Drying Simulations of Various 3D Pore Structures by a Nonisothermal Pore Network Model

Abstract

During drying of a porous medium, pores are subsequently invaded by gas upon evaporation of water, typically disintegrating the liquid phase into clusters. Pore network models describe this invasion process on the basis of void space geometry and physics of pore-scale events. In the recent modeling by Surasani et al., (2008) invasion percolation rules under nonisothermal conditions are described with strong coupling between heat and mass transfer. In this work, the drying of various three-dimensional (3D) cubic pore structures with mono- and bimodal pore radius distributions is simulated for convective heat and mass transfer boundary conditions. Drying rate curves differ significantly for mono- and bimodal networks. A pronounced first drying period is seen for the bimodal case; here, macropore channels empty first and water is evaporated from the still-wet micropores at the surface. Additionally, freely evolving temperature fields in conjunction with phase distributions are presented.