September 13, 2008
Nasa Tests Solar-Powered Engine/Generator for Smaller Users
Looking back at "News and Notes" in the Bulletin of August 1980: A joint government/industry team will design, fabricate, and test a solarpowered, 20 kW engine/generator designed for use by small communities, industries, farms, military bases, and similar users. The project, sponsored by the U.S. Department of Energy, is designed to foster effective and inexpensive methods of using solar energy to produce electric power and industrial heat....Solar energy to power the engine/generator would be focused by a dishshaped parabolic mirror into a receiver where the heat is absorbed to run the engine. The engine/generator unit includes a turbine, compressor, alternating current generator, and gearbox selected from commercially available components. To increase energy efficiently, the engine will include a recuperator through which heat in the turbine exhaust is returned to the engine cycle. The engine/generator also would be equipped with a combustor so that power can continue to be produced at night and when skies are overcast.
The operation of this solar Brayton engine starts with the compressor, which takes in surrounding air and delivers it to a recuperator at about three times atmospheric pressure. In the recuperator the high-pressure air absorbs waste heat from the turbine exhaust and goes on to the solar receiver where it is further heated to ~800[degrees]C. The high-pressure, high- temperature air is used to drive the turbine, which produces sufficient power to generate electricity and drive a compressor. When the Sun's intensity drops, the cooler air leaving the receiver is heated to ~800[degrees]C in a combustor placed in the ducting to the turbine.
The solar thermal generator could perform as the user's primary source of electric power or could be connected to an existing utility grid....
-Bull. Amer. Meteor. Soc., 61, 917
Copyright American Meteorological Society Jul 2008
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