Monday, June 14, 2010

Nanostructure Coating Wicks Heat Faster





This comes as a complete surprise.  Heat transfer is the engineering problem facing everything we fabricate that uses any energy.  It has been a limiting factor off and on with electronics.
Now we have a simple protocol that will be trivial to implement.
It turns out that a simple coating of super thin zinc oxide will wick the heat to the surface as fast as it is produced.  It will not take the engineers long to coat everything in sight with this.
Who would have imagined such a simple solution to the heat dissipation problem?

Nanostructure coatings remove heat four times faster
19:56 June 10, 2010



In a finding that could well revolutionize cooling technology as we know it, researchers at Oregon State University and the Pacific Northwest National Laboratory have discovered a way to achieve near-optimal heat dissipation by applying a nanostructured coating. Because of performance, versatility and economy of materials used, their method could soon lead to better electronics, heating and air conditioning.

We've recently discussed the importance of heat dissipation in electronics; however, while cooling laptops and the likes is an important issue in itself, they are by no means the only area that could benefit from better heat dissipation. The team's work focuses on heat transfer using water in particular and could be used in heating, cooling and air conditioning applications as well as keeping your lap from burning up the next time you check your email at the airport.

The advances claimed by the team are quite significant: achieving heat transfer performances close to the theoretical maximum, the coatings produced a "heat transfer coefficient" ten times higher than with the uncoated surfaces, dissipating heat four times faster than previously possible.

Surprisingly, the principles that brought to such a radical performance improvement are very simple, and consist of covering standard heat conducting materials — such as copper and aluminum — with a thin strate of zinc oxide. The coating develops a multi-textured surface that encourages heat to be transferred via capillary forces, and can be applied to large areas as well as electronic components.

Heat transfer can waste such a large portions of energy that for water to reach its boiling point of 100 degrees centigrade the temperature of adjacent plates often has to reach about 140 degrees centigrade. Using this new approach, however, water will boil at about 120 degrees when analogous, zinc oxide-coated plates are used.

Detailed technical information on the study is contained in a freely available paper published by the team. The research has been supported by the Army Research Laboratory, and further studies are currently being carried out to develop broader commercial applications for this technology.


Enhancement of pool boiling heat transfer using nanostructured surfaces on aluminum and copper


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Title:
Enhancement of pool boiling heat transfer using nanostructured surfaces on aluminum and copper
Authors:
Citation URL:
Abstract:
C. These CHF values on ZnO surfaces correspond to a heat transfer coefficient of ~ 23000 W/m2K. We discuss our data and compare the behavior with conventional boiling theory.°Enhanced pool boiling critical heat fluxes (CHF) at reduced wall superheat on nanostructured substrates are reported. Nanostructured surfaces were realized using a low temperature process, microreactor-assisted-nanomaterial-deposition. Using this technique we deposited ZnO nanostructures on Al and Cu substrates. We observed pool boiling CHF of 82.5 W/cm2 with water as fluid for ZnO on Al versus a CHF of 23.2 W/cm2 on bare Al surface with a wall superheat reduction of 25-38
Keywords:
·   nanoscale heat transfer
·   boiling enhancement
·   electronic cooling
Issue Date:
·   Jul-2010
Publisher:
·   Elsevier
Citation:
Enhancement of pool-boiling heat transfer using nanostructured surfaces on aluminum and copper International Journal of Heat and Mass Transfer, Volume 53, Issues 15-16, July 2010, Pages 3357-3365
Series/Report no.:
·   International Journal of Heat and Mass Transfer
·   Vol. 53 (2010)
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