Peltier questions

Hi,

I did a search but most results were concerned with cooling. The fan on this website uses a Peltier set up to run a motor.

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At $125 it seems a little excessive in cost. I have found a 50W Peltier for $15 and am now wondering what would be involved in make a few of these for my home.

I live off the grid by the way and have 550W of solar and 450W of wind so anything I can get that offers relatively free power to move heat will be a great help.

Thanks in advance.

Dave

Reply to
Dave, I can't do that
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====================================== Just get a brushless dc fan that uses about the same current the module puts out and you are cool.

Reply to
BobG

My mother has one of those. They're OK, but rather overpriced. I have a suspicion you'd be better off with a little 12V electric fan (or whatever voltage your system is) and spending the money on expanding the PV system -- the energy conversion that fan does is *very* inefficient.

Their web page claims that "your computer is using a Peltier chip," which is probably only true in about 1 PC in 1000? Peltier CPU cools are readily available, but not commercially popular due to the price (you mainly see the overclocking guys using them).

I also like their phrase, "passive electric source," which is rather oxymoronic!

Out of curiosity, where are you located?

Reply to
Joel Kolstad

Peltiers are very very very inefficient, not to mention expensive. There is no way a Peltier can ever generate enough electricity to equal the energy it took to create it, so they're net money and energy burners.

As an example, most refrigerators have an EER of at least 15. That means they can pump 15 watts for each watt of electricity. The EER of a Peltier is quite a bit below 1. You have to burn up over one watt of good electricity to move one watt of dumb heat. Plus you end up with TWO watts of dumb heat. Not a good tradeoff.

That's why you see all those Peltier six-pack coolers in all the glossy Sky-mall and "Sharper Image" and Parade magazine ads-- you can only sell them to the "oooh-look-at-all-them-purty-pitchers!" demographic.

Reply to
Ancient_Hacker

Thanks AH and Joel,

I wasn't sure where the Peltier was in the scheme of efficiency. I guess I will pass.

Appreciate the help.

Dave

Ancient_Hacker wrote:

Reply to
Dave, I can't do that

Note that the 50 watt rating is for a ZERO DEGREE drop across the module.

Peltier modules are TOTALLY USELESS at higher power levels because the RISE between their heatsink and ambient EXCEEDS their cooling delta-T.

Forced water cooled heatsinks are pretty much manditory for any higher level use.

See

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Peltier apps above about two watts range from disappointing to totally worthless.

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Many thanks,

Don Lancaster                          voice phone: (928)428-4073
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Reply to
Don Lancaster

=========================================== Wait a minute... they are crappy at converting electricity to heat and cool, but you have plenty of heat and want to create electricity, So what if they are crappy at converting heat to electricity, if you have lots of heat?

Reply to
BobG

I liked the use of high-current tunnel diodes to convert the electricity from a thermocouple in a boiler to AC and then transform to some useful voltage....

Probably better to use just the right material to allow high temperature and pressure.

Thomas

Reply to
Zak

In practice, a Peltier will provide about 1/3 or at most 1/2 of the rated cooling power. So for a 50 W Peltier, around 20-ish Watts.

Mark

Reply to
redbelly

That is 20 watts to the HOT SIDE of the Heatsink.

Typically, the Heatsink RISE will EXCEED the Peltier drop, for net heating.

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Many thanks,

Don Lancaster                          voice phone: (928)428-4073
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Reply to
Don Lancaster

EER = BTU/HR per Watt

Reply to
bogax

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