Maier Lukas, Kufferath-Sieberin Lars, Pauly Leon, Hopp-Hirschler Manuel, Gresser Götz T, Nieken Ulrich
Institute of Chemical Process Engineering, University of Stuttgart, Boeblinger Strasse 78, 70199 Stuttgart, Germany.
German Institutes of Textile and Fiber Research Denkendorf (DITF), Körschtalstraße 26, 73770 Denkendorf, Germany.
Materials (Basel). 2023 Feb 28;16(5):2014. doi: 10.3390/ma16052014.
Mass transport in textiles is crucial. Knowledge of effective mass transport properties of textiles can be used to improve processes and applications where textiles are used. Mass transfer in knitted and woven fabrics strongly depends on the yarn used. In particular, the permeability and effective diffusion coefficient of yarns are of interest. Correlations are often used to estimate the mass transfer properties of yarns. These correlations commonly assume an ordered distribution, but here we demonstrate that an ordered distribution leads to an overestimation of mass transfer properties. We therefore address the impact of random ordering on the effective diffusivity and permeability of yarns and show that it is important to account for the random arrangement of fibers in order to predict mass transfer. To do this, Representative Volume Elements are randomly generated to represent the structure of yarns made from continuous filaments of synthetic materials. Furthermore, parallel, randomly arranged fibers with a circular cross-section are assumed. By solving the so-called cell problems on the Representative Volume Elements, transport coefficients can be calculated for given porosities. These transport coefficients, which are based on a digital reconstruction of the yarn and asymptotic homogenization, are then used to derive an improved correlation for the effective diffusivity and permeability as a function of porosity and fiber diameter. At porosities below 0.7, the predicted transport is significantly lower under the assumption of random ordering. The approach is not limited to circular fibers and may be extended to arbitrary fiber geometries.
纺织品中的质量传递至关重要。了解纺织品的有效质量传递特性可用于改进使用纺织品的工艺和应用。针织物和机织物中的质量传递很大程度上取决于所使用的纱线。特别是，纱线的渗透性和有效扩散系数备受关注。通常使用相关性来估计纱线的质量传递特性。这些相关性通常假设为有序分布，但在此我们证明有序分布会导致对质量传递特性的高估。因此，我们探讨了随机排列对纱线有效扩散率和渗透性的影响，并表明为了预测质量传递，考虑纤维的随机排列很重要。为此，随机生成代表性体积单元以表示由合成材料连续长丝制成的纱线结构。此外，假定纤维为平行、随机排列且具有圆形横截面。通过求解代表性体积单元上的所谓胞元问题，可以针对给定的孔隙率计算传输系数。然后，基于纱线的数字重建和渐近均匀化得到的这些传输系数，用于推导有效扩散率和渗透率与孔隙率和纤维直径的函数关系的改进相关性。在孔隙率低于0.7时，在随机排列假设下预测的传输显著更低。该方法不限于圆形纤维，并且可以扩展到任意纤维几何形状。
