updated on 08/25/06 |
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page
created May 2002 |
Version 3.2
Improvements over version 3.1
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Without affecting the structure and modifying only a few elements, it is possible to significantly improve the performance of this little engine, the operating threshold while passing a gradient of temperature below 10 ° C at a gradient less than 6 ° C
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This represents a performance improvement of 60% and it allows him now to turn to room temperature for about an hour, supplied with energy by only 4 cubes of ice. Almost as though the model N-92 and P-19 built by Dr. Senft for NASA... :-) - (Excerpts rom the book "An Introduction to Low Temperature Differential Stirling Engine", by James R. Senft, 1996, Moriya Press - normally available on amazon.com)
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list of changes
1 - increase the size of piston rings, whose diameter is 22 mm. As it is far from standard, they will be cut from a sheet of aluminum 0.6 mm ep
2 - parallel, using a membrane blisters - see FAQ - substantially prevent the formation of folds, and thereby the friction at this level. It will be closer then the performance of a rigid piston, but without the problems related to manufacturing (available in stores).
3 - the seal between the membrane and washers will be joined by two concentric rings of 1 mm diameter section (details on the above map)
4 - Sealing general will be particularly careful, and the body of the polypropylene cylinder engine will be fixed with glue cyanoacrylate "Super Plastic" (for its models, N. Vivet successfully using the Ara metal). It may then be necessary to add a hole decompression Ø1 mm to stabilize pressure at startup. In operation, the hole will be sealed by a piece of tape stuck to flat.
5 - incidentally, the adjustable rod displacer may be replaced by an elastic rod, which will theoretically increase the race until contact with the upper and lower trays. But more importantly, it has the advantage of absorbing small expansions of the structure, for example when moving from a hot spring source to a cold or sun exposure. For operation with ice, it is preferable to mount a slide in music wire steel (corrosion problems due to internal condensation).
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membrane
strips (2)
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piston
(1,2,4)
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rod
(5)
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6 - in the context of using solar, we can complete the sensor (aluminum foil painted black) with a transparent plastic. The plastics are in general, and unlike glass, transparent in the infrared, I do not think we have a greenhouse very marked. However, by raising the plate 3 to 4 mm by a seal device, it creates an air layer through which acts as insulation.
I found that this system favored the fitted temperature and maintaining the passage of clouds - especially in early summer when the sun is fairly high in the sky (June, July). On the other hand in the fall (late October, early November), the sun never rises so high over the horizon and its rays we arrive at an angle of more shaving. A significant part of radiation is then reflected by the plastic sheet and the profit made by this device seems much less interesting ...
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solar
panel(6)
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Successful
completion ...
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