| Not having kept up with the past history of this project, am I | correct in assuming that this is to be used as a working fluid pump | for a solar heating arrangement?
Actually, the project started out to be a desktop stirling engine - then suffered considerable "scope creep".
I produce and (try to) sell passive solar heating panels; and so have developed an interest in solar energy as a substitute for more expensive energy sources. I haven't followed many of those interests because of R&D costs. I have a particular fondness for mechanisms with no moving parts to wear out and which can be made to exhibit "smart" behaviors.
Anyway, once the little desktop engine was running, I wondered if it could be made useful by growing it larger. The first application that struck me as really suitable was the pumping application. I figured that if I could produce a useful and inexpensive pump that used only solar energy and never wore out - and could be easily reproduced by ordinary folks, it could maybe offer some improvement to quality of life for a lot of people.
It /could/ be used as a circulator pump as part of a solar heating system. Since I'm looking for maximum impact, I decided to first take aim at irrigation and village water supply applications - they're not terribly demanding and would probably benefit the largest number of people in the most significant manner.
One of the interesting characteristics of the stirling cycle is that it is reversible - if, instead of putting heat in and getting work out, you put work in then you'll see the engine work as a heat pump: one side will get hot and the other cold (obviously, I'm one of the "easily amused"). Once a full-sized pump is working, I plan to hook two of these things together back-to-back and see if I can convince the second engine to work as the heart of a solar refrigeration/air conditioner. If I can manage that, people in remote areas without electricity can have free (meaning "no operating cost") refrigeration; and people in Arizona, New Mexico, and Texas can have similarly free air conditioning whenever the sun shines.
Just these first two applications seemed to justify whatever effort is necessary.
| And since you seem to have experience along these lines, an | additional question. I have looked at the large solar water | heating panels on a few homes, and have always felt that due to a | reduction in exposed surface area (thermal loss) that a tracking | parabolic reflector focused on a small cylindrical "boiler" would | be more efficient than the large panel designs. Is this, in fact, | the case? Or am I dreaming again - I haven't kept up with changes | in this technology in 19 years.
I can give you a most definite "maybe". The collector is only one component of a complete system. My rule of thumb is that large temperature differentials relult in "lossy" (less inefficient) systems unless the system really requires high temperatures. In general, you want the most energy (heat) you can get with the lowest possible temperature differential. It's _really_ important to not confuse heat with temperature.
| My other quandary is, "How the heck do you find time and enthusiasm | to pursue all of this stuff?"
I like people: enthusiasm is always a choice - I /make/ time for the things I think worthwhile. Sometimes it's not easy.
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA
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