Which device regulates refrigerant flow based on the needs of the evaporator?

The thermostatic expansion valve (TXV) is designed to regulate the flow of refrigerant into the evaporator based on the cooling demands of the system. It does this by sensing the temperature of the refrigerant leaving the evaporator. When the temperature is lower, the TXV will decrease the flow of refrigerant to prevent excess refrigerant from entering the evaporator, which can lead to inefficiencies. Conversely, if the temperature rises, the TXV will increase refrigerant flow to meet the higher cooling demand. This ability to adjust flow precisely based on the needs of the system leads to improved efficiency and the performance of the refrigerant cycle.

In contrast, an automatic expansion valve regulates pressure rather than flow, allowing the pressure to maintain a constant level without adjusting specifically to the evaporator's needs. A float valve is typically used in applications like refrigeration where liquid levels need to be maintained, not primarily used for flow modulation based on temperature changes. An orifice plate provides a fixed restriction in the refrigerant line, making it unable to adjust flow dynamically as system conditions change, which limits its effectiveness in varying operational demands.