Computer model of heat transfer of moisture transfer in the grain layer under the action of the microwave field and convection
Abstract
Computer model of heat transfer of moisture transfer in the grain layer under the action of the microwave field and convection
Incoming article date: 01.08.2017The action of the microwave field is used for drying, pretreatment and disinfection of grain. In all these processes, it is very important to control the change in the parameters of the grain layer. The use of sensors for direct measurement of temperature and humidity of grain and air is difficult. The microwave field leads to errors in the measurements, and therefore the possibility of an indirect control of these quantities is considered. For the indirect measurement of these quantities, a computer model has been developed. To develop a computer model, a system of equations was used that describes the exchange of heat and moisture in the grain layer under the action of the microwave field and convection. Some equations in the mathematical model are partial differential equations. To develop a computer model, these equations were presented in an operator form. The article shows how this procedure was used to transform the equation showing the relationship between the grain temperature and the microwave field, air temperature and moisture content of the grain. This approach allowed the use of computer software for analysis and syn-thesis of control systems. In this case the Simulink software package was used. Simulink - a model for the exchange of heat and moisture in a thick layer of grain, when exposed to microwave and air, was created using elementary dynamic elements of automation. When developing a computer model, a step-by-step method is implemented. The essence of the method is that the grain layer is divided into elementary layers. The output parameters of one grain layer become input parameters for the next layer. A complete model for the exchange of heat and moisture in a layer of grain consists of models of elementary layers. The results of modeling the change in the temperature of grain heating confirmed the adequacy of the model. The use of this model in the control systems of drying and processing of grain will increase the accuracy of control and regulation.
Keywords: drying grain, grain layer, grain moisture, grain temperature, drying agent, microwave action, heat and moisture exchange, modeling