粮食吸湿及湿空气在粮堆中的扩散特性研究

STUDY ON MOISTURE ABSORPTION CHARACTERISTICS OF GRAIN AND MOISTURE DIFFUSION CHARACTERISTICS IN GRAIN BULK

研究了粮食的吸湿特性和湿空气在粮堆中的扩散特性.结果表明:粮食在湿空气中吸湿速度较快,安全水分小麦直接暴露于RH80%条件下,4 d左右水分即可达到基本平衡.但如果没有外部力量推动,湿空气在粮堆中扩散速度很慢,维持小麦、玉米和稻谷的初始相对湿度与环境相对湿度差值超过10%的条件,30 d、0.5 m粮层的相对湿度升高值均小于4%.温差对湿空气在粮堆中的扩散有较强的推动作用,在温差20℃和RH85%的条件下,对局部粮食的增湿速度,湿空气影响粮堆的深度和粮食的增湿量均显著大于无温差条件的结果.

The moisture absorption characteristics of grain and the moisture diffusion characteristics in grain bulk were investigated.The results indicate that the grain in moisture air has high moisture absorption speed,and wheat with safe moisture content can achieve basic moisture balance in about 4 days when directly exposed to environment with RH 80%.However,the moisture diffused in the grain bulk slowly if no external force was applied.Under the condition of keeping the difference between the initial relative humidity of wheat,maize and rice and the relative humidity of the environment larger than 10%,the relative humidity increments of the 0.5 m grain layers were less than 4% in 30 days.The temperature difference had significant effect in promoting the diffusion of moisture in the grain bulk.Under the conditions of temperature difference 20 ℃ and RH 85%,the moisture absorption speed in the local part of the grain bulk,the depth of the moisture influencing the grain bulk and the moisture increment were remarkably larger than the results in the environment without temperature difference.