Peltier Calculations - Am I mistaken?

Posted elsewhere - http://forums.procooling.com/vbb/showthread.php?s=&threadid=5200

"I am not actively engaged in playing with Peltiers at the moment.
However my currently favored Kryotherm parameters may interest :-
Rc=0.19 - 0.26 (for 40x40x6 mm Cold plate with a 10x10mm heatsource)
Based on:
1) C/W(TIM,Die/coldplate) ~0.1 - from Bill Adams work(e.g http://www.overclockers.com/articles654/index02.asp ) ,making an allowance of 0.05c/w for die thermocouple offset.
2) C/W(Coldplate) ~ 0.09 to ~ 0.16 -- from Waterloo calculations using,possibly mistakenly, an h=10,000 - 100,000W/m*m*c as corresponding to the conditions for a 172W Pelt cooled by a wb with a C/W=0.00625 - 0.0625(cooling a 40x40mm heat source).

Ri=1
Based on my current attemps to cross-correlate Bill Adams data with CPU(Diode)/"Radiate calculated Watts"

All are very iffy and only the thoughts of a dilettante."

Have you seen any data giving h (film coefficient) for turbulent flows? I found an equation for laminar flow but I presume it's fairly irrelevant in the situation we're discussing.

Maybe I'm interpreting your suggestions wrong, but wouldn't you want to make h infinite (taking fluid flow out of the picture) for the coldplate between the CPU and pelt?

The more I play around with the Waterloo simulators, the more convinced I am, that I don't know how to use them.

In any case, I opened my big mouth and told someone I would do some die simulator comparison testing of Shin-Etsu G-751 paste and AS3 if I was sent a tube of G-751. JoeC took me up on it. Darn him.

I'm going to build a 40mm X 80mm heatsource and use that to do some testing. I should be able to get some reasonably useful data, on Maze2-2 hotside performance. (Though certainly not to Bill's standards.) I'll probably be pushing 200-300 Watts through it, so although I can only measure temps to 0.1C, the high power will yield fair resolution on measurements. It's doubtful that I'll know the flowrate through the block, but I can probably get a pressure differential measurement. In the unlikely event that Bill runs a Maze2 through his testing, it should be possible to correlate, the pressure drop I measure, to a flowrate.

I don't have a Maze 2 coldplate otherwise I could do some testing on it too. I'd have to test "backwards" though:

40mm X 80mm heatsource ->
Maze2-2 Coldplate ->
10mm X 10mm X 3mm "die" with embedded thermocouple ->
White Water block with icewater pumped through it.

Since87 said:

1)Have you seen any data giving h (film coefficient) for turbulent flows? I found an equation for laminar flow but I presume it's fairly irrelevant in the situation we're discussing.

2)Maybe I'm interpreting your suggestions wrong, but wouldn't you want to make h infinite (taking fluid flow out of the picture) for the coldplate between the CPU and pelt?

3)The more I play around with the Waterloo simulators, the more convinced I am, that I don't know how to use them.

4)In any case, I opened my big mouth and told someone I would do some die simulator comparison testing of Shin-Etsu G-751 paste and AS3 if I was sent a tube of G-751. JoeC took me up on it. Darn him.

I'm going to build a 40mm X 80mm heatsource and use that to do some testing. I should be able to get some reasonably useful data, on Maze2-2 hotside performance. (Though certainly not to Bill's standards.) I'll probably be pushing 200-300 Watts through it, so although I can only measure temps to 0.1C, the high power will yield fair resolution on measurements. It's doubtful that I'll know the flowrate through the block, but I can probably get a pressure differential measurement. In the unlikely event that Bill runs a Maze2 through his testing, it should be possible to correlate, the pressure drop I measure, to a flowrate.

I don't have a Maze 2 coldplate otherwise I could do some testing on it too. I'd have to test "backwards" though:

40mm X 80mm heatsource ->
Maze2-2 Coldplate ->
10mm X 10mm X 3mm "die" with embedded thermocouple ->
White Water block with icewater pumped through it.

Click to expand...

1) There are several scattered about (e.g http://www.aps.anl.gov/asd/me/ ),but I usually use the "inbuilt" progams in Kryotherm for rectangluar channels.(eg http://www.jr001b4751.pwp.blueyonder.co.uk/LesD7.jpg )
2)Dunno, that is the question.However h=1e+16 still gives a spreading resistance of 0.0777 C/W.
3) Am also struggling.
4) Good luck

Les56 are you the same "Les" of hardforums?

Now think I am wrong:
http://forums.procooling.com/vbb/showthread.php?t=9570&page=3&pp

Did pm RonnieG

Hmm, I'm going to move this towards cooling. Too bad -- if we still had a technical discussion forum, I'd move it there ... I guess I'll send this to extreme cooling and leave a redirect. Good luck! -- Paul