Energy contribution by booster mirrors

Abstract

The standard textbooks and research publications hint at possible methods for computing the energy contribution by plane booster mirrors but do not elaborate the specific stages of a computational procedure. We hope the algorithm presented in this paper fills this gap. An algorithm to assess the contribution of solar energy on a horizontal receiver by plane booster mirrors is discussed in this paper. The choice of horizontal receiver reduces the number of variables and, therefore, simplifies the analysis and enhances understanding of the phenomenon of energy contribution by booster mirrors. The original impetus for this work was to study the input variables in a solar cooker, widely distributed in India. In these cookers, the aperture is invariably horizontal and a single plane booster mirror is the standard complement. A FORTRAN computer code has been prepared based on the algorithm. The computer code can be used for evaluating the contribution from the booster mirrors in different orientations and tracking modes. The input for this computer code can be either estimated or measured values of solar radiation. However, in the present analysis, the estimated values of beam radiation are used. Sample results of the energy contribution by the south facing, north facing and east/west mirrors are presented. The south facing mirror was found to be the best choice for energy boosting, especially at lower solar altitudes which may be due to either an increase in the latitude or the hour angle and a decrease in the declination of the sun.