaporator superheat, the TEV helps optimize the system's performance while ensuring safe operation.

Being aware of this function emphasizes the importance of proper refrigerant management and the role of the TEV in enhancing energy efficiency and system reliability in HVAC applications. The other choices involve different operational aspects of the refrigeration cycle that are not directly controlled by the TEV.