Simultaneous estimation of phase behavior and second-derivative properties using the statistical associating fluid theory with variable range approach.
Simultaneous estimation of phase behavior and second-derivative properties using the statistical associating fluid theory with variable range approach.
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DOI：
10.1063/1.2140276
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发表时间：
2006-01
期刊：
影响因子：
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通讯作者：
T. Lafitte;D. Bessieres;M. M. Piñeiro-M.;J. Daridon
中科院分区：
文献类型：
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作者：
T. Lafitte;D. Bessieres;M. M. Piñeiro-M.;J. Daridon
使用 m-n Mie 势族提出了一种具有可变范围版本的修正统计缔合流体理论 (SAFT)。使用这种分子间势来模拟单体链段之间的排斥-色散相互作用，以及优化状态方程分子参数的新方法，可以非常准确地描述长链正烷烃的气液平衡和压缩液体本体特性（体积和导数特性）。这个新方程改进了其他类似 SAFT 的状态方程，这些方程无法描述等温压缩性和凝聚液相中的声速等导数性质。重点指出对后一个性质进行建模的关键是在分子间势中使用可变排斥项。在正烷烃系列的情况下，得到了特征分子参数对链长度增加的明显依赖性，证明了它们合理的物理意义和所提出的新拟合程序的一致性。这种优化模型参数的系统方法包括饱和线数据以及凝聚液相中的密度和声速数据，结果无疑表明模型性能得到了增强，其适用范围得到了拓宽，在任何情况下都在不同估计特性的准确性之间保持了良好的平衡。
A modified statistical associating fluid theory (SAFT) with variable range version is presented using the family of m-n Mie potentials. The use of this intermolecular potential for modeling repulsion-dispersion interactions between the monomer segments, together with a new method for optimizing the molecular parameters of the equation of state, is found to give a very accurate description of both vapor-liquid equilibria and compressed liquid bulk properties (volumetric and derivative properties) for long-chain n-alkanes. This new equation improves other SAFT-like equations of state which fail to describe derivative properties such as the isothermal compressibility and the speed of sound in the condensed liquid phase. Emphasis is placed on pointing out that the key for modeling the latter properties is the use of a variable repulsive term in the intermolecular potential. In the case of the n-alkanes series, a clear dependence of the characteristic molecular parameters on increasing chain length is obtained, demonstrating their sound physical meaning and the consistency of the new fitting procedure proposed. This systematic method for optimizing the model parameters includes data on the saturation line as well as densities and speed of sound data in the condensed liquid phase, and the results show undoubtedly that the model performance is enhanced and its range of applicability is now widened, keeping in any case a good balance between the accuracy of the different estimated properties.