Dependence of drying speed of grain on distribution and air parameters in microwave-convective zone
Abstract
Dependence of drying speed of grain on distribution and air parameters in microwave-convective zone
Incoming article date: 05.12.2017Energy costs for grain drying are about 30% of the total energy consumption for grain produc-tion. Reducing the energy consumption of drying is possible due to the use of a microwave field. In this case, it is necessary to develop a design of a convection drying zone with a microwave field which will provide uniform drying of the grain throughout the volume. For this purpose, it is advis-able to carry out the simulation of the process. The developed computer model of heat and moisture exchange in the grain layer allows to model one under varying parameters of the grain layer and the drying agent. A computer model implements a stepwise calculation method. According to this method, the grain layer is represented as a series of computer models of the elementary layer. The grain layer is divided into three sections. The specific power of the microwave field is set to con-stant throughout each part. In addition, the model takes into account the features of changing in the specific power of the microwave field in the drying zone from the moisture content of the grain and the distance from the magnetron. The air flow in the microwave convection zone can has an im-portant value for the energy intensity of the process. The paper presents the results of modeling grain drying with two variants of air distribution in the microwave convection zone. Graphs of changes in grain moisture in each of the sections of the layer are given. It is shown that when the air moves from the magnetron, the time and the non-uniformity of drying decrease.
Keywords: drying of grain, grain layer, microwave field, microwave - convection drying, heat and - moisture exchange, computer model, modeling