Self limiting characteristics of a heat pump
A heat pump with a certain type of compressor and a specific amount and kind of refrigerant will alway reach a state of equilibrium.
The hot, high pressure side of the system will reach a certain pressure and temperature at which the refrigerant vapor can still effectively condensate.
The cold, low side will reach a certain temperature where all the liquid still evaporates.
The metering device which seperated high from low pressure can only allow a certain amount of liquid by maximum.
If the refrigerant gets too hot, it won't condensate at the maximum pressure on the high side anymore.
That means there is less heat deposited into the drying air.
That slows down the heat transfer to basically negligible levels.
Thus there is a certain temp at which the heat pump can't raise the temp anymore.
And for most dryers I used so far, that is around 60-70C.
