[norton]

What are the odds that somone in the know might tell the rest of us (me) what a Peltier Chip actually is?

[coloradan]

Semiconductors can be n-type or p-type, meaning that if current is flowing in them, either electrons or holes are carrying the current. As these charge carriers move, they can scatter off of, that is, transfer momentum to, "phonons" which are the quanta of vibrational energy, i.e. heat in a crystalline lattice. In other words, as the charges flows, it sweeps the heat along with it. You can arrange a bunch of these things between two plates, alternating p-type and n-type, such that as the current snakes back and forth between the little elements, nevertheless, the charge carriers are all going in the same direction, and all sweep the heat in the same way.

When you operate one of these devices (by simply passing a current through it - connect it to a battery) the current itself dissipates some heat in the material, but that heat and some of the heat on the "cold" side get swept to the other side, the "hot" side. If you pinch one of the devices between your fingers and run it, one finger gets hot and the other cold. Materials with low thermal conductivity but good electrical conductivity have the highest figure of merit, and it turns out that the winners are made of bismuth and tellurium, especially. (Silicon has excellent thermal conductivity - no good here, it short-circuits the temperature difference.)

Incidentally, if you hook up the battery backwards, it simply reverses the cold and hot sides, with equal efficiency. And if you actively heat one face and cool the other face, it's an (inefficient!) electrical generator - in this case, the heat is being forced to flow, and the charge carriers are what get swept along for the ride.

[andyk]

What are the odds that somone in the know might tell the rest of us (me) what a Peltier Chip actually is?

Whatever it is, it's really bad, this is a stupid idea, the kids are nitwits, it'll never work, and everyone here is a freaking rocket scientist.

[Mycroft Holmes]

What are the odds that somone in the know might tell the rest of us (me) what a Peltier Chip actually is?

A peliter device is a string of diodes hooked together and oriented so that all the P sides of the diodes attach to one plate and all the N sides attache to the opposite plate. The heat is transferred from one side to the other by the motion of the majority carriers in the diodes.

I have used them many times to cool laser diodes and they are terribly inefficient. Without running the numbers I would expect that you would burn more gas powering these than running a standard AC.

regards,

[AFreeBird]

Google is our friend...

Found this page with a listing of links on Peltier Chips.

[Final Authority]

I don't know if anyone replied but a Pelletier cooler is also known as a TE cooler as in thermoelectric cooler. It works on the principle of the thermoelectric effect of dissimilar materials like a thermocouple wherein a thermocouple (TC) generates a voltage proportional to the temperature gradient between the junction of the dissimilar materials and where the voltage is detected. A TE cooler operates by powering dissimilar materials with a DC current and the materials will either absorb heat (get cool) or radiate heat (from the side that is cooler). Changing the polarity of the current reverses the cooling effect.

The best non-semiconductor materials were and are bismuth and antimony for the thermoelectric materials. TE coolers rely on an amorphous semiconductor junction.

It is unlikely that such an invention would be of any benefit as a typical auto AC unit has at least a 12,000 BTU capacity which would equal about 3.5 kW or about 5 HP. Since a typical 2 inch TE cooler component uses about 35 Watts one would need about 100 pieces and figure out a way to cool the hot side and deliver cabin air to the cool sides to circulate. It ain't gonna happen.

[Old Professer]

The Pelteir Effect is the opposite of the Seebeck Effect.