Drying model for softwood and moisture patterns measured by magnetic resonance imaging

A multiphase one-dimensional mathematical model was developed in order to elucidate the spatial moisture pattern (SMP) in Mexican pine wood (Pinus pseudostrobus) during a convective drying process using warm air. The mathematical model is based on the mechanics of the continuous and considers the balance of mass and energy in the representative elementary volume. The liquid, solid, and gas phases were considered. The transition from the nonhygroscopic to the hygroscopic phase was analyzed, dividing the first into two subphases: the funicular and pendular, both delimited by an irreducible saturation point. SMP were simulated in the radial direction and compared with those obtained by the nuclear magnetic resonance imaging-one dimension (MRI-1D). The prediction of moisture patterns and drying kinetics describes the drying phenomenon with no interruption in the transition from capillary to hygroscopic domain, as confirmed by MRI-1D technique.