The temperature or pressure of the refrigerant during the phase change are related as you know. The condensation temperature depend on the sink where to heat will be rejected. if you are thinking condensing with air as cooling substance then you probably have 10-12 degree centigrade approximately for the temperature difference between the air and the refrigerant. The same happen with the evaporator. the temperature of the cooling space is normally 10-12 degree higher than the evaporation temperature. Once the temperature has been determined the pressure are fixed for the selected refrigerant.

The condensation temperature will be equal to the ADP. The value of ADP will dipend on outdoor air and indoor air condition. Generally it is varied from 10 to 14 0C

Thank you Ruben Borrajo and Ranjeet Kumar Jha for the answers.

In the cooling mode, with outside air at 30-35°C, we need air from the nozzles in the cabin at 8-12°C to reach the comfort temperature of about 23°C (these are empirical data I have found). Therefore, in this case the evaporation temperature will range from -4 to 0°C (10-12°C less), right? We must then apply the same reasoning for the condensation temperature in the heating mode, thus the condensation temperature will be 10-12°C higher than the temperature of the air from the nozzles in the cabin, which is higher than the comfort temperature in the cabin, right? For what concerns the condensation temperature in the cooling mode, shall I simply add 10-12°C to 35°C? In the heating mode, instead, with an outside temperature of 5°C, which will be the evaporation temperature? In this case the evaporation temperature can't be less than 0°C because of frosting problem (therefore the temperature gap will be smaller than 10-12°C), so shall I take 0°C as evaporation temperature? Thank you.

Hello

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With regards

Mohsen Jaafarnia

Are you planning to use R1234yf?

Thank you Mohsen Jaafarnia.

Thank you Stan Simon for the answer. At the moment I am working with R134A, but I will consider also other refrigerants, such as R1234yf. Do you agree with my considerations in my last post?

Usually the manufacturer's representative will give you computer printouts of the exact operating refrigerant temperatures at the evaporator and condenser along with entering and leaving air temperatures going thru the coils. Do you have a manufacturer that you are talking to?

I am considering, as reference, the following electric vehicle: BMW i3. The AC system of this vehicle works with R134a. I have found the manual about the AC system of this vehicle, but I haven't found the exact operating refrigerant temperatures at the evaporator and condenser along with entering and leaving air temperatures going through the coils . I have also tried to contact BMW directly for this kind of in information, but I have received no answer. Do you know where I can get them? Thank you.

Likely BMW buys the compressor, evaporator and condensor from a manufacturer that specializes in this sort of thing, I doubt BMW fabricates it.

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Ok, thank you for the indication.