Thermo electric cooler for laptops

Anyone make such a beast. Not necessarily USB powered. For use with really high powered laptops that are usually run on AC.

 

Not likely. You're talking a Peltier cooler, and the problem with them is that they make one side really hot while making the other side cold. Given that the device is going to have to be on the bottom, you're going to need to use more fans (a peltier isn't that efficient... it puts off a lot more heat than it transfers) and a lot larger heatsink, raising the laptop significantly off the surface.

If you're going to be spending money on something that doesn't move, you should be buying a desktop and getting much more performance for your money.

 

I understand their principle but since they are used in portable coolers and in automobiles, some engineer should be able to produce one. Thanks for the input though.

 

I am sure they can produce one, and I am aware that it is possible to use them for desktops in conjunction with a heat sink. But whether or not (right now) it will be more efficient (and cost effective) than the conventional forced convection cooling in your notebook is another question.

 

Pelt's generally do put out more heat then they transfer, but that's not always true. If you "undervolt" a good one and keep it cool enough, you can exceed a COP of 1.

 

That violates the second law of thermodynamics. It uses energy, it's not a superconductor, so it has to put out more heat than it absorbs on the cold side. There is no way to get even close to a 100% efficient peltier, no matter what anyone else tells you

 

No, you don't understand. He is saying that it can transfer more heat from one side to the other than the energy it takes to run it, which is perfectly reasonable. It is still putting out more heat on the hot side than it is removing from the cold side. I think it was that your "put out more heat than they transfer" statement was a little ambiguous.

 

Ahh. So over 50% efficient. Which isn't saying much. It's still twice the heat needing dissipating than if you just ran a fan over the notebook, so you need twice the heatsink area, and so on.

 

I agree that it is a really dumb idea. Nobody even does this on the desktop anymore since there are way better options for cooling.

 

I hope you know you're talking to the guy who was at the top of his class in Thermo I and Thermo II for mech. engineers, out of ~50 students.

Seriously, though, I believe I have seen Pelts exceed a COP of 2 even. Evaluating efficiency is a little more complicated then that. A Pelt with a delta T of 35°F and a COP of 1.1 would still be pretty inefficient from a thermodynamic POV.

 

And I've got an Engineering minor tacked on to my Math/CS degree. From a purely engineering university.

The fact remains that a Peltier cooler is around 5% as efficient as a perfect Carnot engine. A refrigeration compressor is around 45%. A Pelt is NOT an efficient way to move heat. They are effective, but they need a huge heatsink to operate properly, and as soon as "notebook" enters the equation the game is over. It'd be better to speculate about converting a six-pack fridge to cool a notebook.

 

in order for these coolers to really be effective, they need to be in direct contact with the heat source...

your laptop's heat source is connected to a HSF unit that's already built in, then there's a section of air, then your cooling unit...

so, in essence, the TEC unit will, at BEST, cool the air that can be ducted onto your laptop's intake...
or, you can mod and permanently fix the TEC unit onto your laptop... and the radiator/pump units have to stay connected and via tubes... cumbersome?

so, in light of this, why not just go to home depot, buy a vaccuum cleaner tube or equivalent, and duct it to your desk from the AC unit?

cheaper, no?

 

I won't tell them that you don't know how the calculate the efficiency of a refrigeraton cycle, then.
I see you can paraphrase Wikipedia, though.

Anyways, prodding aside, you're generally right. TECs are going to not work for this app. To get decent COP's you have to stack TECs, and to get a COP of 2-3 you need to keep temp differentials below 10°C - absurd. The only way to cool to a decent level below ambient is to have stacked cooling loops.

 

/facepalm...

 

Surprised it hasn't been mentioned yet, but there's a very good reason Peltiers were briefly hobbied, then dropped entirely - they cause very bad condensation on the cool side. Condensation = bad. Even if it's somehow isolated to the exterior of the laptop casing, I foresee mold problems abound.