A high-temperature thermal treatment of wood using a multiscale computational model: application to wood poles.

The present study is devoted to a numerical study with experimental validation of the high-temperature thermal treatment of three-dimensional wood pole. During the heat treatment process, the heat and mass transfer takes place between the solid and the drying medium, and the moisture evaporation occurs within the solid due to the capillarity action and diffusion. The development of the model equations, taking into account both bulk phases and interfaces of the multiphase system is described, starting from the microscopic scale. Fundamental to this model is the ability to quantify the effects of key material and geometric properties of the pole. The three-dimensional and unsteady-state mathematical model equations are solved numerically by the commercial package FEMLAB for the temperature and moisture content histories under different treatment conditions. A detailed discussion of the computational model and the solution algorithm is given. Heat treatment was applied on the test samples in an oven for three final temperatures (180, 200 and 220 degrees C). A series of experimental tests aimed at determination of heat treatment schedules kinetics curves and the temperature and moisture profiles and there time evolution were carried out. A very good agreement between the experimental and predicted results was obtained, implying that the proposed numerical algorithm can be used as a useful tool in designing high-temperature wood pole treatment processes.