An increase of superheat on the bulb of a TXV causes the valve to do what?

An increase of superheat on the bulb of a thermal expansion valve (TXV) causes the valve to stay open or open more. Superheat refers to the temperature of the refrigerant vapor above its boiling point at a given pressure. When the superheat increases, it indicates that the refrigerant has absorbed more heat and is in a vapor state, which is necessary for the system to function effectively.

In this context, if the superheat at the bulb increases, it signifies that the evaporator is not receiving enough refrigerant, and the system may be experiencing a higher demand for cooling. The TXV responds to this by adjusting the valve position to allow more refrigerant flow into the evaporator, ensuring that heat exchange continues optimally. By doing so, the TXV helps stabilize the evaporator conditions, granting sufficient flow and maintaining efficiency in the system.

This function is crucial for preventing issues such as compressor damage, as operating with insufficient refrigerant can lead to overheating and poor performance.