Solar powered stirling engine project

[Morris Dovey]

The woodworking connection isn't exactly obvious (the frame for the solar concentrator is wood) - but I thought the project might be of interest to at least a few of the wreckers.

It's also not so obvious that it's an engine at all - since the only moving parts are air and water. I /think/ it's a stirling engine; and kind of hope that one of you folks can either confirm that or tell me what kind of engine it really is.

It's be like winning the lottery if someone could explain to me (in terms I could understand) why and how (with formulas!) the darn thing works so I could do some actual design.

If you're intigued by weird motors, you might want to build one of these (should set you back less than $5).

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[Smaug Ichorfang]

"Morris Dovey" wrote in news:44ecc013$0$34070$815e3792 @news.qwest.net:

Not a complaint about your posting here, I'm glad you did so I could see it, but these other guys might give you a better answer if you're wanting it explained in numbers.

[Morris Dovey]

| "Morris Dovey" wrote in | news:44ecc013$0$34070$815e3792 @news.qwest.net: | ||

|| Why not repost the url and the question in the sci.engr.mech | newsgroup? Not a complaint about your posting here, I'm glad you | did so I could see it, but these other guys might give you a better | answer if you're wanting it explained in numbers.

Thanks for the suggestion! I'll give it a try - I did also get some good info on news:altsolar.thermal but don't know my way around usenet well enough to puzzle out which groups might be most productive - so I decided to shar it first with friends. :-)

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[BobS]

Here's an interesting site and FAQ about Stirling engines.

It is a Stirling engine and they are in use today in way's you never thought about. From submarines to cooling infrared devices..... according to the FAQ on this site.

S.

[Zz Yzx]

See? Posting here was a good idea:

[Morris Dovey]

| Here's an interesting site and FAQ about Stirling engines. | | It is a Stirling engine and they are in use today in way's you | never thought about. From submarines to cooling infrared | devices..... according to the FAQ on this site. | |

for the confirmation!

Interesting FAQ. I had wondered about the reversability of the stirling cycle (whether the engine would produce both hot and cold if mechanical energy was supplied).

I still haven't found anything I could recognize as computationally useful...

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[Morris Dovey]

| See? Posting here was a good idea: | |

little things, aren't they? I admit that I wouldn't have guessed Garrett Wade would be selling them - but I like the smaller number of moving parts (and the cost) of mine better.

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[Roy]

Morris,

Check out this site. I knew one of these guys about a lifetime ago. He had an old three tailed Mooney he used for aerobatics. Anyway, they've been working on this, originally for third world applications, since the early 70's.

is a great town. Small town feeling, but high tech due to the university.

Regards, Roy

[Morris Dovey]

| Check out this site. I knew one of these guys about a lifetime | ago. He had an old three tailed Mooney he used for aerobatics. | Anyway, they've been working on this, originally for third world | applications, since the early 70's. | |

|| Athens is a great town. Small town feeling, but high tech due to | the university.

Thanks! I'd already visited their web site and decided that those folks and I have very different views about what's affordable for those developing areas most in need of this kind of technology. I've saved their home page URL for revisiting from time to time.

Your comments about Athens echo what I've heard from students and alums. I've never visited there - but think it'd be enjoyable.

I'm very much a newcomer to stirling design - but I've been working (off and on) on the collection of solar radiation since early 70's and that first OPEC crunch.

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[David Merrill]

And other Newsgroups as well:

of model engine enthusiasts in rec.crafts.metalworking; a lot of them seem to be in England.

David Merrill

[Morris Dovey]

| And other Newsgroups as well: |

|| Lots of model engine enthusiasts in rec.crafts.metalworking; a lot | of them seem to be in England.

I've subscribed to alt.engineering, alt.sci, alt.solar.thermal, and sci.engr.mech - and think I'm getting some good info (as I learn to frame my questions better). Web searches have been less productive, but not completely dry. Lotsa people talk about stirlings; but not many have much to offer in the computational area.

I'm not a model enthusiast. My next 'model' will be about 12' (~4m) tall and built of 4" schedule 40 PVC pipe. I'm boning up on the old pressure/volume/temperature equations and worrying over stuff that I haven't looked at since school more than 40 years ago.

