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RoboTech · 03-04-2003, 06:53 AM

Hey mindspat,

I agree with you, Peltier devices are very cool...

There is a lot of good info available from several of the TEC manufacturers web sites (Melcor, TEDistributing, Tellurex, etc.)

You are correct, a TEC will generate DC electricity when placed between diff temp. - this is the Seebeck effect (which also produces a counter-current during normal Peltier effect mode). TECs are not very efficient (usually 25% - 33%), which means they take a lot of power to pump a little bit of heat energy. For example: a typical Pelt might require 240 watts of input power (12 VDC @ 20 Amps) to pump 60 watts of heat energy from cold side to hot side. Another kicker is that total heat coming out the hot side (heat pumped + applied power). In the previous example, a heatsink or waterblock will have to carry away 300 watts of thermal energy. Pelts usually require their own dedicated PSU because of the high current draw, which can use as much power as the regular PC PSU at full load.

The max diff temp quoted for most Pelts (60 to 70 deg C) only occurs under ideal conditions with no load - no heat being pumped. As soon as you start pumping heat the diff temp goes down, eventually to the point where there is no diff temp between the hot and cold side and the Pelt is just acting like a pure thermal conductor. The hotter the Pelt itself gets, the less efficient it operates.

You can do all sorts of cool (and hot) things with Peltier devices, just experiment...

03-04-2003, 06:53 AM	#6
RoboTech Cooling Savant Join Date: Sep 2002 Location: Cincinnati, OH Posts: 229	Hey mindspat, I agree with you, Peltier devices are very cool... There is a lot of good info available from several of the TEC manufacturers web sites (Melcor, TEDistributing, Tellurex, etc.) You are correct, a TEC will generate DC electricity when placed between diff temp. - this is the Seebeck effect (which also produces a counter-current during normal Peltier effect mode). TECs are not very efficient (usually 25% - 33%), which means they take a lot of power to pump a little bit of heat energy. For example: a typical Pelt might require 240 watts of input power (12 VDC @ 20 Amps) to pump 60 watts of heat energy from cold side to hot side. Another kicker is that total heat coming out the hot side (heat pumped + applied power). In the previous example, a heatsink or waterblock will have to carry away 300 watts of thermal energy. Pelts usually require their own dedicated PSU because of the high current draw, which can use as much power as the regular PC PSU at full load. The max diff temp quoted for most Pelts (60 to 70 deg C) only occurs under ideal conditions with no load - no heat being pumped. As soon as you start pumping heat the diff temp goes down, eventually to the point where there is no diff temp between the hot and cold side and the Pelt is just acting like a pure thermal conductor. The hotter the Pelt itself gets, the less efficient it operates. You can do all sorts of cool (and hot) things with Peltier devices, just experiment...