cold plate material
 

i just had a question about using some 3/8" aluminum as a cold plate. would this be ok to use? i just have a ton of 2" by 3/8" by 10ft of it laying around and it would be a lot easier to cut a piece of that off, lap it, and use it as a cold plate.

Copper is slightly better but the alu is ok to use. And since you already got it at home go with it.

Just rememberd that Bill Adams at overclockers.com wrote a good article about coldplatematerials and thicknesses.
Here's a link for ya:
http://www.overclockers.com/articles305

wow....
thx dogfight for that article
here is a nice overview of cold plate materials:

The following are the thermal conductivity values (W/mK) used in the calculations:

Aluminum: 220
Copper: 388
Silver: 418
Silver/Copper (Cusil) Alloy: 515

so....being the cheap bastard that i am, ill still stick to using the aluminium i have. but i might want to make it thinner now after reading that article. maybe 1/8" is a little thin, but with a 226watt pelt and the fat ass water block im making, it doesnt seem too thin all of a sudden

Cusil thermal conductivity to be 371 W/m/K. not 515

Yeah the 515 was a big typo measured with inadaquate equipment. It was remeasured to be 371

Basically, its junk:shrug:

thanks for pointing that out. i had no idea about the new W/m/K number for CuSil. If anybody could post their source....

http://forums.procooling.com/vbb/sho...ighlight=CuSil

Theres a link for ya.

www.onlinemetals.com

Spend the $10 for a 1/4" plate of copper. You'll be very happy you did. It is criminal to use aluminum to save $10 on one of the most important and critical areas of a cooling system. Be warned, you'll have to lap what you get from these guys. You can get your plates cut to any size/thickness you want, so it's worth a look, at least.

that onlinemetals place is great. but a little over 7 bucks for a chunk of copper? eh...ill see if a local machine shop has a piece they can give me or something. i also tried doing it as a 3 inch piece of 2.5" X 1/4" flat bar and got it down to $3.50 this seem alright, but i probly would have got killed in shipping....

its a nice site for people who dont have access to a machine shop or sheet metal shop, but ill just take my chances.

another idea i had was to get some thick copper (~2" thick by 2" X 3") and mill it out and put the pelt in there and directly water cool it. just a thought, if that makes sense to anybody.

Directly cooling a peltier unit can't be a good idea. Plus, where are the leads going to be coming out from. I hope you do a good job sealing it, and I hope your leads don't corrode (plus, you'll be shorting the shit out of it due to your coolant ... do you feel lucky?). You'll hate yourself for trying. Believe me. [Edit: the leads are exposed where they go into the pelt ... current would short between the leads through the coolant and would demolish your powersupply and other components attached to it ... even if that didn't happen and the leads didn't corrode, it would create a battery effect in your coolant due to the fact that the leads aren't copper ... translation: any way around it, you're screwed]

As far as online metals go, what I like is that you're getting the real deal. They guarantee their metal's content ... from most scrap dealers you don't know what you're getting. Pure copper is better than any mixture/alloy. $10 for a near-pure copper coldplate that needs nothing but lapping is a good deal, by my reckoning.

As well as any problems due to shorting and corrosion mentioned by airspirit above, there is one huge fundamental flaw with that design. The peltier is going to be chilling the whole block down to sub zero. In effect the block will be sucking energy out of the coolant, drawing out round to the cold side of the pelt and then pumping it straight back in again.

Now as it is, pelts run at around 5-8% efficiency and this is gonna make it a lot worse.

The idea with having a seperate cold plate is to insulate it so that the only energy the peltier can pump is coming from the core itself.