This may sound crazy, but it just might be the case... - Page 2

snowwie · 11-20-2004, 02:56 AM

question

how about when the diff in temp between the fluid and the die is much greater? aka sub-ambient or chilled cooling? you guys are always talking about overclockability and temp stability

for a chilled water (or ethanol or something) setup, would something like xjinn's block be better than say...a white water?

i am thinking of liquid temps lower than -20c

Brians256 · 11-20-2004, 11:34 AM

The thermal coefficient shouldn't depend upon either hot or cold-side temps.

BTW, Joe did have Xjinn's block at one point, and gave it back to him. Xjinn was going to send it to pHaestus for testing but never did.

As for machining time... I made one too and it took me 2 months of lunch hours to do it (most of the time was spend doing setup and cleanup for each session with the drill press). Small holes are a pain to drill if they are long, and even if it was aluminum rather than copper, I still broke three drill bits. Worked well enough, though. I was running it for about 2 years.

jungle · 11-20-2004, 11:45 AM

the thermal coeeficient wouldnt change, but rate of heat transfer is also proportional to difference in temperature.

P = k(th. cof) * A(cross) * Delta T(temp) / L(length)

and thats about the extent my thermodynamics knowledge (just covering it now and i haven't exactly been to class a couple of times he he).

jungle

Brians256 · 11-20-2004, 11:57 AM

A block with a better thermal coefficient will always be better no matter what the dT across the block is (if all other factors are equal).

Where things might change is if you are dealing with factors that are not consistent across temperature such as viscuosity. This is a very real consideration when dealing with very low temperatures, as you will need to use coolants other than pure water. When adding glycol-type antifreezes or methanol or using non-water coolants, you may move to a design that is less sensitive to viscousity.

jungle · 11-20-2004, 12:44 PM

i dont disagree brians256. really, the block has nothing to do with the temp of the coolant. so basically all the delta T means is colder coolant = better cooling, which is pretty self-evident. judging by that equation, at least, a colder coolant would have the same effect on any block. so it would seem anyway.

jungle

11-20-2004, 02:56 AM	#26
snowwie Cooling Savant Join Date: Mar 2003 Location: New Jersey Posts: 154	question how about when the diff in temp between the fluid and the die is much greater? aka sub-ambient or chilled cooling? you guys are always talking about overclockability and temp stability for a chilled water (or ethanol or something) setup, would something like xjinn's block be better than say...a white water? i am thinking of liquid temps lower than -20c

11-20-2004, 11:34 AM	#27
Brians256 Pro/Staff Join Date: Oct 2001 Location: Klamath Falls, OR Posts: 1,439	The thermal coefficient shouldn't depend upon either hot or cold-side temps. BTW, Joe did have Xjinn's block at one point, and gave it back to him. Xjinn was going to send it to pHaestus for testing but never did. As for machining time... I made one too and it took me 2 months of lunch hours to do it (most of the time was spend doing setup and cleanup for each session with the drill press). Small holes are a pain to drill if they are long, and even if it was aluminum rather than copper, I still broke three drill bits. Worked well enough, though. I was running it for about 2 years.

11-20-2004, 11:45 AM	#28
jungle Cooling Neophyte Join Date: Nov 2004 Location: Louisiana Posts: 7	the thermal coeeficient wouldnt change, but rate of heat transfer is also proportional to difference in temperature. P = k(th. cof) * A(cross) * Delta T(temp) / L(length) and thats about the extent my thermodynamics knowledge (just covering it now and i haven't exactly been to class a couple of times he he). jungle

11-20-2004, 11:57 AM	#29
Brians256 Pro/Staff Join Date: Oct 2001 Location: Klamath Falls, OR Posts: 1,439	A block with a better thermal coefficient will always be better no matter what the dT across the block is (if all other factors are equal). Where things might change is if you are dealing with factors that are not consistent across temperature such as viscuosity. This is a very real consideration when dealing with very low temperatures, as you will need to use coolants other than pure water. When adding glycol-type antifreezes or methanol or using non-water coolants, you may move to a design that is less sensitive to viscousity.

11-20-2004, 12:44 PM	#30
jungle Cooling Neophyte Join Date: Nov 2004 Location: Louisiana Posts: 7	i dont disagree brians256. really, the block has nothing to do with the temp of the coolant. so basically all the delta T means is colder coolant = better cooling, which is pretty self-evident. judging by that equation, at least, a colder coolant would have the same effect on any block. so it would seem anyway. jungle

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