Design and optical optimization of a 45 kW beam-down solar-thermal concentrator

Abstract

[eng] Concentrated Solar Power (CSP) technologies offer significant potential as renewable energy sources, particularly when integrated with storage systems. To address the challenges of energy transport and re-radiation losses, beam-down configurations combined with paraboloid-type dish concentrators provide a compact and efficient solution. In this study, we perform an optical analysis of a Cassegrain concentrator using the open-source software OTSunWebApp, a ray-tracing program that allows for the spectral optical analysis of solar collectors. The analysis accounts for specular scattering of the reflectors, the spectral behavior of the materials, and the angular size of the sun. The geometric design is parametrized with six degrees of freedom, while some other parameters, such as the number of mirrors and the aperture area, have been previously chosen. The resulting aperture area is 67.52 m2. We optimize the optical efficiency for operation at 600 ◦C, identifying the key parameters that influence performance. The system achieves a power output greater than 45 kW under direct radiation of 900 W/m2. Additionally, maintaining optical efficiency above 74% requires a tracking error below 0.2◦, with peak radiation values at the receiver reaching 26 kW/m2. These results underscore the potential of Cassegrain concentrator designs to advance CSP technology, suggesting that they could significantly enhance this field