玉米籽粒缓苏干燥过程动力学分析

Analysis of Drying-Temping Kinetics for Corn Kernel

对玉米籽粒的缓苏干燥过程进行了理论分析,并假设玉米籽粒为轴对称结构、各向同性的均匀物质,建立了玉米籽粒的缓苏干燥数学模型,利用COMSOL Multiphysics模块进行了热质传递过程的模拟研究.结果 表明,该模型可较好地模拟玉米籽粒的干燥过程.利用该模型模拟研究了不同干燥条件下玉米籽粒温度、干燥时间、缓苏时间、缓苏度的变化及其对干燥速度的影响.结果 表明,玉米籽粒内外温度在3~5 min内即可达到热风温度,玉米籽粒内部最大水分梯度出现在热风干燥5 ~ 10 min后,不同干燥阶段不同初始含水率对缓苏度的影响很小,缓苏60 min水分梯度可以基本消除.利用该优化工艺参数对玉米籽粒交替进行热风干燥和缓苏干燥,可使总的热风干燥时间最少,实现节能目的.

Theoretical analysis were conducted to the drying-tempering process of corn kernel,and corn kernel was assumed as isotropic homogeneous material with axisymmetric structure to establish the drying-tempering mathematic model of the com kernel.The caloric transfer process were modeled and simulated by COMSOL Multiphysics Modular.The result shows that the model can better simulaye the drying process of the corn kernel.The model was verified with the experimental results of corn kernel temperature,drying time,tempering time,change of tempering degree and the effect of drying degree under different drying conditions.Simulated research results showed that the com kernel surface temperature and core temperature reach the hot air temperature in 3~5 min,the maximum moisture gradient of the core com kernel appears after 5?10 min of hot air drying,the initial moisture content has very little influence to the tempering degree in diferent drying stage,and the moisture gradient can be basically eliminated if tempering time is more than 60 min.The minimum total hot air drying time and the least energy consumption can be realized by these optimized drying-tempering parameters and alternate processing technique to the com kernel.