Solar Stirling (more)

I've just added the first photos to my solar stirling web page - showing an electrical (resistance) heater being used for testing and the early construction of the wooden prototype parabolic trough frame.
As promised, progress is slow and jerky - but the engine appears to scale nicely (the most recent engine has a stroke of ~5" with 30W input).
Many thanks to all who've offered encouragement!
More later...
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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Morris Dovey (in 452cc810$0$10309$ snipped-for-privacy@news.qwest.net) said:
| I've just added the first photos to my solar stirling web page -
A URL would probably help...
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/StirlingProject.html
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"Morris Dovey" tatlized us with his backyard inventions

Good on ya Morris. The world is a better place with you in it.
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Morris Dovey said:

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?
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.
My other quandary is, "How the heck do you find time and enthusiasm to pursue all of this stuff?"
FWIW
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DGG (in snipped-for-privacy@4ax.com) said:
| 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 http://www.iedu.com/DeSoto
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That is a nice sized trough, it should produce good heat.
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SJC (in wR6Xg.8519$ji5.3676@trnddc04) said:
| That is a nice sized trough, it should produce good heat.
My compadre in this project took the first temperature measurements this afternoon. The results weren't too bad - more photos added to the same web page (link below).
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/StirlingProject.html
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I have used a 20" x 48" trough with 3/4" copper tube in a 1 1/2" glass tube. The glass tube made a lot of difference reducing heat loss.
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Morris Dovey wrote:

