Model-Based Estimate for Time-Dependent Apparent Diffusivity

Abstract

This article presents a method allowing the effective diffusion coefficient to be determined from experimental drying kinetics as a time-dependent parameter. The method combines an analytical solution of Fick's equation in which the Fourier number is raised to the empirical power (a), with a semitheoretical equation derived for quasi-stationary conditions. The method has been validated by applying the resulting equation to literature data on drying kinetics for parboiled rice and cut tobacco leaves as they approach a sphere and a slab, considered to be standard geometries in diffusion problems.

Diffusion Models to Describe the Drying Process of Peeled Bananas: Optimization and Simulation

“…In this case, the solution works well, especially if the effective mass diffusivity varies little within the product at a given instant t, and therefore can be considered constant. The solution also works well if D is considered to vary only as function of the average moisture content in a given instant t, as in Efremov and Kudra [17] and Carmo and Lima. [21] However, if the solution is obtained this way, the possibility of considering D variable, as a function of the local moisture content, does not exist.…”

“…If the geometry of the solid is simple and shrinkage is neglected, in general an analytical solution can be obtained. [16][17][18][19] On the other hand, if the effective diffusivity is supposed to be variable, as well as the volume of the solid, the diffusion equation should be numerically solved. Among the available methods, the finite volume method is commonly used.…”

Study of the drying behaviour in peeled and unpeeled whole figs

“…In this study, a modified form of Eq. (3), presented by Efremov and Kudra (2005), Eq. (4), was employed due to accuracy reasons as has been described in detail by Xanthopoulos et al (2009) …”

Water transport in parchment and endosperm of coffee bean

“…Usually, water transport is evaluated from the fitting of an adequate Fick's law equation to experimental drying kinetic (Mulet, 1994;Maroulis et al, 1995;Wang and Brennan, 1995;Bialobrzewski and Markowski, 2004;Efremov and Kudra, 2004;Hernández-Díaz et al, 2008). Sfredo et al (2005) and Correa et al (2006) have determined the water transport coefficient in coffee cherries.…”