RESEARCH OF THE MATHEMATICAL MODEL OF THE GRAIN PARAMETERS DYNAMICS IN THE CONVECTIVE DRYING PROCESS
Ключові слова:automated control system, drying, grain, mathematical model, finite difference method
The article is devoted to experimental research of the mathematical model of the dynamics of temperature and moisture content of grain mass in the convective drying process using a conveyor dryer. The features of the processes that occur during convective drying are considered. The prospects of using conveyor dryers for improving the grain drying process are shown. Due to the fact that the drying process is conventionally divided into two stages, namely, direct heating the grain with heated air and post-heating exposure, in which the moisture content of the grain decreases due to the received thermal energy, the expediency of developing a mathematical model of the process that will allow predicting the dynamics of temperature and moisture content of the grain mass both at the stage of active drying and during "dry aeration" is proved. When choosing the optimal drying mode and rational design of grain drying equipment, first of all, it is necessary to provide the conditions needed to obtain the specified technological properties of grain. This problem is associated with finding non-stationary fields of moisture content and temperature during the drying process, that is, with solving a system of differential equations for heat and mass transfer. While developing a model for the dynamics of grain parameters, it is proposed to use the method of finite differences. The importance of formulating the initial and boundary conditions, taking into account the design and technological features of grain dryers, and the significant influence of these conditions on the adequacy of the general model of the dynamics of the drying process are emphasized. To check the adequacy of the mathematical model of the grain drying process, a number of experimental researches were carried out using a drying cabinet, three temperature sensors, a humidity sensor and Arduino software and hardware tools for processing the data obtained. Checking the adequacy of the mathematical model, using the obtained experimental data, proved that the developed model, implemented in the Matcad software package, can be used to optimize the drying process, taking into account the quantitative characteristics of the thermophysical and thermodynamic properties of grain, which affect the process of heat and mass transfer in the grain layer.
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