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July 29, 2009

Heat Transfer Can Be 1000 Times Greater than Plancks Law at the Nanoscale


Courtesy / Sheng Shen A diagram of the setup, including a cantilever from an atomic force microscope, used to measure the heat transfer between objects separated by nanoscale distances

A well-established physical law, Planck's law, describes the transfer of heat between two objects, but some physicists have long predicted that the law should break down when the objects are very close together. MIT researchers have determined that heat transfer can be 1,000 times greater than the law predicts.

The new findings could lead to significant new applications, including better design of the recording heads of the hard disks used for computer data storage, and new kinds of devices for harvesting energy from heat that would otherwise be wasted.

By using the glass (silica) beads, they were able to get separations as small as 10 nanometers (10 billionths of a meter, or one-hundredth the distance achieved before), and are now working on getting even closer spacings.

The new findings could also help in the development of new photovoltaic energy conversion devices to harness photons emitted by a heat source, called thermophovoltaic, Chen says. "The high photon flux can potentially enable higher efficiency and energy density thermophovoltaic energy converters, and new energy conversion devices," he says.

Micron gap thermal photovoltaics were described at nextbigfuture.




Nanometer gap thermal photovoltaics could be super-efficient for energy conversion

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