Heat Harvesting Technology

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Summary UCLA researchers have developed a novel way to harvest waste heat by combining thermal radiation at the nanoscale with pyroelectric energy conversion. Background Rising awareness in sustainable and efficient energy technologies has stimulated efforts in harvesting energy that would otherwise be wasted. A pyroelectric energy converter offers the prospect of directly transforming waste heat into electricity. However, the operating frequency of such a device is usually small (~0.1 Hz), and limited by convective heat transfer between the pyroelectric material and the working fluid’s oscillations, which restrict the performance of the device. However, thermal radiative heat transfer is exchanged at the speed of light, and has the potential to increase the operating frequency of pyroelectric energy converters, resulting in significantly better power density and efficiency. Innovation UCLA researchers in the Department of Mechanical Engineering have developed a new technology that combines nanoscale radiative heat transfer and pyroelectric energy conversion in a single device to harvest waste heat with large power output and energy efficiency. The device consists of bringing the pyroelectric element in close proximity successively with a hot surface and with a cold surface while performing the Olsen cycle. Displacement can be achieved using low power piezoelectric actuators, for example. The proposed technology is relatively simple to setup and microfabricate. Applications Harvest low grade waste heat energy and convert it to usable electricity.  Advantages Can operate at low temperatures (< 100°C). Depending on the need, the pyroelectric materials can be selected to operate at higher temperatures