What type of influence does the evaporator pressure exert on the valve in a TXV?

In a thermal expansion valve (TXV), the evaporator pressure plays a crucial role in regulating refrigerant flow into the evaporator. When the load on the evaporator changes, the pressure within the evaporator also fluctuates. A drop in evaporator pressure indicates a decrease in heat absorption, which leads to the TXV closing partially or fully. This response helps prevent excessive refrigerant from entering the evaporator when it is not needed, thereby maintaining the system's efficiency and preventing potential flooding of the evaporator.

The closing of the valve in response to decreased evaporator pressure ensures that the correct amount of refrigerant is introduced based on the evaporator's heat absorption capabilities. It effectively modulates flow to match load conditions, highlighting the importance of evaporator pressure in controlling the TXV’s operation.