WOOD DRYING MODELING BASED ON THE WATER POTENTIAL CONCEPT - HYSTERESIS EFFECTS

The boundary absorption curve of the moisture content - water potentia l relationship of aspen sapwood was determined at 20-degrees-C. In ord er to quantify the impact of the hysteresis of the relationship on the results obtained with a wood drying model based on water potential, t he results obtained were merged to the boundary desorption curve and h ypothetical scanning curves were used to model the forced convection d rying of aspen sapwood. A strong hysteresis was found between the boun dary desorption and absorption curves, the moisture content being high er in desorption than in absorption at a given water potential. The ef fect of the hysteresis on the simulation results was found to be signi ficant. The results show that differences in the predicted drying time as high as 25% can occur depending on the moisture content - water po tential curve used. This demonstrates that the sorption history of woo d should be considered in the development of wood drying models.