What is the primary function of a thermostatic expansion valve (TXV) in a refrigeration system?

The primary function of a thermostatic expansion valve (TXV) in a refrigeration system is to regulate the flow of refrigerant based on temperature and pressure. This device is crucial for maintaining the proper conditions within the evaporator. It achieves this by adjusting the refrigerant flow to ensure that the evaporator does not flood with too much refrigerant, which can lead to inefficient operation and potential system damage.

The TXV senses the temperature of the refrigerant leaving the evaporator and uses this information to control the amount of refrigerant flowing into the evaporator. If the temperature is too high, indicating that the evaporator is not absorbing enough heat, the TXV opens wider to allow more refrigerant to flow in. Conversely, if the temperature is low, the valve closes to reduce the flow. This dynamic regulation helps maintain optimal evaporation conditions and enhances the system’s overall efficiency.

In the context of the other options, maintaining constant pressure in the condenser, increasing refrigerant pressure before entering the evaporator, and controlling airflow over the evaporator coil are not the primary functions of a TXV. Instead, these responsibilities fall to other components in the refrigeration cycle, such as the compressor and fans.