Watercooling in the new scientist

[Groth]

Yes, there's a bunch of different alcohols, but they all suck.

[AngryAlpaca]

I'm with stupid!

If they do it perfectly, 200mL/minute can handle a LOT of heat. However, the block isn't perfect, as Cathar points out, and I doubt they can do much with the space they have radiator-wise.

[Fyber]

The point your missing is that the radiator won't neccessarily look like the ones we have today. Looking at the maya renderings, it looks more like an Aerocool heatsink that will be mounted in a remote location. It's not going to have the same cooling properties that regular heatercores/automotive radiators have. It'll be designed differently.

Cathar, as you have much more experience with cooling, I'll agree with you.

It should do fine as an OEM heatsink, and I doubt it's been perfected yet. I'm sure they'll figure out more efficient ways of conducting heat before it's final release to the OEM market.

Speaking of microchannels Cathar, how's that microchannel block coming along (Hydra I believe)?

[Cathar]

Originally Posted by Fyber

Speaking of microchannels Cathar, how's that microchannel block coming along (Hydra I believe)?

I've pretty much given up on micro-channels. The smallest channel block I had made up was 0.5mm. It performed well enough but really only roughly matched the 1mm channelled White Water as the impingement nozzle becomes largely ineffectual as the channels are reduced, and it's better/easier to just do the standard one-side-in to one-side-out style of channels once you get below about 0.8mm channel width.

The issue with smaller channels (truly micro-channels) that I could see was that as channel size is reduced further, meaning much below 0.5mm, the pressure drop required to push the water through those channels starts to climb fairly steeply, meaning that the pumps that hobbyists use today start to struggle to push even moderate amounts of flow.

My predictions were that somewhere around 0.2mm was the practical channel width limit for the pumps hobbyists typically use. It's possible to make 0.2mm channelled blocks in copper using photochemical resist etching. Given that we need to cool about a 20x20mm area to cover all types and orientations of CPUs, a 0.2mm wide set of channels with appropriately sized channel walls would present a total block restriction that would make the block barely able to achieve 1LPM flow rates even for higher-end pressure hobbyist pumps (MCP600, Mag3, Laing D4).

Now 1LPM, with water, is what I personally estimate the balance point is in terms of the point where the thermal capacity of the liquid flow through a block starts to become an increasingly dominant source of total thermal resistance within the block's operation regardless of how high h, being the rate of thermal convection, is raised.

The other issue with making the channels smaller and then raising the pressure is pump heat. This is something that the EK pumps that Cooligy are looking at are an absolute necessity to solve. I do see a problem here though, Cooligy keep quoting 1W pump power consumption, but at some of the flow rates and estimated pressure drops that are being quoted, I see that 1W must be a lower end figure, and that to achieve some of what they're predicting to happen, pump power draw (according to the physics) must be approaching 10W or more.

Cooligy's graph:

http://www.cooligy.com/images/microchannel2.gif

Is true, but only for a fixed flow rate. Once we start factoring in pressure drops, and perhaps more correctly plotting a 3-D surface of pressure-drop vs channel-width vs h, we would see a surface that was hyperbolaic for h as well as for pressure-drop. Plot a flat realistically achievable pressure-drop plane through the surface and the picture doesn't look so attractive any more.

Look, I'm not out to discredit Cooligy at all, but instead to critically analyse what they have presented so far. It does look like a decent form of waterblock technology, but I absolutely will not swallow the marketing material hook, line and sinker without first applying what I understand, have experimented, and can see, to the material as it is presented.

[jlrii]

The only way I can see this technology really working well is by 1) raising flow rates, 2) setting it up as a heat tube that incorparates the micropump, which means the entire system must be sealed (read oem), 3) incorparating the channels into the design of the CPU (read expensive, oem, and years down the road). In any case whatever is used for materials would have to insure that absolutlely no contaminants are able to form in the system to avoid blocking the pump and channels. In short and if it can be made to work, I would not expect to see this sort of cooling for quite some time. I do find it interesting but it is definetly not anything that will be DIY.

[jlrii]

Originally Posted by Groth

Yes, there's a bunch of different alcohols, but they all suck.

Unless used in a heat tube, in which case water would be the better choice anyways unless -0c cooling is used.

[AngryAlpaca]

Heat pipes with water can actually go below zero. Well below zero in some cases. With liquids, the pressure is lowered, so they stay in liquid and gas forms for a wider temperature range. 1LPM is scary. It's so small! 10W for 200mL per minute is TERRIBLE. That makes the Mag 3's and the MD20RZ's heat figures look good.

[jlrii]

Originally Posted by AngryAlpaca

Heat pipes with water can actually go below zero. Well below zero in some cases. With liquids, the pressure is lowered, so they stay in liquid and gas forms for a wider temperature range. 1LPM is scary. It's so small! 10W for 200mL per minute is TERRIBLE. That makes the Mag 3's and the MD20RZ's heat figures look good.

I thought that water under a lower pressure froze @ the same point hmmm...

[jlrii]

actually water under a vacuum of .006 atm freezes @ -.01c

From Thermacore:
"Q. Do water heat pipes freeze?
A. Yes, heat pipe working fluids including water maintain the normal freezing point. Properly designed heat pipes, however, will not be damaged by the freezing and thawing of the working fluid. Heat pipes will not operate until the temperature rises above the freezing temperature of the fluid."

[Cathar]

Originally Posted by AngryAlpaca

Heat pipes with water can actually go below zero. Well below zero in some cases. With liquids, the pressure is lowered, so they stay in liquid and gas forms for a wider temperature range.

That's true for most liquids, however for water, as pressure is increased then water will remain a liquid at lower temperatures.

In fact, under a pressure of ~210MPa (~30500 PSI), water can remain as a liquid down to -22C.

[kronchev]

Originally Posted by Cathar

That's true for most liquids, however for water, as pressure is increased then water will remain a liquid at lower temperatures.

In fact, under a pressure of ~210MPa (~30500 PSI), water can remain as a liquid down to -22C.

yeh, if I had my scanner up i'd scan the state chart for water. thats whats great about it, its the only chemical that remains liquid the higher pressure/lower temp you go.

[AngryAlpaca]

Oh yeah, that would make sense... Forgot about ice being less dense than water.

[AngryAlpaca]

Cathar, you say you gave up on the microchannels GPU block. Can't you do a design similar to the Cascade? It doesn't hurt flow too much, and it's the best cooling around...

[Cathar]

Originally Posted by AngryAlpaca

Cathar, you say you gave up on the microchannels GPU block. Can't you do a design similar to the Cascade? It doesn't hurt flow too much, and it's the best cooling around...

That's exactly what I'm doing...

[Pears0]

Originally Posted by Groth

No moving parts does not mean no breakdowns.

They've been talking this up for a while now; I'll believe it when I see independent tests.

If no moving parts means it cant breakdown, y the hell cpu's fail (afater many years of use/abuse) and psu fail eventhough they havent been over loaded?

No moving parts means its simpler so is less likly to fail and/or will last longer.

Everything fails eventually. else it would b possible for life to become immortal, n i dont c that happening, ever. LOL

EDIT: sorry, i read that as dose mean no break downs. Man is my concerntration all over the place. I reall shouldnt work l8 nites!