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PostPosted: Thu May 31, 2007 11:47 pm 
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Posts: 6
This is entirely and absolutely possible.

people do this with stationary motors all the time. Ever since they had motors. If you have a diesel or gasoline motor that you use for running pnuematic pumps or generating electricity or something like that then having a water pump is actually a _bad_ thing.

The reason you need water pumps in cars and such things is because everything needs to fit into a engine compartment. Having a water cooling system without a pump means less things to go wrong.. it's inexpensive, effective, and have much higher reliability. No pump to break, less lines, less places for water to leak.


The trick is something called the thermo-syphon effect. Hot water rises, cool water sinks.

So you have it going both ways.. cool water wants to go down, hot water has to go up. So you have to carefully design your system to take advantage of this.

So your not fighting gravity or anything like that. It will work just like any other syphon, the weight of the water is what drives it.

So you have the radiator above the heatsource. The 'hot water' empties out into the top of the radiator. The cool water empties out of the bottom of the radiator. (so obviously you can't have a rad were the input and the output are the same height.)

It's tricky to design it so it works correctly. For example if you have a even very small dip in a mostly vertical stretch of hose then hot water will get trapped there, much like a air bubble would, and it would destroy the syphon effect.

But once you have it designed correctly, all the hoses and the radiator correctly sized, and have it tested then it's going to be dead silent.

In fact the more heat your dealing with.. the greater the effect. If its correctly designed and the mass of the water never allows the thermo-syphon to work that just means everything is running to cool to realy require a pump in the first place.

Obviously your probably figuring out that whatever your going to build is going to be fairly large. And it definately won't be a tiny thing.

But here is a example of somebody pulling it off:
http://www.vonslatt.com/proj-cc.shtml

He uses his water cooling system on the cpu and the powersupply. He uses a oversized heatsink for the vga card. He uses a store-bought waterblock for the cpu.

Unfortunately he ended up needing a slow fan for the power regulators for the cpu, but I expect that slices of a old aluminum heatsink or something like that glued to them would be enough to fix that.


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PostPosted: Fri Jun 01, 2007 12:45 am 
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Joined: Fri Jun 01, 2007 12:31 am
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Location: France
Hi, very interesting link but quite a huge thing indeed
And a lot of work, though


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 Post subject: compact way
PostPosted: Fri Jun 01, 2007 12:47 am 
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Joined: Fri Jun 01, 2007 12:31 am
Posts: 3
Location: France
Hi,
May I suggest a liquid-cooling,
no-fans,
no-pump,
silent,
compact solution ?

http://www.tuxboard.com/index.php/?2007/05/15/746-transformer-son-pc-en-aquarium-avec-une-huile-minerale

well I might be out of the subject as this is not exactly water-cooling. :oops:

But it still can be interesting, efficient and cheap.
take a look at the video on the bottom of the page


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PostPosted: Fri Jun 01, 2007 7:03 am 
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Joined: Tue Jul 15, 2003 11:50 am
Posts: 70
Location: Houston, TX
Seems to me like a water-cooled system using convection only would not use a conventional water block because there is no input or output water flow, there is just a column of water.

Why not use a "convection assisted" setup using an existing heatsink? You would have an existing heatsink with a large flat surface on the top side of it. To that you would attach (with thermal epoxy) a metal cylinder of the appropriate diameter. You would then clamp a large diameter tube to the metal cylinder. None of this 7/16 stuff, you could use a full inch diameter or more! Then the tubing would go straight upwards through a hole in the ceiling of the case and then to a reservoir. To increase transfer area between the water and the cylinder, the cylinder could be hollow like a copper plumbing pipe. The only problem would then be how to attach it to the heatsink and still be able to transfer the heat.

This approach would use a straight, thick, solid column of water to allow for the "thermo-siphon" effect.

I drew a pretty picture but I don't know how to attach it here. :(


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PostPosted: Sat Jun 02, 2007 5:55 am 
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Joined: Wed May 10, 2006 6:15 pm
Posts: 6
For a picture you could probably post a link to imageshack. easy to do uploads on that site.


The guy in the link I posted above used a convential waterblock.

It's the type that instead of a channel carved through it, it uses a grid-like arrangement, were the water passes through a fairly tight grid cut into the surface of the copper plate.

I think that with a waterblock with a channel you could run into problems with 'bubbles' of hot water not wanting to decend to get out of a loop.

Your going to need some sort of restriction or something to cause the water to swirl around or be forced to go around or through.. something to provide ample surface area. Otherwise the water wouldn't be able to absorb enough heat.


