h a l f b a k e r yQuis custodiet the custard?
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A series of Peltier devices each moving the heat through a small
gradient in temperature so that total affect is constant heat
flow in a certain direction (presumably out, for cooling)
Useful for cooling inner rooms, cars and what not.
Perhaps aluminum or copper wiring may be set between the
stacked peltier devices, setting them at a distance from each
other where the small temperature change is still effective.
Connected to solar panels, this could be quite a powerful
device.
Flexible Heat Pipe
http://www.thermaco...ducts/flexible.aspx
[MechE, Jun 15 2015]
[link]
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" Connected to solar panels, this could be quite a powerful device " |
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So the proposal is for a stack of Peltiers, longer (ie,in
the direction of heat transfer) than it is wide? |
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I think you'll have problems due to the inefficiency of
the Peltiers - they generate a fair amount of heat
themselves. So your net result will be to warm up
the hot end a lot, and to cool down the cool end by
only a small amount. |
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As an example, a single Peltier might (depending on
its rating) produce a cold-side temperature of -30°C
at a push, but it will be belting out a lot of heat on
the hot side. Stacking two Peltiers doesn't get you
down to -60°C (more like -35 or -40°C). |
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heat pipe: skip the multiple peltiers in the middle |
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There is also the problem of power supply. You either wire
them up in series, where a stack of 30 will have you over
300V in supply, or you wire them up in parallel and you have
to move a lot of current through thick wires with the
potential of heat issues. |
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Much better to shift the heat with a heatpipe. |
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Agreed - what [pashute] is proposing is, in fact, an
elaborate means of encouraging heat to do what it
would do anyway, only less efficiently. |
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//encouraging heat to do what it would do anyway, only
less efficiently// |
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A lot of fun could be described this way. For example, you
can just burn scotch. Much faster than drinking it. |
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The idea is that each peltier only needs to move the heat
down a very small temperature gradient. So a small voltage
and current is needed, and not as Maxwell calculated. |
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A plus and minus copper wire will supply the current in
parallel. Not something unusual. |
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I am not aware of a flexible thin wire that can lead heat
out of a location. Instead there exist pneumatic air-
conditioning pressurized gas pipes, large air ducts, or
coolant liquid leading pipes, with thick insulation around
them. |
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// [This] is, in fact, an elaborate means of encouraging
heat to do what it would do anyway, only less
efficiently. // |
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[marked-for-tagline] because, as [bs0u0155] said, it
applies to just about anything. |
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// The idea is that each peltier only needs to move the
heat down a very small temperature gradient. So a
small voltage and current is needed, and not as
Maxwell calculated. // |
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FOR EACH ONE. There's no getting around
energy/power requirements. |
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// A plus and minus copper wire will supply the
current in parallel. Not something unusual. // |
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Those wires will be very thick. Better to go with the
series configuration and give it a high voltage. You
can still use just two wires, one of which is your
Peltier wire. |
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In air conditioning you use thick insulated gas pipes, and
then a very large pump and fan. |
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The Peltier "wire" will be like a thick electric cable no
more. Which makes it much more flexible. |
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"There's no getting around energy/power requirements". Of
course not, but they are the same energy/power
requirements as those for a standard air conditioner
system. Its mostly a question of different configuration
(granted: being less efficient, means it would do less
cooling). |
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BTW - I once saw a Dutch company that advertised a
"gradual" cooling system that worked on continuous cooling
of the house day and night rather than the on/off ad-hoc
cooling. I'll try to find a link to it. They claimed their
analysis showed that they actually saved a lot of energy. |
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"magic" - even aluminium won't transfer that much heat that fast, by several orders of magnitude. |
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Problem is thermal mass. Houses are (or should be) designed such that they store heat from the sun during the day then release it into the house at night. Over the course of a regular year it averages out to be the most efficient. |
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But there's seasonal variations. So, an active element. |
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Polished, clearcoated aluminium strips, vertically or horizontally on the sun-side exterior of the house. During the summer they're closed during the day and open at night. During the winter, open during the day and closed at night. |
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As others have said, at most 1-2 peltiers at each end
(depending on how cold you want it) and a heat pipe in
between. That will be a lot more efficient at moving heat. |
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Better yet, if you've got the space, just go with a traditional
refrigeration system, which will be even more efficient. |
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Peltier Thistle - A bowling ball-sized aluminium sphere, (almost) filled with water, the outside coated with Peltier semiconductor pairs... and a battery as well as plug-in. et cetera. |
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But a heat pipe isn't flexible, which seems to be
something [pashute] wants for some reason. |
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