Low Temperature Differential Stirling

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    Default Low Temperature Differential Stirling

    Hi all,

    Just thought I'd put some pics up of a stirling that I bought from ebay. There are ones like it on there all the time, I paid about 70 pounds.

    I always intended making one but I still haven't got around to setting my workshop up yet so just bought one so I can get an idea of sizes. I could probably then sell a couple I've made and get my money back.

    The engine can run from the heat of your hand, even on a hot day. It will run better on the top of a coffee cup or better still on ice cubes. The ice cubes take longer to warm to room temp than the coffee does to cool down to room temp.

    Here are some pics anyway. I believe most of the components for this are done on CNC.

    Nick









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    I think they are really neat.

    How large would one have to be in order to create some useful energy? Could some modifications be made (such as heat generated by the sun, the electrical energy from solar cells, or water from solar collectors) be utilized to generate electrical power?

    Would attract a lot of attention.

    Jerry



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    sweet

    I wish it wouldn't crash.


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    I think you'd really struggle to get any useful energy from one of these. People have tried the solar ones before I think, they will run but not provide any useful energy.

    On this model scale, it's hard enough just to get the engines to run! It's difficult to produce an engine that overcomes the frictional losses in the mechanisms. That's why this one uses a glass cylinder and graphite piston and gland, aswell as ptfe in some places.

    I bet someone has tried larger scale ones somewhere though.

    Nick



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    There are larger ones and yes capable of producing energy.
    http://www.sprol.com/?p=265
    http://www.stirlingenergy.com/
    http://www.stirlingenergy.com/products.asp?Type=solar
    "In 1996, SES acquired the patent, tooling, and equipment rights to the world's most efficient solar dish concentrator system: the Dish Stirling. Initially developed in the 1980s by McDonnell Douglas (now The Boeing Co.) the Dish Stirling system was field-tested by Southern California Edison and Georgia Power for over 175,000 hours between 1982 and 1988. Edison's test data indicated the Dish Stirling out-performed all other solar-to-electric generating systems by a factor of two, yet had comparable start-up costs. SES optimized the McDonnell Douglas dish to operate with a 25kW Stirling power conversion unit (PCU) developed in Sweden by United Stirling, Kockums and Volvo. The resulting system, the "Dish Stirling", has fewer moving parts than comparable diesel engines and operates relatively quietly. The SES Solar Test Site and related tooling and equipment facilities are located at the Boeing facility in Huntington Beach, California. The 25kW SES Dish Stirling system has an operating track record of more than 17 years. Since 1984, it has held the world record for efficiency in converting solar energy into grid-quality electricity."

    Since 84 when my old company did the above, think how much energy could have been produced with thousands.................
    Since I don't have room for a 37sqft dish in my back yard, and I don't need 25KW my thinking is doing one or several much smaller to produce 500 watts(hr during peak sun) or so in my back yard.

    Phil, Still too many interests, too many projects, and not enough time!!!!!!!!
    Vist my websites - http://pminmo.com & http://millpcbs.com


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    Quote Originally Posted by pminmo
    Since 84 when my old company did the above, think how much energy could have been produced with thousands.................
    Since I don't have room for a 37sqft dish in my back yard, and I don't need 25KW my thinking is doing one or several much smaller to produce 500 watts(hr during peak sun) or so in my back yard.
    I really want to thank you for the links.

    Only one problem that I can forsee with the above power generation:

    It would really cripple the oil companies, the coal companies, and the nuclear power plants if our INCOMPETENT government officials would provide funding for realistic energy production.

    I would be interested in seeing the engine plans for this unit.

    Jerry



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    Quote Originally Posted by CJL5585

    Only one problem that I can forsee with the above power generation:

    It would really cripple the oil companies, the coal companies, and the nuclear power plants if our INCOMPETENT government officials would provide funding for realistic energy production.

    Jerry
    First mistake is relying on the government, more has been acomplished and will be accomplished by private concerns. The government is for politicians, 70% +++ of them are interested in their future as politicans not the well being of citizens. If they have some interest in the citizens, the other percentage trashes them for making them look bad. It's been that way for decades. Our founding fathers when they wrote the constitution realized a large body such as the senate or house couldn't keep their mouths shut. Doesn't make any difference on which party, you tow the party line or be trashed or allowed to be trashed.

    Before the net, this stuff was to hard to find, now it's routine research. There is more open source stuff going on than you can shake a stick at, and I mean more than software. sourceforge.net the center of the software universe for open source, is now otherstuff also but no stirlings that I can find

    Phil, Still too many interests, too many projects, and not enough time!!!!!!!!
    Vist my websites - http://pminmo.com & http://millpcbs.com


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    Quote Originally Posted by pminmo
    My thinking is doing one or several much smaller to produce 500 watts(hr during peak sun) or so in my back yard.
    I would like to have a unit capable of about 3500 to 5000 watts.

    Any plans, etc.

