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Thread: TEGS - Thermoelectric Generators

  1. #21
    There have been some pretty convincing arguments against this technology being much use to us. I must admit I have my doubts that it would be worth the effort of trying it out. I think, though, that Richard's enthusiasm will give it a good try, and you never know, maybe he can find a way to make it work effectively enough to be of use. I think he should be supported in the effort no matter how unlikely it may appear that it will be successful. Sometimes unlikely things can work in a certain way if we can find the angle on it.
    Don't put a man down for trying. It's all good, even if just to make certain that that way won't work.

  2. #22
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    Ide love to see something like this work, even though the math doesnt add up to much, but with Richard, he has a lack of showing that anything he speaks of working outside of his brain in the real world. just sayin.
    The way I see it, if you're gonna build a time machine into a car, why not do it with some style?
    www.hhounderground.com

  3. #23
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    Yeah, you're right, Buster. I know from experience that sometimes things SHOULD NOT WORK, yet for some reason, they do. More commonly it's the other way around(with LOADS of hair pulling) where something SHOULD work, yet it doesn't.

    However, I don't think this is one of those things where I say it won't work, and it just might. This isn't so much a clash of theory and science, as much as it is a clash of purpose. What I mean, is that we are talking about getting, what - 500W TOPS out of this TEG system? That's a decent gain(maybe 3.4% increase in available power, assuming an average power usage of 20hp or 14.92kW), but at what cost? Even if you could get these TEGS at $1/Watt, that's a $500 investment for 3.4% gains...

    How long would that take to break even? Assuming you get 30MPG, and you drive 1200 miles a month, that's 40 gallons of gas. At $2.50 a gallon, that's $100 a month in gas. If you save 3.4% in gas due to the TEG, you'd be saving $3.40 a month. With the $500 investment, it would take over 12 YEARS to pay for it.

    Sometimes, you just have to do a little math and think things through. Richard, you're more than welcome to try it out, but you may save some time and money by focusing on some more lucrative ideas. It's your time/money, so it's not costing me anything, so I'm happy.

  4. #24
    Yeah, I think you're probably right on this one. It may need the technology to develop further before it is ready. A lot of stuff is like that, it just needs a bit more development before it's useful. I vaguely remember some new technology which took years before someone figured out a use for it. At least we have some use for this one if it becomes efficient enough.
    Personally, I still think it's putting out the fire after it's burnt the house down. I mean, it makes more sense to me if we can utilise the excess heat to expand water vapour inside the combustion chamber, as many seem to be having success with doing, via water injection systems.

  5. #25
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    Agreed!

    On a different topic... Buster, WHAT is your avatar a picture of? Maybe it's my dirty mind, but it LOOKS like a boxer with it's junk in it's mouth... or at least trying to get there. LOL

  6. #26
    It's of a stupid dog just about to bite it's own b####cks off.
    Very painful it looks too!! Definitely not recommended.

  7. #27
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    Talking

    Quote Originally Posted by HurstOlds View Post
    Richard, your second link in Post #5 of this thread is not set up correctly, can you please fix? Thanks
    here http://www.nextreme.com/pages/power_gen/power_gen.shtml
    sorry about that

  8. #28
    Join Date
    Apr 2010
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    Phil - My thermodynamics professor once told me that understanding units was the difference between an ME and an EE. I decided to get both. Richard has some fundamental flaws in some of his reasoning, but let me back up the TEG a bit (as I have a masters degree in Thermo acoustics, it's kind of my baby). The seebeck coefficient is in volts per Kelvin. So, using your example of S=.036, R=.35 and dT=200C (473K):

    V=.036v/k * 473K
    V= 17V not 4V (the unit advertises 15V)

    V=IR
    15V = .35I
    I = 43A (unit advertises 30A)

    P=IV
    P = 30A * 15V
    P = 450 W (unit advertises 289W)

    I think if you apply your maximum power transfer theorem, you will find they are pretty accurate in their advertisement.

  9. #29
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    I think if u attach the Tegs onto the headers u might beable to get a deferential great enough to use a simple radiator in computers

  10. #30
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    theegb,
    The voltage you are getting is based on the absolute temperature of only the hot side(right?). That would be accurate IF the cold side were near absolute zero... However, I was under the impression that the temperature we are interested in is the difference in temperatures of the hot and cold side. In the example, you don't have 473k difference - you only have 200k, which would yield about 7.2V OPEN CIRCUIT. That voltage, of course, drops off as you draw more and more current. The device can be modeled as a voltage source in series with the 0.35 ohm internal resistance. Granted, there are some discrepancies due to the non-linear seebeck coefficients over a broad range of temperatures, but they are fairly negligeable when compared to the differences in our calculations.

    In your power calculations, you multiplied the open circuit voltage and the short circuit current... That equation is meaningless because the open circuit voltage won't be the same voltage when you short circuit the device - it will be 0V.

    Now, using MY numbers:

    Open circuit voltage = 0.036V/K * 200K = 7.2V
    Using maximum power transfer theorem:
    Pmax = (V/2)^2/0.35 = ~37W

    I'm looking at the company website again, and I don't think the 289W is refering to output power... Since it's "Qc", it's refering to ACTUAL heat flowing through the TEG. That number should NOT be used in any kind of reference to the available power output, unless you are computing efficiency of the device. If this is the case, then the TEG is indeed fairly efficient at about 12.8%(37W/289W). Not TOO bad, but Richards idea about using it is still insanely stupid and worthy of the government giving him a disability check each month.

    Anyway, I stand by my calculations. This thing doesn't put out anywhere near 450W @ 200K difference in temperature.

    EDIT: That website is flakey... I've thought about it some more, and they are CLEARLY advertising these things to generate electricty, yet the numbers they give are not for generating juice, but instead, they are for creating a temp differential(i.e. using them to cool something like a CPU, etc.). Also, their pricing seems to be for very low volume customers(price break is for 10 units? Really???). That says they aren't interested in long term buyers, or volume buyers because those customers would see through their shady advertising. Shady, shady, shady... I wouldn't buy from them..........

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