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Cooling alternatives for a TEG

Discussion in 'General Electronics Discussion' started by Granstubbe, Dec 6, 2014.

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  1. Granstubbe

    Granstubbe

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    Dec 6, 2014
    I'm trying to create a module for my wooden stove so during my frequent power outages during the winter I'll still be able to charge different devices. I've solved all problems so far except for the cooling and I hoped you might be able to help me a bit. What it all comes down to is that I have a Peltier module (a thermoelectric generator) with the size of 40x40 mm that produces during maximum heat ~220W and I need to bring the heat down to be able to get some current going.

    So! What I need is some way to disperse 220W into the air from a surface of 40x40mm with minimum active cooling. I've been thinking of using a CPU cooler but I doubt it will disperse 220W without a lot of fans which in turn reduces the netto effect of the module.

    I've also been thinking of using a large pot of water on top, hoping that the water can give of that energy to the environment without starting to boil, although I haven't been able to get some good calculations on it.

    A third option would be some kind of radiator (perhaps from a MC) with a low wattage pump, but same problem here, been having some trouble to calculate/model the cooling effect.

    So what do you think would be the best option? Any ideas of ways to model the cooling effect of the different options? What would be the most efficient passive cooler or active cooler with minimum required effect?
     
  2. Arouse1973

    Arouse1973 Adam

    5,164
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    Dec 18, 2013
    What I have done in the passed is use two large heat-sinks and sandwich the element between the two with some insulating thermal sheet and then bolt the two heat-sinks together . Heat one side of the heat-sinks only. You could use a fan on the other heat-sink to improve this even further.
    Thanks
    Adam
     
  3. Granstubbe

    Granstubbe

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    Dec 6, 2014
    What kind of heat sinks did you use and did you mange to get the temperature on the cold size down enough to get a decent effect out of the TEG?

    Based on the little thermodynamics I know maximum area of the heat sink is preferred instead of purely large volume (like how CPU-heat sinks look like). But I right be completely wrong about it?
     
  4. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    It was an extruded type we used to use at work but I cant remember the spec. It was 10 years ago, sorry. But it shouldnt be too much to workout what you need.
    Adam
     
  5. Bluejets

    Bluejets

    3,684
    758
    Oct 5, 2014
    Just heated 1 litre of water in a jug.
    Took 140 seconds for a temperature rise of approx. 80 degrees C with a 2000w heater....if that helps... :)
     
    Granstubbe likes this.
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    I would use water cooling. If it's cold enough for a fire then it's probably cold enough that you need some warm water.

    Water convects too, so it can be done without a pump.
     
  7. KJ6EAD

    KJ6EAD

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    Aug 13, 2011
    Ironically, anything you use to cool the peltier that's in the room you're heating will become less effective as the room warms. An insulated duct to outside air may be a viable option if the stove is close to an outside wall but normally stoves are positioned near the center of the room.

    By the way, I've never heard of a "wooden stove". Wouldn't it quickly consume itself once lit? A wood burning stove would seem a more practical device. ;)
     
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  8. Granstubbe

    Granstubbe

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    Dec 6, 2014
    Then I guess it will take ~1400 seconds for my application to reach that temperature, plus the time given due to heat given off to the environment.

    Heat itself and warm water is no problem, a lot of wood lying around but if the power is gone for more than ~8hours I'm basically cut off from the rest of the world due to my smartphone shutting down, probably even less since I'll be pretty bored after an hour. So I only need roughly 5W effect from the module to keep the most essential things going.

    I've been thinking of using one or two of these CPU-radiators in parallel or series with a low effect pump. Don't know if one will be sufficient enough. The thing is, if I manage to get the cold side of the Peltier element down to 30°C I'll have almost 4W to use for cooling and still remain over 5W netto, but if it reaches 80°C I'll only have 1W.

    Any idea of what's required to get that amount of cooling out of a water based cooling radiator?

    My wood burning stove is in the center of the room and I agree that the best would be an outside cooling. Although the room temperature tend to stay close to 25°C even if I only use the stove as heat source. So a cooling device that works in that range would be optimal.
     
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