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Will it be possible to fry eggs in Sahara desert by just keeping them under the sun? If so, then will the radiated eggs be any different? Or will we have to use the solar cooking concept to some extent? What is the minimum Intensity required and the temperature to achieve this? (With and without solar cooker)

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There are many models of solar cookers relying on various phenomena.

Two that come to mind are :

  • greenhouse cooker : the cooker is a box close by transparent material that will let in solar radiation but will not let out radiation produced by the heated material inside the box. So energy accumulates. Same as greenhouse for growing food in winter or cold climate.

  • mirror cooker : the radiation from the sun is concentrated by several mirrors. You can also get a parabolic mirror, but they are harder to come by, though metallic foldable ones exist.

You could also use a lense to concentrate radiation, but there is probably loss in the lens, and it is heavy as soon as it is large.

It should often be usable in other places than desert as long as the sun shines, and makes for more ecological barbecues.

If you meant to cook without any equipment at all, you might try to bury the food in very hot sand, preferably dark. I am not sure whether it works or how fast. I read you can cook an egg at 55 Celsius, which is very hot on the feet, but still a temperature found in desertic grounds (sometimes even in cities).

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In principle, yes, if you can prevent the egg (and the surface it is on) from being cooled too much by the air. The temperature needed to cook the egg is around 100c or less, while the temperature of the sun's surface is around 5000c. All a solar cooker does is make the sun look larger, from the egg's perspective.

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So keeping the egg in an evacuated chamber with a thermally insulated base would cook the egg? How much time would it take? –  udiboy1209 Jul 9 '13 at 13:55
    
@udiboy: Should work, except if you pump all the air out, the egg would boil. (That would be a mess.) How long would it take? I don't know. BTW, it would probably be a good idea to shield it from the sky around the sun, because that's colder, and could lose heat through radiation. (For the same reason, the chamber should be insulated so it can also come up to temp.) –  Mike Dunlavey Jul 9 '13 at 14:36

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