EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: elimenohpee on November 20, 2016, 06:24:00 pm
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I have a couple of projects in mind that make use of a thermoelectric generator for the power source, unfortunately a quick scan of newark and mouser shows that the max differential temperature a lot of the peltier plates can handle is generally less than 100C (unless I want to shell out a lot of money which would defeat the purpose of the project). The application I'm thinking of using them in could reach temperatures up to 400C potentially. I was wondering if there is a way I could insulate the hot side of the peltier to reduce the temperature it sees. Does anyone have any suggestions to point me in a particular direction? Usually the goal is to couple as much heat the heat sink as possible, but I want to do the reverse. Thanks!!
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How about instead having a longer path to the element, using a thin aluminium Z plate so the heat has to flow along the long side, then spread out over the end. Insulate with glass wool ( about the only cheap thing that will survive 400C) and put a decent heatsink on the cold side, so the element is closer to ambient temperature. You want a steep gradient, so the long thermal path is a lot better and having a low thermal resistance at the cold side is a lot better.
BTW most peltier elements are specced for 70C maximum, they might start melting at 100C, as they are based on Gallium bismuth alloys, which are very low melting point alloys.
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If the temperature anywhere on the Peltier device exceeds about 90 C, you will unfortunately need to shell out for the ones using more expensive alloys. Marlow Industries has reasonable prices for TEG modules rated at 230 C, and sell some in small quantities to private individuals. http://www.marlow.com/power-generators/standard-generators.html (http://www.marlow.com/power-generators/standard-generators.html)
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I'm going to do some more testing to see what the actual temperatures the device would see, but if it gets as high as I think, I'll probably just scrap it. Thanks for the info though!
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At that temperature you should probably be looking at conventional thermopiles that use thermocouple junctions rather than Peltier based devices.