Keith Moore wrote:

Paul/Perry:

Perhaps you may wish to consider the "heat pipe" concept.   Instead of the
tubes filled with water, seal the tubes and add just a little distilled
water and ammonia.  Pull a vacuum until you get down to the vapor pressure
of the mixture.

Now you have a very high efficiency (transfers heat at the speed of sound) &
"light weight"  heat transfer device!

 Position the engine water manifold at the bottom (low side - rotate your
sketch 90 degrees, clockwise).  The water would enter one side and return in
the other side.  The engine water manifold should have some  surface area
contact with the heat pipes. The heat from the engine will quickly boil the
liquid to steam which  rises up the pipe.  And as the steam cools
(condense), the liquid returns to pick up more heat.

A similar but simpler fabrication scheme would be formed from two sheets of
aluminum, each with a series of dimples to keep them apart, rolled into the
diameter you want, and then seal welded on each edge.

If you are serious, there is some heat transfer analysis necessary.

Regards,

Keith "BlackHat" Moore
Long Easy

----------------
Having worked with heat pipes in the past, a couple of comments.

1. The achilles heel of this scheme is the heat transfer from the water manifold into the heat pipe. You will likely be surface area limited.

2. You don't want to use a water-ammonia mixture. Water ammonia makes a good refrigerant for an absorption heat pump, because you boil the fluid in one location, and recombine them in another. The recombination *raises* the temperature of the fluid, which is then cooled in a separate heat exchanger. Working in a heat pipe this would be counter productive. You want pure fluids in a heat pipe -- ammonia is used in the 70-80 foot long heat pipes for the Alaska pipeline, but it is *anhydrous* ammonia.

3. The heat transfer up the heat pipe is at the speed of the flow of the fluid (vapor) through the pipe, not at the speed of sound. It is however, impressively fast.

Bill Schertz
KIS Cruiser # 4045

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