    Jerry



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    Quote Originally Posted by pminmo
    ...............Since I don't have room for a 37sqft dish in my back yard, and I don't need 25KW my thinking is doing one or several much smaller to produce 500 watts(hr during peak sun) or so in my back yard.
    What efficiency do you expect to get? Full sun at the earth's surface is around 1000 watts per square yard. At 20% conversion efficiency you would need 2-1/2 square yards, i.e. 22-1/2 sq ft.

    edit; calculation error, wrong area.

    Last edited by Geof; 07-06-2006 at 11:29 PM.


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    I've been looking for plans haven't found any suitable. Seems like most plans are models.

    5' square is do able. Where did you come up with 20% conversion efficiency?

    Phil, Still too many interests, too many projects, and not enough time!!!!!!!!
    Vist my websites - http://pminmo.com & http://millpcbs.com


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    Quote Originally Posted by pminmo
    I've been looking for plans haven't found any suitable. Seems like most plans are models.

    5' square is do able. Where did you come up with 20% conversion efficiency?
    It is more or less in the middle of different efficiency claims I have read. I was wondering if your 37 sq ft and 25000 watts had any relationship; it is close to the efficiency you can get with a passive solar collector heating a fluid.



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    Actually I made a goof it was 37' diameter, not 37 sqft. Some claim 30% conversion efficiency these days on solar to motive via stirlings

    Phil, Still too many interests, too many projects, and not enough time!!!!!!!!
    Vist my websites - http://pminmo.com & http://millpcbs.com


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    Quote Originally Posted by pminmo
    Actually I made a goof it was 37' diameter, not 37 sqft. Some claim 30% conversion efficiency these days on solar to motive via stirlings
    I take 30 with a grain or two of salt but on a big installation yes maybe. The problem is you need focussing collectors; I think they do it direct focused solar onto the Stirling. For a small scale version possibly a stationary parabolic trough collector heating water which is the heat source for the hot side of the Stirling and for the cool sink have another water loop through ground pipes. Not unimaginably complex for diy.



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    heres something that might help
    A TRACKING SOLAR CONCENTRATOR (diy)
    http://www.ida.net/users/tetonsl/solar/solarhom.htm

    mike,
    when you do things rite,
    people won't be sure you've done anything at all.


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    Yeouch, 1200 degrees, no wonder they no longer publish the manual with todays liability ambulance chasers. I think my neighbors might complain....
    I'm still trying to grasp power verses temperature differential. Using a ground loop for cooling you should be able to keep a cold side 60 degrees or less. A simple box solar water collector I believe will do 150 degrees or so. I wonder if that is enough?

    Phil, Still too many interests, too many projects, and not enough time!!!!!!!!
    Vist my websites - http://pminmo.com & http://millpcbs.com


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    I had a look at the Teton collector and it looks like an idea I had using a lot of CDs attached to a frame all focused on the same point. But the problem with a focusing collector is moving it and making it strong enough to withstand wind or snow loading.

    Regarding temperature differential and power they are related but not directly. How much power is available is, of course, dependent on how much sunlight your collector intercepts. How much power you get out of your Stirling depends on the temperature differential between the heat source and the sink because the thermodynamic efficiency depends only on this differential. A small area focussing collector will give a greater temperature differential than a larger non-focussing so because the efficiency is higher your output power from the smaller collector could be the more.

    You need to find someone with a stash of 'Mother Earth News' dating from the mid to late 1970's and read all the articles on alternate energy sources written by and for the hippy era back-to-the-landers.



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    so.. in edmund scientific, when i was young, i would often gaze at the giant fresnel lenses. they claimed that one of their 36x36" fresnels could 'melt concrete', whatever that means...

    anyhow,anyone considered fresnels as opposed to parabolic concentrators?

    also, there are tons and tons of DIY solar concentrators on the internet. As well as many DIY solar power controllers, solar trackers for concentrators, and other interesting do-hickies....

    if someone was really interested in an opensource project of this type, i can donate some web space and set up a community for it.. i hate the way we are ruining the environment.. it makes me literally want to cry... and worse still, i now work in 'the power industry'... cringe.cringe..

    i have a development project at http://development.1318cermak.com

    this is sort of like what i could setup for a solar generator open source project... most of the meat is in the private portion, and my work internet wont loginto it for some reason, but it has file bases, message boards, etc... based on the fabulous Joomla...

    Robert

    cheerio



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    I'm in, "colaboration tool" is new to me, but could be awsome. where do I look for one?

    Phil, Still too many interests, too many projects, and not enough time!!!!!!!!
    Vist my websites - http://pminmo.com & http://millpcbs.com


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    regaring fresnel lenses vs a parabolic. A parabolic will reflect even non visable IR, will a fresnel focus non visable IR?

    Phil, Still too many interests, too many projects, and not enough time!!!!!!!!
    Vist my websites - http://pminmo.com & http://millpcbs.com


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    Quote Originally Posted by pminmo
    regaring fresnel lenses vs a parabolic. A parabolic will reflect even non visable IR, will a fresnel focus non visable IR?
    Probably not; most plastics and glass absorb infrared. This would not be a great loss because the portion of solar energy at ground level that is in the infrared range is not large. It is possible a greater loss would come from surface reflection on the fresnel but this would depend which side was facing the incident radiation.



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