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Passive water cooling!

A

amohedas

Limp Gawd
Joined
Mar 26, 2003
Messages
230
I plan on building a large resevoir out of Aluminum (1/8" thick) to be the basis of a water cooling setup. I was wondering how many gallons of water will this thing need to hold in order for it to be effective, and dissipate heat faster than the computer can dish out. I realize that the effictiveness will also depend on the surface area of aluminum in contact with the water and outside air.

Lets just assume a simple situation were the resevoir is a cube. Approximately how much water do you think this will need to hold???

Thx for the help.
 
I don't know the thermal dissapation rate of water and aluminum off the top of my head... I bet I can look it up sometime when I'm not too tired. Anyone want to google this?

Once you have the dissapation rate, you can easilly compute the volume of water needed. The other things we would have to know are the exchange rate of the water (i.e. the flowrate), and the wattage of heat produced by the processor in your computer.

I'm willing to bet my physics degree that after we calculate all this you are not going to like the results. Its going to take quite a bit of water to achieve a radiator-less cooling system. I'm talking dozens, if not hundreds of gallons of water. The enclosure would be massive to house more than a couple gallons of watter any way, so at this level the entire project becomes ludicrous and absurd. I really don't think its possible to cool a computer like this and have the size and enclosure be of reasonable size.

-OMP
 
Perhaps more creative design for the reservoir.

Rather than just making a big container, consider snaking copper tubing and affixing fins to it. Etc etc. Let the reservoir act also as a large radiator of sorts. I've seen mention to similar things around here and if I were going to do it I'd have a (as I believe Zalman calls it) reservator.

Whatever you do you want to maximize contact with the metal>water interface and the metal>air. Perhaps the box theory would work, but would need some kind of fins extending in to the reservoir to provide more contact area with the water.

Think outside the box some.
 
I really wasnt considering building just a box :) . I said that to simplify the calculations and therefore estimate a worst case situation.

What I was thinking would be a rectangular prizm with a divider going down the length. Aluminum fins would extend from inside the box to the outside. Everything would be welded shut so as to avoid leaks. The intake would go on on side of the divider and the outake on the other. The divider would stop a few inches from the end of the prism. Therefore the water would be directed around the divider and before being pumped out again.

I know that there are some people that have used fish tanks to house their water and have had good results, so the amount of water I would need shouldnt be rediculous.

I'll research some more and see what the dissipation of aluminum is.

Thx for the replies!
 
The Zalman unit is a reservoir, radiator and a pump, all in one. It has fins to increace contact surface area with air, and relies on thermal convection (rather than fans) to exchange the air around itself; this means you can't mount it inside and expect good results.
 
Well actually a fish tank in theory wouldnt be a bad idea. But you need to clean them often. Unless you start modding the fish tank to reduce the bacteria buildup youll get, in which case youre just better off using a 5 dollar heatsink :D

I think its assumed that this cant be a 100% internal unit. Not enough airflow.
 
I would consider a fishtank full of water pretty absurd when a small radiator and a near silent fan will accomplish the exact same thing...

That new Zalman radiator tower looks pretty interesting, check it out.
 
I never considered this being an internal unit lol. I just didnt want to have a lot of fans on a hudge radiator, and was wondering if I could accomplish comprable cooling passively. I have seen the zalman reserator and it performs decently, so at least I know that with some thought something can be made to perform well, but it also costs $280, and for that much I might as well get a really nice traditional WC setup.

Im still playing with the idea, and I'll see if I can design something in Inventor to get the point across.
 
Build your own reservator, perhaps instead of fins you can use pins that go from the inside of a cylinder to the outside (a la swiftech heatsinks).

It would be an interesting experiment to see how well that performed.
 
I believe someone posted a passive watercooling setup that was from a german site a little while ago. I retrieved all of the pictures as eventually I would like to do the same. But they used a copper setup with the copper tubing winding down a set of about 5 copper hollow rectangles. The main thing is is that it looked more like modern art then anything else. I'm sure mounting it on the wall (once proven to be leak free), would be an interesting way of showing it off. As well as if you were daring enough, you could spay vinegar, or salt water on the copper (not the piping), but the rectangular parts to make it rust a bit to show off a greenish blue rust. Which would make it more of an appealing object of discussion.

Why not on the piping? Because if the piping where to rust, it would not have as much contact with cool air in order to cool off the water better.

Either way, I would eventually like to test this method out.

But I don't have the proper tools for welding these things together.
 
I saw that one as well.

I think building one like that or a vertical cylinder with pins that pass through the skin would be easier than something comparable to the reservator. It's easier to stick pins (little metal rods) through something than it is to build lengthwise fins in to a cylinder I should think. Particularly since you want them on the inside and the outside of the cylinder.
 
I like the pin idea..... I'm going to keep thinking about different ideas. I wont build this until I get out of school though. I'll post when it finally does happen.
 
I would suggest using something other than water.
(for example isopropyl alcohol)
It will allow heat to dissipate much better than water.
 
bah, passive water cooling is not just a dream!

one day, way back when, i was tinkering around trying to mount some fans directly to my radiator. suddenly it started bleeding all over me so i had to remove it from the loop. not to be without my beloved games, i rigged up my water system back as it was with the exception that there was now no radiator in the loop, just cpu, vid card, pump, and res. now, my cooling components were all internal, but my res was fairly large. i had approximately 1.5 gallons or so total in my loop, and running a radeon 9700pro and a 1.6A p4 oc'd to 2.7ghz. not the largest heat load, but still significant. surprisingly even after stressing the system for hours on end, in a non-air conditioned room, in the middle of an oregon summer, the cpu never climbed above 58*C.

now mind you my res was nothing special, just a big piece of PVC pipe capped on both ends and tapped for fittings. the whole thing heated up and kept my case fairly warm, but there was no significant airflow in the case to speak of so it's not out of the question to do the same in a different setup.
 
I just use a car rad set at an angle inside a wooden box ontop of my desk.
With a total heat load of around 200 watts full load and no fans on tops out just over 60C.
Dont need any fans on if it ever idles.
Just have 4x120mm fans at 6v to keep it cool.

Luck........:D
 
I think I am going to go with a aluminum cylinder with aluminum pins stuck along its length. I will make a model in inventor and post it.
 
Originally posted by amohedas
I think I am going to go with a aluminum cylinder with aluminum pins stuck along its length. I will make a model in inventor and post it.
Click to expand...
I'm glad my idea has had some influence. I'll be very curious to see how it comes out and how it performs too.
 
Ok here is a rev 1 of the design. It is 3 feet long and the OD is 3 inches. The wall thickness is .25 or something like that.

I found something on ebay that will probably work perfectly.

Tube

Here is a picture of what i made in Inventor.

viewpubimage.asp


suggestions are welcome !!!

Thx
 
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Just in case you guys are wondering this "tube" will be able to hold approximately 1 gallon taking the volum occupied by the aluminum rods into consideration. I am still trying to figure out a way of calculating the thermal dissipation of this thing. I dont really know how to go about it so anyone with any ideas please do tell :D .

Thx
 
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