This is an invention for harvesting energy from a small temperature difference, with some assistance from gravity.

There are two heat exchangers, a heated one at a lower altitude, a cooled one at a higher altitude.

The bottom of the top heat exchanger is connected to a pipe, which runs down to a hydroelectric generator, whose outlet is the bottom of the lower heat exchanger.

The top of the lower heat exchanger is connected to the top of the upper heat exchanger via a second pipe.

The whole system is vacuum purged, then filled with enough refrigerant that one heat exchanger, and one vertical pipe, could be filled with liquid refrigerant, with the rest of the system filled with gaseous refrigerant.

To maximize efficiency, the density difference between liquid and gaseous refrigerant, divided by the latent heat of vaporization, should be maximized.

Mercury has such a low latent heat of vaporization, and such a high density as a liquid, that it might be a good choice... provided we can be absolutely certain that it won't leak.
-- goldbb, Oct 01 2009

The exact opposite Active_20Heat_20Pipe
The active heat pipe came first, then I realized it could be reversed [goldbb, Oct 01 2009]

Mini hydro unit http://www.google.c...=onepage&q=&f=false
Stick this in your pipes and spin it! [bdag, Oct 02 2009]

Heat Pipe http://en.wikipedia.org/wiki/Heat_pipe
[goldbb, Oct 04 2009]

Sooo... A heat pump with one of these installed? [link]
-- bdag, Oct 02 2009


No, a heat *pipe* (or a phase change thermosiphon) with one of those installed.

Incidentally, can anyone tell me how far off from the Carnot cycle this idea is?
-- goldbb, Oct 04 2009



random, halfbakery