Downside of an open loop WC system

[flxnimprtmscl]

So here's what I was thinking. I've got tons of room, don't like buying kits for things, and want really good cooling so here's my proposed cooling loop. Tell me why it's really good or why it sucks horribly.

Output from the CPU waterblock flows to a large heatercore in a pressure box with 4 or so 120mm fans to pull air through the heatercore. After water leaves the heater core it would drop down into a 15 or so gallon sump/reservoir with a submersible pump in it which would pump water back through the system.

To my untrained eye it seems like:
1) Cooling would be better due to the water not being in a closed loop. Ie: water in the sump/res can bleed off heat there as well.
2) No need to ever bleed the system
3) Easy to fill.

etc.

I know it would be really important to pick a low wattage pump so I'm not putting more heat into the water than I'm taking back out. So, what do you think? And how many gph is really ideal for water cooling?

 

[aigomorla]

open loop, meaning you have moments where evap can occur because your loop is not sealed.

The only way i can see to pull this effect off, is via BONG Cooler. Using Evap and vent fans to maintain a h2o temp slightly below ambients.

Benifits:
Slightly lower then ambient temps held on coolant.

Dangers:
Due to the increased evap conditions, your humidity will sky rocket. If this system is kept indoors, you will need a dehumidifer.

Your sump would also be open... so chances of it get contaiminated with particle matter and clog your blocks.

 

[flxnimprtmscl]

Well, I'd be keeping the sump sealed with a few mesh covered vents to let air pass through and keep detritus out. As far as humidity, I had a setup kind of like this in my office at my old house as a wet/dry filter for my 125gal fish tank and while it made the room slightly more humid it wasn't bad. Certainly not a danger to my electronics or anything like that.

 

[relttem]

how are you going to change the pressure in the pressure box? If you are going to use evaporative cooling to that degree you are going to have to change the pressure in order to effectively get any evaporation, and that will be the only way you get it below ambient - you are going to have to go to a refrigeration system. It takes a lot of energy to evaporate water..if you are blowing on it etc things change.
Q=mass*(hfg)
mdot - mass flow of your water
hfl - change in enthalpy from fluid to gas at 100C

Secondly, when water is flowing thru a radiator the amount of surface area that is contact with the water is a lot - that is why they work. But, with the water just sitting in a open container the free surface area isn't going to be much..unless it is a swimming pool. you might lose some heat out the sides etc. You'll also have to worry about crap getting in it.

to find the mass flow rate - which you can change to gpm or whatever you are basically balancing this equation:

Q = mdot*Cp*(T2-T1)

Q - how many watts you want to cool. This is NOT how many watts your chip is puting off, since you aren't going to pick all that heat. You can still use the amount of heat your chip is expelling to get a worst case scenario.

mdot - the mass flow rate of your cooling liquid. Divide that by the cooling liquids density (1000kg/m^3 for water) to get m^3/s and you can convert that to gpm. www.onlineconversion.com.

T2 - the temp of the liquid coming out of the block

T1 - the temp going into the block.

That will give you a good ball park number of the gpm you need.

 

[aigomorla]

Originally posted by: flxnimprtmscl
Well, I'd be keeping the sump sealed with a few mesh covered vents to let air pass through and keep detritus out. As far as humidity, I had a setup kind of like this in my office at my old house as a wet/dry filter for my 125gal fish tank and while it made the room slightly more humid it wasn't bad. Certainly not a danger to my electronics or anything like that.

Did you have a salt water tank with high powered lights?

Thats about = to a high end computer on h2o.

Your gonna evap a TON of liquid each day.

In short, just work in a closed loop. Things are so much easier that way.

 

[flxnimprtmscl]

Originally posted by: aigomorla

Originally posted by: flxnimprtmscl
Well, I'd be keeping the sump sealed with a few mesh covered vents to let air pass through and keep detritus out. As far as humidity, I had a setup kind of like this in my office at my old house as a wet/dry filter for my 125gal fish tank and while it made the room slightly more humid it wasn't bad. Certainly not a danger to my electronics or anything like that.

Did you have a salt water tank with high powered lights?

Thats about = to a high end computer on h2o.

Your gonna evap a TON of liquid each day.

In short, just work in a closed loop. Things are so much easier that way.

No, I had a freshwater tank with about 400w of heaters, 350w of light, and I was pumping 1200gph though the sump. In addition to that the water into the sump was about 1' above the water level of the sump and was being dispersed into small droplets by a trickle plate so I kind of had an evaporative cooling thing going on there. I doubt this could be any worse as I'll only be cooling the CPU and not the NB or GPU.

I think I'll just give it a shot and see how it works out. If it doesn't work the way I want I can always close the loop up. I'll post back with results when I've got this up and running.

 

[Billb2]

Originally posted by: flxnimprtmscl
.. heatercore in a pressure box with 4 or so 120mm fans to pull air through the heatercore.

