Modelling the processes of hygrothermal mechanics in rice drying

Grain-crops are justly considered to be the staple food in Russia as well as all over the world. The specific feature is that postharvest processing of the grain and, above all, drying is an essential stage of providing products of high quality in the sufficient amount. The changes of the technological parameters of the drying process which take place over time, have a significant practical value in terms of monitoring the process and defining the modes providing the quality of the product as well as calculating energy demands necessary to carry out this process. Hereof, the quality of the product received is defined by minimum crack formation of rice grain after the process. The aim of the work is to get a mathematical model of hygrothermal mechanics of rice drying. On the basis of A.V. Lykov’s system of differential equations which describe the changes in moisture content, temperature and pressure, transition to the system of ordinary differential equations was offered which is based on drawing up balance of mass and heat during the process of drying. This approach does not consider the properties of moisture content and temperature within the material but takes into account their mean value. Using a simplified model of hygrothermal mechanics of rice drying that we have got enabled us to reproduce the process of drying in the conditions of minimum crack formation within the studied range (the temperature of the drying agent from 50 to 70 °C, speed from 2.3 to 2.8 м/sеk). The dependences we have got enable us to predict the quality of rice grain during drying.