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PostPosted: Sun Jun 24, 2007 1:30 am 
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Joined: Sat Jun 16, 2007 11:47 am
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A pumpless watercooling system is a little pointless, there are up market pumps these days which are lower-than-ambient noise ratings.
Have a look at the Zalman Reserator 2: http://www.guru3d.com/article/content/393/
It's fanless, silent (as I can make out from reviews) and will cool a CPU and NB happily
Dunno about a GPU as well though. Plus, it doesn't look hard to mount a BIG (200+mm) fan on the radiator if you want things a little cooler. I'm sure you can buy up to 300mm 12v fans around somewhere, one of those at 600 rpm would be pretty good.

Think about the passive immersion cooling as well, thats what I'm currently doing.


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PostPosted: Thu Jul 12, 2007 6:24 am 
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Joined: Wed May 10, 2006 6:15 pm
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Quote:
A pumpless watercooling system is a little pointless



Well there is a very important point to it all.

If you have no fans, there are no fans that are going to fail.
If you have no pump, there is no pump to fail.

That's the reason you'll find them used in large stationary engines (for example, if your using biodeisel to generate electricity in the wilderness). These things will run for months on end with little matainance. A pump would drasticly reduce reliability.

If you have a computer that runs essentially 24/7 then this sort of thing should be a attractive concept. Using this you should be able to acheive a more reliable cooling system then traditional fan stuff. Generally speaking 'highly reliable' and 'watercooling' rarely go in the same sentence. :)

total submersion in oil or something like that, if you can pull it off with oversized passive heatsinks then that should be very nice also. Probably nicer because you don't have to worry about leaks.


The thing that sucks about oil is that as it's tempurature changes it's vicosity changes. Cool oil is resistant to movement. So you can't realy depend on convection to move oil like you can with water or air.


I'd like to have a oil setup, but I don't trust the oil to work without something agitating it, unless I use truly massive heatsinks for the powersupply and other things.

I was thinking of maybe a big 24volt fan undervolted or something like that. Something as big as the motherboard, more or less.

How reliable are DC fans under oil?


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 Post subject: Re: Who has watercooling with no fan, no pump, and no case f
PostPosted: Tue Jul 17, 2007 5:06 am 
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Joined: Tue Aug 03, 2004 1:26 pm
Posts: 261
Location: Helsinki, Finland
Visitor wrote:
Have any of you made such a thing? I imagine it'd take a large external radiator?


If you want all-passive system, I'd go for heatpipes for heat distribution. They have more limited range and capacity, but they are passive and with proper engineering you should be able the get almost all the advantages of water cooling if you thermal envelope is lowish (for water-cooling) as most of the modern PCs are.

Essentially the trick in water cooling is the same than in heat pipes: it enables you to effectively move heat out of the heat source and spread it to larger area for more effective dissipation. The difference is just that water cooling is cheaper to build if amount of heat transported is anything bigger and that heatpipes are smaller and without moving solid parts.


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PostPosted: Fri Jul 20, 2007 3:48 pm 
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Joined: Tue Sep 20, 2005 1:21 pm
Posts: 412
Location: UK
Agouti wrote:
Have a look at the Zalman Reserator 2: http://www.guru3d.com/article/content/393/
It's fanless, silent (as I can make out from reviews) and will cool a CPU and NB happily


I've had a Zalman Reserator 2 for a little over a month now. It's cooling a Nvidia 8800GTS 640mb card in a single loop.

Compared to an active graphics card cooling fan it's quiet and works very well: Just don't expect literal silence. :)

Although it's very quiet it's not literally silent as some noise can be heard from it. Compared to a low noise fan such as a Scythe SFF21D 800rpm 120mm case fan it's a lot quieter but there are still moving parts in it.

When the Reserator 2 is cool (i.e. the PC is just idling and the reservoir and fins are cool to the touch) there is a faint whooshing noise and also a faint ticking noise from the flow meter on the front. You have to really be close to it before that's noticeable and this level is what the reviews are probably describing as "silent".

When the Reserator 2 is hot to the touch after sustained full load on the graphics card it becomes louder. It's difficult to describe the noise: think hot metal expanding or a kettle sizzling just before it starts boiling.

It's still quiet and as soon as the Reserator 2 cools back down after 30min or so it returns to the lower noise levels again.

There are some pics and temperature comparisons between stock aircooling and the Reserator 2 for a single 8800GTS graphics card here if anyone's interested: :)

http://www.silentpcreview.com/forums/vi ... hp?t=40686

.


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