Analysis of a Two-Stage Linear Fresnel Reflector Solar Concentrator

Abstract

The two-stage linear Fresnel reflector solar concentrator is analyzed via an in-depth study of an installed, nominally 220 KWt system. The concentrator includes: (1) a primary linear Fresnel reflector comprised of curved mirrors and (2) a secondary nonimaging CPC-type trough with a tubular receiver. The principal practical design options for the secondary concentrator are evaluated. Via a computer simulation which includes ray-tracing of the primary reflector, we evaluate the sensitivity of energy output to: concentrator optical errors, system geometry, tracking mode, and the option of using flat versus curved primary mirrors. The two-stage Fresnel concentrator can be considerably less expensive than the corresponding parabolic trough collector, but is found to deliver about one-fourth less yearly energy. However, much of this difference could be eliminated through the use of higher-quality CPC reflectors.