Compound parabolic concentrators (CPCs) are good candidates for secondary concentrators in solar applications. Practical considerations, however, sometimes dictate the use of planar as opposed to curved reflectors. In addition polygonal apertures may be desired in order to tile a large area with several smaller secondary concentrators. We analyze in our contribution secondary concentrators which approximate a CPC but consist of plane facets with various numbers of subdivisions in axial and circumferential direction. We found that an `intuitive' axial profile with a constant angle between neighboring facets does not lead to optimal performance. We optimized by ray-tracing the size and orientation of the facets and found concentrators with significantly higher performance as compared to the `intuitively' facetted CPCs. The resulting shapes are usually significantly longer than classical CPCs. The higher the reflectivity of the surfaces, the longer the optimized concentrators get, approaching the infinite cone as an ideal concentrator for perfect reflectivity.
|Number of pages
|Proceedings of SPIE - The International Society for Optical Engineering
|Published - 1999
|Proceedings of the 1999 Nonimaging Optics: Maximum Efficiency Light Transfer V - Denver, CO, USA
Duration: 21 Jul 1999 → 22 Jul 1999