Some investigations on moisture injection, moisture diffusivity and thermal conductivity using a three-dimensional computation of wood heat treatment at high temperature

Wood is a porous, anisotropic and hygroscopic material. The heat treatment of wood at high temperature improves dimensional stability and increases durability and resistance to biological degradation like fungi attack. The improved characteristics of heat-treated wood offer many potential and attractive opportunities to the wood product industry. Furthermore, the quality of treated wood depends on several parameters that must be monitored and controlled. In the present paper, a three-dimensional modeling of thermal treatment of wood at high temperature is presented. This model is based on the coupling of the energy and mass conservation equations for wood with the average Reynold Navier-Stokes equations as well as the energy and concentration equations for the fluid field. Some parametrical investigations have been done using the coupled system in order to optimize the process design. First, the quality of heat-treated wood was improved by moisture injection in the fluid flow during the heat treatment process. Then, the quality highly depends on the physicochemical properties like thermal conductivity and moisture diffusivity. These two parameters should preferably be parameterized within the modeling, more particularly the mass diffusion coefficient, to improve the realism of the modeling. (C) 2014 Elsevier Ltd. All rights reserved.