Heat and Mass Transfer Model in Wood Chip Drying
Keywords:
Capillarity, chips, diffusion of vapor, diffusion of bound waterAbstract
A model of simultaneous transport of heat and mass in a hygroscopic capillary porous medium was developed and applied to the drying of wood. Water is considered to be present in three forms-free water, bound water, and vapor—which remain in local equilibrium. It is assumed that the heat and mass transport mechanisms are: capillarity of free water, diffusion of vapor due to the concentration gradient, and diffusion of bound water due to the gradient of chemical potential between the water molecules. The constants of the phenomenological coefficients were adjusted. Finally, the drying process in wood chips was simulated in a unidimensional mesh. The results were compared with experimental data on drying kinetics obtained from the literature. Concentration profiles are shown, and the weight of each of the mechanisms present in the drying phenomenon is shown in graphic form and discussed.References
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