Performance of Highly Concentrating Mirror Collectors and Mirror Systems

摘要

The optical performances of axisymmetric mirror collectors and mirror systems were investigated, and the theoretically obtainable thermal efficiencies were estimated. The focusing concentration ratio of solar collectors and collector systems has a decisive influence on the obtainable thermal efficiency, but is strongly affected by errors of the miror surfaces (sigma value). The concentration ratios of parabolic and spherical mirror and mirror systems, including secondary concentrators, were geometrically calculated. The sigma-dependent radiant flux density was determined using the HELIOS computer program. For sigma values between 1.5 and 5 mrad, ratios between 1000 and 8000 are found for parabolic mirrors, and between 600 and 2000 for spherical mirrors. The maximum thermal efficiencies range between 55 pct and 80 pct for receiver temperatures between 400 and 800 C.