Not surprising that the Brits are more interested - the engine was invented by the Rev R. Stirling, a Scottish minister. Here in the States we sometimes have a NIH (not invented here) problem...

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[jo4hn]

PV/T = constant (if memory serves) mahalo, (and apologies if memory doesn't serve) jo4hn

[Robatoy]

As usual, you have found something very interesting, Morris.

I'm doing some in-depth research into PV's. Wind interests me too.

Ahhhh to have the time...

r

[J T]

Wed, Aug 23, 2006, 3:48pm (EDT-1) [e-mail] (Morris=A0Dovey) said something about: The woodworking connection isn't exactly obvious (the frame for the solar concentrator is wood) - but I thought the project might be of interest to at least a few of the wreckers.

Put it ta work.

was invented by the innocent. Mercy and lawyers were invented by the guilty.

[fredfighter]

If you brouse the engineering texts at your local University Library you can probably find an explanation of the underlying theroy--if you don't find it online.I remember covering it and the professor demoed a sterno powered desktop unit in the classroom. It has been too long for me to remember much about it though.

Also many years ago a friend told me that the had seen a solar- powered Stirling engine powered water pump that had been designed for farm use--similar to the wind powered uints. It may have been a manufactured unit.

I'll bet it was similar to your design. One problem I see with the simple open loop design is that evaporation and condensation will transfer water from the engine to the pump resevoir. It will require periodic repriming.

Maybe that could be done automatically.

Thanks for posting.

[fredfighter]

heating part of the cycle corresponds to when the water is being heated, and the cooling part of the cycle occurs when the water level in the heater drops below the heater so I think that evaporation and condensation of the water plays a role. There is no phase change in a true Stirling engine, right?

It looks to be a more sophisticated version of the 'putt-putt' toy boat engines made in India and sold as toys. Basicly a vaccuum engine (low-pressure steam engine) with the water doing double duty as both the working fluid and the counterweight.

This one would operate without actually boiling, depending on the vapor pressure of water as a function of temperature.

But if most of the volume change in the air loop is due to expansion rather than evaporation then the phase is just a means of transfering heat to the air and it would be predominately a Stirling engine.

[Morris Dovey]

| Morris Dovey wrote: || || It's be like winning the lottery if someone could explain to me (in || terms I could understand) why and how (with formulas!) the darn || thing works so I could do some actual design. | | If you brouse the engineering texts at your local University Library | you can probably find an explanation of the underlying theroy--if | you don't find it online.I remember covering it and the professor | demoed a sterno powered desktop unit in the classroom. It has been | too long for me to remember much about it though.

I've had two "toy" sterlings - one was heated by a small alcohol burner and the other used a small parabolic dish. Both engines had two pistons separated by 90 degrees tied to a common crankshaft. They were fascinating; but not particularly educational. As far as I was concerned, they may as well have been PFM-powered.

| Also many years ago a friend told me that the had seen a solar- | powered Stirling engine powered water pump that had been | designed for farm use--similar to the wind powered uints. It | may have been a manufactured unit.

I wish I'd seen it!

| I'll bet it was similar to your design. One problem I see with | the simple open loop design is that evaporation and condensation | will transfer water from the engine to the pump resevoir. It will | require periodic repriming. | | Maybe that could be done automatically.

Perhaps. I'll just have to get the darned thing built and see how much fluid loss there actually is. I may be able to get by with just a few drops of oil or some styrofoam beads/fluff in the open column.

| Thanks for posting.

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[Morris Dovey]

| Wed, Aug 23, 2006, 3:48pm (EDT-1) [e-mail] (Morris Dovey) | said something about: | The woodworking connection isn't exactly obvious (the frame for the | solar concentrator is wood) - but I thought the project might be of | interest to at least a few of the wreckers. | | Put it ta work. |

've been fascinated by stirling-powered boats; but don't have the metalworking skills or tools to build anything other than the boat itself. :-(

Of course, I'd want the boat to be solar-powered...

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[J T]

Fri, Aug 25, 2006, 7:05pm (EDT-1) [e-mail] (Morris=A0Dovey) doth sayeth: I've been fascinated by stirling-powered boats; but don't have the metalworking skills or tools to build anything other than the boat itself. :-( Of course, I'd want the boat to be solar-powered...

I think this one is even cooler.

