Peltier Sandwich

Dreaz

[H]ard|Gawd
Joined
Aug 30, 2004
Messages
1,656
I was reading on some other forums and wanted to know what the general consensus here was on sandwiching a waterblock between two pelts to cool down the water in a water cooling setup.

Assume you do this right after the rad(thus the water has lost most of its heat, since a rad can only cool to ambient).

Assume you use two 80W pelts that only use up 8amps and will run at 75% efficiency on a 12V line.

And then you put a pelt on the top and on the bottom of a waterblock like this

http://www.frozencpu.com/cgi-bin/fr.../ex-blc-37.html

so the water travels through it and gets cooled down, comes out, and goes to the cpu parts.

What are your thoughts? I was wondering if one 172W pelt on a 12V line would be better, but I thought two pelts would increase surface area and cool it better.

Of course you'll need to throw a heatsink/fan on each of the 80W pelts but a heatsink/fan can cool an 80W pelt@75%(even at 100%).

How would you stick a pelt on both sides? Would stacking two 80W pelts be better?

Feedback appreciated. Thanks.
 
three quick things. Firstly your link doesnt work cause its been cut, can tell by the '.....' in the address. Secondly, you'd have to deal with condensation problems on the tubing and waterblocks if it got below room temp, which is what your trying to do.

Lastly, it might be dangerous and impractical and probably wouldnt do much but hey? It'd be mad fun to see what happens, try it out with a shite computer, and if you do, tell us the results :)
 
Using both a radiator and pelts to cool the water in the same loop doesn't work. If you have above ambient water temps, then the pelts are wasting energy doing work that a bigger rad could do better. If the water is below ambient, then the radiator will be absorbing heat from the air which is counterproductive.

So, pelt chiller...Swiftech makes a decent one, the MCW-CHILL 452. If want to make your own, you'll get better results the more pelts you use and the bigger they are. Even if you don't want absurdly low temperatures, using more and bigger pelts will be more energy efficient. Water cooling the hots side will work better than air, but if you use plenty of pelts to distribute the heat to more and bigger heatsink, air is feasible.

How much time/money/tools/creativity do you have to work with?
 
sorry about that link

http://www.frozencpu.com/cgi-bin/frozencpu/ex-blc-37.html

Yeah, I've seen the swiftech one but it's $300+! I figured if I made my own I could cut it in at least half if not more.

I know i'd have to deal with condensation. I can look up how to do that later.

I was figuring using the 80W TECs 'cause I could throw two on one 12V line and still have plenty of amps for the PSU to handle. Plus I can air cool 80W TECs with a simple heatsink/fan.

And I get what you're saying about it being counterproductive. A rad can only cool to room temp and if I cool the water below that and it is still below that by the time it reaches the rad then the rad will just be heating it up. If that is the case, then I suppose I could always throw in a very small rad or no rad at all, but I doubt this little mod will be able to handle all that.

If anyone has any ideas about blocks to use or whatever I'm all ears. Or even different TECs, though I think the 80W are best for what I'm doing. Anything higher and air cooling will simply choke under all the heat and I'll have a fuckin' fireball on that WB =)

Ideally, I want a block with two flat surfaces(top and bottom) to attach the pelts too and then a MAZE inside to keep the water in there as much as possible.
 
A rad can only cool to room temp and if I cool the water below that and it is still below that by the time it reaches the rad then the rad will just be heating it up.
I'm thinking that you don't realize how little the temperature of the coolant varies as it flows around the loop. Think a few tenths of a degree C between the hottest and coolest part of the loop.

The Maze4-GPU you linked to would be fine with one pelt, but the aluminum top would give crappy results if you tried to sandwich the block between two pelts. If you want sandwich, you'll pretty much have to make you own.

A pair of 80 W pelts will struggle to keep up with a CPU, especially if you only have heatsinks on the hot side. If you run a pair of 226's at 5V you'd get more cooling for less electricity and heat.

What's you goal? Looks? Fun? 1° C water? -30° C antifreeze?
 
goal is to not spend too much money, run the pelts on an unmodded PSU(enermax 350W just modded so it turns on without a mobo), and to achieve a noticeable differnece in my water's temp. If you think I can only get 1C diff then I wont even bother. At the least I'm hoping for 10C difference. That swiftech chiller thing can get like 30+C difference but I don't need all that.

How about attaching a pelt to a rad thus cooling the rad to cool the water? I might consider running a 226W off the 5v wire depending on how I could do this. I saw one mod that let me make the 12V line a 24V line but that required me not pluggint the PSU into the ground part of the wall socket and I'm iffy on that(unless someone can convince me otherwise)

plus I figured two 80W pelts would increase surface area of cooling.

I'm just trying to find a way to make my W/C setup unique and not just another W/C comp =)
 
10° C better would almost certainly put your water below ambient, so the rad needs to be off the cooling loop. With a pair of 226's running at 5 or 6 volts with good heatsinks, you could just about do it. A pair of 80s at 12V would be less efficient, and would probably need to to have the hot sides water cooled to make a 10° improvement.

Do you have the tools to make a simple water block? Electric drill or drill press, hacksaw or bandsaw, Dremel or other rotary tool, propane torch and soldering supplies, miscellaneous files/punches/etc.?
 
I have a dremmel.

So you think runnin' 2 226s at 5 volts would be better? How would I go about making them run at 5V? It would put the 226s at 120W capacity but then there's one problem with two 226s; i'll need two power supplies.

