Ah, I finally found it, including the full show. If anyone is interested it was Science Shack with Adam Hart Davis. I've not rewatched the show but I guess it was either the heat pump or the vortex tube...
In 1988 R.T.Balmer applied liquid water as the working medium. It was found that when the inlet pressure is high, for instance 20-50 bar, the heat energy separation process exists in incompressible (liquids) vortex flow as well.
http://www.youtube.com/watch?v=ggzfqRTzJ9M