Could you make one by altering the emmisivity in response to diurnal changes
(white cover during the day to reflect as much as possible, black cover at night to radiate heat?) Or the other way around (passive oven?) Obviously it wouldn't get colder than the surrounding air, but it would be better than nothing.
2007-04-12 08:01:15 · 7 answers · asked by theonlymaxsdream 2 in Science & Mathematics ➔ Physics
Yes, it's possible, even easy.
And yes, if you do it the right way it will be able to
maintain temperature way below the temperature
of surrounding air. In fact the lowest temperature
theoretically achievable by this method is about
2K (-270C), which is the temperature of background
relict radiation.
Passive oven is possible too, its maximum temperatre
is similarly limited by the temperature of sun (6000K in
optical spectrum, millions of Kelvins for neutrio-coupled ovens).
2007-04-12 08:26:47 · answer #1 · answered by Alexander 6 · 0⤊ 1⤋
Yes, this will work in principle. A better technique, though, would be to have an insulated box with a tank of water inside Open the door at night to let the water cool, and close the door in morning so its doesn't warm up during the day. This is better because convection and conduction are much more efficient at transferring heat at moderate temperatures than radiation.
2007-04-12 16:11:41 · answer #2 · answered by Dr. R 7 · 0⤊ 1⤋
No. With no refrigeration unit doing work and moving heat, the only way to remove heat is to expose it to something cooler through radiative cooling or physical contact. That means in a passive system it could never get colder than its environment so why bother.
2007-04-12 08:20:39 · answer #3 · answered by Gene 7 · 0⤊ 0⤋
You would still need some type of evaporation or chemical reaction to reduce the temperature below the ambient outdoor temperature. The best you could hope to do would be to use the ultimate insulation... a complete vacuum between mirrored glass... like a glass thermos. Even then, some radiant heat could still get through. Heat is energy. In order to remove that energy you would have to develop some kind of innovative one way energy flow device.
2007-04-12 08:13:02 · answer #4 · answered by Anonymous · 1⤊ 0⤋
If I understand the question that would not work. For refrigeration you need to maintain at 41° to keep bacteria from growing in and on items inside the fridge. And the oven would need to heat at least to 165° (I believe it is) to kill any bacteria during cooking.
2007-04-12 08:10:51 · answer #5 · answered by psychoholiday1976 3 · 0⤊ 0⤋
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2016-10-21 23:29:52 · answer #6 · answered by ? 4 · 0⤊ 0⤋
Unless it's standing in direct sunlight all day, it wouldn't really have any noticable effect.
2007-04-12 08:10:31 · answer #7 · answered by Scottofthedead87 2 · 0⤊ 0⤋