Effect of Side Reflectors on the Performance of Flat Plate Solar Collector: A Case Study for Asir Region, Saudi Arabia

The solar collector's efficiency is directly depended upon the solar radiation intensity falling on its surface. In order to increase the solar concentration over the collector, side reflectors are introduced which will concentrate both diffuse and direct radiations from the sun toward the collector surface. Therefore, in this study the influence of side (left and right) reflectors on efficiency improvement of the flat plate solar collector (FPSC) was analyzed. For determining the optimum tilt angles of side reflector and collector, a simulation model was developed by using TRNSYS software. The results obtained from simulation were validated with the experimental results for whole year during the daytime of semiarid Asir region of Saudi Arabia. Both simulation and experimental results indicate that optimal left side reflector angle is lowest in winter with the value of 38 degrees and highest in summer with the value of 68 degrees, while the optimal angle of right side reflector is lowest in summer with the value of 43 degrees and highest in winter with the value of 74.5 degrees. The thermal efficiency of FPSC has been improved significantly by adding side reflectors. The average thermal efficiency of FPSC without reflector was 46% which was increased to 58% by adding side reflectors. The addition of side reflectors increases the concentration of solar radiation falling on the collector surface and thus increases the output temperature of water by 12 degrees C as compared to input water temperature. Thus, the effective size of the system was reduced by adding side reflectors as thermal efficiency was enhanced which implies less space requirement for heating an appropriate quantity of water.