Soybean drying as a moving boundary problem: Shrinkage and moisture kinetics prediction

Abstract

AbstractIn this work, the diffusion of moisture in the drying process of soybean grains is mathematical modeled considering shrinkage. Moisture and radius data as a function of time were obtained by experimental tests in a drying oven for three different drying temperatures. Radius decrease was registered by image analysis. The parameters of the diffusion model were obtained by nonlinear regression. The model provided diffusivity values and drying constants at the surface of the grains as a function of temperature. The average moisture profiles presented good agreement with the experimental values. Although the radius profiles predictions presented higher deviation when compared with the experimental values, a good agreement were found, especially at the higher drying rates of the process. The model provided good predictions of the moisture and radius profile for the drying process of soybean grains and the diffusivities and drying constants for considering the grain shrinkage during the process.Practical ApplicationsDiffusion coefficients are crucial parameters to be estimated in order to design highly efficient drying process for food industry. Thus, if the mass transfer is mathematically modeled considering realistic aspects, which occur during the drying process, such as the shrinkage of the grains, the diffusion coefficients estimated become more trustable, allowing the project and optimization of drying equipment for the grain processing industry.