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Monday, 30 January 2012

Keeping high-performance electronics cool

Jan 30, 2012

The development of sophisticated electronics using high-performance computer chips that generate much more heat than conventional chips is challenging scientists to come up with a new type of compact cooling system to keep temperatures under control.

For the past few years, a collaborative team of engineers and other scientists from academia and industry has been investigating an advanced cooling system for electric and hybrid cars as well as computers and telecommunications systems, particularly for military use in radar, lasers, and electronics in aircraft.

The technology, which is capable of handling roughly 10 times the heat generated by conventional chips, is a device, called a vapor chamber, using tiny copper spheres and carbon nanotubes to passively wick a coolant toward hot electronics, according to Suresh V. Garimella, the R. Eugene and Susie E. Goodson Distinguished Professor in the School of Mechanical Engineering at Purdue University, West Lafayette, IN.

The current thermal solution it would replace is typically a solid heat spreader using solid aluminum and copper to conduct heat, an approach inadequate for removing large amounts of heat in powerful electronics components while maintaining low operating temperatures.

A Passive System

The vapor chamber comes in the same form factor as a solid heat spreader, says Dr. Garimella, but "The working fluid contained inside continuously undergoes [evaporation] at the heat source to more efficiently remove heat than is possible by devices that rely on conduction alone."

An advantage of vapor chambers compared to other high-performance cooling technology alternatives is that a vapor chamber is a completely passive system. According to Dr. Garimella, "It can…operate continuously without any additional pumps or valves. Such passive systems are associated with high reliability. Active cooling options which allow for high heat dissipation, such as forced liquid cooling, require an external fluid flow system including a separate pump and condenser, adding to the solution cost and size."

Much of the work is being conducted at the Industry/University Cooperative Research Center's Cooling Technologies Research Center, established by Dr. Garimella at Purdue.

Integrating Nanostructures

After publishing its findings last year about the effects of conventional sintered powder copper structures on the performance of a vapor-chamber cooling technology, the team is preparing to report on the feasibility of integrating nanostructures, specifically carbon nanotubes, into the devices to further improve performance. These results and proposed techniques for integrating carbon nanotubes into vapor chambers are expected to be published in the near future, says Dr. Garimella.

"The next step is to experimentally investigate the performance enhancement provided by integration of carbon nanotubes into vapor chambers," he says. "Another critical step in converting performance enhancements observed in the lab to actual devices is to develop engineering models and methods that allow accurate prediction of device performance for specific applications."

When the program, which is being funded by the U.S. Department of Defense's Defense Advanced Research Projects Agency, is completed at the end of this year, the hope is that there will be transition to actual applications, especially for the Department of Defense, where there is significant need, says Dr. Garimella.

Source: American Society of Mechanical Engineers (ASME)


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