Multiphysics modeling of vacuum drying of wood

Drying of porous media is characterized by the invasion of a gaseous phase replacing the evaporating liquid. Vacuum drying is an alternative method to alleviate discoloration for oakwood, so description of its underlying physics is important to understand this process. In this work, a coupled modeling is proposed to describe vacuum drying of oakwood at lab scale. This model describes the physics of wood-water relations and interactions with the vacuum dryer. Results provided important information about liquid and gas phase transport in wood. Water vapor and air dynamics in the chamber were simulated linking large scale (dryer) and macroscale (wood) changes during drying. We analyses results at 60- 100 bar and 250-300 mbar both at 70 degrees C. The phenomenological one-dimensional drying model is solved by using the COMSOL's coefficient form and an unsymmetric-pattern multifrontal method. Good agreement was obtained for these drying conditions. The numerical results and experimental measures provide some confidence in the proposed model. (C) 2011 Elsevier Inc. All rights reserved.