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

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 (dp) — 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

Numerical modelling of evaporation in a ceramic layer in the tape casting process

Evaporation of water from a ceramic layer is a key phenomenon in the drying process for the manufacturing of tape cast ceramics. This process contains mass, momentum and energy exchange between the porous medium and the free–flow region. In order to analyze such interaction processes, a Representative Elementary Volume (REV)–scale model concept is presented for coupling non–isothermal multi–phase compositional porous–media flow and single–phase compositional laminar free–flow. The preliminary results show the typical expected evaporation behaviour from a porous medium initially saturated with water, and its transport to the free–flow region according to the existent results from the literature

Drying of a tape-cast layer: Numerical investigation of influencing parameters

In this study, the evaporation of water from a ceramic-water mixture is investigated numerically with the purpose of understanding the drying process of the thin sheets produced by the tape casting process. In the scope of this work, a Representative Elementary Volume (REV) scale model concept for coupling non-isothermal multi-phase compositional porous-media flow and single-phase compositional laminar free-flow developed by Jabbari et al. (2016), is used for a thorough analysis of the influential parameters. Specifically, we investigate the influence of ventilation speed magnitude, vmax, the equivalent diameter of particles of the porous medium, dp, the porosity of the porous medium, ϕ, the initial temperature in the free-flow region, Tff, and the initial temperature in the porous-medium region, Tpm, on the characteristic drying curves of a thin ceramic layer. We, moreover, conduct a statistical analysis based on numerical experiments in combination with a fractional factorial design of the aforementioned parameters. The analysis accounts for the effects of parameters on the characteristic drying curves of a thin ceramic layer. The effects of varying each of the parameters as well as their mutual interaction are shown with particular attention to the maximal drying rate as well as the final time for the drying process