Wind flow around a parabolic dish solar concentrator

Abstract

Wind flow around parabolic dish solar concentrators can significantly affect the loss of heat from the receiver, and thus the performance of these systems. Numerous studies have examined the heat loss from various receiver geometries under natural and forced convection conditions; however there is a marked absence of studies that take into account the effect that the dish may have on the heat loss, particularly for forced convection conditions. Given that forced convection can greatly increase the heat loss from such systems, there is a need for an improved understanding of the effect of the wind velocity and flow structure around parabolic dish solar concentrators. In this work, computational fluid dynamics is used to model the flow of air around a parabolic dish concentrator operating at varying angles of attack. The results show that the orientation of the dish has a significant effect on the flow structure near the receiver. For flows normal to the surface of the dish, fore or aft, the dish acts much like a bluff body, or pressure blockage, “shielding” the receiver from the flow, such that the air velocities near the receiver are relatively low. However, other operating conditions exhibit recirculation areas near the receiver that could lead to increased heat loss. Further work is required to determine the magnitude of this effect and subsequently the overall effect on the performance of parabolic dish solar concentrators.