Passive Water Cooling .. with a fish tank

[racolvin]

might need input from someone versed in hydraulics/fluid mechanics on this one

I like the idea of a passive radiator/resevoir like the Zalman Reserator 1, but it seems ... limited .. somehow. So, with that in mind, here's the idea <drumroll please>

I use a 30 gallon fishtank, with all the little fish tank acoutrements (colored gravel, plastic plants, the little guy in the old divers bell helmet and the treasure chest) along with some plastic fish perhaps, for ambiance.

I'd have to cut holes in the bottom of the tank to have an inlet/outlet connections for the circulation. I'd like to have an immersible pump that that shouldn'be be hard to get from your average aquarium shop.

So, the question is, would the weight of the column of water of that volume be too much pressure for the average tubing of a WC solution for a computer blow out the connections? I dunno enough physics to even hazard a guess

R

 

[racolvin]

Hmm ... also, I'm thinking that glass or acrylic isn't a very good conductor of heat ... that might be a problem as well

 

[Umberger]

the volume of the water column does not matter, only the height. A 2 foot high column of water at 32 degrees farenheit by my calculations, should generate 0.86 psi. (I think I did that right, someone correct me if i screwed something up). If I'm right, that is not a very appreciable pressure, and shouldn't bother the tubing one bit. I think most cooling towers are that tall anyway, so it would be the same pressure that the tubing would see under standard use. You may be right about the glass/acrylic not dispersing heat very well. Maybe with an open top that would be enough surface area to dissipate the heat? Not sure on that front.

 

[imported_bum]

You don't want an open top, though, because then you'll have dust and who knows what flowing through your computer.

 

[racolvin]

yea, paritculate matter in the air as well as biologicals would make an open top impractical I think..

However, a finned copper top on it might do some good .. hmmm

R

 

[racolvin]

Originally posted by: Umberger
the volume of the water column does not matter, only the height. A 2 foot high column of water at 32 degrees farenheit by my calculations, should generate 0.86 psi. (I think I did that right, someone correct me if i screwed something up). If I'm right, that is not a very appreciable pressure, and shouldn't bother the tubing one bit. I think most cooling towers are that tall anyway, so it would be the same pressure that the tubing would see under standard use. You may be right about the glass/acrylic not dispersing heat very well. Maybe with an open top that would be enough surface area to dissipate the heat? Not sure on that front.

Well, the hight would probably be more like 4ft, since I'd put the aquarium on stand that would raise it up like that.

R

 

[CycloWizard]

You'd have to have a very, very tall aquarium to bother even cheap tubing due to pressure. Very interesting idea...

 

[n yusef]

You could put a whole lot of something cold into your fish tank (even ice cubes may work), and then you could get pretty good temps compared to a normal radiator/heatercore. Cool idea. If you try it out, post some pics please.

 

[imported_fatal]

How would the water get cooled down?

 

[CycloWizard]

The water in the tank would cool very slowly. However, the idea is that it would reach some equilibrium temperature that would be very close to room temperature - in essence, it's a huge heat reservoir. If you remove 300 W from your system, then you input 300 W to your reservoir. That's a very small rate of heat addition relative to many gallons of water. Then, you disperse this energy throughout the water. The water will be slightly heated over time until the rate of heat input from your system matches that of the surroundings. I could actually tell you about what temperature the water would be at when I get some time, but apparently my taxes are due in two hours, so...

 

[Leros]

How about a half filled aquarium with a waterfall in it? That would provide for plenty of evaporative cooling. Or you could could buy a $3-400 aquarium chiller.

 

[Umberger]

Originally posted by: racolvin

Well, the hight would probably be more like 4ft, since I'd put the aquarium on stand that would raise it up like that.

R

Then it would just double the pressure. Still nothing to worry about.1.6 psi is negiligble

What if you put the water resirvoir in a refrigerator!? That would be awesometacular.

 

[CycloWizard]

Originally posted by: JToxic
How about a half filled aquarium with a waterfall in it? That would provide for plenty of evaporative cooling. Or you could could buy a $3-400 aquarium chiller.

