APPLICATION OF NON-EQUILIBRIUM THERMODYNAMICS TO THE ESTIMATION OF PHENOMENOLOGICAL TRANSFER COEFFICIENTS IN CONVECTIVE WOOD DRYING

Abstract

Convective drying is an important process within the wood industry since it improves the physical, mechanical and technological properties of wood. Starting from the critical moisture content, the evaporation surface gradually becomes deeper inside the wood board and thus the intensity of evaporation is different as compared to that one that occurs on the wood surface. The present study aimed to determine the heat and mass fluxes occurring during the falling-rate drying period in the boundary layer, based on the non-equilibrium thermodynamics, according to which the forms of molecular transfer (momentum, energy and mass) are coupled. The variation of the fluxes along the wood board was investigated and the influence of each flux component on the heat and mass fluxes was assessed. The phenomenological coefficients, as variables in the fluxes equations were also calculated.