Numerical simulation for the determination of the radiative properties of spherical packed bed porous media: A COMSOL Multiphysics Study

The determination of the radiative properties of porous media has become a critical issue in various industrial and engineering applications. The aim of this paper is to characterize the radiative heat transfer process through porous media, assumed to be spherical packed beds. A prediction model was developed using the software COMSOL Multiphysics to simulate the interaction of each of the three proposed structures with a plane-heating surface. The distribution of normalized fluxes was assessed allowing the computation of effective radiative properties, namely the transmissivity, reflectivity, and absorptivity for diffusely and specularly reflecting particles. The results show that the arrangement of the particles has a noticeable influence on the media properties. Two layers of the third model were enough to obtain an opaque surface. Correlations have been developed to allow effective reflectivity, transmissivity, and absorptivity coefficients to be easily and accurately defined as a function of emissivity in future models. The suitability of the proposed models was discussed through a comparative study of the results found using numerical simulations with analytical calculations, with a good agreement obtained.