SUMMARY

The use of particulate media as solar thermal energy storage (TES) materials in concentrated solar power (CSP) systems enables dispatchable grid-scale electricity generation. The solar-to-thermal conversion process takes place in the solar particle receiver, where solar TES materials in the form of particle curtain absorb solar irradiation and increase temperature. The conversion efficiency is affected by both the radiative properties of the TES material, and the radiative heat transfer processes specific to the configuration of the curtain. With the merging significance of bauxite- and silica-based particulate media in the field of CSP, this thesis aims at fulfilling the relevant knowledge gaps to accurate modeling of conjugate heat transfer in a solar particle receiver. The radiative properties of bauxite particles are studied by measuring and modeling the spectral absorptance. Using the effective medium approach, the optical constants are modeled and used to calculate the theoretical absorptance. A high-temperature emissometer is developed to measure the temperature-dependent emittance of bauxite and silica particle beds. The temperature-dependent infrared phonon modes are characterized by fitting the results with a Lorentz oscillator model. Polydisperse silica particles of different types and sizes are measured for reflectance and transmittance. The effective absorption and scattering coefficients are retrieved from an inverse determination method. Results are compared with the prediction by independent scattering theory to study the effect of dependent scattering. From a geometric optics standpoint, a discrete scale Monte Carlo ray tracing (MCRT) algorithm is developed to simulate the radiative properties of particle beds numerically. The effects of particle volume fraction, particle mixing, and refractive index on radiative heat transfer are analyzed.