Optical Characteristics of Glass Mirror Reflector for off-axis Concentrators: A Ray-Tracing Approach

摘要

Less acceptance and penetration of solar concentrating technology due to its high cost has inspired the research for alternative low-tech technologies and reflecting-materials. This paper aims to model and experimentally investigate optical characteristics of cost effective reflecting-materials on low-tech concentrators, which are easily available in the local market for wide low to medium temperature applications. Ray-tracing methods were employed to model and adjust the solar-concentrator position and geometry of reflecting-material. From the ray-tracing simulation, optimum glass mirror sizes of 1.5cm, 3cm, 4.5cm, and 6cm were selected to be tested at the optimum tracking position. Validation of the model was done by artificial laser-beam and ground radiation tests. Results gathered from the simulation and experimental tests were in a number of rays received and reflected back as well as temperature level at the focal point. The study from the simulation and laser beam test yields intercept ratio varied from 56.06% to 51.4% and 51.21% to 45.61% respectively. The respective results from the thermal test range between 52% and 31 %. These results together with the observed image sizes indicate that the use of small sized glass mirror reflector at 00 incidence angle best fits the curvature of low-tech off-axis concentrator and attains higher efficiency.