A WOOD DRYING FINITE-ELEMENT MODEL BASED ON THE WATER POTENTIAL CONCEPT

A two-dimensional finite element model of isothermal wood drying based on the water potential concept is presented. An original algorithm is used to update moisture content and water potential during the computations. The moisture content - water potential relationship and the effective water conductivity functions obtained during independent experiments are used as model parameters. In order to assess the possibilities and limitations of this approach, the calculated drying curves and moisture content profiles are compared to results obtained during convective drying of aspen sapwood at 20, 35, and 50-degrees-C, from full saturation to a final moisture content of about 10 %. The experimental and calculated results are in reasonable agreement although differences are observed at intermediate drying times. These differences could be attributed to the description of the convective boundary condition or to possible thermal effects.