What is the main function of the thermostatic expansion valve (TEV)?

The main function of the thermostatic expansion valve (TEV) is to control the superheat in the evaporator. The TEV regulates the flow of refrigerant into the evaporator based on the temperature and pressure conditions present. By maintaining a specific level of superheat, the TEV ensures that the refrigerant is fully evaporated before it leaves the evaporator, allowing the system to efficiently absorb heat from the environment. This control is essential for optimizing the performance of the refrigeration system and preventing liquid refrigerant from returning to the compressor, which can cause damage.

While the other options mention important aspects related to refrigeration systems, they do not define the primary role of the TEV as accurately as the correct answer does. Reducing pressure and increasing refrigerant temperature are functions associated with other components in the system, such as compressors and condensing units. Maintaining a consistent refrigerant flow is important, but it is the regulation of superheat that directly influences system efficiency and safety, making it the core purpose of the TEV.