Calculation of optical efficiency of the heliostat field based on Reverse Projection Box Counting Model

Abstract

A more accurate and reasonable calculation model is proposed for the calculation of total optical efficiency, shadow blocking efficiency, cosine efficiency, atmospheric transmittance, collector truncation efficiency and output thermal power of heliostat field in tower solar photovoltaic power plant. In this paper, under the condition that the relevant parameters of heliostat field are determined, the Monte Carlo Ray Tracing method is used as the basis for the calculation of each optical efficiency. At the same time, the innovative Reverse Projection Box Counting Model is established to accurately identify whether there is a shadow blocking problem or not, and the differential idea is used to effectively solve the problem of repeated calculation of the blocking shadow area and the irregularity of the blocking area difficult to be calculated caused by one heliostat being blocked by multiple heliostats, so as to estimate the shadow blocking efficiency of the heliostat field more accurately. Finally, the heliostat field in Gansu, China, is taken as an example for calculation, and the results are compared with those of other scholars and the real value of the heliostat field to prove the superiority of the model constructed in this paper and the accuracy of the solution results.