Cold Electricity?

[suneel112]

This is all complicated stuff, and I heard something to that extent of electron cooling. I though for a split second that it would work well, but then I remembered P=IV, and that a metal will dissipate heat. For the frat boys, a better solution is to have a camoflaged refrigerator to house the keg (ie, a desk with a "computer bench", a false floor, a bed/refrigerator, or just (because they will most probably be up north) in the ground at the frat building. My 2cents

[Dan Richardson]

Thermo Electric Modules ( Pell Cells ) are pretty neat but are really only very useful in certain applications, and have to be designed specifically for it.

A Thermo Electric Module in ideal conditions ( with correct voltage amperage blah blah blah ) will be roughly 40 degrees centigrade cooler than the hot side. Now of course this is what it should be but there are many x factors that can bring this down. ( Ie fluxuation in voltage and not properly connected ) Which makes it useful, but usually only in certain applications, because you typically need to try to keep the hot side cool . The cooler the hotside, the cooler the cold obviously.

Another thing is that a thermo electric module can only peak about about 140 btu's of cooling,which is somewhat a small amount, if you consider 1lb of ice has 143.3 btus of stored cooling energy in it, And then it takes a .48 btu's to raise it each degree F which I believe is close to about 1btu per degree c.

But for this application acting as a chiller with not too much other involvement if your boys want to use thermo electric modules just to chill it should work well atleast well enough. As long as they design the packaging correctly and make sure that none of the dispensed heat re-enters the cooling package and dispensed into the atmospher then your ambient temperature could actually do the cooling. I mean your not asking for the thermo electric modules to cool the liquid .. just to keep it cold. Again it could perform fine if designed correctly. Plus, for as long as it would keep it cold, it prob. would be killed off before the effects of the chiller began to digress :-P.

Main problem with most heat sink designs is lack of common sense and double checking things. People fly by with the calculations then design things that completely screw up everything they already figured out. Of course it happens in all kinds of engineering.. but you see it soo much commercial style heatsink product.

As for FIRST applications of thermo electric modules, i doubt you'll see them incorporated. One they drain more battery life, 2 they are hard to adapt to the units you'll need them on. The work put into them and the benefit produced is likely to be in great disfavor. I tends to work better if you are worried about cooling a motor by more effecient power management and maybe bonded fins with a muffin fan. We had custom designed heatsinks by the heatsink company I work for now ( as a psuedo intern/lab rat ) and the amount of work put into them/ over benefit recieved was very disfavorable. So its all where you find your nitch as far as FIRST goes.

Dan

[Sparks333]

I got a few things to say...
As an overclocking advocate and avid cooling freak, I need to put in my two cents about peltiers.
One: They are not very controllable. Adjusting the voltage or current does NOT adjust the heat difference. You must remeber, the peltier is always working to keep those two sides at an exact temp away from each other. (I heard 20 degrees C, but I guess 40 isn't unthinkable) By adjusting the voltage or current to a peltier, you start preventing the unit from keeping those sides at different temps. Simply put, you cannot adjust the amount between the hot side and the cold side, but you can adjust its ability to keep the hot side and cold side different. A slight difference, but important nonetheless.
Two: Battery life. These things drain current like no other. I have had one pull 15 amps out of a battery, and that was a small, low powered one. If you were to keep that up constantly, you may blow one of your fuses on the robot or maybe even run the battery down. Keep in mind that even though some motors drain at 40 amps, that's typically not a continuous measure. It spikes at 40 amps. A peltier stays at a high number all the time.
Three: This may sound like a mundane problem, but one thing a peltier causes a lot of is CONDENSATION, the bane of electronics. CPU coolers typically use copious amounts of thermal paste or neoprene to block off airflow, but nothing is for sure. When you turn it on, stuff freezes on it. When it's off, it melts back into water and frys what you are trying to cool. Bad.
Four: Stud Man Dan is absoultely correct in his post. A peltier is not so much a cooler as a, as many overclocking sites refer to it as, a heat pump, so it may be farther away from the component being cooled, but you still have the heat to deal with. People often do water or phase-change cooling on peltiers to get the drop in temp, but it often is hard and complex. Not the kind of thing you want on a robust machine that is going to get pummeled by two robots that are about 130 lbs each. (three, if your teammate is really mean!)

That's my 2 cents. Peltiers are cool, but rather complex. Try putting a heat sink on your component. Even better, connect a block of aluminum to your component and the other end to the chassis. Don't use peltiers.

Sparks