Kinetics model of convective drying

Abstract

The article considers various approaches to modeling the drying of finely dispersed products: based on the classical theory of diffusion, from the standpoint of the thermodynamics of an irreversible process. An analysis of the scientific and technical literature on the problem revealed not high accuracy of the convective drying models of finely dispersed products developed on the existing theoretical basis. It is shown that the improvement of drying modeling can be based on the kinetics theory of chemical reactions. In this case, drying is considered as a quasi-topochemical heterogeneous reaction. At the same time, a combined approach to drying modeling is proposed: the phenomenological equation of chemical kinetics, which describes the speed of the process, is supplemented by the experimentally established relationship between the temperature and moisture content of the material. Based on the proposed approach, mathematical models of the kinetics of convective drying of finely dispersed products for periods of constant and decreasing speed have been developed, which allow to establish a clear type of the influence of the temperature regime on the kinetics of the process and reduce the amount of experimental research. A mathematical model of the temperature curve of drying for a period of decreasing speed is developed. The relationship between the speed of the first and second drying periods is established. The reliability of the obtained mathematical models is confirmed by experimental verification of the kinetic equation obtained for a period of constant velocity.