SECTION II SYSTEM DESCRIPTION Two basic solar power plant systems are described which use parabolic dish solar collectors. The first is distributed generation of electric power in which small closed cycle Brayton engines are coupled to each collector. The second is central generation of electric power in which heat is collected from the field of dish collectors and is used to drive a central heat engine (steam Rankine). The only operational mode considered in the present study is the sun following mode. That is, the solar plant is used to generate electric power during the daytime hours only and no storage is provided. Storage subsystems are presently being characterized, and they would be combined with the sun following solar plant for peaking, intermediate and baseload operation at a future time. 2.1 DISTRIBUTED GENERATION Small closed cycle Brayton engines are placed at each parabolic dish to minimize the distance required for high temperature heat transport. Preliminary studies indicate that the Brayton engine should not be placed at the focal point of the collector because although these engines are small and relatively light, the extra costs in the collector structure and counterweight would offset gains. A short gas duct can connect the heat absorption cavity to the engine. A critical area is the minimization of the pressure drop and heat losses in this short duct. The Brayton heat engine could also be located at the base of the dish with a flexible line, or actually mounted on the dish as the counterweight. Another approach is to locate a Cassegrain second surface mirror at the parabolic dish focal point. The optical energy would reflect through the center of the dish to a cavity receiver located behind the dish surface. No detailed design study has been carried out at this time to compare these various approaches. For this preliminary evaluation,
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