Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button

Home > Press > Better surfaces could help dissipate heat: Heat transfer in everything from computer chips to powerplants could be improved through new analysis of surface textures

Time-lapse images of vapor bubble departure on the microstructured surfaces (a-d).
Image: Kuang-Han Chu et al, Applied Physics Letters
Time-lapse images of vapor bubble departure on the microstructured surfaces (a-d).

Image: Kuang-Han Chu et al, Applied Physics Letters

Abstract:
Cooling systems that use a liquid that changes phase — such as water boiling on a surface — can play an important part in many developing technologies, including advanced microchips and concentrated solar-power systems. But understanding exactly how such systems work, and what kinds of surfaces maximize the transfer of heat, has remained a challenging problem.

Better surfaces could help dissipate heat: Heat transfer in everything from computer chips to powerplants could be improved through new analysis of surface textures

Cambridge, MA | Posted on June 26th, 2012

Now, researchers at MIT have found that relatively simple, microscale roughening of a surface can dramatically enhance its transfer of heat. Such an approach could be far less complex and more durable than approaches that enhance heat transfer through smaller patterning in the nanometer (billionths of a meter) range. The new research also provides a theoretical framework for analyzing the behavior of such systems, pointing the way to even greater improvements.

The work was published this month in the journal Applied Physics Letters, in a paper co-authored by graduate student Kuang-Han Chu, postdoc Ryan Enright and Evelyn Wang, an associate professor of mechanical engineering.

"Heat dissipation is a major problem" in many fields, especially electronics, Wang says; the use of phase-change liquids such as boiling water to transfer heat away from a surface "has been an area of significant interest for many decades." But until now, there has not been a good understanding of parameters that determine how different materials — and especially surface texturing — might affect heat-transfer performance. "Because of the complexities of the phase-change process, it's only recently that we have an ability to manipulate" surfaces to optimize the process, Wang says, thanks to advances in micro- and nanotechnology.

Chu says a major potential application is in server farms, where the need to keep many processors cool contributes significantly to energy costs. While this research analyzed the use of water for cooling, he adds that the team "believe[s] this research is generalizable, no matter what the fluid."

The team concluded that the reason surface roughness greatly enhances heat transfer — more than doubling the maximum heat dissipation — is that it enhances capillary action at the surface, helping keep a line of vapor bubbles "pinned" to the heat transfer surface, delaying the formation of a vapor layer that greatly reduces cooling.

To test the process, the researchers made a series of postage-stamp-sized silicon wafers with varying degrees of surface roughness, including some perfectly smooth samples for comparison. The degree of roughness is measured as the portion of the surface area that can come into contact with a liquid, as compared to a completely smooth surface. (For example, if you crumpled a piece of paper and then flattened it back out so that it covered an area half as large as the original sheet, that would represent a roughness of 2.)

The researchers found that systematically increasing roughness led to a proportional increase in heat-dissipation capability, regardless of the dimensions of the surface-roughening features. The results showed that a simple roughening of the surface improved heat transfer as much as the best previous techniques studied, which used a much more complex process to produce nanoscale patterns on the surface.

In addition to the experimental work, the team developed an analytical model that very precisely matches the observed results. Researchers can now use that model to optimize surfaces for particular applications.

"There has been limited understanding of what kind of structures you need" for effective heat transfer, Wang says. This new research "serves as an important first step" toward such analysis.

It turns out heat-transfer is almost entirely a function of a surface's overall roughness, Wang says, and is based on the balance between various forces acting on the vapor bubbles that serve to dissipate heat: surface tension, momentum and buoyancy .

While the most immediate applications would likely be in high-performance electronic devices, and perhaps in concentrated solar-power systems, the same principles could apply to larger systems such as powerplant boilers, desalination plants or nuclear reactors, the researchers say.

Satish Kandlikar, a professor of mechanical engineering at the Rochester Institute of Technology who was not involved in this work, says it is "quite remarkable to achieve heat fluxes" as great as these "on silicon surfaces without complex micro- or nanofabrication process steps. This development opens doors to a new class of surface structures combining micro- and nanoscale features." He adds that the MIT team "should be complimented for this major research finding. It will provide new directions especially in chip-cooling applications."

The work was supported by the Battelle Memorial Institute and the Air Force Office of Scientific Research. The team received help in fabrication from the MIT Microsystems Technology Lab.

