Modelling the drying process in case of combined energy supply

Abstract

In many chemical, food, biochemical and other industries, drying is the prime process that is characterized by high energy consumption and determines the quality of the finished product. In this regard, the development of mathematical models that allow of optimization and reliable control of the drying process is relevant. A large set of physical and physicochemical phenomena accompanying drying, as well as their mutual influence on each other, gives rise to numerous uncertainties in the mathematical description of this process. The modeling process becomes more complicated under conditions of combined energy supply, for example, convective and microwave energy supply. In this article, based on the laws of chemical kinetics, the authors propose the original approach to modeling the drying process, which, together with experimental studies, allows obtaining a reliable mathematical model that can be used as the basis for optimizing and controlling this process. During the mathematical modeling of drying, it was proposed to apply new process parameters: the degree of drying (the share of removed moisture) and the degree of absorbed energy (the ratio of the amount of energy absorbed by the product at a given moment to the amount of energy absorbed by the product during the entire process). The expediency of characterizing the kinetics of drying by the dependence of the degree of drying on the degree of absorbed energy is demonstrated. The scientific hypothesis was substantiated and confirmed: the generalized characteristic, the kinetics of drying - the dependence of the degree of drying on the degree of energy absorbed by the product, does not depend on the parameters characterizing the drying mode. The proposed model makes it possible to determine the ratio of the components of convective and microwave energy flows when moisture is removed from the material, which can be used as the basis for optimization and reliable control of the process.