Study on the Performance Evaluation of Heliostat Field Based on Multiple Ray Tracing Method

Abstract

Environmental pollution and the energy crisis are two significant obstacles impeding the sustainable development of human society today. Tower solar thermal power generation emerges as a promising low-carbon and environmentally friendly clean energy technology. Consequently, the meticulous evaluation of the performance of the fixed-sun mirror field in tower solar thermal power generation is paramount in optimizing its output power. Taking the example of the 100 MW molten salt tower solar thermal power station in Gansu Dunhuang City Photovoltaic Industrial Park, this paper delves into its performance research. Since the sun's rays cannot uniformly reach the collector tower, an analysis based on the angle of incidence reveals an annual average cosine efficiency of 0.7565. Moreover, shading losses due to reflections between heliostat mirrors can occur. To address this, the paper employs the multi-ray tracing method to ascertain the shading loss rate, arriving at an annual average shading efficiency of 0.8268. Additionally, the reflected light, even without shading, may fail to reach the collector, resulting in truncation losses. The energy flow density method is adopted to determine an annual average truncation efficiency of 0.7418. Other factors, such as an air transmittance rate of 0.9652 and a specular reflectance rate of 0.92, contribute to an overall annual average optical efficiency of 0.4134. With these efficiencies in mind, the annual average thermal power output of the mirror field is calculated to be 25.13 MW. The number and area of heliostat mirrors jointly determine the total lighting area, and calculations reveal that the annual average thermal power output per unit area of mirrors stands at 0.4001 kW/m2. This comprehensive analysis offers crucial insights into the performance optimization of tower solar thermal power generation systems, paving the way for a more sustainable energy future.