Written by: David Chandler, MIT News Office

####

For more information, please click here

Contacts:
Caroline McCall
Media Relations Assistant

phone: 617-253-1682

Copyright © MIT

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Ultra-flat circuits will have unique properties: Rice University lab studies 2-D hybrids to see how they differ from common electronics July 25th, 2016

Attosecond physics: Mapping electromagnetic waveforms July 25th, 2016

Borrowing from pastry chefs, engineers create nanolayered composites: Method to stack hundreds of nanoscale layers could open new vistas in materials science July 25th, 2016

Physics

Ultra-flat circuits will have unique properties: Rice University lab studies 2-D hybrids to see how they differ from common electronics July 25th, 2016

Attosecond physics: Mapping electromagnetic waveforms July 25th, 2016

Govt.-Legislation/Regulation/Funding/Policy

Designing climate-friendly concrete, from the nanoscale up: New understanding of concrete’s properties could increase lifetime of the building material, decrease emissions July 25th, 2016

Ultra-flat circuits will have unique properties: Rice University lab studies 2-D hybrids to see how they differ from common electronics July 25th, 2016

Borrowing from pastry chefs, engineers create nanolayered composites: Method to stack hundreds of nanoscale layers could open new vistas in materials science July 25th, 2016

Integration of novel materials with silicon chips makes new 'smart' devices possible July 25th, 2016

Chip Technology

Ultra-flat circuits will have unique properties: Rice University lab studies 2-D hybrids to see how they differ from common electronics July 25th, 2016

Attosecond physics: Mapping electromagnetic waveforms July 25th, 2016

Borrowing from pastry chefs, engineers create nanolayered composites: Method to stack hundreds of nanoscale layers could open new vistas in materials science July 25th, 2016

Integration of novel materials with silicon chips makes new 'smart' devices possible July 25th, 2016

Discoveries

Attosecond physics: Mapping electromagnetic waveforms July 25th, 2016

Borrowing from pastry chefs, engineers create nanolayered composites: Method to stack hundreds of nanoscale layers could open new vistas in materials science July 25th, 2016

Integration of novel materials with silicon chips makes new 'smart' devices possible July 25th, 2016

Accurate design of large icosahedral protein nanocages pushes bioengineering boundaries: Scientists used computational methods to build ten large, two-component, co-assembling icosahedral protein complexes the size of small virus coats July 25th, 2016

Announcements

Borrowing from pastry chefs, engineers create nanolayered composites: Method to stack hundreds of nanoscale layers could open new vistas in materials science July 25th, 2016

Integration of novel materials with silicon chips makes new 'smart' devices possible July 25th, 2016

Accurate design of large icosahedral protein nanocages pushes bioengineering boundaries: Scientists used computational methods to build ten large, two-component, co-assembling icosahedral protein complexes the size of small virus coats July 25th, 2016

XEI Scientific Partners with Electron Microscopy Sciences to Promote and Sell its Products in North and South America July 25th, 2016

Military

Ultra-flat circuits will have unique properties: Rice University lab studies 2-D hybrids to see how they differ from common electronics July 25th, 2016

Borrowing from pastry chefs, engineers create nanolayered composites: Method to stack hundreds of nanoscale layers could open new vistas in materials science July 25th, 2016

Integration of novel materials with silicon chips makes new 'smart' devices possible July 25th, 2016

Accurate design of large icosahedral protein nanocages pushes bioengineering boundaries: Scientists used computational methods to build ten large, two-component, co-assembling icosahedral protein complexes the size of small virus coats July 25th, 2016

Energy

Designing climate-friendly concrete, from the nanoscale up: New understanding of concrete’s properties could increase lifetime of the building material, decrease emissions July 25th, 2016

An accelerated pipeline to open materials research: ORNL workflow system unites imaging, algorithms, and HPC to advance materials discovery and design July 24th, 2016

Researchers discover key mechanism for producing solar cells: Better understanding of perovskite solar cells could boost widespread use July 21st, 2016

The future of perovskite solar cells has just got brighter -- come rain or shine: Korean researchers at POSTECH have succeeded in developing high-efficiency perovskite solar cells that retain excellent performance over two months in a very humid condition July 21st, 2016

Solar/Photovoltaic

An accelerated pipeline to open materials research: ORNL workflow system unites imaging, algorithms, and HPC to advance materials discovery and design July 24th, 2016

Researchers discover key mechanism for producing solar cells: Better understanding of perovskite solar cells could boost widespread use July 21st, 2016

The future of perovskite solar cells has just got brighter -- come rain or shine: Korean researchers at POSTECH have succeeded in developing high-efficiency perovskite solar cells that retain excellent performance over two months in a very humid condition July 21st, 2016

Scientists develop way to upsize nanostructures into light, flexible 3-D printed materials: Virginia Tech, Livermore National Lab researchers develop hierarchical 3-D printed metallic materials July 20th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic