An irregular pore network model for convective drying and resulting damage of particle aggregates

Abstract

An irregular pore network model for convective drying of random aggregates composed of mono-sized primary particles is introduced in this study. The network structure is generated by Voronoi tessellation of the aggregate and by designating the Voronoi edges as interconnected cylindrical pores; pore radii are computed from the distances to the neighboring particles. The obtained irregular structure captures many essential features of the pore space of real aggregates such as random node locations, distributed coordination number of nodes, randomly established pore connections as well as random spatial correlations of pore radius. In a next step, an isothermal pore network drying model, which uses invasion percolation concepts, is generalized to irregular structures, and drying simulations are carried out. Results are given as phase distributions, moisture profiles and drying rate curves. From this information, local capillary forces are approximated. These are seen as the reason for micro-cracks in the network of bonded particles. In a one-way coupling approach, the capillary forces are applied to the aggregate and the mechanical behavior is simulated by Discrete Element Method (DEM) to investigate inter-particle bond responses for different drying conditions.