Enhancing thermal efficiency of a parabolic trough collector through geometric modification of absorber tubes: a performance analysis

Abstract

The study aims to investigate the impact of geometric modifications to absorber tubes on the thermal efficiency of a parabolic trough collector (PTC). Three absorber tubes with different cross-sectional areas were manufactured and tested, and the behavior of thermal efficiency was analyzed at different flow rates. The tests were conducted on sunny days, using water as working fluid. The results show that the thermal efficiency of the absorber tube is higher than that of the PTC, with an average value of 35.84% compared to 25.10% for the PTC. Increasing the cross-sectional area of the absorber tubes led to a reduction in fluid velocity, longer heat exchange time, and improved thermal efficiency. Despite reducing the concentration factor, the largest absorber tube (27 mm) showed the best thermal efficiency behaviour. Additionally, an increase in the volumetric flow of the fluid led to higher thermal efficiency values and absorption for each absorber tube. The study also compared characteristic curves for different volumetric flow rates and found that the largest absorber tube achieved the highest thermal efficiency for agricultural applications. These findings can be applied in designing and manufacturing absorber tubes for PTCs, leading to increased energy conversion efficiency and reduced energy costs.