aqua ammonia as coolant

i was just browsing the web and saw something interesting. i was wondering if anyone here had ever played with this idea:

i was looking at specific heats of different fluids and saw that the only one comparible with water (at any temperature) - and even slightly better, is ammonia: 1 Btu/lb F//4.2 kJ/kg K (water) vs 1.1 Btu/lb F//4.6 kJ/kg K (ammonia at 32C). so that got me looking into water+ammonia (commonly known as aqua ammonia). other than being corrosive to copper and most of the metals we use in water cooling (silver and aluminum) its thermal properties actually look quite promising - and the corrosive properties can be negated with nickel coatings. at 33% (sweet spot for low temps) ammonia solution its freezing point is -100C, and its boiling point is 19C. i was looking specifically for a good sub-zero coolant that maintained water's high specific heat. this "looks" like it could be a promising candidate so i thought i would see if anyone here had ever played with it before - especially since it seems like it would be relatively easy to get (note: i don't know what percentage ammonia based cleaning products are actually at, but i do know they are basically "aqua ammonia")

thoughts/inputs ??!?!?!!

ammonia has been discussed multiple times before for same reason. But both high thermal conductance (ability to transfer heat well) and high specific heat (ability to absorb heat with minimum rise in temps) are important. Ammonia is ~15% higher specific heat, but ~15% lower thermal conductance than water at 32C.

We know from mixing ethylene glycol and water, that if you decrease both the thermal conductance and specific heat of water by 15% you increase temps about 2-3C on a loaded OCed cpu of ~ 185W. So even if a liquid exists that improves both thermal conductance and water 15%, you might decrease temps ~2-3C. But since you are decreasing thermal conductance 15%, and increasing specific heat 15%, if their was a temp improvement it wouldnt be enough to warrant the effort, the only interesting thing (aside from could it even be done reasonably) would be an experiment on which variable has greater impact and by what magnitude.

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Originally Posted by bds71

..other than being corrosive to copper and most of the metals we use in water cooling..

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Well, other than that Mrs. Lincoln, how did you like the play?

Being corrosive to copper is kind of a big deal.

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Being corrosive to copper is kind of a big deal.

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initially, i was only thinking about the blocks - which is fairly easily remedied by getting nickel plated blocks (it seems everything thing these days has a nickel plated option). but what i hadn't thought about at the time is the rest of the system. specifically, radiators - even though they wouldn't necessarily be used in a TEC chilled system. /shrug i don't know - if there is any other component other than blocks which are not readily nickel plated then that would obviosuly be a show-stopper. **compressor type system would obviously be a no-go, but since this is posted in the TEC section.....

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...but ~15% lower thermal conductance than water at 32C.

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ahhh - for the life of me, i could not find any thermal conductance info on aqua ammonia lol....i kind'a just assumed similar (uniform) properties compared to H2O. but something also to consider when comparing to eg/h2o - the common mixture with eth glycol is 40/60 or 50/50 (in order to get to a sufficient tolerance on the low end at around -38C) - and with this mixture you need +50 to 100% flow at 0-15C for equivalent perameters. with aqua ammonia (20-33%) you will likely have much better viscosity/flow at those temps. my comparison was basically thus:

Aqua Ammonia (compared to eth glycol): better viscosity than eg due to lower percentage solution, better than eg heat capacity (on par with h2o), same (lower w/respect to h2o) thermal conductance as eg, HIGHLY corrosive to Cu, Ag, Al, et al...

I never tried Aqua Ammonia, but I'll give it a shot next time I need a coolant.
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Dumitru from ammonia gas detector