Study Of Heat And Mass Exchange And Energy Consumption Of During Grain Drying

The moisture content of post-harvest corn is relatively high.In order to ensure the safety of storage process,it is necessary to reduce its moisture content to safe moisture.Most of the current methods of drying grain are based on experience,which will increases the blindness in the drying process to a certain extent and result in low production efficiency and waste of energy.It is of great significance to study the process of heat and mass transfer in the hot air drying process of corn for mastering the energy consumption characteristics of grain drying and finding methods to save energy.In this paper,a deep bed drying model is adopted and combined with a practical drying tower..The main research contents are as follows:Firstly,The drying tower in operation was studied by establishing a mathematical model of dry bed to predict the temperature and moisture content of corn and the temperature and relative humidity of drying medium.The operational parameters of the actual drying tower are measured.Then the measured value is compared with the predicted value,which verifies the correctness of the model.The structure of the air flow in the tower under empty load was simulated by using GAMIT and FLUENT software.The results showed that the penetration ability and uniformity of the air flow in the tower were poor in all directions.Secondly,based on the heat transfer coefficient model provided by Bakker-Arkema,the mathematical model of heat transfer coefficient of the tower is obtained by matching with the test parameters actually measured;Taking the convection heat transfer coefficient as the breakthrough point,the correlation between the heat transfer coefficient and the width C of the corner box is determined and optimized when the other conditions do not change.According to the results of corner box optimization,the FLUENT simulation and numerical calculation were carried out again.Then compared it with the results before the optimization,it was found that the corn rate was increased,the unit heat consumption was reduced,and the uniformity and penetration of the air flow under empty load were improved.Finally,on the basis of corner box optimization and the cost of corn drying,two kinds of energy saving renovation schemes are proposed.The results show that the improved scheme of shortening drying time is economical and optimal.