Solar flat plate collector enhanced by two reflectors: optimum tilts of reflectors

Abstract

Introduction. In some solar concentrating system applications, in which the incoming sunlight is augmented by using commercial flat plate reflectors placed on different sides of the planar collector, it is very important to choose the optimum tilts of boosters (attached edge-to-edge on the top and bottom sides of the solar collector) for each month, to enhance their received solar irradiation over the year in the southern Algeria. The novelty of the proposed work consists of the development of a novel mathematical model in which the reference of the reflector’s tilt angles is the collector plane, and optimal tilts are optimized on the average day of each month. Purpose. This paper proposes a novel analytical model of two identical planer reflectors, placed on the top and bottom of a latitude tilted flat plate solar collector, for optimizing their optimal inclination angles during the daytime throughout the year in Ouargla city, southeast of Algeria. Methods. Optimal tilt angles of reflectors were obtained by searching for the optimum captured solar irradiation on the collector’s surface from each reflector in the representative day of each month of the year. After that, the obtained tilts were used for calculating incoming solar irradiation on the received area and comparing them to the solar collector without reflectors. Results. The findings of this paper showed that the reflector’s inclination angles were variable from one month to another in which the upper reflector’s tilts reached its maximum in June and minimum in December, contrarily for the lower reflector. Again, an increase of 28.05 % in the daily received solar irradiation on the collector surface with reflectors compared to the conventional one.