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Registered Member #3637
Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068
2Spoons wrote ...
The problem with that is that peltiers use semiconductors, and as they get colder the resistance goes up (less thermal energy means fewer current carriers), so the I2R self heating goes up, and the heat pumping ability gets worse.
So the short answer is most likely 'no'.
But do all semiconductors have that property? Im pretty sure some have positive temp coefficient, in which case their resistance would go down as they get cooler. (MOSFET's or transistors do, I can't remember which)
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061
Yes, nearly all semiconductors exhibit this property.
The latest modification of thermoelectrics is to use lead telluride in place of bismuth telluride, which can achieve over 12% efficiency in the lab if strontium telluride is also present. A mixture of the two or nanostructured BiPbTe could improve this still further.
Interestingly one possible explanation for observations of transient room temperature superconductivity is the presence of thermoelectric fibres within the bulk, which harness differences in temperature and convert them into Cooper pairs.
I thought this was my original theory but as it turns out others have done work in this field decades earlier.
However the very earliest documented effects were observed back in 1988 during testing of 1-2-3 aka YBa2Cu3O7 with excess barium or copper doping.
Others have noticed very small fractions of a larger bulk briefly superconduct but only under certain conditions. The most pronounced effect is noticed with a compound with small amounts of tin and indium substituted in a basic perovskite at close to dry ice temperatures.
It is possible that the effects seen are simply due to minute quantities of tellurium introduced with the strontium by accident..
Registered Member #2893
Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242
Unfortunately I can't access the nature article on that lead telluride TEC, but from what I gather it's the nano-hair layer, not the substance which makes it more efficient. Kind of like heat transporting fiberglass insulation, if that makes any sense.
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stacking peltiers
