Modeling of the drying process of agro industrial products

Abstract

Drying is one of the most fundamental methods to preserve agricultural products, such as cereal beans, coffee, food and wood. The behavior of the material during drying operations depends on heat and mass transfer mechanisms interesting the product under drying processes. In this work we give a physical and computational model of the drying process, based on heat and moisture transport phenomena in porous media. The model is obtained from the Fourier’s law of heat conduction and Fick’s law of mass transfer and it is based on Luikov’s (1975) and Sokhansanj and Bruce’s (1987) works, the latter coupling heat and mass transport by means of a boundary condition on the grain surface. The equations are computationally developed using the finite volume method and the numerical solutions are compared with experimental and numerical literature data for soybean grains drying. The values of the moisture and temperature fields inside the grain, calculated by using an implicit finite volume scheme, agree with the literature data. However, the numerical results of temperature obtained by solving the Sokhansanj and Bruce’s equations differ from the values computed with the Luikov’s model, due to the modeling of moisture evaporation mechanisms on the grain boundaries.