DISCONTINUOUS VACUUM DRYING OF OAK WOOD - MODELING AND EXPERIMENTAL INVESTIGATIONS

Vacuum drying and especially discontinuous vacuum drying is a very att ractive process for such a wood as oak, because of a reduced drying ti me and a high quality of the final product. In this paper, a model des cribing heat, mass and momentum transfer in a capillary porous and hyg roscopic medium under vacuum drying with no external heating agent (th e material is pre-heated during a convective phase), is presented. The choice of the following three independent unknowns, moisture content, enthalpy and dry air density, leads to a fully well described problem where the effect of gaseous pressure inside the material is taken int o account. A new formulation of the boundary conditions and its numeri cal resolution are validated by experimental results.