Cooling a water-reservoir

I was thinking of a 56W TEC, rated @15,7v. I'd be running it @12v, so it should be 43W. That PEP66T should be good enough to cool it down, with 80mm thermocontrolled fan sucking or blowing.

I read that article, it's not for me... Besides, I'd have to order abroad, which is not a thing I'll do easily.

That picture I drew up is from the side, so there would be 4 coils. I think I'll put 2 coils for the water that comes from the cpu & the rest 2 for the water that goes to the cpu. That TEC would be just before the output to the cpu, so it should cool the water down atleast few degrees.

The sad thing is that I'm still waiting for the kit to arrive. I'll start making some serious drawings when I get the kit. It SHOULD come today or tomorrow... We'll see about that.

Thanks.

Sticking the two 60W peltiers on the side of the resevoir would work perfectly. Well, I'm lying. They would cool the water just fine, BUT, they MAY cool the metal casing below ambient, and cause condensation. Especially when you first turn on the system, because the water wouldn't have had a chance to do any warming up yet(if there was any warming up to do). Anyway, just my two cents...I think the pelts would work fine.

Condensation wouldn't be a problem, because the reservoir will be under the case, outside. Maybe this'll explain it a bit better: 4 coils, 2 atop each other, with the TEC in between. Oh heck, I'll draw a picture.. Done.
It's from above. The gray area would be the TEC. I haven't figured out how to put the output to the cpu yet.

Any suggestions?

Thanks.

Here's an idea that's just so stupid, it's probably kinda dumb. But it might work.

Ever see those "ice packs" that are some supercooled gel thing? Suppose you could take those copper coils that are outside of your resivoir, and enclose them in a box filled with that gel from those ice packs, then stick a pelt on the outside wall of the box?

Here's a drawing. Don't laugh. I'm better with pencil and paper.

you would want the copper pipe to be coiled INSIDE the resevoir, and have the TEC(s) flush against the resevoir. Then have the end of the coil exit into the resevoir.

Thanks Wa11y & Spewn!

I'll have to do some searching around the local shops to find that gel. Might be a nice idea.

I'll be having those coils outside, atleast. They'll be getting some cool air with 4 thermocontrolled 80mm fans.
I just might coil them inside the reservoir too.

Oh, that white area in my superiously artistic and well drawn picture is the PEP66T. It gets also one of those 80mm thermocontrolled fans.

That gel raises few questions, tho. How does it like the temperatures? Does it dry? What does it cost?

This'll be an expensive endeavor... I'll propably go broke, but so what.

Almost forgot, little changes... I'll be ditching the waterlevel meter, it's not very useful. I'll put in a flow-indicator instead.

You wouldn't necessarily want to use ice pack gel. The only reason ice packs have gel in them is so they'll be flexible as they thaw. You should look into different materials that require less energy to change temp. I know alcohol is one, so using alcohol in that chamber might work well. The reason why you want something that requires less energy to change temp is because the peltier's are going to be transferring energy out at a certain rate. The faster this can cool the substance down, the higher the temperature difference between the copper coils and the cooling substance will be, and the more efficient the energy transfer will be.

The only problem with using alcohol is that because it cools at a lower temp, it also evaporates at a lower temp. I suggested that ice pack gel because it doesn't seem to evaporate, and keeps cold for a pretty long time. But that was just something I came up with at work, while I was bored. I don't actually know how it would work, and haven't done any testing or anything. It just seemed like a good idea.

And those ice packs shouldn't be too expensive, Asmodean. I think they're about $2 each, and I don't think it'll take more than two. Again, just guesses. But if you do decide to go with it, let me know how it works. It's always good to find out that some weird idea that pops into your head is a good idea. As rare as that is.

I definitely will try the icepacks, if they're that cheap. Just remembered, they're available at sports stores.

Sports stores, WalMart, anywhere that sells medical supplies for home use.

