DICE Thoughts

[Weatherlite]

I did some searching and haven't seen this mentioned so I figured I'd bring this up...

I've been reading a lot lately how people are trying to cool their systems to sub-ambient or sub-zero without using a pot and LN2 or DICE directly, ie they want a more long term solution. While I don't have an answer, I do have an idea.

When I was active duty military, we would train to dispose of chemical munitions (yep, I disarmed bombs) using a slurry of DICE and alcohol, preferably methanol, but isopropyl alcohol usually sufficed. I know everyone here who has read up on using dry ice for cooling a computer knows about using these ingredients, but I don't know if the advantages of a slurry are known, or how to make it. Simply, a slurry holds a lower temperature for a longer amount of time. As for making it, there are two ways. The hard way: breaking apart the dry ice manually or with a blender (pretty sure that's what's recommended on here) and mix it in. The easy way...though expensive: use a CO2 fire extinguisher. That's also not very useful for benching because to do it requires a lot of solvent. But here's where my idea comes into play.

For liquid cooling systems I've heard about some who put the radiator into an ice bath to get maximum cooling during their runs. So, why not do the same with an alcohol (whatever type you choose to use)/DICE slurry? We would take a five gallon bucket, cover it with several layers of insulation (including the lid) then fill it about 2/3 of the way with the solvent. Cover it with a thick towel and insert the fire extinguisher under the towel then discharge...a lot. lol You'll get a slurry usually around -90 to -75. With the lid on it can last quite some time, depending on the ambient temperature of course. Yes, this can all be done manually with chunks of dry ice chopped or chipped, it just takes longer. Anyway, the thought is, run the insulated tubing through a hole in the lid and have the radiator in the bucket. Use an appropriate coolant in the system (anti-freeze/water mix, cooling system safe alcohol, etc) and you should have quite an effective sub-zero system without the hassle of downtime while setting the system up for a DICE pot. Just keep an eye on solvent/DICE levels and top off if necessary...and make sure it's vented.

Just a thought anyway.

 

[hokiealumnus]

It's not a bad idea, but we pretty much do use a slurry for benching with a pot. We put acetone in the pot prior to any DICE. Then we crush the DICE and put it in the acetone.

You can run into problems benching a water loop at that kind of temperature too. I know at least one person who has cracked a radiator by putting a coffee can of DICE in a cooler with antifreeze, then submerging their radiator in that antifreeze. They're just not able to stand up to temperatures quite that cold.

You'll still have downtime too, because you will need to insulate the board against the cold. If you're tearing down, you might as well go with a pot.

Please don't think I'm trying to shoot your idea down, it's not a bad idea, it's just that practicalities get in the way. Never hurts to try to come up with new ways to do stuff!

 

[dejo]

nice thoughts there, and I agree with Hokie that we tend to use a slurry.

another thought is that it is usually the board tending to get wet that limits up time while at extreme temps, the boards just tend to get a rather heavy frost on components and often will just start causing issues with stability.

 

[TsunamiJuan]

we tend to use acetone and dice, since the acetone doesn't freeze at those temperatures, it helps improve the contact with the pot. Sometimes people use isoprohpyl and dice, if they are cold bugging to prevent the temperature from going to low.

 

[Weatherlite]

I didn't realize that water cooling had those kinds of limitations, but then again it would make sense, considering the fact that they're designed to cool the system using the ambient atmosphere. Well, it was a thought anyway! lol

 

[TsunamiJuan]

anytime you deal with something that cold its gonna cause insulation issues. There are ways to do it. But they are not 100% and can require additional levels of commitment.

High quality insulations like armaflex can certainly help with the problems, but you need to use alot of the stuff. There is an equation out there somewhere for figuring out how much thickness you need to prevent heatloss and condensation on piping. However at the same time you need to make sure that it bonds well on the inside of the insulation to piping aswell, or is atleast airtight.