Conjugate Heat and Mass Transfer in Wood Drying

The wood preservation by the dehydration process is one important preparation step in wood manufacturing industry. The drying process can help to strengthen the durability and resistance of wood from being destroyed by the fungus, to enhance the dimensional stability. In this work, a CFD model of hot air drying process of wood material in which the heat and mass transfer inside the wood sample are coupled with the external convective gas flow is presented. By using the continuum approach, the spatially resolved energy and mass conservation equations of internal transport process are derived. The thermophysical properties of wood particles required as input data for the continuum model are determined experimentally. This continuum-scale model is coupled with the external laminar gas flow by the heat and water vapor balance equations at the wood sample surface in CFD software named Comsol Multiphysics. The result of conjugate heat and mass transfer model is validated against the experimental observations made by using a magnetic suspension balance. Afterward, the CFD model is expanded to simulate the drying process of wood kiln dryer. The results indicate a noticeable moisture content maldistribution of wood plates.