Wa11y (Jun 01, 2001 08:27 a.m.):
The only problem with using alcohol is that because it cools at a lower temp, it also evaporates at a lower temp. I suggested that ice pack gel because it doesn't seem to evaporate, and keeps cold for a pretty long time. But that was just something I came up with at work, while I was bored. I don't actually know how it would work, and haven't done any testing or anything. It just seemed like a good idea.

And those ice packs shouldn't be too expensive, Asmodean. I think they're about $2 each, and I don't think it'll take more than two. Again, just guesses. But if you do decide to go with it, let me know how it works. It's always good to find out that some weird idea that pops into your head is a good idea. As rare as that is.

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You wouldn't want this stuff exposed to the air, so the evaporation of the alcohol wouldn't be an issue. You'd want it sealed in a box so that less heat would be absorbed from the air.

Another note, the fact that icepacks stay cold for longer just means that either A) they're bad at absorbing heat, which isn't what you want here. Or B) they take more energy to warm up, which also isn't what you want here(since you want the peltiers to be able to easily cool the substance down).

The gel pac won't work as it will not transfer the "cold" from the peltier to the reservoir (no convection current, only conduction), they are designed to hold more latent heat than just water and that is why they stay colder longer. You need to get the cold side to pull the heat from the reservoir as quickly as possible - the copper tubes/pipes need to be inside of the reservoir in contact with your coolant so that convection and conduction can cool the water more efficiently.

Your 50 watt peltier will be putting out about 100 watts of heat (approx). 50w from the reservoir and 50w it generates itself because of the current flowing through the peltiers resistance. Just slapping a heatsink on it is not going to work, you are going to need a good sized fan to accomplish the task - if you don't get rid of the heat you'll just end up heating the coolant rather than cooling it and I doubt that is the effect you are looking for.

In essence you are trying to build an intercooler that is cooled with air rather than a liquid coolant, you'll need a much bigger heatsink to accomplish the task. A radiator is the most efficient at removing heat from your coolant as it has a large surface area, if you can fit a old automobile heater core in the comp with say a 120mm fan running on 7v and the peltier on the cpu I think you will have better results than the way you are trying to do it now.

If you want an aesthetically acceptable evaporative cooling system how about a nice indoor table fountain? If you have enough surface area then the water in the fountain could be used to cool your cpu. It would also mask the sound of any case fans you have running. Or, you could put a coil of copper tubing into the fountains' reservoir and then pass your computers coolant through it (indirect cooling).

surlyjoe (May 19, 2001 07:08 a.m.):
more watts than you think youll need, a good radiator will keep you about ambient , using a chiller and a rad is kind of iffy , cause the water always returns to ambient when it goes through the rad. as far as the coils

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Only if the rad is after the resevoir. Put the radiator after the block, get the water near ambient, then send it to a resevoir where the extra cooling would occur.

There's been some changes to the plans... I took the measurements yesterday with my friend, who'll make a proto for next weeks end.
While taking those measures, I noticed that I can't use a TEC, there simply isn't enough space for it and the heatsink. Sad but true.

This seems to be the current "release candidate": 4 coils outside, 8 coils inside (if I can fit them). The outer coils will be cooled by 4 fans, of which 2 will blow and 2 suck.
Those 8 inner coils will be attached 2 each to 1 outer coil.
I'll split the outer coils for incoming & outcoming water.

I'll be sure to post some images of the proto.

Thanks for the ideas. I might be able to incorporate some of them, when I get the proto.

Spewn (Jun 01, 2001 07:16 a.m.):
You wouldn't necessarily want to use ice pack gel. The only reason ice packs have gel in them is so they'll be flexible as they thaw. You should look into different materials that require less energy to change temp. I know alcohol is one, so using alcohol in that chamber might work well. The reason why you want something that requires less energy to change temp is because the peltier's are going to be transferring energy out at a certain rate. The faster this can cool the substance down, the higher the temperature difference between the copper coils and the cooling substance will be, and the more efficient the energy transfer will be.

Click to expand...

I know a gel which is usefull for you:it is the gel Agar Agar used by physicians. If you tried ??? That's not expensive.

What is the gel used for? I've never had need for any of gels...