Dielectric Coolants

[ColdFlo]

Hello,

I'm doing an extreme version of the Drewmeister AC-X, but pressure testing my rig with regular water has scared me half to death about 3 times now so my attention is turning to dielectric coolants. I understand that fluorinert is 300 a gallon along with Exxon Coolanol, Fluid Xp is 100 a gallon, and PC ICE is like 80 a gallon, but, the thing is, I need 2 gallons, and if I have another spill I can't be forking out 200 dollars or more everytime. Besides, I read PC ICE is really just conductance free, not really dielectric, and Fluid XP I have found few reviews on. Not only that, but I think slipperiness of the coolant is also another consideration along with the fact I am using a sealant on my heat exchanger, and the coolant must be inert with respect to the strength of the sealant.

Searches for a cheaper less commercial alternative have turned up mineral oil which I have read spoils overtime and only reaches -20c im looking a -50c or more, and the synthetic blends and full synthetics I have had trouble finding. Besides, I'm not sure with the viscosity of these fluids that they are even a viable option. Another cheap alternative I came up with was brake fluid or silicone brake fluid which comes in a variety of dots, but I also have concerns about pump heat, life and compatibility with my white water les especially since I am determined to get my hands on an Iwake RD-30. I tried ask a scientist the website but they said my question was outside the scope of thier site prolly cause I could make some money with the ans So, I'm kind of at a loss at this point Any help anyone could provide would be greatly appreciated.

[Ice Czar]

you have found the rub

both expensive and with a viscosity that requires or encourages welded lines and canned pumps
is exactly why you don't see most of them being adopted

when you push past that however is when you learn about employing at least fluorinert as a phase change coolant massively increasing its heat transfer potential

I can think of transfer fluids that are suitable for your temperature range
but not that are also dielectric, affordable, with a viscosity that allows for affordable sealing and pumping.

[ColdFlo]

Ok Ive been getting as extreme as I can on this all day. I've rejected all the possiblities above at least by themselves. I know it would be dangerous, but what about pure methanol and zerex racing coolant? No one knows the composition of the Zerex and I don't have any at the moment. Also will mineral oil dissolve in methanol or some other kind of oil also used in conjunction with the racing coolant or another corrosion inhibitor? Maybe fire retardants would be an area to look into also....

[Ice Czar]

you want this

not sure where the charts are if they are anywhere still (they generally escape even the internet archive)

http://forums.procooling.com/vbb/pri...2&page=1&pp=25

most of your "cold" range heat transfer fluids are going to be hydrocarbon based
I did considerable research into this about 4 years ago (which is about as old as that thread cited )
the expensive Perfluorocarbons are really the best solution, but as you have mentioned, sealing against them, the expense is tough, I actually have some pics of the stainless steel plumbing on the Cray that used to be up at NCAR. Unfortunately they are on a RAID array that is currently offline.

Methanol's drawbacks as both flammable and toxic require nearly the same level of plumbing and precautions that make the flurocarbons such a pain, I came to the conclusion - in for a dime in for a dollar

there are also brine solutions but not as low as your talking about
methanol is a solution but with different tradeoffs

expand your searching to spray cooling
and dual phase change microchannels
that might be the justification youd need to go back to Perfluorocarbons

the trick is finding a pump, getting the plumbing done and making it a totally closed system that doesnt have evaporative issues.

[Butcher]

Brine solutions are unlikely to be dielectric also.

FluidXP is mainly water FWIW, similar stuff to PC ICE.

I can't really see any alternatives to fluorinet (or similar), especially if you're concerned about leaks. Unless the system is in a very well ventilated area, a methanol leak is likely to be more than just an inconvenience - it could be life threatening.
Make no mistake about it, methanol is a dangerous toxic chemical and should not be used lightly. You can quite easily kill or blind yourself with methanol vapours if you have a couple of gallons of it kicking about.

[Ice Czar]

Originally Posted by Butcher

Brine solutions are unlikely to be dielectric also.

highly unlikely to be dielectric

still far safer than methanol, better to fry than burn
not to mention Methanol doesnt play well with aluminum
a methanol leak would likely qualify you as a superfund site
if it didnt catch fire that is.

[bigben2k]

Methanol, aka methyl alcohol, combined with water should do it, but you'll have to mix it right because as stated above, you want to stay away from pure methanol, as much as possible.

Here's the recipe:
http://www.overclockers.com/articles609/
ref page 2; looks like 50:50 will get you near -50deg C.

As previously noted, keep in mind that you'll have to keep your loop *sealed* to prevent vapors from escaping.