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Using a peltier in reverse on a CPU

Discussion in 'Alternative Energy' started by Thunderchild, Jan 11, 2009.

  1. kchriste

    kchriste New Member Forum Supporter

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    All kinds of neat things on that site duffy! Good find.
     
  2. killivolt

    killivolt Well-Known Member

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    If he doesn't get a job we may see him create his company.


    He's already done a great job of Advertising.


    kv
     
  3. tcmtech

    tcmtech Well-Known Member Most Helpful Member

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    I actualy built one of these only a few weeks ago. It used the pelter cooler out of a old computer and heres what I got for actual numbers. It was for my dads elementry school science class room.

    I used a 12v 36 watt peltier. I mounted it betewwn two heat sinks. One was 2" by 4" with 1.5" fins. the other was 4" by 4" with the same fin style.
    If you put the small sink in simmereing water( 210 F) and put snow (0 F) on the big one you would get about 2.1 volts open circuit.
    At load it could hold 1.5 volts at 500 ma. Or about the same as a D battery.
    It could spin small motors and run a small lamp.

    Not a real power monster but the kids think its pretty cool!
     
  4. dave

    Dave New Member

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  5. Sceadwian

    Sceadwian Banned

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    Any power created by a peltier device in operation is automatically electrically regenerated into the circuit itself. So it's either increasing it's cooling effect through thermocouple effect or re-supplying the bus itself with power from it. If you do NOTHING at all you automatically recover the maximum amount of thermoelectric power without doing a single thing.
    If you want power from your PC, you'd have to recover the heat from the CASE itself.
     
    Last edited: Mar 9, 2009
  6. Thunderchild

    Thunderchild New Member

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    could you translate that into laymans term please I'm not sure what you saying
     
  7. Sceadwian

    Sceadwian Banned

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    I re-read your original post, seems like I was a little bit off. Do you have any idea what the peltier device you have in mind is using for a thermocouple material and how many junctions it has? These things are sometimes listed on the tech sheets for the cooler. You could always test it, but to generate any reasonable amount of electricity from a thermocouple you need a sharp temperature gradiant, try setting the 'cold' side on a small bowl of ice cubes and using a lighter on the hot side and see what kind of voltage you get on a multimeter.
     
  8. tcmtech

    tcmtech Well-Known Member Most Helpful Member

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    Do some web search for a Seebeck junction. its the more efficient power producer, less efficient heat pump device. him an peltier did independent reasearch I think. one was doing power from temperature differentials the other was doing heat pumping from voltage differentials. Very similar but not the exact matrials used in both, I think.
     
  9. steveB

    steveB Well-Known Member Most Helpful Member

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    There are some cases where power is generated from Peltier Coolers. I've heard that they have been used to power devices along oil pipelines in cold climates. The oil is heated so that it will flow in the pipes, and the temperature difference from the warm oil pipe and the very cold atmosphere (interfaced with a heat sink) can drive the Peltier device to generate useful electrical power.
     
  10. Thunderchild

    Thunderchild New Member

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    thats interesting
     
  11. Mikebits

    Mikebits Well-Known Member

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  12. duffy

    duffy New Member

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    Anyone remember that supposed "breakthrough" in thermoelectric generation announced a year or so back?
     
  13. Sceadwian

    Sceadwian Banned

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    There's an announcement of some great breakthrough in power generation pretty much every 6 months. They're either quacks or it's stuff that is going to take years to develop into a reliable product.
     
  14. Mikebits

    Mikebits Well-Known Member

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  15. Sceadwian

    Sceadwian Banned

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    The thermal difference needed for those isn't too bad. They claim 260mws for a 1.6X3.2 mm square TEG, but they're ungodly expensive. The evaluation kit is almost 300 dollars for a thumbnail sized device.
     
  16. Thunderchild

    Thunderchild New Member

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    then I doubt many hobbiests will be evaluating them....
     
  17. Sceadwian

    Sceadwian Banned

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    For the cost though could it possibly be worth recovering the power? Power would have to be oddly expensive to use a TEG rather than more conventional methods of generating power.
     
  18. Thunderchild

    Thunderchild New Member

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    well let me see for £ 60 I can get 20 W of solar panel and don't have to worry about how to make all thgat heat
     
  19. Sceadwian

    Sceadwian Banned

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    If they were cost effective making the heat is easy. flexible mirrors, that's how many large scale solar plants work.
     
  20. duffy

    duffy New Member

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    The TEG is only about 2% efficient in power generation mode. TWO PERCENT. So 100 watts of heat flows through it, and you get two crummy watts of electric power.

    Even a modest stirling engine can get a 20% Carnot efficiency. Coupled with an 80% efficient electric generator, that gives you a 16% thermal-to-electric output.
     

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