Grand Equilibrium: vapour-liquid equilibria by a new molecular simulation method
Grand Equilibrium: vapour-liquid equilibria by a new molecular simulation method
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大平衡：通过新的分子模拟方法实现气液平衡
DOI：
10.1080/00268970210153772
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发表时间：
2002
影响因子：
1.7
通讯作者：
H. Hasse
中科院分区：
文献类型：
--
作者：
J. Vrabec;H. Hasse
提出了一种新的计算混合物汽液平衡的分子模拟方法。在该方法中，独立的热力学变量是温度和液体组成。在第一步中，对液相进行等压等温模拟，其中计算了所有组分及其导数相对于压力的化学势，即偏摩尔体积。根据这些结果，确定了恒定液体组成时化学势随压力μi(P)的一阶泰勒级数展开式。这一信息是必要的，因为液体中的指定压力通常不等于平衡压力，而平衡压力必须在蒸汽模拟过程中找到。在第二步中，对汽相进行伪正则模拟，其中化学势是使用先前确定的函数μi(Pv)根据瞬时压力pv来设置的。通过这种方式，获得了在给定温度和液体组成下一致的蒸气压力和蒸气组成的结果。将新方法应用于纯Lennard-Jones流体、Lennard-Jones球的二元和三元混合物，与文献中的相应数据吻合得很好。
A new molecular simulation method for the calculation of vapour-liquid equilibria of mixtures is presented. In this method, the independent thermodynamic variables are temperature and liquid composition. In the first step, one isobaric isothermal simulation for the liquid phase is performed, in which the chemical potentials of all components and their derivatives with respect to the pressure, i.e. the partial molar volumes, are calculated. From these results, first-order Taylor series expansions for the chemical potentials as functions of the pressure μ i (p) at constant liquid composition are determined. This information is needed, as the specified pressure in the liquid will generally not be equal to the equilibrium pressure, which has to be found in the course of a vapour simulation. In the second step, one pseudo grand canonical simulation for the vapour phase is performed, where the chemical potentials are set according to the instantaneous pressure p v using the previously determined function μ i (p v). In this way, results for the vapour pressure and vapour composition are achieved which are consistent for the given temperature and liquid composition. The new method is applied to the pure Lennard-Jones fluid, a binary and a ternary mixture of Lennard-Jones spheres, and shows very good agreement with corresponding data from the literature.