I don't think the speed at which the air is compressed or decompressed plays a factor, other than if compression or decompression were happen slowly, there would be increased opportunity for heat transfer from the walls of the air containment system, which may be a heating or cooling factor, depending on where in the system the air is. This can be realized with the time it takes the system to warm up. The source air from the compressor should have a fairly stable temperature once the engine is running, but it takes some time for the warm compressed air to heat up the pipes delivering it to the cockpit. If you where to turn on the heater in the summer, you would have almost instant high heat, which is not being transferred to the air from the delivery system istelf...
So, where is the extra heat, left over after decompression back to atmosperic pressure, coming from?
(yes, it is all about conservation of energy, and I am sticking with mechanical friction for now, but I still don't 'KNOW').
Last edited by hovering; 22nd February 2006 at 16:06.