Abstract Transport coefficients (like diffusion and thermodiffusion) are the key parameters to be studied in non-equilibrium thermodynamics. For practical applications, it is important to predict them based on the thermodynamic parameters of a mixture under study: pressure, temperature, composition, and thermodynamic functions, like enthalpies or chemical potentials. The current study develops a thermodynamic framework for such prediction. The theory is based on a system of physically interpretable postulates; in this respect, it is better grounded theoretically than the previously suggested models for diffusion and thermodiffusion coefficients. In fact, it translates onto the thermodynamic language of the previously developed model for the transport properties based on the statistical fluctuation theory. Many statements of the previously developed model are simplified and amplified, and the derivation is made transparent and ready for further applications. The n ( n + 1 ) / 2n(n+1)/2 independent Onsager coefficients are reduced to 2 n + 12n+1 determining parameters: the emission functions and the penetration lengths. The transport coefficients are expressed in terms of these parameters. These expressions are much simplified based on the Onsager symmetry property for the phenomenological coefficients. The model is verified by comparison with the known expressions for the diffusion coefficients that were previously considered in the literature.

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多组分混合物中扩散和热扩散系数的热力学理论

摘要 传输系数（如扩散和热扩散）是非平衡热力学中需要研究的关键参数。对于实际应用，重要的是根据所研究混合物的热力学参数来预测它们：压力、温度、成分和热力学函数，如焓或化学势。目前的研究为这种预测开发了一个热力学框架。该理论基于物理可解释的假设系统；在这方面，它比先前建议的扩散和热扩散系数模型具有更好的理论基础。事实上，它转化为先前开发的基于统计波动理论的传输特性模型的热力学语言。之前开发的模型的许多陈述被简化和放大，推导变得透明，为进一步应用做好准备。n ( n + 1 ) / 2n(n+1)/2 个独立的 Onsager 系数减少到 2 n + 12n+1 个确定参数：发射函数和穿透长度。传输系数用这些参数表示。这些表达式基于现象学系数的 Onsager 对称性得到了极大的简化。该模型通过与先前在文献中考虑的扩散系数的已知表达式进行比较来验证。n ( n + 1 ) / 2n(n+1)/2 个独立的 Onsager 系数减少到 2 n + 12n+1 个确定参数：发射函数和穿透长度。传输系数用这些参数表示。这些表达式基于现象学系数的 Onsager 对称性得到了极大的简化。该模型通过与先前在文献中考虑的扩散系数的已知表达式进行比较来验证。n ( n + 1 ) / 2n(n+1)/2 个独立的 Onsager 系数减少到 2 n + 12n+1 个确定参数：发射函数和穿透长度。传输系数用这些参数表示。这些表达式基于现象学系数的 Onsager 对称性得到了极大的简化。该模型通过与先前在文献中考虑的扩散系数的已知表达式进行比较来验证。