Just getcha a hacksaw and a wire welder, then buy tubing the right size. No biggie. Personally, my thing is steam, more power.

Solar would be OK, if you were going to run a water pump, that wouln't be expected to pump constantly, clouds you know, in a remote location. Or, just wanted a toy. For a boat, or something serious, you'd pretty much have to be in a desert to get sufficient sunlight to run whatever, and there ain't that much water in deserts.

In a boat, I would consider solar a dream. Too many days with clouds that would hamper the solar part, unless you had batteries as a backup. Solar sounds very ecologically sound, but then you've got to figure in the manufacturing processes required to make the solar panels and/or batteries - some of them are very nasty. The tree huggers and dandylion eaters never seem to factor any of that in when they applaud solar and all. If you were serious you'd pretty much have to use a gaseous, liquid, or solid, fuel to get any useful work out of one. Why not go for sawdust as fuel? Then you could tell your wife you'd have to do more woodworking to get enough fuel to take her out joyriding in your boat.

Me, I'm eventually planning on steam, Diesel or propane for fuel - better control than solid fuel. Probably a side-wheeler - I like the looks better, and much better for shallow water than a prop. Monotube boiler of course. Definitely a wooden boat. Mind not made up on engine(s) choice yet. I can get plans to make one from scratch, no casting. Got several plans to make several versions from scratch, machining needed. Or, convert something to steam. Many possibilities. But other projects have precedance, for now.

May check out this for a propulsion option later, different boat of course.

was invented by the innocent. Mercy and lawyers were invented by the guilty.

[Morris Dovey]

| Fri, Aug 25, 2006, 7:05pm (EDT-1) [e-mail] (Morris Dovey) | doth sayeth: | I've been fascinated by stirling-powered boats; but don't have the | metalworking skills or tools to build anything other than the boat | itself. :-( | Of course, I'd want the boat to be solar-powered... | | I think this one is even cooler. |

like that. My dream boat is (would be) a 50' sailing cat with fuel cells for on-board power and stirling cycle backup auxillary engines. I'd need an on-board workshop, of course.

| Solar would be OK, if you were going to run a water pump, that | wouln't be expected to pump constantly, clouds you know, in a remote | location. Or, just wanted a toy. For a boat, or something serious, | you'd pretty much have to be in a desert to get sufficient sunlight | to run whatever, and there ain't that much water in deserts.

You might be surprised. There are a number of major deserts that are deserts precisely because all the water is unusably/inconveniently below the surface.

| In a boat, I would consider solar a dream. Too many days with | clouds that would hamper the solar part, unless you had batteries | as a backup. Solar sounds very ecologically sound, but then you've | got to figure in the manufacturing processes required to make the | solar panels and/or batteries - some of them are very nasty. The | tree huggers and dandylion eaters never seem to factor any of that | in when they applaud solar and all.

I agree (unless someone points out that the breeze that pushes a sailboat is just an indirect use of solar energy) - PV manufacturing can be pretty clean; but I'm not as sure about batteries. We still have a lot to learn about how to store energy.

The greenies are just like everyone else - they see what they want to see and ignore the rest until it bumps 'em in the nose. I think their intentions are good - but they seem as prone as anyone to not consider what the consequences would be if all their dreams came true.

| If you were serious you'd pretty much have to use a gaseous, | liquid, or solid, fuel to get any useful work out of one. Why not | go for sawdust as fuel? Then you could tell your wife you'd have | to do more woodworking to get enough fuel to take her out joyriding | in your boat.

This is a non-problem. The x decided I was too boring and left. I work wood (to pay the bills) or sail as /I/ choose.

| Me, I'm eventually planning on steam, Diesel or propane for | fuel - better control than solid fuel. Probably a side-wheeler - I | like the looks better, and much better for shallow water than a | prop. Monotube boiler of course. Definitely a wooden boat. Mind | not made up on engine(s) choice yet. I can get plans to make one | from scratch, no casting. Got several plans to make several | versions from scratch, machining needed. Or, convert something to | steam. Many possibilities. But other projects have precedance, for | now.

I enjoy sailing in deep water and I enjoy paddling my kayack in shallow water.

| May check out this for a propulsion option later, different | boat of course.

I wonder how efficient it is...

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA