Tell me more about peltiers

[metroplex]

I just bought a compact dehumidifier and it turns out that it's nothing more than a large peltier unit with a 90x90 CPU fan. It seems to draw out about 4 oz of water per 12 hours, which isn't too shabby for a 95W unit.

It got me thinking, why could I not develop an even larger peltier based dehumidifier with a quieter 120x120 fan? Or multiple units for that matter.

 

[BonzaiDuck]

Are you interested in building a dehumidifier, or cooling a CPU?

 

[metroplex]

Both actually.

 

[BonzaiDuck]

I'm going on the seat-of-the-pants common-sense here, but I've read white papers explaining why TEC cooling is no longer feasible for Intel P4 and higher and AMD processors with the same thermal power.

The CPUs and CPU caps have been getting smaller -- the die-size is getting smaller. TEC coolers with a certain areal size (square cm or mm) only remove so much thermal energy per unit of time. To remove more, takes greater and greater power in watts, which in turn generates more and more waste thermal energy. So there is a limit of feasibility.

It seemed to me that if you were willing to settle for the additional power consumption, multiple TECs could be used to build a water chiller or cool a water reservoir. Or less effectively, create an insulated refrigerator chamber around mobo, CPU and heatsink.

I'm just speculating about this. I'm sure much of what we have here includes "speculation."

 

[mindwreck]

like what bonzai duck said... using a TEC on modern cpus just doesn't work too well. TECs are mainly used as water chillers and sometimes people mount them on machined blocks of alu or copper instead of straping it directly to the cpu.

 

[H0witzer]

Peltiers have advantages and drawbacks, most people find the drawbacks too much to deal with. The biggest is the heat output. You need to draw the heat away from the HOT side. If you do not draw enough heat away, then the hot side will actually heat the cool side and fry your CPU.

The only practical way to cool a Peltier properly on a CPU is with a water cooled system and one which has a large enough capacity to adsorb the heat from the Peltier and then be able to release it efficiently.

Another thing to keep in mind is how Peltiers are labelled. A 176W Peltier is rated at being able to draw 176W of heat. So your Peltier must be matched to your CPU properly or you will once again fry it if it isn't strong enough. If you cool it too much then your temperatures will drop well below ambiant temperatures and depending on your dew point you will get condensation. The only way to deal with the condensation is to seal the CPU and effected areas usually in neoprene or some other insulating type foam, some people also use dielectric grease etc.

Also as stated if you are planning on mounting it to the CPU then be prepared to have a custom milled Copper block to mount properly. I am currently in the beginning process of doing just that.

Hope that helps.