Different Effects on Evaporator Temperatur
It is not uncommon, when doing trainings on metering devices in general, but specifically it seems with TXV’s that there is a perception that the TXV is responsible for controlling the temperature in the evaporator. Lets look at a TXV equipped system and how it behaves.
The key here is the word “control” and how it differs from “has an effect on”. Being adjustable, if the TXV controlled evaporator temperature, then you would be able to adjust it (TXV) to control the evaporator temperature to maintain a desired level. From this point of view, you pretty much couldn’t get farther from the truth. In fact the TXV couldn’t give a crap about the evaporator temperature. It will happily regulate refrigerant for evaporator temperatures for freezers right up to wine coolers with no preference for one over the other.
However, it does have an effect on evaporator temperature by regulating the amount of refrigerant that enters the evaporator. It is not trying to change the temperature but rather regulate the amount of refrigerant based on the level of superheat at the evaporator outlet. The corresponding temperature change is a collateral effect so to speak.