A fast and accurate methodology for the calculation of the shading and blocking efficiency in central receiver systems. (July 2020)

• Record Type: Journal Article
• Authors: Ortega, Guillermo; Rovira, Antonio
• Is Part Of: Renewable energy. Volume 154(2020)
• Page Start: 58
• Page End: 70
• Publication Date: 2020-07
• Subjects: Concentrated solar power -- Central receiver -- Heliostat field design -- Shading and blocking calculation; Renewable energy sources -- Periodicals; Power resources -- Periodicals; Énergies renouvelables -- Périodiques; Ressources énergétiques -- Périodiques; 333.794
• DOI: 10.1016/j.renene.2020.03.005
• Languages: English
• ISSNs: 0960-1481

Abstract

Abstract: In order to determine the efficiency factors of central receiver systems (CRS) in a reasonable time frame, in particular those relating to shading and blocking, the performance simulation and optimisation codes typically use simplification techniques. One frequent simplification is the assumption that the sunshape model is a point source sun. This paper examines the effect of the sunshape model on the shading efficiency, the findings illustrating a dependent relationship between the two. In particular, if the sunshape model considers the finite size of the solar disk, the performance results depend on the angle that the candidate heliostat forms with the main direction. Additionally, with the objective of reducing both computation times and error levels, a new method for the determination of the shading and blocking efficiency is presented, developed specifically for use in performance simulation and optimisation applications in CRS. The proposed method is compared with other methods, using the results of a conventional Monte-Carlo ray-tracing method as reference, through a study of computation times and error levels. The results demonstrate that the proposed methodology produces a reduction in both computation times and error values. The causes of the main errors associated with each method are also discussed. Highlights: Analysis of the effect of the sunshape model on the shading efficiency. A new methodology for the determination of the shading and blocking efficiency. Comparison of the methods with a Monte-Carlo ray-tracing model. Suitability for performance simulation and heliostat layout optimisation. Improvement of accuracy and reduction of computation time at low resolution rates.