WOOD DRYING MODELLING BASED ON THE WATER POTENTIAL CONCEPT: HYSTERESIS EFFECTS

ABSTRACT

The boundary absorption curve of the moisture content - water potential relationship of aspen sapwood was determined at 20°C. In order to quantify the impact of the hysteresis of the relationship on the results obtained with a wood drying model based on water potential, the results obtained were merged to the boundary desorption curve and hypothetical scanning curves were used to model the forced convection drying of aspen sapwood.

A strong hysteresis was found between the boundary desorption and absorption curves, the moisture content being higher in desorption than in absorption at a given water potential. The effect of the hysteresis on the simulation results was found to be significant. The results show that differences in the predicted drying time as high as 25% can occur depending on the moisture content - water potential curve used. This demonstrates that the sorption history of wood should be considered in the development of wood drying models.