STRUCTURAL OPTIMIZATION OF A LINE-FOCUSSING SOLAR COLLECTOR WITH STATIONARY ABSORBER TUBE

Abstract

A preliminary study on a line concentrating solar collector with stationary absorber tube has revealed significant cost reduction and performance enhancement compared to state-of-the-art Parabolic Trough Collectors. To decide whether this so called Fixed Focus Parabolic Trough concept is worth continuing, a pre-design of the concentrator structure for such a collector must be investigated. In this paper, the effects of operating conditions represented by wind forces and dead load on the shape accuracy of the concentrator are determined via finite element method (FEM). An optimization procedure written in ANSYS is applied to determine appropriate geometry and dimensions of the structure to obtain best optical performance at lowest material consumption. To maintain a mean focus deviation of the reflected rays from the focal line of less than 6 mm under operating conditions, a specific weight of 14 kg/m2 could be reached. As structural elements of the collector are located between mirror and absorber, ray tracing analysis is performed for one selected conceptual design to estimate the effects of blocking and shading on the optical performance. The ray tracing revealed a reduction of the optical performance due to blocking and shading of 27 % for an incidence angle of 45° compared to 0° incidence angle.