A vortex tube seperates compressed air into jets of hot and cold air.

Hilsch Vortex Tube: Air vortex is separated into hot and cold jets. High pressure air enters a stationary generator and is released with a vortex motion, spinning along the tube's walls toward the hot air end at sonic speeds up to 1,000,000 rpm. Air near the surface of this spinning vortex becomes hot, and some of it exits through the needle valve in the hot end. The air that does not escape through the hot air needle valve is forced back through the center of the warm air vortex. Because the air forced back moves at a slower speed, a simple heat exchange takes place. The inner,slower-moving column of air gives up heat to the outer, faster-moving column. When the slower, inner column of air exits through the center of the stationary generator and out the cold exhaust, it has attained a low temperature. NOTE: See Vortec Catalog for greater detail. SURFACE TENSION AND CAPILLARY ACTION.