There is some good info here but for the most part these charts are useless. The heat transfer is greatly affected by the differential and hot side temp, as are voltage needed for a given current. These are semiconductor devices and have non-linear characteristics so none of the simple formulas being used here are going to give anything near correct results. Anyone who is serious about using TECs needs to learn how to read TEC operating curves.Originally Posted by THE JEW (RaVeN)
I have designed using TECs for years, but always up near the .5 to .8 CoP level (CoP is basically power transferred over power wasted so a CoP of 1 means for example you burn 100W to transfer 100W, for a total heat load of 200W on the hot side). Recently, because of feedback from other posters here, I took a good look at moving very low on the curve. You can achieve big CoP ratings (3 or higher) with a differential under 5C, but for a differential over 15C, nothing over CoP of 2 is possible. So high efficiency TEC use requires WC on the hot side and operation way down on the curve. If you need max performance in a small package, you will pay the price in power wasted. Sometimes that's what you need but there is no magic bullet to get high power at high efficiency - you need lots of TECs run low in their voltage curve to do that.
Anyone interested in understanding the way TEC design using the curves works should go to http://www.ferrotec.com/products/the.../highPower.php
pick a TEC and play around with the curves. Default hot side is 50C but you can plug in whatever you want. Also you can used advanced settings and get performance for a certain heat sink performance. You will understand a lot more about how these things work if you put an hour or two into that exercise. Ferrotec does not have TECs like most of those being discussed but they have similar ones - the performance will also be similar, except the absolute values will be scaled based on the Ferrotec unit you are looking at.
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