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  1. #21
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    Reading this I remembered what our French friends made in Odeillo in the Pyrenees. It's a monster solar tracker (1Mw). On google I saw mentioned that there is also Stirling technology involved. The only thing is, that if you search in French, you get better response than English.

    http://fr.wikipedia.org/wiki/Image:F...meu_France.jpg

    Carel



  2. #22
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    And searching a little further you stumble on the "Eurodish", a solar/Stirling project of the EEC. Here is the site of the producer:

    http://www.stirling-engine.de/engl/index.html

    Carel



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    Quote Originally Posted by fkaCarel
    Reading this I remembered what our French friends made in Odeillo in the Pyrenees. It's a monster solar tracker (1Mw). On google I saw mentioned that there is also Stirling technology involved. The only thing is, that if you search in French, you get better response than English.

    http://fr.wikipedia.org/wiki/Image:F...meu_France.jpg

    Carel
    I believe this one was done for experiments in making ultra-pure high temperature alloys.



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    Quote Originally Posted by pminmo
    I'm in, "colaboration tool" is new to me, but could be awsome. where do I look for one?
    here: http://www.opensourcecms.com/

    i suppose those links i just looked at intimidated me... for some reason, earlier in the day, focusing some sun on a sterling type generator seemed totally logical and 'easy'... when it is overcast, just use the power that is 'stored'(somewhere).

    i suppose, unfortunately, a opensource solar generator of any use is rather unlikely to emerge soon, considering the (insert cliche method of indicating 'strangle hold'(get it), here). especially involving me, since i still havent finished most of the projects ive started(but geeze, ive learned alot).

    so, a altpower.opensource.1318cermak.com(or similar, 1318cermak.com just being a domain i own and dont mind using for such things) would be easy for me to setup. i will do it. however, i dont have much to contribute.. all i know is that between the sun, wind, tides, and other gravity or celestial related energy is probably way more than enough to sustain us.. plus then we could kiss muslims on the cheek and all agree that it's rad that cars are quiet and electric, now that we have finally used fresnel lenses to make stirling engine-driven generators power everything...

    please, please, show interest..

    Last edited by vacpress; 07-09-2006 at 05:47 AM. Reason: impossible should never be used instead of unlikely.


  5. #25
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    development.1318cermak.com

    user: guest
    pass:guest

    i was working on a project that aimed to program micronctrollers using a macromedia flash-like timeline interface and possibly a scripting language.. this is obviousely a good idea. however, the software development proved exceedingly difficult, so i dont know... i never wanted to be a great programmer... making a full featured application is obviousely possible, given alot of hours i dont have..


    anyways, seting up a sweet forum for people interested in developing an alternative energy project is easy. that i can accomplish, with passable graphics, and alot of features.. my inexpensive hosting would accomidate a small but active group of misguided visionaries.... plus, as soon as a usefull idea emerges, i look forward to producing some extremely high quality 3d models and related drawings...

    parabolic dishes... surely it is simple to begin designing around an 'ideal' concentrator geometry, based on some actually usefull persons research?



  6. #26
    Member greybeard's Avatar
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    Years ago, (1967)a fellow eccentric and I were discussing stirling engines(he was doing most of the talking and I was looking for flaws in his logic) and he made a point that I've remembered but not verified. He said that, all other things being equal, the power from the engine would be proportional to the diameter of the piston. Therefore if you double the diam, you get x4 the output. So he thought that the way to go would be enourmous pistons, probably made out of foam, with only a relatively small and slow movement. It might be possible to think in terms of the flexing of the surface of the "piston" as the movement, rather than a sliding piston in a cylnder.
    We thought of a surface made up of a honeycomb of foam, each hole being filled with coarse steel wool as a "displacer" if that's the right term.

    Re parabolic mirrors - start with a large hoop(plastic tube pulled into a circle) with each surface covered in aluminised melinex film and pump out the air between, each surface is a pretty good parabola. Use the pipe as an air duct as well as being the frame.
    If you control the pressure, you can control the focal length.

    John

    It's like doing jigsaw puzzles in the dark.
    Enjoy today's problems, for tomorrow's may be worse.


  7. #27
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    I believe this one was done for experiments in making ultra-pure high temperature alloys.
    Yes, they are fiddling with ceramics amongst others. The place is also a general test site for solar energy, because they have (quote from Trevanian) "no weather".

    Re: Greybeard. One thing when sizing up is mentioned, reminds me always of the question: Why does a mouse eat, measured in proportion, more than an elephant, to maintain by burning food it's temperature?

    If we dimension (dimensions chosen for ease of calculation, not for reality) a mouse 1 cubic centimeter, it's cooling area is 6 square centimeters, dimension a human 1000 cubic centimeters (cubic decimeter), cooling area 600 square centimeters, elephant 1000000 cubic centimeters (cubic meter), cooling area 60000 square centimeters. From these ratios you can derive that everything has an ideal size. Human: not eating all day and yet not massive. Massive pistons: slow through dead areas. Small pistons: high surface and friction losses.

    Carel



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    Registered balsaman's Avatar
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    power is force times distance, so a large piston over a short stroke would produce more force, but is not more power than a small piston over a longer stroke. What I am saying is it is a larger displacement that produces more power, not a larger diameter.

    Eric

    I wish it wouldn't crash.


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    Quote Originally Posted by fkaCarel
    Yes, they are fiddling with ceramics amongst others. The place is also a general test site for solar energy, because they have (quote from Trevanian) "no weather".

    Re: Greybeard. One thing when sizing up is mentioned, reminds me always of the question: Why does a mouse eat, measured in proportion, more than an elephant, to maintain by burning food it's temperature?

