3D-modelling of conjugate heat and mass transfers: Effects of storage conditions and species on wood high temperature treatment

Abstract

Wood is definitely advantageous for industry because it is a renewable resource environment-friendly produced. However, the biological origin of wood requires some treatments to preserve and stabilise it. Heat treatment of wood at high temperature is one of the new techniques that reduce the hygroscopicity, improve dimensional stability, and increase resistance to biological degradation of wood material without the use of chemical products. In this work, transient heat and mass transfers during heat treatment of wood at high temperature were numerically studied. The averaged energy Reynolds Navier–Stokes equations and concentration equations for the fluid were coupled with the energy and mass conservation equations for the wood. The numerical conjugate problem considered also heat and mass exchange at the fluid-wood interface and was used to study the effects of specie-dependant (specific gravity) and storage-dependant (initial temperature and moisture content) parameters during the heat treatment. Both temperature and moisture content were affected by a low initial temperature during the first hours of the treatment, representing hypothetically a risk for wood quality. A high specific gravity or a high initial moisture content required supplemental heating time to reach the targeted final moisture content that potentially represent a supplemental energy and cost for industry.