摘要
本文提出了粮食多段干燥过程排粮速度、各段温度的检测与统计计算方法。根据玉米四段干燥过程粮层通过干燥段2与缓苏段2及干燥段3与缓苏段3的温度差值,将玉米干燥温度变化特征分为:缓苏段温度平衡型,缓苏段温度上升型,缓苏段温度下降型以及6种复合型。利用谷物表面温度为空气温度、颗粒内温度由内向外逐渐升高、水分在颗粒内部解吸附并汽化沿毛细通道逸出颗粒表面的模型和多孔介质内在压力梯度作用下沿毛细通道流动的水分传输机理解释了产生这种温度变化差异的原因,即近表皮层水分逸出阻力主要取决于玉米颗粒表皮层的致密性,而远离表皮层水分选出取决于表皮层与毛细通道阻力的作用之和。通过比较℃以上与0℃以下入机粮温样本温度特征类型占总样本量百分比,提出冷冻后玉米颗粒干燥时,表皮层致密性受到破坏,易于干燥过程水分的选出。给出了利用玉米干燥过程温度和干燥时间预测各类型玉米样本出机含水率的方法。本文研究成果对于指导干燥过程操作和实现干燥过程出机含水率的智能控制具有重要意义。
The method of measurement and statistic calculation for the flow speed and the temperature of dried maize in the drying process with multi - stage is proposed in this paper. According to the variation of differences in maize temperature between in tempering stage 2 and in drying stage 2 and between in tempering stage 3 and drying stage 3, the temperature characteristic of dried maize is classified into temperature balance group in tempering stage, temperature raise group in tempering stage, temperature decline group in tempering stage, and 6 combinatorial groups. The model of temperature profile for grain losing vapor at air temperature and the moisture transfer mechanism of flow by a pressure gradient along capillary passages are used to explain the differences of maize temperature variation, i. e. , the resistance that maize kernels lose the moisture close to the epidermal layer （outside cell layer ） is dependent on the close - grained of epidermal layer, and the resistance that maize kernels lose the moisture far from the epidermal layer is dependent on the close - grained of epidermal layer and the resistance of capillary passages. By comparing the sample percents of different groups that inlet temperature of the samples is lower than 0℃ with that higher than 0℃, it is proposed that the close - grained of epidermal layer of maize kernels becomes lower during the drying process after the maize kernels have been frozen, and this makes grain losing moisture easy. By the virtue of the temperature of maize layer during the drying process or the drying time, the forecast method of the moisture content of discharge grain is proposed. The results of research in this paper are important to guide the operation of grain drying and to realize the intelligent control of grain drying.
出处
《中国粮油学报》
EI
CAS
CSCD
北大核心
2006年第3期358-365,共8页
Journal of the Chinese Cereals and Oils Association
基金
国家自然科学基金重点项目
编号:5053010
关键词
谷物干燥
温度
玉米
缓苏
出机粮含水率
gGrain drying, temperature, tempering, moisture content of discharge grain
