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Solar power when the sun goes down

Sudhakar Neti, professor of mechanical engineering and mechanics, explained recently that one of the most promising ways to generate renewable energy clean, is to convert sunlight into heat. By employing reflectors, says Neti, engineers can concentrate the heat from sunlight to many times its power density and use it to heat water, other fluids or molten salts to temperatures exceeding 400 degrees Celsius—and soon, 800 degrees C.

Solar thermal energy power plants are in use or under construction around the world, with the United States, Spain and China producing, or projected to produce, the most megawatts of solar power. While solar energy is currently stored by heating water or salts and cooling them—a method called sensible heat exchange—the Lehigh group attempted to take advantage of the latent heat of materials while their phases change from solid to liquid and back.

The researchers filled the capsules with phase-change materials that have different melting temperatures to achieve thermal energy storage around a range of temperatures providing for isothermal energy storage.

The magazine article, titled “Canned Heat,” was coauthored by D. Yogi Goswami of the University of South Florida and by Arun Muley and George Roe of Boeing Co. It was published as an ASME (American Society of Mechanical Engineers) Task Force on Thermal Energy Storage effort led by Neti, Goswami and Muley.  The article’s publication came as Neti and a team of Lehigh researchers concluded a four-year research project that demonstrated the effectiveness of using encapsulated phase-change materials (PCMs) to store solar thermal energy at high temperatures.

The study was funded by the U.S. Department of Energy (DOE). The Lehigh researchers presented the results of their research recently at an Engineering Conferences International Inc. (ECI) conference in California.  Articles by group members have been published in Applied Thermal Engineering, Solar Energy, Renewable Energy and other journals.

Read the full story in the Lehigh University News Archive.

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