Numerical simulation of the temperature distribution of elliptical cavity tube receivers in the parabolic trough solar collector

The elliptic cavity tube absorber is used in the parabolic trough solar collectors to increase the optical efficiency and decrease the thermal loss. But the non-uniform heat flux distribution on the tube receiver will cause non-uniform temperature distribution, thus leading to asymmetric thermal stress and deformation of the tube receiver. In this paper, the geometric as well as thermal parameters of the elliptical cavity tube receiver are analysed through numerical simulation. The temperature distribution of the tube receiver in the single-phase liquid zone, viz. the water zone and the vapour zone, is analysed. It is found from this study that there are two extreme temperature areas in the elliptical cavity tube receiver. When the major semi-axis of the elliptical cavity is 63mm, the maximum temperature of the water zone is the largest, which occurs at (-35mm, 0mm) of the tube receiver. When the major semi-axis of the elliptical cavity is 67mm, the maximum temperature appears at (-9mm, 0mm) in the vapour zone, and the minimum temperature rise appears at (-13.88mm, 0mm).