Experimental investigation of a compound parabolic concentrator with aerogel and polycarbonate cover

Abstract

This study experimentally investigates the performance of a novel compound parabolic concentrator integrated with aerogel and polycarbonate cover for process heat generation in low to medium temperature ranges. The experimental setup included a compound parabolic concentrator with a flat absorber surface at its focal plane, with an optically transparent and thermally insulating aerogel placed over it. The assembly was enclosed within a compound parabolic shape made of anodised aluminium sheets, with a concentration ratio of four, and protected by a transparent polycarbonate cover. The under-the-sun experiments were performed in Mumbai, India between March and June, 2022. A test set-up was developed to characterise the performance of this collector using the Indian Standard code 16648 (Part5, 2017). Four compound parabolic concentrator configurations were examined: only compound parabolic concentrator, compound parabolic concentrator with aerogel, compound parabolic concentrator with aerogel and polycarbonate cover, and compound parabolic concentrator with polycarbonate cover. The results indicate that while the addition of the polycarbonate cover offered protection to the reflector against environmental elements such as rain, wind, dust, snow, and bird droppings, it also led to a reduction in optical performance by about 16 %. It was also observed that using compound parabolic concentrator with aerogel results in a 30.6 % increase in the collector efficiency at the testing site with an inlet water temperature of 60°C, ambient temperature of 20°C, and an incident solar radiation of 700Wm-2. Thus, this research contributes to the advancement of stationary, non-imaging concentrating collectors, catering to the thermal energy requirements of various processes in the low to medium temperature range.