Originally Posted by
hawk37
So here is my dilemma; the air starts out at -20 degrees C, and maybe 1 atmosphere of pressure. It gets compressed to a higher pressure and temperature, and then reduces pressure to gently enter the cabin. The flow is smooth and seemingly of a pressure very close to ambient, ie 1 atmosphere again. However, the temperature of the incoming air has not cooled to - 20 degrees C, it is maybe 35 deg C. Shouldn't the amount of heating due to compression equal the amount of cooling due to expansion?
Would that not imply that the pressure inside the cabin would be then equal to ambient? But it obviously isn't.