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The new cooler design uses copper-coated carbon nanotubes.  (Source: Wikimedia Commons)

It essentially offers a pumpless liquid cooler, which can dissipate massive amounts of heat by boiling the cooling fluid -- water -- in microchannels.  (Source: School of Mechanical Engineering, Purdue University)

Purdue has implemented and tested the nanotech cooler and expects to bring it to market with a few years.  (Source: Purdue University School of Mechanical Engineering)
Forget traditional metal block coolers a nanowick could remove 10 times the heat of current chip designs

A collaboration of university researchers and top industry experts has created a pumpless liquid cooling system that uses nanotechnology to push the limits of past designs.

One fundamental computing problem is that there are only two ways to increase computing power -- increase the speed or add more processing circuits.  Adding more circuits requires advanced chip designs like 3D chips or, more traditionally, die shrinks that are approaching the limits of the laws of physics as applied to current manufacturing approaches.  Meanwhile, speedups are constrained by the fact that increasing chip frequency increases power consumption and heat, as evidence by the gigahertz war that peaked in the Pentium 4 era.

A team led by Suresh V. Garimella, the R. Eugene and Susie E. Goodson Distinguished Professor of Mechanical Engineering at Purdue University, may have a solution to cooling higher frequency chips and power electronics.  His team cooked up a bleeding edge cooler consisting of tiny copper spheres and carbon nanotubes, which wick coolant passively towards hot electronics.

The coolant used is everyday water, which is transferred to an ultrathin "thermal ground plane" -- a flat hollow plate.

The new design can handle an estimated 10 times the heat of current computer chip designs.  That opens the door to higher frequency CPUs and GPUs, but also more efficient electronics in military and electric vehicle applications.

The new design can wick an incredible 550 watts per square centimeter.  Mark North, an engineer with Thermacore comments, "We know the wicking part of the system is working well, so we now need to make sure the rest of the system works."

The design was first verified with computer models made by Gamirella, Jayathi Y. Murthy, a Purdue professor of mechanical engineering, and doctoral student Ram Ranjan.  Purdue mechanical engineering professor Timothy Fisher's team then produced physical nanotubes to implement the cooler and test it in an advanced simulated electronic chamber.

Garimella describes this fused approach of using computer modeling and experimentation hand in hand, stating, "We have validated the models against experiments, and we are conducting further experiments to more fully explore the results of simulations."

Essentially the breakthrough offers pumpless water-cooling, as the design naturally propels the water.  It also uses microfluidics and advanced microchannel research to allow the fluid to fully boil, wicking away far more heat than similar past designs. 

This is enabled by smaller pore size than previous sintered designs.  Sintering is fusing together tiny copper spheres to form a cooling surface.  Garimella comments, "For high drawing power, you need small pores.  The problem is that if you make the pores very fine and densely spaced, the liquid faces a lot of frictional resistance and doesn't want to flow. So the permeability of the wick is also important."

To further improve the design and make the pores even smaller the team used 50-nm copper coated carbon nanotubes.

The research was published in this month's edition of the peer-reviewed journal International Journal of Heat and Mass Transfer.

Raytheon Co. is helping design the new cooler.  Besides Purdue, Thermacore Inc. and Georgia Tech Research Institute are also aiding the research, which is funded by a Defense Advanced Research Projects Agency (DARPA) grant.  The team says they expect commercial coolers utilizing the tech to hit the market within a few years.  Given that commercial cooling companies (Thermacore, Raytheon) were involved, there's credibility in that estimate.



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RE: Help me understand...
By MrTeal on 7/27/2010 10:10:45 AM , Rating: 2
The numbers you give are completely different quantities. One is thermal conductivity in Watts per meter Kelvin, the other is not really a formal unit, it's just power dissipated per unit area. It's kind of a useless measurement since it doesn't indicate the heat delta.

But yeah, if you assume a 1cmx1cm area, and if you have to move the heat 1cm up from the surface of the chip, that's
[(6600W/mK)*0.01m*0.01m/0.01m], or 66W/k for the number you quoted. IE, you can move 66W of heat per degree of temperature difference. Start adding in some interface losses, and it seems like a pretty good number they posted.


RE: Help me understand...
By MrTeal on 7/27/2010 10:17:25 AM , Rating: 5
I should probably also point out that, if one reads the article, they aren't actually using the CNTs as a bulk transfer medium. The system is basically a traditional heat pipe design, but with a smaller pipe size that's stuffed with copper coated CNTs.

Not that I can blame anyone for not reading the original article, it takes awhile to find the damned thing when you have to mouse over 20 links to find the one that doesn't link back to another DailyTech article. How about placing the original article in the subheading or footer of every post so that we can find it, DT?


RE: Help me understand...
By KillerNoodle on 7/27/2010 10:56:37 AM , Rating: 2
WOW...After reading the original article I understand how they are using nanotubes....They aren't . They are using particles of copper bonded to one another not copper coated nanotubes.

The only mention of nano in the article is the authors' institution of research.

This article seems to be an evaluation of a pore size's ability to evaporate a fluid, in this case water.


RE: Help me understand...
By MrTeal on 7/27/2010 11:13:50 AM , Rating: 2
quote:
The researchers are creating smaller pores by "nanostructuring" the material with carbon nanotubes, which have a diameter of about 50 nanometers, or billionths of a meter. However, carbon nanotubes are naturally hydrophobic, hindering their wicking ability, so they were coated with copper using a device called an electron beam evaporator.


quote:
The carbon nanotubes were produced and studied at the university's Birck Nanotechnology Center in work led by mechanical engineering professor Timothy Fisher.


My impression was that they actually are using carbon nanotubes in their test setup, not so much for the properties of CNTs as much as their nano-ness. They're just using them to get the small feature size they need to get really strong wicking. It's hard to tell even from the original article, though. You'd probably have to read the actual journal article to get a better idea.


RE: Help me understand...
By KillerNoodle on 7/27/2010 11:22:19 AM , Rating: 2
When you said original article I thought you meant the journal article so that is what I was reading when I commented about not using nanotubes. The last link in the DT article takes you to the published journal article.


RE: Help me understand...
By KillerNoodle on 7/27/2010 11:42:16 AM , Rating: 2
Just read the Purdue press release... http://www.purdue.edu/newsroom/research/2010/10072...

I really am lost now as to where the nanotubes are coming into play.

The press release talks about nanotubes and says that
quote:
The findings are detailed in a research paper appearing online this month in the International Journal of Heat and Mass Transfer and will be published in the journal's September issue. The paper was written by mechanical engineering doctoral student Justin Weibel, Garimella and Mark North, an engineer with Thermacore, a producer of commercial heat pipes located in Lancaster, Pa.

But the journal article referenced says nothing about nanotubes.

Are they getting their research mixed up?


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