    If we dimension (dimensions chosen for ease of calculation, not for reality) a mouse 1 cubic centimeter, it's cooling area is 6 square centimeters, dimension a human 1000 cubic centimeters (cubic decimeter), cooling area 600 square centimeters, elephant 1000000 cubic centimeters (cubic meter), cooling area 60000 square centimeters. From these ratios you can derive that everything has an ideal size. Human: not eating all day and yet not massive. Massive pistons: slow through dead areas. Small pistons: high surface and friction losses.Carel
    A lazy person like me just says it is the surface to volume ratio.

    Quote Originally Posted by Greybeard
    Re parabolic mirrors - start with a large hoop(plastic tube pulled into a circle) with each surface covered in aluminised melinex film and pump out the air between, each surface is a pretty good parabola.
    Are you sure? I thought this method gave you a spherical surface, the force acting on the film is normal to the surface at all points



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    Member greybeard's Avatar
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    < Massive pistons: slow through dead areas. Small pistons: high surface and friction losses.

    Carel - I'm not sure what your analogy is leading me towards. I go with there being an ideal ratios in all areas, but if one's "ideal" is lowest capital cost/power ratio, presumably this would lead to a different result than if your ideal was say maximum power/size. To be honest I've no idea, but to look at off the wall ideas may be useful in both learning and achieving, don't you think ?

    Geof - I'm sure you're right. I'm probably getting mixed up with chains draping in catenary curves. Put it down to the drink - I need another one.

    John

    It's like doing jigsaw puzzles in the dark.
    Enjoy today's problems, for tomorrow's may be worse.


  11. #31
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    Eric - I'm sorry, I made a cardinal error of condensing several thoughts into one. What I should have said was given the larger output of a large diameter piston(strokes the same) then the flexibility of the larger area would allow you to consider it as a flexing surface, rather than a sliding piston. This in turn would remove frictional forces and replace them with the stiffness of the "membrane" to be considered.
    The drift of the ideas at that time was to look for an approach that would allow the use of cheap materials/engineering even though it would be radically different.

    John

    It's like doing jigsaw puzzles in the dark.
    Enjoy today's problems, for tomorrow's may be worse.


  12. #32
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    A lazy person like me just says it is the surface to volume ratio.
    Yes, it is lazy. I did an effort to explain the volume/surface ratio. This explanation was an introduction of the general principle that things can be too small or too big.

    Carel



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    If you have Pyreneean weather, solar furnaces are a great starting point.
    But if you only have a large dirt patch, consider a hole in the ground as the "cold" end of your design, with a moving solar panel above it as the "hot" end, and with a large diameter membrane over the hole as the "piston"(or should that be "displacer" ?)
    Just a thought.
    John

    Edit

    Geof - if the target of the mirror is a piston end, then the spread of focus that a spherical surface will give you may be an advantage ?

    It's like doing jigsaw puzzles in the dark.
    Enjoy today's problems, for tomorrow's may be worse.


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  15. #35
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    Quote Originally Posted by greybeard
    Geof - if the target of the mirror is a piston end, then the spread of focus that a spherical surface will give you may be an advantage ?
    I don't know that it would make much difference; for the amount of curvature you are talking about a spherical reflector and a parabolic reflector are pretty much indistinguishable. Your statement that "each surface is a pretty good parabola" is quite correct. I only asked if you were sure .



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    Just found this idea/site when I googled "sterling engines diaphram".
    Thought it was a very clever way to get the 90 degree phase lag into a simple construction based on the diaphram idea.
    90 x 4 = 360 = swashplate ... brilliant.

    I'm now trying to think of my own method.

    www.jameeladesigns.co.uk

    It's like doing jigsaw puzzles in the dark.
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    I had a thought about a heat source for small generation, way back when I was in school there was mention of large amounts of heat generated within grain silo's and large piles of organic material, I wonder if that would be a possible heat source for a stirling engine, granted most people dont have 100 ft grain silo's in their backyard, but even smaller style hobby farms and such might have something similiar, and they are probably the most likely to benifit from alternative energy production.

    There are probably good reasons why it wouldn't work but as I said it was just a thought.

    Russell.



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    Hi Russell.
    I would guess that any heat source could be used for a sterling. It's more a case of what is appropriate in a particular case in terms of economic or physical effort.
    If you've only got a garden, then the muck heap rotting down organic matter would be a possible source of waste heat, bearing in mind that you need to keep the temperature up to keep the process going.
    However, if you've got a silo, you've probably also got a large piece of land feeding it, with lots of sun to ripen your crops. In this case you might be better considering direct solar heating with the sun(admittedly only 8 - 12 hours a day at most) "wasting" more heat on any spare piece of land than your silo is producing in 24 hours.

    John

    It's like doing jigsaw puzzles in the dark.
    Enjoy today's problems, for tomorrow's may be worse.


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    I like the diaphram, and have seen the 4 phase/piston approach. It's a good way to handle the 90 degree phase shift. It would seem that diaphrams would be eaiser to DIY manuracture rather than machining pistons and sleeves.

    Since helium is a gas of choice of some of the commercial stirlings, I wonder what the temperature vs pressure/volume is for it vs. air?

    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 helium is a gas of choice of some of the commercial stirlings, I wonder what the temperature vs pressure/volume is for it vs. air?
    All gases are the same (to within a fraction of a percent) in terms of the temperature/pressure/volume relationship. The advantage with helium in a Stirling is that it has the highest heat conductivity of any gas except hydrogen. The Stirling cycle requires the operating gas to gain and lose heat to its surroundings and this is largely what limits how fasten a Stirling can run. The higher the heat conductivity of the gas the faster this process can occur.



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