Half a croissant, on a plate, with a sign in front of it saying '50c'
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Solar sterling engine

Perpetual motion from sunlight
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As I understand it, Sterling engines work by heating one end of a sealed tube, while maintaining the other end at a cooler tempreature. By displacing most of the air mass within the tube with a moving plunger, this air either expands or contracts, which can have an effect on a piston to produce motion. With no atmosphere in space to dilute the suns energy, the light could be focused to heat one end of a tube while the other faces away in the shadow of the machine.

Alternatively, just one piston could be used, driving a large rotor disc which will partially shade the piston during half of it's rotation i.e. from tdc to bdc.

Maybe a small PV panel could be included to give it the initial kickstart.

Apothecary, Jan 28 2006


       //With no atmosphere in space to dilute the suns energy// There's space in space to dilute the sun's energy. (sp. tempreature)
zigness, Jan 28 2006

       I think I've seen the rotary shading idea, before. But not in space. Why in space?   

       By the way it's:
Sterling Silver, or
Not a Sterling idea.

       But it's a Stirling heat engine.
Ling, Jan 29 2006

       //With no atmosphere in space to dilute the suns energy// Sorry, I meant no cloud cover. The heated part would have to be either behind a vacum or in one to retain it's own gains in infra red, low emisivity glass perhaps?
Apothecary, Jan 29 2006

       Drop the "perpetual motion" claim and its a novel way to get power in space. I'm concerned about the rate of heat radiation on the cold side, though...
sninctown, Jan 29 2006

       /heat radiation/ - yah. It is tough to get rid of heat in space. I have a new appreciation for this after much reading to better understand the IKECE idea.
bungston, Jan 30 2006

       Perpetual motion refers to the idea that energy can be created within the workings of the machine. As we now know that energy cannot be created, only be converted from one form to another, the idea of perpetual motion is defunct. The term Perpetual motion should not be applied to machines like this, which have an obvious power source...
Minimal, Jan 30 2006

       I can imagine an engine like this, slowly turning in the sun. The gas containing chambers would be affixed to a large mirrored block, except for the part directly adjacent to the tube which would be black. The dark half of the tube would unload its heat to the block, which is fitted with all manner of radiators (and maybe some IKECE!). The light half would heat up in the sun. The block would rotate perpetually, since that is what happens in space.   

       I do not think this would be more efficient than a solar panel, but it would probably be more robust: no electronics or even electricity needed.
bungston, Jan 30 2006

       I don't like the single-piston part, which automatically rejects half of the incoming energy. By going to multiple cylinders and replacing the shutter with a shifting focal point (or even a fixed focal point with a rotating engine), you eliminate the need for initial startup assistance and gain back this rejected energy.
Freefall, Jan 30 2006

       Moving parts... Perpetual.... something tells me you've never heard of friction, or wear....   

       Photovoltaics (PV) are much better suited to machines in "hard to service" areas (such as space), as there are no moving parts, thus no friction, wear, or need to service.
sophocles, Jan 30 2006

       [bungston] holy kamolee. System overload. IKECE was very interesting. I somehow knew it would be a [Vernon] idea.   

       Thanks for the reference to it. I didn't know about waste heat problems in vacuum.   

       Some day I may try & print out [Vernon]'s ideas & put them all w/ the anno's into a binder labeled "The Oddyssey". I can read through it any time I want to achieve the state of mental calm that comes from overexertion so I can blissfully drift of to sleep without overactive thoughts fighting each other for attention.
Zimmy, Feb 01 2006

       I think the gasses in this engine would eventually leak out, and then, of course, it would stop working.   

       [sophocles], electrical resistance can be considered equivalent to friction.
Vernon, Feb 01 2006

       Solar powered Stirling cycle engines are not new. Just putting one in space is hardly an idea, but it does make the disposing of waste heat more difficult, since it must now be done radiatively.
ldischler, Feb 01 2006

       /I think the gasses in this engine would eventually leak out/ - one could use solids just as easily.
bungston, Feb 01 2006

       Researched, developed, baked and available on the Net. I found a design in a 70's issue of Pop Science that generated 60hz AC, no control electronics required, regardless of load.
elhigh, Feb 05 2006


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