h a l f b a k e r yBirth of a Notion.
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Run by solar batteries on the lower part of your suit and on your
hat, so on a hot and sunny day you get the benefit of the sun and
no drawbacks.
No good for Ghana where its hot but hazy all year round and you
never see the sun.
Very good for Israel, where its always too hot, and all trees
are
being cut down for construction reasons, car parking, fires
(politically ignited) and competition with birds and bats on land
ownership.
[link]
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Humans dump about 100W into the environment, at rest. Peltiers are about 10-15% efficient. |
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Right: The whole body puts out: 350kJ for an hour =
350kJ/3600s = 97.2 W |
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We'de need 1kW to do the job by Peltier instead of sweat. |
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BUT, the sun at the heat of the day, gives us 5 unharvested
kW, for 1 square m, and PV cells at 15% can harvest a
whopping 750 W !!!
With the Peltier 10% that gives me 75 watts. The body
would
receive 75 out of 97W needed, more than 77%. I still think
that is cool. |
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The only number I don't disagree with is 100 W resting
heat output of the human body, and that's only because I
haven't read any number for that before. |
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I have read in the past that Peltier coolers are up to 5%
efficient in general. I have also read, on one
manufacturer's website, that that is because most people
use them wrong, and they can get much better efficiency
(somewhere around 60–90%?) by 'using them properly', but
they didn't give any details on how to do that. |
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I have always heard that usable solar power at Earth's
surface is 1 kW/m^2, not 5. It's 1.6 kW/m^2 on the Moon
(without air in the way), IIRC from the recent EEVblog
lunar rover videos. |
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I have recently been looking into building such a device,
or rather a pair of devices, worn on the wrists. However,
mine were not planned to be solar-powered, and they
were planned to use Stirling heat pumps for better
efficiency. On the wrists, they have access to lots of
blood flowing by, and you can swing your arms around to
collect hot blood there and then hold them up in the air
to cool it and drain it back into the rest of your body
(which works even with only air cooling). Also look into
CoreControl, which does that with the aid of suction, and
is also capable of supplying heat for use in cold weather. |
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// with the aid of suction // |
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What, sucks your blood ? Vampire refrigerator ? |
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[notexactly] The figures I read, somewhere, were 100W at rest, 200 for moderate effort and 300 for a trained athlete. Also 1kW'ish/m3 insolation above the atmosphere, 500W best case on the surface. I'm not saying you'd actually need a m2 mortarboard; perhaps concentrating on the wrists, ankles, underarms and neck (where blood flow is just under the surface) and using heatpipes would work when combined with other, passive methods. belated + |
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