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HAL-9000 · 05-15-2004, 07:22 PM

Have been reading up on CO2, and if such a coolant were to be used in a 'puter cooler, some issues would have to be addressed.

For one, the system can never reach STP unless the CO2 is in a gaseous state. At STP the compound directly sublimes from a gas to a solid, never develops a liquid phase. So the system would always have to be around half a megapascal of pressure whenever the engineered spec called for the CO2 to be a liquid in the system.

The other issue is thermal shock. Unlike say, a Vapochill, which ramps around -15C and cools down as it runs, is the coolant that comes out when the thing starts up in a CO2 rig will be incredibly cold to begin with. (Think CO2 BB gun cartridge leaking out). If the chip is really ramped, 200 watts of heat could meet 200 watts of cold basically, and crack the die. But if the chip is started to run, and then the coolant loop starts, it probably won't look like a chip anymore by the time the coolant gets there!

I am intrigued by the cascade coolers I see out there, but the reason CO2 interests me is it seems to offer the heat capacity to actually integrate a supercold computer into a reasonable volume, and not fill up a garage and burn multi-KW/hr's out of the wall.

05-15-2004, 07:22 PM	#5
HAL-9000 Cooling Savant Join Date: May 2004 Location: San Diego, CA Posts: 202	Properties of CO2 Have been reading up on CO2, and if such a coolant were to be used in a 'puter cooler, some issues would have to be addressed. For one, the system can never reach STP unless the CO2 is in a gaseous state. At STP the compound directly sublimes from a gas to a solid, never develops a liquid phase. So the system would always have to be around half a megapascal of pressure whenever the engineered spec called for the CO2 to be a liquid in the system. The other issue is thermal shock. Unlike say, a Vapochill, which ramps around -15C and cools down as it runs, is the coolant that comes out when the thing starts up in a CO2 rig will be incredibly cold to begin with. (Think CO2 BB gun cartridge leaking out). If the chip is really ramped, 200 watts of heat could meet 200 watts of cold basically, and crack the die. But if the chip is started to run, and then the coolant loop starts, it probably won't look like a chip anymore by the time the coolant gets there! I am intrigued by the cascade coolers I see out there, but the reason CO2 interests me is it seems to offer the heat capacity to actually integrate a supercold computer into a reasonable volume, and not fill up a garage and burn multi-KW/hr's out of the wall.