Recent gains in solar concentrator technology.

Abstract

Continuing development of solar concentrator technology has been directel toward the improvement of methods and materials of construction to satisfy the particular design requirements of various space power conversion devices. Fabrication techniques and recent results from investigations made on concentrators are discussed. For one-piece concentrators, the stretch-formed aluminum process now yields the high accuracy formerly obtained only by electroforming nickel. The aluminum electroforming process has been scaled up to 0.76m-diam concentrators. Two accurate 2.90-m-diam plastic spin castings have been fabricated; however, the concentrators subsequently electroformed of nickel were not of comparable quality. In the area of expandable concentrators, a modified model of the whirling membrane concept has given improved concentration of energy; however, the design parabolic cross section has not been attained. A 1.52-m-diam inflatable concentrator that was rigidized with a polyurethane foam in a simulated space environment gave an efficiency of 0.65 compared to a Rankine cycle design efficiency of 0.85.