PROCESS OF ABSORPTION AND DESORPTION OF METHANOL WITH A 3-DIMENSIONALTRANSPORT THROUGH PICEA WOOD

The process of absorption of methanol in liquid state by a wood sample , as well as the following step of desorption, is studied. A 3-dimensi onal transfer takes place within a cubic wood sample, this cube being cut in such a way that the sides of the cube are parallel with the lon gitudinal, radial and tangential axes of diffusion. A numerical model taking into account all the facts, e.g. diffusion within the solid and constant concentration on the surface during the stage of absorption, and diffusion within the solid and evaporation from the surface durin g the stage of desorption, is built and successfully tested. A pseudo- equilibrium of absorption is attained after an immersion time of about 3 hours in the liquid, and the whole amount of methanol is evaporated during the stage of desorption. The process can be described by a 3-d imensional diffusion with constant principal diffusivities.