A Variable Diffusivity Model for the Drying of Spherical Food Particulates

Abstract

Abstract. An investigation of the drying of spherical food particles was performed, using peas as the model material. In the development of a mathematical model for drying curves, moisture diffusion was modelled using Fick's second law for mass transfer. The resulting partial differential equation was solved using a forward-time central-space finite difference approximation, with the assumption of variable effective diffusivity. In order to test the model, experimental data was collected for the drying of green peas in a fluidised bed at three drying temperatures. Through fitting three equation types for effective diffusivity to the data, it was found that a linear equation form, in which diffusivity increased with decreasing moisture content, was most appropriate. The final model accurately described the drying curves of the three experimental temperatures, with an R 2 value greater than 98.6% for all temperatures.

Modeling the Kinetics of Potassium Diffusion in Estima Potato under Different Leaching Conditions

“…Whilst empirical models have often been used to describe the concentration kinetic of extractable solutes in extract during solid-liquid extraction [ 11 , 12 ], the extractable solute effective diffusivity ( D eff ) has frequently been estimated by different methods characterized by concentration at a punctual given time [ 10 , 13 ]. By building concentration-time profiles of mass transfer processes and quantifying the diffusion coefficients, researchers have characterized diffusion processes in carrots [ 14 ], green peas and kiwi fruits [ 15 ], and cereals (oats and grains) and green beans [ 16 ], as a way of assessing the effect of critical variables.…”