MHVOS混合规则在高压汽液相平衡中的应用

Application of HVOS Mixing Rule in Vapor-liquid Phase Equilibria at High Pressure

为改进HVOS混合规则应用于非对称体系汽液平衡的能力,将混合规则能量参数表达式中的结合项与活度系数模型UNIFAC结合项中的Flory-Huggins部分进行相互抵消,并相应地修改交叉体积参数项。利用改进后的混合规则MHVOS,结合Peng-Robinson状态方程及UNIFAC模型对14种二元体系的高压气液相平衡进行预测,并与HVOS和MHV1混合规则比较。结果表明,对于小分子且相对分子质量相近的极性或烷烃类二元体系MHVOS混合规则预测能力并未得到提高。而针对相对分子质量差距较大非对称性强的烷烃类二元体系,HVOS和MHV1混合规则的预测精度均明显下降,MHVOS混合规则的预测精度反而有所提高。

To improve the capacity of HVOS mixing rule used in vapor-liquid phase equilibria of asymmetric system, the combinatorial part of energy expression parameter of mixing rule and the Flory-Huggins part of combinatorial part of activity coefficient model were counteracted simultaneously, and alter the volume parameters accordingly. This modified mixing rule MHVOS combined with Peng-Robinson equation of state and UNIFAC model was applied to the prediction of high pressure vapor-liquid phase equilibria of 14 binary systems and was compared with both classical HVOS and MHV1 mixing rules. The results obtained by the modified HVOS mixing rule were not better than the prototype for the polar or alkane system with similar small molecular weight.For the high asymmetric alkane system, the prediction accurateness by the modified HVOS mixing rule were preferable while the results with the HVOS and MHV1 mixing rules became bad.