Effective Diffusivity Determination Considering Shrinkage by Means of Explicit Finite Difference Method

Drying data of salted shark (Carcharhinus limbatus) muscle pieces samples, dried in a convective dryer, by using three different air conditions and two different air velocities, were treated by Fick's second law. The shrinkage during drying process was considered as a linear function of sample moisture. The Fick's second law equation was numerically solved by the explicit finite difference method to obtain effective diffusivity, considering shrinkage and with and without simplification of moisture content profile. The experimental data fitted very well independently of the simplification introduced on the moisture content profile. The best fit was obtained by considering volumetric average of sample moisture content. The effective diffusivity values calculated considering the shrinkage varied from 0.72 to 2.20 × 10−10 m2/s with the mean relative deviation modulus from 1.02 to 6.51%. The activation energy expressed in function of air temperature varied from 3.42 to 19.23 kJ/mol.