Have you looked at other peoples liquid piston stirling pumps?
http://www.linux-host.org/energy/sstirling.htm http://www.fieldlines.com/story/2004/12/12/181043/68 http://www.engin.swarthmore.edu/academics/courses/e90/2005_6/E90Proposal/FK_AO.pdf http://www.ornl.gov/~webworks/cppr/y2001/rpt/27113.pdf
Anthony
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Anthony Matonak (in Y7qdnQ5ZKM4ekbDYnZ2dnUVZ snipped-for-privacy@comcast.com) said:
| Have you looked at other peoples liquid piston stirling pumps? | | http://www.linux-host.org/energy/sstirling.htm | http://www.fieldlines.com/story/2004/12/12/181043/68 | http://www.engin.swarthmore.edu/academics/courses/e90/2005_6/E90Propos al/FK_AO.pdf | http://www.ornl.gov/~webworks/cppr/y2001/rpt/27113.pdf
Anthony...
I've looked at some - but none as informative as either the Swarthmore or Oak Ridge documents.
Thanks for the links!
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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Wed, Oct 11, 2006, 5:31am (EDT-1) snipped-for-privacy@iedu.com (MorrisDovey) doth off-topically posteth: I've just added the first photos to my solar stirling web page <snip>
Hi ya Morris. Thenks for the link. LMAO Not entirely certain you're on the right path, but what the heck, few of us are. I tak it you want a "solar pump" type of thing. Somewhere I have seen an article on a solar type pump, supposedly steam powered. I've got the article around somewhere, don't even dream I can find it, or weould ven look. I don't remember details, but I guess the system works, used for irrigation, somewhere in the mid-east if I recall right. The reflectors seemed similar to what you're doing, but mor of 'em. Of course, that could be because the system was so much larger. Didn't pump a huge amount of water, but steady - as long as the sun ines. The reflector(s) also had a plastic, or glass, cover. Dunno what a DAGS would turn up, it just popped up in my mind, so may, or not, try one.
In the meantime, I just ran across this link to a museum quality Stirling, that may help you. http://dailydiy.com/2006/10/10/boyds-tin-can-stirling-hot-air-engines /
JOAT It's not hard, if you get your mind right. - Granny Weatherwax
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J T (in snipped-for-privacy@storefull-3334.bay.webtv.net) said:
| Hi ya Morris. Thenks for the link. LMAO Not entirely certain | you're on the right path, but what the heck, few of us are. I tak | it you want a "solar pump" type of thing. Somewhere I have seen an | article on a solar type pump, supposedly steam powered. I've got | the article around somewhere, don't even dream I can find it, or | weould ven look. I don't remember details, but I guess the system | works, used for irrigation, somewhere in the mid-east if I recall | right. The reflectors seemed similar to what you're doing, but more | of 'em. Of course, that could be because the system was so much | larger. Didn't pump a huge amount of water, but steady - as long | as the sun ines. The reflector(s) also had a plastic, or glass, | cover. Dunno what a DAGS would turn up, it just popped up in my | mind, so may, or not, try one.
Yup - followed your link and the links on the web page. The problem with the usual stirling engine (power piston and displacer piston connected to a common crank 90 degrees apart) is that they require costly machining and/or aren't readily scalable to produce really useful amounts of power. Building a tin can engine to operate in the kW power range looks pretty iffy.
The object is to work out a design that can be built inexpensively, require no fuel or electricity, will run reliably over a long period of time with little or no maintenance, and deliver at least 2hp. Scalability (the ability to do more work with a larger version of the same design) would be a major plus. I'm trying to design the pump so that anyone who can cement two pieces of PVC pipe together can build one for themselves.
The trough shouldn't require much in the way of woodworking skill to build; and the "plumbing" between the trough and the stirling isn't critical (and doesn't even need to be leakproof.)
I don't know that I'm the right path, too; but it's the best I've been able to manage so far. I had some ideas last night for an easy-to-build (hacksaw only) multi-stage regenerator that might (or might not) make this design a lot more efficient by capturing a part of the heat used in each cycle and recycling it for use in powering the next cycle. It's one of those "why didn't I see this from the beginning?" kinds of things...
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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Wed, Oct 11, 2006, 8:30pm (EDT-1) snipped-for-privacy@iedu.com (MorrisDovey) doth mumbleth: Yup - followed your link and the links on the web page. <snip> The object is to work out a design that can be built inexpensively, require no fuel or electricity, will run reliably over a long period of time with little or no maintenance, <snip>
Yeah, but you've gotta admit, that Stirling is definitely museum quality. LOL And, no, I don't think you'd get anywhere with a tin can Stirling. However there used to be some hot-air engines that could do some serious work. But, I don't think they'd be what you're after here.
What you want is something like a hydraulic ram, no moving parts. There's also a propane powered outboard based on that - that one I don't think you need. The hydaulic ram would need a moving source of water tho, and I don't think you'd have that. Seems to me that I've read somehing about something that's along t he lines of a hydraulic ram that you could use, but I can't remember what or where. No way could one put out your 2hp, but make multiples instead and that would work.
I'm thinking what you want to do has already been done. But where I've seen something you can use, I don't remember. However, I used to check out a lot of NASA inventions, and it seems to me I may have seen something there. It'd be in the public domain. I don't think you'd want to scale up, I think adding units until you get what you want/need would be preferred.
How igh do you want to lift? A series might work best. With multiples efficiency wouldn't be as much of an issue. Ever see a river-powered water wheel, for irrigation? It might only lift a cup of water with each "bucket", but with a lot of buckets, and continual operation, it can pump a huge amount of water. I've seen 'em made with an old wagon wheel, and some out of just bamboo - not very high tech, but they all worked.
Hmm, somewhere in the filing cabinet of my mind, I've got the feeling you're close, but not quite the right path. Been a long time since I was interested n stuff like this, and I'm not sure how much of my reference material I have left. Seems like one of the gubmint organizations to help underdeveloped countries may have something that'll work for you. I'll keep pondering a bit on this, and maybe see what reference material I have left. If I come up with something concrete I'll make you a good price on it. LOL
JOAT It's not hard, if you get your mind right. - Granny Weatherwax
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I like the idea of running a pump. One of the links showed water pumping where there is no other source of power. This could be a real plus to people that live in remote places and need water pumping. One of the things people mention when they put in water pumping in third world countries is, "who will maintain the pumps?". Anything that is simple and self sustaining would be much better for those conditions.

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    --You should post the link to rec.crafts.metalworking as there are quite a few Stirling and solar nuts over there, me included! ;-)
--
"Steamboat Ed" Haas : Proud to be the
Hacking the Trailing Edge! : family crackpot!
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