Local-scale variability in packed beds of polyhedral particles: Structural and thermal distribution

Abstract

Heat transfer in packed beds largely depends on the bed structure, which is strongly linked to particle shape, yet most prior work focuses on spherical particles. This work contributes towards a better understanding of particle shape effect on the local-scale and its variability. Particle beds are generated numerically and steady-state thermal simulations are conducted for 12 different particle shapes and three particle-to-gas conductivity ratios. Voronoi cells are extracted to obtain local cell porosities; distributions are studied statistically. Another crucial parameter, particle-particle contact areas, are evaluated and compared with shapes. Variability in local structure results in varied temperature profiles. Thermal fluctuations are substantially affected by irregular shapes, an effect that increases for highly conductive particles. Notably, the spatial distribution of phases with different conductance has a strong influence on the distribution of local heat flux. Predominantly, these outcomes also indicate the relevancy of including shape parameters in developing reactors or modeling other granular applications.