Performance Enhancement of Parabolic Trough Collector by Using Homogenizer and Spiral

In conventional parabolic trough collectors (PTCs), sunlight is concentrated at the bottom of the absorber tube, resulting in a significant circumferential temperature gradient across the absorber tube, heat loss and thermal deformation, which affects the safety and thermal performance of PTCs. In this study, a new receiver with homogenizer and spiral (RHS) is proposed, achieving the optical and thermal synergy to ameliorate the thermal deformation of the absorber tube and enhance thermal efficiency. A plane structure homogenizer is designed to improve uniformity of the concentrated solar flux of absorber tube through second reflection. In combination with the spiral, it improves the optical-thermal efficiency of the PTC by enhancing heat exchange between the fluid and the backlight side of the absorber tube. The performance of the collector is numerically studied by building a three-dimensional coupled light-thermal-structure model. The results show that the thermal deformation of the RHS is reduced by more than 96% and the optical-thermal efficiency is improved by 1.2%-0.63% compared with conventional receivers (CRs) under the same inlet temperature conditions. The proposed receiver is validated to be effective in reducing thermal deformation and improving optical-thermal efficiency.