...a 15 or so gallon sump/reservoir

...a submersible pump i

To my untrained eye it seems like:
1) Cooling would be better due to the water not being in a closed loop. Ie: water in the sump/res can bleed off heat there as well.
2) No need to ever bleed the system
3) Easy to fill.

Pressure box? What's that?

a 15 gallon rez will just cause the water to take longer to get to it's equilibrium temp.
Submersible pumps dump ALL their heat into the loop. Regular pumps, only some.

1.) Ain't enough surface area to make a hill of beans of a difference in temps.
(Just make a grid out of 10' sections of copper pipe and have a BIG. passuve rad.)

2.) Except start up or component replacement.

3.) Now how hard is that really. twice a year?

 

[flxnimprtmscl]

Originally posted by: Billb2

Originally posted by: flxnimprtmscl
.. heatercore in a pressure box with 4 or so 120mm fans to pull air through the heatercore.

...a 15 or so gallon sump/reservoir

...a submersible pump i

To my untrained eye it seems like:
1) Cooling would be better due to the water not being in a closed loop. Ie: water in the sump/res can bleed off heat there as well.
2) No need to ever bleed the system
3) Easy to fill.

Pressure box? What's that?

a 15 gallon rez will just cause the water to take longer to get to it's equilibrium temp.
Submersible pumps dump ALL their heat into the loop. Regular pumps, only some.

1.) Ain't enough surface area to make a hill of beans of a difference in temps.
(Just make a grid out of 10' sections of copper pipe and have a BIG. passuve rad.)

2.) Except start up or component replacement.

3.) Now how hard is that really. twice a year?

Pressure box is what I've heard it called but maybe it goes by another name. It's basically a box with a hole cut one one end that you cover with your radiator/heatercore and a few holes on the other end that you cover with fans. It basically seems to be a large replacement for a fan shroud and keeps you from having any dead spots on your radiator.

 

[aigomorla]

Originally posted by: flxnimprtmscl
No, I had a freshwater tank with about 400w of heaters, 350w of light, and I was pumping 1200gph though the sump. In addition to that the water into the sump was about 1' above the water level of the sump and was being dispersed into small droplets by a trickle plate so I kind of had an evaporative cooling thing going on there. I doubt this could be any worse as I'll only be cooling the CPU and not the NB or GPU.

I think I'll just give it a shot and see how it works out. If it doesn't work the way I want I can always close the loop up. I'll post back with results when I've got this up and running.

ok!

yup you totally understand what your getting into... 😀

Ditch the rad completely, and setup a bong tower.
http://en.wikipedia.org/wiki/Bong_cooler

 

[flxnimprtmscl]

Originally posted by: aigomorla

Originally posted by: flxnimprtmscl
No, I had a freshwater tank with about 400w of heaters, 350w of light, and I was pumping 1200gph though the sump. In addition to that the water into the sump was about 1' above the water level of the sump and was being dispersed into small droplets by a trickle plate so I kind of had an evaporative cooling thing going on there. I doubt this could be any worse as I'll only be cooling the CPU and not the NB or GPU.

I think I'll just give it a shot and see how it works out. If it doesn't work the way I want I can always close the loop up. I'll post back with results when I've got this up and running.

ok!

yup you totally understand what your getting into... 😀

Ditch the rad completely, and setup a bong tower.
http://en.wikipedia.org/wiki/Bong_cooler

Yeah, I've been thinking about that. One question, though. if I do a bong tower I'd actually prefer to put it outside. Mostly because I just don't want to listen to it. Would I run into any condensation problems doing this? Bear in mind, I'm in Oregon so it's not the warmest of climates.

 

[Gillbot]

Originally posted by: flxnimprtmscl

Originally posted by: aigomorla

Originally posted by: flxnimprtmscl
No, I had a freshwater tank with about 400w of heaters, 350w of light, and I was pumping 1200gph though the sump. In addition to that the water into the sump was about 1' above the water level of the sump and was being dispersed into small droplets by a trickle plate so I kind of had an evaporative cooling thing going on there. I doubt this could be any worse as I'll only be cooling the CPU and not the NB or GPU.

I think I'll just give it a shot and see how it works out. If it doesn't work the way I want I can always close the loop up. I'll post back with results when I've got this up and running.

ok!

yup you totally understand what your getting into... 😀

Ditch the rad completely, and setup a bong tower.
http://en.wikipedia.org/wiki/Bong_cooler

Yeah, I've been thinking about that. One question, though. if I do a bong tower I'd actually prefer to put it outside. Mostly because I just don't want to listen to it. Would I run into any condensation problems doing this? Bear in mind, I'm in Oregon so it's not the warmest of climates.

Yes, you will.

 

[mpilchfamily]

Here is an open loop idea for you.

http://www.thebuehls.com/pool_cooling/