Numerical modelling of radiative heat transfer in a polydispersion of ceramic particles under direct high-flux solar irradiation

•Radiative transfer and thermal response are studied in a polydispersion of ceramic particles.•The transient heat transfer model couples radiation and interfacial convection.•Effects of polydispersity are investigated using three alternative modelling approaches.•Strongly size-dependent effects are predicted using the novel multi-component model.•Net radiation absorption is 18× more intense for particles with d = 7.5 µm than with d = 153 µm.