I have my enermax
http://www.newegg.com/app/ViewProductDesc.asp?description=17-103-455&depa=0

but only has 26A on the 12V line and 32 on the 5V.

Either way, two power two 24Amp TECs I'm gonna need two psu.

As for the heatsinks, you think they can handle 120W of heat? I mean are you talking about buying like two SLK900as(20 bucks a pop) and throwing those bigasses on it?

I'm very interested in that 226W pelt on the 5v line, since then if I ever need better cooling I have it...plus it does sound better.

And once I decide this I'm going to have to look up how to make waterblocks, materials, attachments, etc i need to make 'em and then designs.

This just keeps sounding better and better ;)
 
As you decrease the voltage applies to a pelt, it draws less current. Give it half the voltage, and it uses half the current. So at 5V the typical 226 would draw a little less than 8 amps, or 16 A for the pair. Or you could hook them in series on the 12 V lines so that each was getting 6V, that would draw around 9.5 amps for the pair. No problem for your PSU either way. :)

SLK900a's are a good size, but the base of them is too small. It won't completely cover the pelt. And if you can get heatsinks that use the four hole bolt mounting, that would make assembling the chiller a lot easier.
 
HeThatKnows, you're a life saver.

Ok, so if I ran them in a series it would draw equally? I woulda thought that the first device would grab as much as it could and then the leftovers go to the second, but I know shit about PSU units anyway.

Here is my design for now

peltwich.jpg



And all the heatsinks with that 4 hole mounting are not on the cheap....like close to 40 is the cheapest after shipping

this lil device is going to be 80 for heatsinks, 80 for pelts, and then whatever the waterblock is :mad:

the hard drive waterblocks give me great surface area, only problem is they got some stupid crap on their outsides and aren't made of copper.

this one little part is looking to be 200-250 dollars....but at least it'll be unique ;)
 
ya know, I should just grab this puppy and fool around with it

http://www.frozencpu.com/cgi-bin/frozencpu/ex-blc-106.html?id=ZRJCzJEY


either flip the wires so the cold/hot side are reversed(thus water getting cool) or just place it directly on the cpu....

and it's only 150...heh, only huge problem would be cooling 360W on the TEC hot side ;)

even a thermalright wont handle that...I could throw it on the 5v and then its only 120W or I can throw it on the 12V and get 288W out of it

I dunno, its just that I could cool the cpu with it but then my grakka and NB don't get the same lovin'

sigh, well it's a good thing I have a bit to think about all this.
 
Now you know why Swiftech can get 300 bucks for their chiller. :D

I like the 360 W pelt in that Dominator block, the waterblock itself is kinda lame with the four barbs. A half dozen of those pelts would make for some serious chilling.
 
If you want to use air cooled peltiers to cool water then This is probably the best design.
Your design is the best for water cooled peltiers.

Luck.......... :D
u=Tigerbiten.gif
 
Hmmmmm some Questions.

the MCW-CHILL 452 looks like a very interesting water chilling solution. It looks as though I would have to install a second water circuit in order to utilize the TEC water chiller.

new circuit: (requires new plumbing, extra cost: second pump, 24V worth of Auxillary Power)


TEC chilled water circuit

<--blocks--<
v . . . . . . .|
| . pump1. ^ . . (H20 sub ambient)
>--->-->->-^
TEC Xchngr
|-<--<--<--|
| .pump2 ^ . . .(H20 @ ambient)
v . . . . . . |
Conventional radiator


Why not go for a commericially available 1/4Hp water chiller unit, which utilizes Phaze Change methods to chill the water?
this unit will replace existing pump and radiator.
no additional costs.

plus, the circuit is much simpler and more elegant with a conventional water chiller.
K.I.S.S. less things to go wrong IMO
 
okay, so you already have a water loop, or are going to create one... why not just put the pelt on the CPU? why waste time and money? the pelt on the cpu directly will provide better performance and cost either less or the same.
 
mwarps said:
okay, so you already have a water loop, or are going to create one... why not just put the pelt on the CPU? why waste time and money? the pelt on the cpu directly will provide better performance and cost either less or the same.



yes actually I agree. I don't have my Heat Transfer Textbook in this office so I can't give you numbers... but typically, the heat xfr coefficient (q) between two metals separated by aluminum thermal conductor paste is much better than that between metal-to-water-back to metal.

since it's being used for chilling water, there are better ways.

Personally I believe that TEC is a black art, along with witchcraft etc. ...you still have to so something with the thermal energy.. you're just moving it from one place to the next.

Is TEC that good? Assuming you're getting it ambient temperature water?
 
I saw some results and that sandwich thing doesn't work so well. I just wanted it as an alternative form of water chilling and wanted loving going to my grakka and NB.

after pricing it all, I decided it'd be best just to get the Dominator TEC/WB combo for my CPU only and the rest water.
 
It's more efficient to just use a metal block and put the peltier directly on the cpu. Cooling water is expensive energy wise.
 
you can use any powersupply for 12v all you have to do is borrow some amps from the 5v line. its not hard to do. you can run 2 225w tecs from 2 350w psu's if you do it this way. you will want to use both ground plugs on the line from the power suply to the ground on the pelt.
red wire: 5v | black wire: ground | black wire: ground | yellow wire: 12v..... note 2 grounds use both of them if you do this!!! you will have to connect the 12v line to + on the pelt and the 5v line to a limmiting resistor or a variable pot and then to the + on the pelt.... then connect both grounds to the - side of the pelt. if you use the variable resistor you will have controll over temp to some extent. ;)
 
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