Design boundaries of large-scale falling particle receivers

Abstract

A free falling particle receiver has been studied to investigate the design boundary of large-scale falling particle receivers. Preliminary receiver geometry and condition of falling particle curtain were scoped according to the nominal receiver capacity (135 MWth), receiver outlet temperature (800 °C) and temperature difference (147 °C) recommended by the research program. Particle volume fraction and solar energy absorptivity were analyzed for two particle sizes (280 µm and 697 µm) in different flow range. The results were then converted to part load efficiency of the receiver. Ray tracing with a scoped receiver design provided the amount of spillage and overall performance of the receiver which comprises multiple cavities with different solar energy inputs. The study revealed and quantified some inherent problems in designing falling particle receivers such as, transmission energy loss caused by low solar energy absorption, efficiency decrease in part load operation, and uneven temperature distribution across falling particle curtain.