Optical performance analysis of a porous open volumetric air receiver in a solar power tower

摘要

An optical model for a solar power tower with an open volumetric air receiver(OVAR) was developed in this paper, and the optical performance andcharacteristics of the OVAR were studied based on the model. Firstly, thedetailed distributions of the non-uniform solar flux (qsr) on the aperture andthe solar source (Ssr) in the OVAR were studied. The solar flux was found to berelatively uniform across the aperture for a single OVAR. However the incidentangle of the rays varies between 0o and 42o, which indicates that the parallelassumption of the rays is not appropriate at this condition. Furthermore, theSsr in the absorber decreases from the inlet to the outlet, and the maximumsource (Ssr,max) of 2.414X108 Wm-3 appears at the inlet. Moreover, the Ssr,maxwas found to appear at the region near the wall rather than the center of thereceiver as usual for the combined effect of the non-parallel incident rays andthe diffuse reflection on the wall. In addition, study on effects of the porousparameters indicates that the solid emissivity influences both the Ssrdistribution and the receiver efficiency significantly. However, the porediameter and the porosity influence Ssr distribution importantly, but havenegligible effect on the efficiency. Finally, the optical efficiency of 86.70%,reflection loss of 13.20% and transmission loss of 0.10% were found to beachieved by the OVAR.