Effect of multiple reflections on the performance of plane booster mirrors

This paper presents an analytical study of a stationary V-trough concentrator. It consists of an array of east-west oriented trapezoidal channels with two side reflecting walls and a tubular absorber as a receiver at the base. The formulae for concentration factor and reflector surfaces have been derived. It is explicitly shown that the concentration ratio and reflector surface area depend upon the number of reflections the solar rays undergo before reaching the absorber, the cone apex angle, the coefficient of reflection and the acceptance angle. Results are presented graphically in such a way that one can choose the optimum configuration and the minimum material required to achieve a given concentration factor. The concentration ratio ranges from 1·2 to 3·6. The variations of the collector's efficiency with temperature difference for different numbers of reflections, acceptance angles, convective heat transfer coefficients and coefficients of reflectivity have been predicted.