What is the function of a thermal expansion valve in a refrigeration system?

The function of a thermal expansion valve in a refrigeration system is primarily to control superheat. This is essential for the efficient operation of the system. The thermal expansion valve regulates the flow of refrigerant into the evaporator based on the temperature of the refrigerant leaving the evaporator. By doing this, it ensures that the refrigerant is at the appropriate superheat level when it exits the evaporator. Proper superheat is necessary to prevent liquid refrigerant from returning to the compressor, which can cause damage and inefficiency. The thermal expansion valve adapts to varying conditions within the refrigeration system, ensuring that the refrigeration cycle operates effectively while maintaining the desired temperature and preventing potential compressor failures.

In contrast, decreasing refrigerant flow solely would not account for the dynamic requirements of the system; maintaining system temperature encompasses broader functionalities that include more than just superheat control; increasing pressure typically is a role fulfilled by compressors, not by the thermal expansion valve itself. Therefore, controlling superheat is a specific and critical function that makes the thermal expansion valve essential in refrigeration systems.