What is the purpose of a thermal expansion valve (TXV)?

The purpose of a thermal expansion valve (TXV) is to regulate refrigerant flow into the evaporator coil of a heat pump or refrigeration system. By controlling the amount of refrigerant that enters the evaporator, the TXV ensures that the right amount of refrigerant is available to absorb heat, thereby maximizing the efficiency of the system. This regulation is crucial, as it helps maintain the proper pressure and temperature for optimal heat exchange, allowing the heat pump to operate effectively in heating or cooling modes.

The working mechanism of the TXV involves sensing the temperature of the refrigerant leaving the evaporator. Based on this temperature, it adjusts the flow rate of the refrigerant, ensuring that the evaporator is neither starved (too little refrigerant) nor flooded (too much refrigerant). This balance is vital for efficiency, longevity of the equipment, and overall comfort in the conditioned space.

The other options do not accurately define the function of the TXV. Increasing refrigerant pressure relates more to the compressor's role in the system, measuring system temperature is typically done by sensors or thermostats, and purifying the refrigerant is not a function of the TXV; rather, filter driers are used for that purpose.