COP and Superheat - does is it help?

[Peter_1]

....
The more you increase the SH inthe the TXV the further down the evaporator pressure gets depressed and so COP falls off.
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Chef, the SH isn't created in the TXV but at the end of the evaporator and then further not usefully outside the cold room. If it comes from the room, even from the suction line inside the room, then energy that needed to be removed from the room was removed, so this energy was useful.
So with the energy needed to evaporate the refrigerant, we add some additional energy also taken from the room to become a total energy retracted versus needed energy. If we add some more energy,then TE will also slightly increase, TC as well but influence of Te is much bigger resulting in a COP increase.

In fact, I guess this explanation wasn't usefull :-) for you at all and it's me not following for 100% due to a 'language-misunderstanding-barrier' from my side?

[Chef]

Chef, the SH isn't created in the TXV but at the end of the evaporator ?

I got this and the bulb is positioned at the end of the evaporator and is set to 8C so the TXV and the bulb act together to control the SH. That is how it was input to the program. It seemed to understand.

So if my temperature is set to -20C then the system keeps on running till the Te is -29C and the SH is 8C.