I'm actually considering the waterfall idea when I build my own watercooling system, just to spice it up a bit. Actually, the waterfall increases heat transfer more from convective transport than from phase change (evaporation), but that would also play a part. The only problem is that whatever evaporates needs to be replaced.

 

[Devrin]

Just something to throw in here since I have a few sw fishtanks... you can't just cut into any glass tank. By far the majority of them use tempered glass on all sides including the bottom. Trying to drill or cut tempered glass would end up with a bunch of glass all over the place. However they do make some tanks where the bottoms aren't tempered to allow for the cutting of a hole for a overflow filter system, but as far as I know this is only done on larger tanks, I think about 60 gallon ones or so is where they start doing this.
So either you would have to go with a larger more expensive tank, or go with an acrylic tank. Last I priced an acrylic tank it was a bit on the expensive side though and I'm not even sure how small they make them. An option might be to find a place to purchase some sheets of arcylic though and make your own wannabe fishtank. I don't recall the name of the stuff at the moment but theres a type of 'acrylic adhesive'. Although it's not really a adhesive in the normal sense as it actually chemically melts the acrylic together so it's as one piece. Would be a bit of work but I think it would almost be the cheapest alternative. Just my .02¢.

 

[Umberger]

I know it would be less aesthetically appealing, but nothing really says that you have to run the water lines through the side or the bottom of the tank. you could just take them up and over the edge, it wouldn't really make a difference as far as pumping the water is concerned. (similar to a siphon, the path the tube takes doesn't matter, only the inlet and outlet) it would sure be easier (and cheaper) than having to build a tank just so you could put a hole in the bottom.

 

[CycloWizard]

I came up with a very, very simple model to get an idea of whether or not this would work. I wrote it up and scanned it in here so you can have a look at it and see what you might have to do to get it to work. I wrote a quick example at the end so you can see what kind of temperatures we're looking at here, though it's important to realize that you can vary these depending on how you design your system. You can play with the dimensions of the system (using the boxed equation on the second page) and see how it effects the water temperature pretty easily. I can tell you right now that the lowest temperatures will come from an very tall, skinny tank since it has a lot of surface area for the amount of water, but this obviously isn't very practical.

Clearly, glass is the better material, though like someone else said, it's a lot harder to work with unless you're blessed with diamond bits and so on.

 

[Wuzup101]

I could probably do this with some stuff I have laying around the house (assuming I would buy the CPU blocks). I'm not sure that my PC would provide adaquate heat for my fishies though... using a 200 (or possibly 250) watt tank heater so as it is. The angels like it warm

Good luck w/ the project, I doubt you'll have any problem with the pump or the tubing, lets face it, they were probably deisgned to work for a fish tank anyway. Many people with larger tanks have their filters hidden under the tank itself in which case the pump has to provide enough head pressure to get the water back into the tank... and of course the tubing has to take the pressure. This would be my reasoning behind saying it's safe... take it for what it's worth . Actually if you managed to work out the heat generated by your computer and had the proper sized tank, you could easily throw an aquarium heater in there with it and put fish in it without a problem (as long as you didn't die the water of course). Aquarium heaters are throttled of course, so when there was adaquate heat thhe wouldn't run. And if you shut the system down or it was running at idle the heater would kick on...

Dammit wish my fish were here at school w/ me... so relaxing

 

[racolvin]

So far what I'm looking at is a 20 Gallon hexagonal aquarium that's made of acrylic ... I've got a PetSmart store right near me

The tank itself is 2ft tall, 15" wide, so its sorta tall and skinny, but since acrylic isn't much of a heat conductor, I dont' think that matters much

I'd put it up on a 2ft stand. Depending on the look of the stand that I can find, hopefully that would hide the tubing at the bottom.

As for heat dissipation, that's my biggest concern. I kind of like the idea of half filling the tank and introducting waterfall effect but the heat would still have to go somewhere out the top. Not sure how I'd handle venting that, since I'd prefer to keep any airborn particulates out of the system, as well as any airborne biologicals.

