Subzero chiller for top rigs from A/C

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Have decided to make chiller from window airconditioner. Got already one in good working condition.

Just power on and got almost -20°C on evaporator



My goal is to get as low temperatures as possible, both with high wattage rating (600W+, better more) for cooling bench right with i7 CPU and two dual-chip or four single chip GPU's.

Engine is working on R22, specs and detailed pics will post bit later.

First step I will try is to submerge evaporator totally into insulated plastic tank and fill it with automotive antifreeze (rated -45). I'll use rotary pump to keep antifreeze flowing. But I'm afraid about power loss on tubing from chiller to PC and back. Will it usable to get zero or less temperature on waterblocks, or better not to waste time and make tube-in-tube HX?

Also there are two possible usage variants - with ~3-4 m of 1/2" (12.5mm tubing) or second (more badly for performance, but best for long benchies, coz chiller will be placed on a balkony, and only cooled pipes go into room with rig) - 6-10m of 1/2" tubing.

Did anybody tried long pipes for chillers? So, little confused what to make first to get good frost on hardware

[equinox1]

my piping is probably longer than most people use, maintains -10c
http://www.xtremesystems.org/forums/...d.php?t=234693

[Plan.B]

for your setup I would start with about 2/3 distilled water and 1/3 denatured alcohol or auto antifreeze and see what happens. too slushy, then add more denatured or antifreeze. for tubing i use tygon 3/4 od & 1/2 id. longer tubing runs should not result in substantial cooling loss if they are properly insulated. insulate with armaflex (or generic equivalent, 1/4 - 3/4 inch thickness), armaflex foam tape, and/or foam pipe insulation (from a hardware store).

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Spend few weeks to find good tank for chiller.



Found one, but it's lacks of height, to cover all the evaporator. Still decided to try with this.



Insulate,insulate,insulate. ~5-10cm of foam around all sides except top. Top will be closed with isolation sheets,which are used to building insulation.



First run with empty tank. TC hooked to evaporator rad.



Filled 5L of antifrezze, ~20min runtime. Pump is 65W WILO circular.



Frosty WB

After next 20mins temp stopped at +4..WTF?



Doh, that antifrezze FROZEN at -26°C on chiller evaportator.. Whoa...



Now have to find good antifreeze

[apt403]

Ethanol or isopropanol maybe? Ethanol freezes at about -114c, and 99% isopropanol at about -89c. Ethylene glycol freezes at about -13, so automotive antifreeze isn't the right choice unless you use propylene gycol. Less toxic, and it freezes at -60c IIRC.

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Some initial chiller testing was done already

Lowest temp with STOCK AC unit, without even gas recharge. Just emply insulated tank with evaporator inside



Hooked to simple watercooling loop with 65W pump and single CPU waterblock
Rig used:

QX9650 retail
Gigabyte X48-DS5
2x512MB Aeneon DDR2-667
8800GTX Engineering sample
Enermax Revolution 1250W



Pump top was bit frosty after 10min
First test was done without any insulation of water loop, so don't say about this anything

Also phase pipes need insulation too.



Tank was filled with only 5L of ethylene-glycol. It's didn't freeze this time, yeah.



Temps was ~-20°C on WB intake, negative during idle, +10...+20°C with max loads on all cores (wprime), with QX9650 volted at 1.7-1.75V. I think it's good for system without any insulation and stock AC unit

MAX valid:



SuperPi



Had some 1M runs with 5GHz, but failed to save them :-D

Next step : full insulation, and run with frankenshtein 7800GTX GPU chilled and same C2E 9650 chilled too.