多孔物料干燥中物料体积的收缩特性

以生姜、胡萝卜、土豆和香蕉为实验材料，引入体积收缩系数和各向同性率的概念，研究了多孔物料干燥过程中的体积收缩特性，分析了脱水量与物料收缩率之间的关系，并探讨了干燥介质温度和相对湿度对收缩特性的影响．结果表明，干燥强度越大则物料的体积收缩率越大，且多孔物料的微观结构也对收缩特性有着重要的影响．最后通过无量纲化方法建立了考虑收缩特性的土豆-水分扩散模型，实验数据与模拟结果趋于一致．

Volume Shrinkage Characteristics of Porous Materials in Drying Process

The volume shrinkage characteristics of the definitions of Volume Shrinkage Coefficient and porous materials in the drying process are investigated based on Shrinkage Isotropicity, with fresh ginger, carrot, potato and banana as the drying materials. The relationship between the volume reduction of the material and the removed moisture is then analyzed, and the effects of the drying stream temperature and the relative humidity on the shrinkage characteristics are also discussed. The results show that a fast drying rate will result in great volume shrinkage, and that the microstructure of the porous materials significantly affects the shrinkage characteristics. A dimensionless moisture diffusion model is also presented in this paper for the drying of potato, the obtained results of which accord well with the experimental ones.