Though you might be interested in the physics of vortex
tubes from Exair. No moving parts, just compressed
air in and one outlet is hot air, the other is cool air - at
up to -50 degrees?
For a look at the physics of such a tube:
http://www.exair.com/vortextube/vt_page.htm
Almost worth just buying one to experiment with! I wonder
if this is similar to vortex overunity generators?
v/r Ken Carrigan