多孔材料热风干燥过程中收缩特性研究

The Shrinkage Characteristics of Porous Materials in the Hot Air Drying Process

为了更好的研究多孔材料热风干燥过程中内部干燥特性,将干燥过程中整体体积、尺寸收缩比与平均干基含水率的函数关系运用到内部各单元层。以胡萝卜颗粒为例,建立了干燥中物料内部各单元层收缩模型。运用MATLAB编程的方法对胡萝卜颗粒内部各单元层体积和尺寸变化及分布规律进行数值模拟计算。模拟结果表明:片状胡萝卜颗粒在热风干燥过程中随着水分不断对外扩散迁移、干基含水率降低的过程中,表单元层由于水分首先扩散蒸发到热空气中而首先收缩,内部单元层水分滞后扩散蒸发而滞后收缩;外部单元层水分扩散速率大于内部单元层,边界收缩位移量最大。通过实验对模拟结果进行验证,验证结果表明此模型可以用来表述干燥过程中多孔材料内部收缩特性变化规律。

In order to better study porous internal dry hot air drying process features a porous materials inside each cell shrinkage model was established by used the overall volume,size shrinkage ratio as a function of the average dry basis moisture content to the inner units layers,Using the method of MATLAB to study the inside each units＇ volume and size change and distribution rule in the hot air drying. The results showed that： with the external moisture diffused and the moisture content decreased,the table cell layer was shrink first and the inside layers＇ shrink last,and the external unit layers＇ moisture diffusion rate is greater than the internal unit,the external shrinking boundary displacement was larger. The results show that this model can be used to describe porous material internal shrinkage characteristics change regularity in drying process.