Odd question

Imagine a Zalman Reserator type reservoir. It normally has two hose connectors at the bottom. What if the hose that brings back the warmer water was connected on the top of the reservoir and the reservoir itself is filled 50% of its capacity.

Would the freefall of the water help cool it down?

Basically, my question has got nothing to do with the zalman, i'm just wondering if the freefall (and the resulting increased activity of the surface water as the water comes crashing down from above) would make a noticable difference in temperature.

I'll throw a disclaimer at this while i still got the chance

I don't own a watercooling system myself, nor have i really done any research in what is 'best'. This is just a brainwave/fart that i needed answering by the experts

In my mind, it would. By creating a waterfall, or forming droplets, you increase the surface area of the water itself. It should cool it more effectively, but remember you still won't get below ambient temperature. It kinda sounds like an evaporator bong, just without the evaporation. I've been wanting to tinker with this idea for a while now. And it would sound like a waterfall in your own room, whoa!

what you are thinking of is bordering what is called evaporative or bong cooling. unfortunately the way you propose it is not enough. for it to be effective ( and it can be VERY effective) you need to spread the water out using more surface area. so if oyu where to run it through several horizontal layers of green scrub pad or some other form of strainage you get more surface area you would then be able to make it work.

thorilan said:

what you are thinking of is bordering what is called evaporative or bong cooling. unfortunately the way you propose it is not enough. for it to be effective ( and it can be VERY effective) you need to spread the water out using more surface area. so if oyu where to run it through several horizontal layers of green scrub pad or some other form of strainage you get more surface area you would then be able to make it work.

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Without the strainage you would be making lots of bubbles in the res that could get into your pump. Just my .02 cents

I always had the idea of using a 2 foot length of 2" diameter or so PVC pipe. Put a shower head on the top and run the water through it. Fill the tube about half way and put the outlet on the bottom of the tube. If you think about it, that is really cheap to rig up. But what I wonder is does creating a waterfall cool the water enough? Would using just a setup like that instead of a radiator and fans cool just as effectively?

striker85 said:

I always had the idea of using a 2 foot length of 2" diameter or so PVC pipe. Put a shower head on the top and run the water through it. Fill the tube about half way and put the outlet on the bottom of the tube. If you think about it, that is really cheap to rig up. But what I wonder is does creating a waterfall cool the water enough? Would using just a setup like that instead of a radiator and fans cool just as effectively?

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The bong coolers I have seen have a 'y' in the tower section in which is mounted a fan. these things are cheap to make, but 'relatively' high maintainance.

Yeah, but what if you were to eliminate the bottom y-section and leave it as a closed loop?

striker85 said:

Yeah, but what if you were to eliminate the bottom y-section and leave it as a closed loop?

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No idea. If I had to imagine it, I'd assume that eventually the falling water would efficiently heat the trapped air in the tower section. I dont think that it would be anything more than a large res.

If you have the inclination, build one and post your results. They might surprise me.

striker85 said:

Yeah, but what if you were to eliminate the bottom y-section and leave it as a closed loop?

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Then you would have a very noisy reservoir with no temp reduction at all.

The bong cooler only works- and quite effectively at that- because the falling water mist can give up heat to the rising air column.
It's a crude and basic example of phase-change and the core principle behind the design.

Close the loop and eliminate the fresh air intake and you've lost any advantage of the "waterfall" design.

Thanks so far guys.

What about the surface of the water below? It is in motion more as the water from above comes down, might be compared a little with softly blowing in your spoon as your eating hot soup?

SKiNNiEH said:

Thanks so far guys.

What about the surface of the water below? It is in motion more as the water from above comes down, might be compared a little with softly blowing in your spoon as your eating hot soup?

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True, the water will have motion. You can look at it like this: The air is still, and the spoon is moving through it.

In a setup like you are considering (sealed res) the air in that res will heat up and negate almost any benefit from the falling motion. My .02 cents

I suppose I didn't think about that. But I was thinking like one of those soda fountain things where the water is spread out over the sides of the reservoir. And considering he mentioned the Zalman reserator, I was thinking that the reservoir would be some kind of metal, likely aluminum, that had fins and a cooling capacity. Perhaps it still is impractical, though.

Well to see the waterfall thing for yourself, turn on your shower and when the water gets hot, put your hand by the showerhead and feel the water, then put your hand where the water almost touches the ground, you should feel a difference.

striker85 said:

I was thinking like one of those soda fountain things where the water is spread out over the sides of the reservoir.

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The old fountains you described were refridgerated units that would freeze the liquid if it were not pumped up a tube in the middle, The liquid would then casscade across the underside of the lid and down the sides. The circulation was only to keep it from freezing, not to cool the drink.

Wouldn't an "open air" system tend to build up debris faster than a closed system?


If you want to use "fountain" cooling then you really need a double pump system. Build a normal WC system on the computer side then put your rad at the bottom of a real wall of water. With your rad at the bottom (or as part of!) a falling water column you should get pretty decent cooling just like an old fashioned building chiller unit (before A/C was common).

http://www.spiritelements.com/ProductDetail.aspx?c=1006&p=1795
http://www.spiritelements.com/ProdList.aspx?c=1006

Of course you wouldn't need anything as fancy (or expensive) as that - it's the idea that counts. Something as simple as a copper pipe with a bunch of small holes in it mounted horizontally on top of your rad would work. Then mount the rad just above a pan of water deep enough for a small submersible pump. Add colored rocks if you're feeling "artistic".

I've seriously thought about this design but there are 2 issues with it:
1. My system also shares room space with my home theater - the waterfall would create too much ambient noise, and
2. The humidity in the room will go up (that's the cost of old fashioned phase cooling).

#1 is the biggest hitch for me but for most people that would be a plus ...

Yeah, it'd get dirty REAL fast, and I'd be nervous about using anything toxic in the water if it was sprinkling though the air I was breathing. The cooling capacity would be crazy-high, though. One could use a two-stage system where a sealed loop transferred the heat to a radiator bathed in the secondary open loop that used the bong cooler...it'd be a wee bit on the complex side though.

I don't think you would get better temps since there will get tiny air bubbles in the water. It's the same when you put new water in the heating system, it has microscopic bubles of air in it.

striker85 said:

I suppose I didn't think about that. But I was thinking like one of those soda fountain things where the water is spread out over the sides of the reservoir. And considering he mentioned the Zalman reserator, I was thinking that the reservoir would be some kind of metal, likely aluminum, that had fins and a cooling capacity. Perhaps it still is impractical, though.

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Hmmmmm - wouldn't work well for a radiator but it might look pretty cool for a res!

whines said:

... One could use a two-stage system where a sealed loop transferred the heat to a radiator bathed in the secondary open loop that used the bong cooler...it'd be a wee bit on the complex side though.

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Not really that complex - you're just building two independent systems. One is a standard closed-loop WC system w/out the fans on the radiator and the other is a table-top water fountain that happens to have a radiator at it's core. If you feel really artistic you can even enclose the sides in some brass or copper sheet metal and use a brass/copper pan on the bottom. I'd build one in a heart-beat if I had a separate office for the computer ...