基于van der Waals状态方程的剩余自由能模型

An Excess Free Energy Model from van der Waals Equation of State

结合 Wong- Sandler的混合规则 ,即在无穷大压力下剩余 Helmholtz自由能与无穷小剩余 Gibbs自由能近似相等的关系 ,给出了一个基于 van der Waals状态方程的剩余自由能模型 ,由此得到可以描述汽液相平衡的活度系数模型。通过对 35个体系的考核表明 ,该模型可以较好的关联实验数据 ,包括极性与极性物系 ,其结果好于 Wilson、Mar-gules、NRTL与 Uniquac等模型的计算结果。同时 ,因为该模型基于 Wong- Sandler的混合规则 ,因此可以实现在理想溶液中 ,由 Wong- Sandler混合规则到 van der Waals混合规则平滑过渡。

An excess Helmholtz free energy expression based on generalized van der Waals equation of state and Wong Sandler mixing rule was derived in accordance with the approximate equality of excess Helmholtz free energy from equation of state at indefinite pressure and excess Gibbs free energy.The result shows that this proposed expression is effective for correlating vapor liquid equilibrium as compared with the other activity coefficient models such as Wilson, Margules, NRTL and Uniquac by checking 35 polar and non polar systems. It allows the smooth transition from the Wong Sandler mixing rules to the classic van der Waals mixing rules when the deviation is negligible from ideal behaviour in the liquid phase.