Modelling reflection in the centrifugal solar particle receiver

In this study, a novel reflection model for particle beds formed by diffuse, gray, opaque and spherical particles is developed, and applied to the Centrifugal Solar Particle Receiver (CentRec). The reflection from particle beds comprised of diffuse reflecting particles are neither diffuse nor specular but incidence angle dependent due to the spherical surface of the particles forming the particle bed. The reflection characteristics of a particle bed being representative for the CentRec application is derived for a wide range of incidence angles of the incoming rays (0° ≤ γgen ≤ 85°). Later, the derived characteristics are imported to the in-house ray tracing tool SPRAY. A realistic ray distribution is generated by taking the heliostat configuration into account. The absorbed power distribution on the particle film surface in the CentRec is found after several reflections inside the CentRec cavity. The model results are compared with resolved MCRT results for typical CentRec operating conditions. Very high accuracy in terms of reflection loss through the aperture and absorbed power distribution in the receiver is achieved with the developed reflection model. The required computational time to model the solar irradiation in the CentRec is reduced significantly and there is still room for improvement.