The one other solution that occured to me might be a bit pricey - a custom made copper radiator at the top of the tank that seals the top. The hot-water return would be tubed up the back side of the tank (internal to the water) and given to an inlet on this custom radiator. The radiator would be two chambered: the top later would be the standard twisted radiator tubing and copper fins - no fans, only passive radiation, but the room where this goes has a ceiling fan going constantly, so that would provide some generic airflow over the radiator. The second chamber would be under the radiator - the outlet of the radiator copper tubing would feed directly into the second chamber. The second chamber is nothing more than a 3/4" tall open space that is perforated, like a huge showerhead - the water would just drip out like rain through all those little holes.

Not sure what that would cost me to make tho

Anyway, it would all be driven by an immersible pump inside the aquarium, so as to minimize noise, just like the way the Zalman Reserator works - I just like that idea

R

 

[imported_llama]

yeah, to raise the temp of 30 gallons of water (4.5litres ish to 1 gallon) by 1 *C would take roughly 190,000w of heat, that is a lot!

 

[Lasthitlarry]

Ok, I don't know much about water cooling, and it seems very dangerous, but I had an idea, probably a dumb one, but here we go:

Split the aquarium in two with some kind of either plastic or glass wall (could even go high tech and get a seperator that transfers heat from one side to the next, if there is such a thing) and have the tubes going to the computer from one side (the cold water side), and tubes from the computer to the other side (not cold water side). Maybe even put a top on the cold side and leave the hot open for the heat to rise and leave the aquarium. Then it wouldn't take so long for the water to cool, and it wouldn't reach room temperature so quickly. You could even put some sort of coolant or long lasting ice cubes in the cold side to keep the computer even colder. You could even make the aquarium look cooler by doing this by placing your favorite action figures on either side, all looking ready for battle (like superheroes on the cold side, and villians on the other side).

Maybe I should just grow up.

 

[CycloWizard]

Originally posted by: racolvin
...R

You just HAD to go with the hexagonal tank, didn't you? I'll crunch some numbers for you and see if it'll work without the radiator if you want.

 

[racolvin]

Originally posted by: CycloWizard

You just HAD to go with the hexagonal tank, didn't you? I'll crunch some numbers for you and see if it'll work without the radiator if you want.

lol ... well, they don't make a circular tank I'm afraid .. hexagonal is about the closest I could find

Don't go to any trouble unless you just like crunching numbers .. right now its a flight of fancy, since I have no idea how the wife would react to having a 20 gallon tank with no actual fish in it. And when I then tell her its to cool my computer for no other good reason that the sheer geek-factor, I'm liable to be sleeping next to that tank and computer for a while

R

 

[CycloWizard]

Haha... Well, I'm the consummate nerd and I haven't slept for a few days, so instead of sleeping I'll whip up another model real quick and see what we can see. Actually, I can use most of the old one that I posted previously....

One question: how many watts is your PSU?

 

[CycloWizard]

Yeah, it's not even going to be close. You'll definitely need some sort of active cooling or all your water will boil off, but not until after your system cooks. I made a slight typo in the calculations I made yesterday... The real temperature difference will be a factor of 10 higher than my calculations show. Apparently that decimal point really matters!

 

[hans030390]

Originally posted by: Lasthitlarry
Ok, I don't know much about water cooling, and it seems very dangerous, but I had an idea, probably a dumb one, but here we go:

Split the aquarium in two with some kind of either plastic or glass wall (could even go high tech and get a seperator that transfers heat from one side to the next, if there is such a thing) and have the tubes going to the computer from one side (the cold water side), and tubes from the computer to the other side (not cold water side). Maybe even put a top on the cold side and leave the hot open for the heat to rise and leave the aquarium. Then it wouldn't take so long for the water to cool, and it wouldn't reach room temperature so quickly. You could even put some sort of coolant or long lasting ice cubes in the cold side to keep the computer even colder. You could even make the aquarium look cooler by doing this by placing your favorite action figures on either side, all looking ready for battle (like superheroes on the cold side, and villians on the other side).

Maybe I should just grow up.

I like this idea!