manley@optilink.UUCP (Dave Manley) (09/19/90)
What is the physical mechanism whereby a thermoelectric cooler (TEC)
cools? I been told it has to do with the Peltier effect.
(TEC's along with precision thermistors are used in diode lasers.)
-
Dave Manley Optilink Corporation (707) 795-9444
{uunet, pyramid}!optilink!manleygrayt@spock (Tom Gray) (09/20/90)
In article <4486@optilink.UUCP> manley@optilink.UUCP (Dave Manley) writes: >What is the physical mechanism whereby a thermoelectric cooler (TEC) >cools? I been told it has to do with the Peltier effect. > >(TEC's along with precision thermistors are used in diode lasers.) > >- >Dave Manley Optilink Corporation (707) 795-9444 >{uunet, pyramid}!optilink!manley Its the same effect as the heat temperature driven potentials derived in a thermocouple only in reverse. A current passed through dissimilar materials will pump heat from one side of the junction to the other. A physics text book should give a good explanation of the Peltier effect - much better than any handwaving I could do.
markz@ssc.UUCP (Mark Zenier) (09/23/90)
> In article <4486@optilink.UUCP> manley@optilink.UUCP (Dave Manley) writes: > >What is the physical mechanism whereby a thermoelectric cooler (TEC) > >cools? I been told it has to do with the Peltier effect. > > > >(TEC's along with precision thermistors are used in diode lasers.) There's a good writeup of thermoelectric coolers in Don Lancasters Hardware Hacker column in the January 1990 Radio-Electronics "And to further shatter some hacker dreams, no way will they make ice in the real world" markz@ssc.uucp
larry@kitty.UUCP (Larry Lippman) (09/24/90)
In article <266@ssc.UUCP>, markz@ssc.UUCP (Mark Zenier) writes: > There's a good writeup of thermoelectric coolers in Don Lancasters > Hardware Hacker column in the January 1990 Radio-Electronics > > "And to further shatter some hacker dreams, no way will they > make ice in the real world" I don't know if the above quote was intended to be serious or not. In the event that it was intended to be serious, it is most assuredly not true. Readily available thermoelectric cooling devices will easily achieve temperatures of -10 to -20 deg C, which is certainly sufficient to freeze water. Cambion is probably one of the largest and most well known manufacturers of thermoelectric cooling devices. Larry Lippman @ Recognition Research Corp. "Have you hugged your cat today?" VOICE: 716/688-1231 {boulder, rutgers, watmath}!ub!kitty!larry FAX: 716/741-9635 {utzoo, uunet}!/ \aerion!larry
chuck@mitlns.mit.edu (09/25/90)
-Message-Text-Follows- In article <266@ssc.UUCP>, markz@ssc.UUCP (Mark Zenier) writes... >> In article <4486@optilink.UUCP> manley@optilink.UUCP (Dave Manley) writes: >> >What is the physical mechanism whereby a thermoelectric cooler (TEC) >> >cools? I been told it has to do with the Peltier effect. >> > >> >(TEC's along with precision thermistors are used in diode lasers.) > >There's a good writeup of thermoelectric coolers in Don Lancasters >Hardware Hacker column in the January 1990 Radio-Electronics > >"And to further shatter some hacker dreams, no way will they >make ice in the real world" > JC Witney markets several refrigerators for vans which are thermo-electrically cooled. That is at least almost real world ;-) I've certainly formed frost on the front surface of one. Interestingly the ones manufactured for these purposes are a lot cheaper for the same heat capability than the ones made to cool chips. So far as I can tell there is no significant difference in the materials used. The company I bought from had a $100 dollar minimum, but I bought an assortment of 7 or 8 for slightly more than that, the company was in NJ. If there is interest I'll dig up the address and a few representative prices. You can definetly make a good refrigerator with these puppies. It will not be nearly as efficient as a compressor. But it can be small and with a big heatsink no moving parts. The big thing to keep in mind is you need a LOT of power to cool more than a small thing. Even an eraser sized cooler needs an amp or two at 6-12 volts to work. If you want to make a small refrigerator think TENS of amps, at low voltage. Thats not surprising any reasonable fridge is a lot more than 100 watts, and these things are less efficient than a CFC standard fridge. I think the primary reason for their efficiency problem is that they are thin (5mm) and the semiconductor junctions are wide. So the heat conduction from the cold side to the hot side is quite large. Kind of like trying to keep one side of a frying pan hot and the other side cool. Making them thicker helps minimize this heat loss since the heat has to flow farther. But since the current has to flow from one side to the other you lose on I^2R ohmic heating when you do that. Also you need more semiconductor ($$). Chuck@mitlns.mit.edu