Over the years, many researchers have sought to convert heat to electricity directly, without benefit of turbine or generator. Now, professor Peter Hagelstein of MIT's Department of Electrical Engineering and Computer Science, working with Yan Kucherov of ENECO Inc., reports a device based on semiconductor technology that achieves this goal. Their approach builds on earlier thermionic "vacuum gap" design where electrons boil off a cathode, traverse the gap, and are absorbed into a colder anode, to convert heat to electricity. However, operating temperatures greater than 1,000C limited the usefulness of such scenarios. The new strategy improves performance by replacing the traditional vacuum gap with a multi-layer semiconductor structure. These solid-state conversion devices operate between 200 and 450C–typical temperatures for waste heat recovery. Hagelstein suggests that captured heat lost through automobile engine exhaust might be converted into electricity. The researchers' work has been sponsored by ENECO and DARPA. Patents have been applied for in the U.S. and Europe. For more information, contact Elizabeth Thomson at the MIT News Office, email@example.com.
An in-depth survey of 700 current and future users of 3D printing holds few surprises, but results emphasize some major trends already in progress. Two standouts are the big growth in end-use parts and metal additive manufacturing (AM) most respondents expect.
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