Precise and fast spillage estimation for a central receiver tower based solar plant

Abstract

An accurate and computationally cheap method to estimate the optical efficiency of a heliostat field associated with a central receiver tower (CRT) system is essential for an optimized design. In this article, an improved method is developed to estimate the intercept efficiency of a field with flat heliostats. Based on the slant distance, a judicious combination of two different schemes, i.e. Elliptical Gaussian Distribution (EGD) and Pseudo Ray Tracing (PRT), is employed to estimate flux in an image plane. The flux from the image plane is translated to the receiver to estimate spillage. The proposed method is rigorously validated against the state of the art tool, SolTRACE, under various conditions which demonstrates robustness and accuracy of the method. The deviation of intercept efficiency from SolTRACE is small (within 1.5 %). However, such a high degree of accuracy is achieved at a meagre computational cost (below 15 %) compared to SolTRACE even without parallel computing. Thus, the intercept efficiency or spillage estimation of a given heliostat field is rendered ten times faster by the method presented in the current article without a loss of accuracy. An earlier study by the same authors showed the accurate and fast estimation of shading and blocking efficiency. The present study adds to the previous effort and proceeds towards the objective of achieving a fast and precise tool for the design and analysis of heliostat fields. The proposed tool is developed in Python environment which exploits the parallel computing features based on NumPy, Pandas and multiprocessing.