Drying of a tape-cast layer: Numerical modelling of the evaporation process in a graded/layered material

摘要

Evaporation of water from a ceramic layer is a key phenomenon in the drying process for the manufacturing of water-based tape cast ceramics. In this paper we present a coupled free-flow-porous-media model on the Representative Elementary Volume (REV) scale for coupling non-isothermal multi-phase compositional porous-media flow - for the ceramic layer - and single-phase compositional laminar free flow - for the air above it The preliminary results show the typical expected evaporation behaviour from a porous medium initially saturated with water, and water-vapour transport to the free-flow region in accordance with the available results from the literature. We elaborate on and discuss the characteristic drying-rate curve for a single layer ceramic, and compare it with that of a graded/layered ceramic. We, moreover, show the influence of the mean diameter of particles of the porous medium (d_p) - which directly affects the intrinsic permeability (K) based on the well-known Ergun's equation - of each single ceramic layer on the drying behaviour of a graded/layered ceramic.