What is the purpose of a thermostatic expansion valve (TEV)?

• A. To measure the refrigerant temperature
• B. To control the evaporator superheat
• C. To increase refrigerant pressure
• D. To compress refrigerant vapor

Answer: (B)

The purpose of a thermostatic expansion valve (TEV) is to control the evaporator superheat. This is crucial in refrigeration and air conditioning systems because maintaining the correct level of superheat ensures that the refrigerant is fully vaporized before it returns to the compressor. By adjusting the flow of refrigerant into the evaporator based on the temperature of the refrigerant exiting the evaporator, the TEV prevents liquid refrigerant from entering the compressor, which could cause damage. Additionally, managing superheat increases system efficiency, improves performance, and helps to avoid issues like compressor failure or overheating. This control mechanism is vital for the proper functioning of any cooling system.