A control volume finite element numerical simulation of the drying of spruce

Drying is a process which involves heat and mass transfer both inside the porous material, where a phase change in moisture occurs from the liquid to the gaseous state, and in the external boundary layer of the convected hot dry air, which heats the porous medium, The equations which govern this process consist of three tightly coupled, highly non-linear partial differential equations for the unknown system variables of moisture content, temperature, and pressure. Due to the inherently complex boundary conditions and intricate physical geometries in any practical drying problem, an analytical solution is not possible. In order to obtain a transient drying solution it is necessary to resort to a numerical technique, Earlier researchers in this field have employed finite difference,finite element, and cell-centered control volume computational models to obtain a numerical solution to this complex problem. This paper presents a novel application of the hybrid control volume finite element scheme, which will lay the foundations for the solution of a timber drying problem on a deforming mesh. In order to test the performance of the simulation code over a range of differing drying conditions, numerical solutions to two timber drying problems are presented in this paper: first, a low temperature drying case with a dry bulb temperature of 80 degrees C, and, second, for a case where the dry bulb temperature is above the boiling point of water at 120 degrees C. (C) 1996 Academic Press, Inc.