On the Uncertainty of a Mathematical Model for Drying of a Wood Particle

The reliability of the predictions of a mathematical model is a prerequisite to employ it. The drying process of a pine wood particle is modeled using a quasi-continuous multiphase porous media model. Different values and expressions from the literature of nine physical properties and transport coefficients are listed in this study. Lower and upper bounds of these model variables are determined and applied to the model, and a bounded output of the model is calculated. This study shows that taking arbitrary values of the model variables from the literature may lead to approximately 16 times differences in the calculated drying time of a single wood particle. By global sensitivity analysis, the most effective variables are determined. The variations of the coefficients of water vapor transport, except gas relative permeability, have a high impact on the presented drying model. For reliability of the predictions of the drying model, at least the values of the gas intrinsic permeability and water vapor diffusivity as well as capillary pressure have to be determined by own measurements in the studied conditions. One can use any of the reported values or expressions of effective thermal conductivity and specific heat capacity of wood as well as gas relative permeability and bound water diffusivity for modeling drying processes of wood particles, because all of them produce similar model predictions.