A comprehensive mathematical approach and optimization principle for solar flux distribution and optical efficiency in a solar tower

Abstract

While designing and optimizing a concentrating solar central tower, it is crucial to obtain the accurate solar flux distribution and optical efficiency for a given heliostat field. Here we present a new model describing solar flux distribution on the surface of an external receiver, based on ray-tracing and a convolution algorithm. The receiver is located at the top of a center tower surrounded by abundant heliostats. The Ray-tracing algorithm allows to predict whether the incident ray is obstructed by adjacent mirrors or not, and the convolution algorithm yields the solar flux distribution on the reflected beams. The performance of single and multi-mirrors are compared with experimental data. Results show that the optical efficiency and solar flux distribution are mainly controlled by the interception factor, and shading and blocking factor. A comprehensive optimization principle is proposed to optimize the optical efficiency of heliostats field. Accordingly, application of this principle increases the average optical efficiency by+2% during daytime, while decreases the ratio of maximum solar flux to the minimum one from 8.6 to 7.8.