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Unread 03-14-2009, 05:51 AM   #6
Cooling Savant
Join Date: Jun 2005
Location: Skokie, Illinois
Posts: 322
Default Re: Fairly Large Project: Oil+TEC Tank PC

Originally Posted by AkkerKid View Post
Hopefully, this image will clear the idea up some.

The reason people use TECs for cooling insn't because they are efficient at removing heat. Actually, they are very inefficient. In the example below, the TEC would actually be adding about 200 watts of heat.

The primary reason TECs are used for computer cooling is because they will operate at sub-ambient temperatures, not because they are better at removing heat than air or water cooling. Removing 100 watts of heat from 5 gallons of oil dissipates the same amount of energy whether the oil is at +50°c or -50°c. A TEC, a heat sink/fan or a water cooling system that will remove 100 watts of heat all remove tha same amount of heat, the TEC just does it at sub ambient temperatures. Both air and water cooling depend on the temperature differential between the hot side of what is being cooled and the ambient air temperature, and as such, can not cool to temperatures below the ambient air temperatures.

But, since the temperature of the cold side of a TEC depends on the amount of electrical power added to it (not the ambient air temperature), surface temperatures far below ambient are achievable. The penalty though, is that the added heat of the hot side of the TEC (in addition to the heat from whatever is being cooled) must also be dissipated.

In your application, having the surface of the cold side of the TEC at a sub ambient temperature serves no purpose. The surface of whatever you are cooling (the CPU I assume) can not be any cooler than the temperature of the oil, and the temperature of the oil can't be any lower than the ambient air temperature. If the oil was cooler than the ambient air temperature, the radiator would heat it up to ambient. If your goal is to increase the delta T (oil to air) across the radiator with a TEC, and thereby gain added efficiency, I think the net/net effect would be negative because, as I said, the TEC will add quite a bit more heat than it will be removing, and whatever gains you get from radiator efficiency will be more than offset by the added heat from the TEC that needs to be dissipated.

By the way, you have some amazing construction skills there.
Attached Images
File Type: jpg TEC 2.jpg (62.5 KB, 8 views)
File Type: jpg TEC 3.jpg (63.4 KB, 10 views)
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Last edited by billbartuska; 03-14-2009 at 06:36 AM.
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