Aasen Ailo, Hammer Morten, Müller Erich A, Wilhelmsen Øivind
Department of Energy and Process Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
SINTEF Energy Research, NO-7465 Trondheim, Norway.
J Chem Phys. 2020 Feb 21;152(7):074507. doi: 10.1063/1.5136079.
We extend the statistical associating fluid theory of quantum corrected Mie potentials (SAFT-VRQ Mie), previously developed for pure fluids [Aasen et al., J. Chem. Phys. 151, 064508 (2019)], to fluid mixtures. In this model, particles interact via Mie potentials with Feynman-Hibbs quantum corrections of first order (Mie-FH1) or second order (Mie-FH2). This is done using a third-order Barker-Henderson expansion of the Helmholtz energy from a non-additive hard-sphere reference system. We survey existing experimental measurements and ab initio calculations of thermodynamic properties of mixtures of neon, helium, deuterium, and hydrogen and use them to optimize the Mie-FH1 and Mie-FH2 force fields for binary interactions. Simulations employing the optimized force fields are shown to follow the experimental results closely over the entire phase envelopes. SAFT-VRQ Mie reproduces results from simulations employing these force fields, with the exception of near-critical states for mixtures containing helium. This breakdown is explained in terms of the extremely low dispersive energy of helium and the challenges inherent in current implementations of the Barker-Henderson expansion for mixtures. The interaction parameters of two cubic equations of state (Soave-Redlich-Kwong and Peng-Robinson) are also fitted to experiments and used as performance benchmarks. There are large gaps in the ranges and properties that have been experimentally measured for these systems, making the force fields presented especially useful.
我们将之前为纯流体开发的量子修正米氏势统计缔合流体理论（SAFT-VRQ Mie）[Aasen等人，《化学物理杂志》151, 064508 (2019)]扩展到流体混合物。在该模型中，粒子通过具有一阶费曼-希布斯量子修正（Mie-FH1）或二阶费曼-希布斯量子修正（Mie-FH2）的米氏势相互作用。这是通过对非加和硬球参考系统的亥姆霍兹能量进行三阶巴克-亨德森展开来实现的。我们调查了氖、氦、氘和氢混合物热力学性质的现有实验测量值和从头算计算结果，并利用它们来优化二元相互作用的Mie-FH1和Mie-FH2力场。结果表明，采用优化力场的模拟在整个相包络范围内都能紧密跟踪实验结果。SAFT-VRQ Mie再现了采用这些力场的模拟结果，但含氦混合物的近临界状态除外。这种失效可以用氦极低的色散能以及当前混合物巴克-亨德森展开实现中固有的挑战来解释。还将两个立方状态方程（Soave-Redlich-Kwong和Peng-Robinson）的相互作用参数拟合到实验中，并用作性能基准。这些系统的实验测量范围和性质存在很大差距，这使得所提出的力场特别有用。
