Directly irradiated spouted and fluidized particle receivers can potentially store thermal energy at higher temperatures than conventional molten salt receivers in concentrated solar power (CSP) applications. The design of prototype spouted and fluidized thermal receivers requires the development of gas-solid multiphase flow models validated by experimental data. In this study, a gas-solid flow model was developed to investigate the thermal discharge behavior under convective cooling, excluding radiative heating, for spouted and fluidized bed thermal receivers using Eulerian-Eulerian (two-fluid) approach. The predictive capability of this model was assessed using data sets from the literature, as well as the results of in-house experiments. The Zehner-Schlunder model for solid-phase effective thermal conductivity performed better than the kinetic theory approach based on the benchmark experimental data sets. The validated model was then applied to simulate the thermal discharge behavior (after charged with a metal halide lamp) of a conical spouted bed receiver under convective cooling with CarboHSP particles. The cooling results show good agreement within 7–8 °C of experimental data and provide additional insights into the system’s cooling dynamics.