Copper Chimney

[EBFoxbat]

What if I take some copper stalk and attach it to my cpu? It would be like a foot tall heatsink. The top would be outside the case It wouldn't be too hard to cool once outside the case. Could I thermally insulate the copper sink inside the case so that it would only radiate out the top? Or would that cause a backup of heat and overheat the cpu ? any thoughts? if I did a poor job explaining, let me know and I'll draw up a picture! Thanks!

EBFoxbat

 

[Revx]

the larger it is the harder it is to cool, logic tells me that if you were to insulate the copper inside the case it would indead cause the copper to simply heat up more, in other words you can't cool one part and hope it cools next, i doubt if a foot tall heat sink would bring that much benefit, though i'm not completely read on to the thermal transfer capabilities of copper. I'd say a slightly taller than average heatsink would bring some performance incread. What really matters in cooling is surface area, not so much as weight. The more surface area, the better cooling, look at the swiftech models and all. If you could use the copper to make a slightly taller heatsink with a large surface area and then stick some fans on in a manner that would allow good flow then you would probably see some nice results. Just my 2 cents.

 

[Hoot]

The longer the lever, the greater force it exerts. In a tower case, that chimney is going to be pulling sideways on its mount. That can cause it to lift off on one side of the core slightly and the temperature of the core will rise, possibly to a dangerous level. Heat escapes from exposure to air. Do not insulate any of the chimney. The more surface are exposed to air, the better, regardless of whether it is inside or outside your case.

Hoot

 

[EBFoxbat]

Of coure the chimney would be supported as not to put any physical stress on the cpu. I thought is to carry the heat up the heatsink and let it escape into the air once its outside the case. I was thinking of maybe making it look like a heatsink, that is a bunch of copper ribbons parallel to each other. That was it looks like a really tall heat sink. I would then put the entire contraption of parellel copper ribbons in a pipe. On the bottom of the pipe there would be a fan pushing the heat (as it radiated off the ribbons) up the pipe and out the top without ever letting it enter the case. The pipe would be a poor heat conductor, so that it would not get hot and radiate its own heat. Perhaps I shall draw a picture. I'll post it in a hour or so.

 

[Revx]

i still say go for maximum surface area in a smaller heat sink idea, but that's just me.

 

[nihili]

Won't work.

Heat transfer depends on a number of variables. One of those variables is the distance that the heat needs to be conducted. The longer the distance, the poorer the heat transfer. So that foot long piece of copper won't conduct heat out of the case, or at least it will do so *very* inefficiently.

There's a variant of this idea that uses something called a heat pipe rather than solid copper. A heat pipe is a sealed metal tube that transfers heat along the pipe by convection of an internal substance rather than by conduction through the copper. A heat pipe could successfully transfer the heat out of the case. How well this would work would depend a lot on the particular heat pipe. Heat pipes tend to be pretty expensive though.

However, the idea of putting the whole thing in a pipe is a good one. Many people use "ducts". The idea is to put a pipe from the top of your heat sink to the outside of your case. The best is a short straight pipe directly to the side of your case, but a bent pipe running to the back of the case also works. With the pipe in place you can either exhaust the warm air directly out of the case (using fans of course) or supply fresh cool air to the heatsink.

nihili

 

[EBFoxbat]

What if I force the heat to go from one heat sink...radiate (through air) to another and so for and so on..movinf it up the pipe? Basically putting sever heatsinks mar apart?

 

[nihili]

What if I force the heat to go from one heat sink...radiate (through air) to another and so for and so on..movinf it up the pipe? Basically putting sever heatsinks mar apart?

The problem is that this is less efficient that simply moving the warm air out. You would get much better cooling by simply taking the extra heat sinks out of thetube so as to get better airflow through it.

nihili

 

[Hoot]

I sincerely think that the best place to provide surface area (heatsink) is as close to the source as possible. Certainly, some heat will migrate along the chimney, but it falls off pretty quickly the further away you get.

Hoot

 

[vandersl]

Just FYI:

Assume your CPU generates 80W of heat. Using a 2cm square 'pipe' insulated on the sides, drawing heat 15cm away from the CPU:
Q = TC * A * dT/dx
80W = 4.01W/cm*C * 4cm^2 * dT/15cm
dT = 74.8C

You would need a temperature differential of 75C to 'push' the heat from one end of the pipe to the other.

The only ways to reduce the required temperature difference is to
- increase the cross-sectional area
- decrease the length
- increase the thermal conductivity
- decrease the heat flow

It doesn't get any better breaking it into several HS's separated by air - once you get the heat into air, the most efficient way of moving the heat is to move the air.

 

[EBFoxbat]

crap.....another idea shot down......thanks for the info though...i'm learning

 

[Ugmore Baggage]

I wonder if a copper duct would be any better than a plastic one. If it was powered (by a fan) could it draw (even more) heat from the rest of the case?

Copper, good to the last drop!

 

[Revx]

well a copper duct would certainly have advantages over a platic one, such as helping disapate heat, but it'd probably minimal, that's why i just stick to ducting tubing.

 

[EBFoxbat]

there MUST be a better way to cool a case w/o using LN2 or using water. I'd love to be daring enough to use water. But I'm 17, 18 in a few weeks and my early birthday present was a loan for all my computer components, enought to build a completely new system to put in my room.

 

[nihili]

Actually a copper duct will perform worse than a plastic one. There are two cases to consider depending on whether the duct is intake or exhaust.

Intake
Since the duct is bringing cool air in from the outside, the interior of the duct is cooler that the exterior. Thus heat will transfer from the case into the duct. But this means that the air supplied to the heatsink is warmer than it otherwise would be. So you get worse cooling.

Exhaust
Since the duct it exhausting off the cpu, the interior of the duct is warmer than the exterior. Thus heat will transfer from the duct into the case. But this means that the air inside the case, which is where your heatsink gets its air, is warmer than it otherwise would be. So you get worse cooling.

In general you want the duct to be as insulated as possible. Having said that, I should also say that IMO typical ducts aren't long enough and don't have enough of a temperature differential to spend a lot of time worrying about it. But PVC will generally be cheaper and work better than copper for a duct. Ducting hose works well too, but the corrugation can impede airflow somewhat.

nihili

 

[nihili]

there MUST be a better way to cool a case w/o using LN2 or using water. I'd love to be daring enough to use water. But I'm 17, 18 in a few weeks and my early birthday present was a loan for all my computer components, enought to build a completely new system to put in my room.

Get a good heatsink, PAL 8045 or better. Build ducts for both intake and exhaust (this is tricky). Add a couple moderate case fans and you should do well. I would use three identical fans on the duct system.

nihili