A New Method for Separating Diffusion Coefficient and Surface Emission Coefficient

Jen Y. Liu


An analytical procedure has been developed to separate the diffusion and surface emission coefficients in Newman's solution of the unsteady-state diffusion equation from a single lumber-drying curve. Previous methods required two to four drying curves corresponding to as many specimen thicknesses to achieve the same purpose. The new procedure reduces the experimental effort by 50% and more. The separation of the two coefficients will make it possible to study the dependence of diffusion coefficient on moisture concentration and that of surface emission coefficient on viscosity and velocity of airflow in any specified drying environment. Numerical examples are included to demonstrate the application of the new technique.


Diffusion coefficient;diffusion equation;lumber-drying curve;moisture concentration;moisture in wood;surface emission coefficient

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