Numerical study of flow patterns and performance of a coupled cavity–dish system under different focal lengths

Abstract

The effectiveness of the parabolic dish system (PDS) is greatly affected by the heat losses associated with high temperatures. The complexity of flow and temperature patterns in and around the cavity receiver makes it a challenging task to determine the convective heat loss from the cavity. Various studies have been carried out to determine the convection heat losses from isolated cavities of different shapes. In the presence of dish structure, the free stream wind may affect the stability of structure and the heat losses from the PDS. In this study, effect of focal length on the performance of the coupled cavity-dish system was analyzed using numerical simulations. The loading and the convective heat loss from the cavity were examined with three different cavity positions and different operating conditions in the presence of the dish. The results showed that the shallow dish experienced higher local air velocities near the cavity receiver than in the case of the deep dish. It was concluded that the heat loss is a stronger function of tilt angle rather than focal length, and in essence, the heat losses due to variation of this are negligible.