Optical-thermal-mechanical comprehensive performance of the concentrating and collecting subsystem for the next-generation solar power tower based on heliostat field layouts optimization

Designing and optimizing heliostat field layout is an important prerequisite for solving higher energy demand and safety issue of the concentrating and collecting subsystem (CCS) in the next-generation solar power tower (SPT). This paper proposed an improved biomimetic heliostat field layout to improve the optical efficiency and reduce the energy loss of CCSs. Then, the random photon trial method and the emission position limitation method were developed to speed up the optical process simulation, which shortened the computational time by 63.36% in one year. Furthermore, the improved biomimetic heliostat field layout, the related biomimetic heliostat field layout and the radial staggered heliostat field layout were optimized for the highest optical efficiency in conjunction with the rectangular, the square quadrilateral, the square pentagonal and the square hexagonal heliostats. Finally, the effects of these three field layouts on the thermal performance and safety of CCSs under different conditions were investigated. The results show that the proposed improved biomimetic heliostat field layout can obtain the highest annual weighted optical efficiency using the square hexagonal heliostats and the receiver efficiency is improved by the improved biomimetic heliostat field layout by homogenizing the solar heat flux distribution. It is also reveals that the receiver is more prone to stress failure at noon of winter solstice due to the most inhomogeneous solar heat flux and the highest peak equivalent thermal stress, which may be improved through novel heliostats aiming strategies, more advanced field layouts and receiver structure optimizations. This study provides an efficient heliostat field layout and design guidance for the CCS in the next-generation SPT.