Optical performance evaluation of a large solar dish/Stirling power generation system under self-weight load based on optical-mechanical integration method

Abstract

Solar dish concentrator system is an optical device that provides high quality thermal source for thermodynamic devices such as Stirling heat engine, the structural deformation caused by self-weight load leads to change of mirror shape and receiver position, reducing its optical performance to affect the safe and efficient operation. In this paper, a previously developed large-scale 38 kW dish/Stirling system with 17.7 m diameter (XEM-Dish system) is used as object, an optical-mechanical integration model of XEM-Dish system is established by combining finite element method and ray-tracing method, which is used to evaluate the effects of self-weight on its optical performance at different elevation angles, including the results of mirror slope error and flux distribution, etc. A method of measuring the deformation of XEM-Dish system using Leica TS30 total station combined 360° prism is presented for validating the correctness of finite element model. Results show that the mirror slope error components SDx and SDy both increase with increase of elevation angle when only concentrator is deformed; mirror slope error increases with its deformation, but their distribution laws in different. The excellent optical efficiency 87% and flux distribution are maintained for XEM-Dish system under self-weight load, with SDx around 0.58 mrad at 0°–60° elevation angle.