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

Physics

Searching for errors in the quantum world September 21st, 2018

News and information

Searching for errors in the quantum world September 21st, 2018

Viral RNA sensing: Optical detection of picomolar concentrations of RNA using switches in plasmonic chirality September 21st, 2018

UT engineers develop first method for controlling nanomotors: Breakthrough for nanotechnology as UT engineers develop first method for switching the mechanical motion of nanomotors September 21st, 2018

Nanobiotix: Update on Head and Neck Phase I/II Trial with NBTXR3 and Other program data presented at ImmunoRad 2018 September 20th, 2018

Govt.-Legislation/Regulation/Funding/Policy

UT engineers develop first method for controlling nanomotors: Breakthrough for nanotechnology as UT engineers develop first method for switching the mechanical motion of nanomotors September 21st, 2018

Researchers develop microbubble scrubber to destroy dangerous biofilms September 19th, 2018

Researchers managed to prevent the disappearing of quantum information September 14th, 2018

New photonic chip promises more robust quantum computers September 14th, 2018

Chip Technology

Researchers managed to prevent the disappearing of quantum information September 14th, 2018

New devices based on rust could reduce excess heat in computers: Physicists explore long-distance information transmission in antiferromagnetic iron oxide September 14th, 2018

New photonic chip promises more robust quantum computers September 14th, 2018

How a tetrahedral substance can be more symmetrical than a spherical atom: A new type of symmetry September 14th, 2018

Discoveries

Searching for errors in the quantum world September 21st, 2018

Viral RNA sensing: Optical detection of picomolar concentrations of RNA using switches in plasmonic chirality September 21st, 2018

UT engineers develop first method for controlling nanomotors: Breakthrough for nanotechnology as UT engineers develop first method for switching the mechanical motion of nanomotors September 21st, 2018

NUS researchers invent new test kit for quick, accurate and low-cost screening of diseases: Test results are denoted by a color change and could be further analyzed by a smartphone app, making it attractive as a point-of-care diagnostic device September 19th, 2018

Announcements

Searching for errors in the quantum world September 21st, 2018

Viral RNA sensing: Optical detection of picomolar concentrations of RNA using switches in plasmonic chirality September 21st, 2018

UT engineers develop first method for controlling nanomotors: Breakthrough for nanotechnology as UT engineers develop first method for switching the mechanical motion of nanomotors September 21st, 2018

Nanobiotix: Update on Head and Neck Phase I/II Trial with NBTXR3 and Other program data presented at ImmunoRad 2018 September 20th, 2018

Military

Ultracold atoms used to verify 1963 prediction about 1D electrons: Rice University, University of Geneva study focuses on theory that's increasingly relevant to chipmakers September 5th, 2018

Neutrophil nanosponges soak up proteins that promote rheumatoid arthritis September 3rd, 2018

Virginia Tech researchers develop novel process to 3D print one of the strongest materials on Earth August 23rd, 2018

Biomimetic micro/nanoscale fiber reinforced composites August 10th, 2018

Energy

Leti Announces EU Project to Develop Powerful, Inexpensive Sensors with Photonic Integrated Circuits: REDFINCH Members Initially Targeting Applications for Gas Detection and Analysis For Refineries & Petrochemical Industry and Protein Analysis for Dairy Industry September 19th, 2018

S, N co-doped carbon nanotube-encapsulated CoS2@Co: Efficient and stable catalysts for water splitting September 10th, 2018

September 5th, 2018

Rice U. lab probes molecular limit of plasmonics: Optical effect detailed in organic molecules with fewer than 50 atoms September 5th, 2018

Solar/Photovoltaic

September 5th, 2018

NUST MISIS scientists present metamaterial for solar cells and nanooptics July 23rd, 2018

Northwestern researchers achieve unprecedented control of polymer grids: Materials could find applications in water purification, solar energy storage, body armor June 22nd, 2018

Team achieves two-electron chemical reactions using light energy, gold May 15th, 2018

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



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project