The Temperature and Relative Humidity Change in Wheat Bulk under the Condition of Temperature Differences

Abstract

-In stored-grain bulk, its state would be affected by the coupling actions of temperature, humidity, moisture, gas and so on. However the most important factors are temperature and humidity. In the paper, the wheat was sealed in the 30 ℃ temperature difference simulation bin for about 75d. The results indicated that the fastest of the temperature change rate was the upper of grain bulk in the same vertical direction of the same plane. In the same way, the grain with nearer to the high temperature district was faster temperature rise and higher amplitude. To the relative humidity of grain bulk, the change of the close to higher temperature grain zone was fiercer than the others. And the relative humidity of low temperature area would change gently. The micro-airflow in grain mainly stemmed from the temperature differences. So the migration and redistribution of the temperature and relative humidity in wheat bulk was caused by the actions of conduction and convection. And the convection was the predominant action in grain bulk. In addition, the differences between heat and mass transfer in vertical and horizontal direction could demonstrate that the grain is anisotropy.