Round Robin Test of Absorptance and Emittance of Particles for CSP

Precise knowledge of particle optical properties is crucial to the advancement and success of directly-irradiated particle receiver technologies. This work presents the results of a Round Robin Test (RRT) that was conducted between seven laboratories, where each participant measured the absorptance and emittance for a set of five different particle types. This research was performed within the framework of the SolarPACES Task III group, and the results helped establish a guideline for evaluating the optical properties of particles. The guideline was published on the SolarPACES Task III website in May 2022.