Re: How does a minto wheel work?

  I found a couple of sources on the Web that explain this device:
 http://www.eskimo.com/~billb/freenrg/minto.html, and http://users.mildura.net.au/users/egel/tempw.htm.

It looks reasonable from a thermodynamics point of view. That is, it
doesn't seem to violate the second law, and it goes through a
thermodynamic cycle. It operates using a phase change of the working
fluid, like most vapor-system cycles do, but instead of taking advantage
of an expansion process, as in a steam plant, it uses the buoyancy of the
gas to overcome gravity. It also looks like a demonstrator model could be
built rather easily using some low-boiling-point substance like a
refrigerant or propane. Also, the heat source doesn't need to be solar;
any source of high temperature would do. This feature would make it
atractive as a cogeneration scheme, like absorption refrigeration, which
is a very similar cycle using a binary working fluid. The Kalina power
cycle is also very similar in this respect. I think that, due to the slow
rotational speed. it wouldn't be very good as a prime mover for power
production, but for water pumping it might be useful. A good reference on 
some of these cycles, if you can find it is: Applications of
Thermodynamics by B.D. Wood.
I hope this helps.

Frederick J. Carranti, P.E.