冻干物料孔隙特性表征的分形模型与分形维数

    Characterizing pores in freeze-dried materials by fractal models and fractal dimensions

    • 摘要: 为了定量表征冷冻干燥物料孔隙结构和形貌特性,采用两种多孔介质分形模型,通过压汞法研究冻干牛肉和冻干腊牛肉孔隙结构的分形特性。研究表明:对于孔隙特征尺度为1~100 μm的冻干牛肉和腊牛肉,采用Menger海绵模型表征孔隙结构时,尽管表观上表现出无标度区分段线性的特性,却无法确定合理的分形维数用于表征物料的孔隙分形结构;而采用热力学关系模型分析物料孔隙结构时,物料孔隙呈现显著的分形特性,并可给出合理的分形维数,该方法可用于定量表征冻干物料的孔隙分形结构特性。

       

      Abstract: In order to represent structure and shape of pores in freeze-dried materials quantitatively, based on mercury intrusion, two fractal models of porous media were employed to characterize pores in freeze-dried bovine muscle and cured beef. The results show that the fractal dimensions are not reasonably presented when Menger sponge model is utilized to characterize the structures of pores in the samples, in which the characteristic scale of pores is 1~100 μm, although the linear relations in segments apparently exhibit. However, while the thermodynamic model is adopted, the fractal properties of the pores in the same samples are remarkably available, and the reasonable dimensions of the samples are obtained in the meantime. It deduces that the fractal features of pores in freeze-dried materials can be determined through the thermodynamic model.

       

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