摘要
从热力学出发对Nasrifar-Moshfeghian(N-M)两参数立方形状态方程进行评价,并将其应用到混合物的汽液相平衡计算中.N-M状态方程结合MHV1(the first modified Hurm-videl)混合规则(N-M+MHVI)对17种双元混合物的汽液相平衡数据进行了关联,与PR(Perg-Robinson)+MHV1、SRK(Soare-Redlich-Kister)+MHV1模型相比,(N-M+MHVI)的关联精度比后两种模型所关联的精度低.为了更进一步提高关联精度,对于MHV1混合规则进行了两方面的改进:1)引入了新的非对称参数f;2)参数b经验地采用非线性结合规则.N-M方程结合改进后的MHV1混合规则对17种混合物的汽液相平衡数据进行了关联,关联结果与采用原MHV1混合规则所得的结果相比,精度有了一定的提高,而且绝大部分混合物关联的精度比采用PR+MHV1、SRK+MHV1模型进行关联的精度要高.但是对于极性体系,如丙酮/水、甲醇/水,精度仍然较差,原因为:N-M状态方程本身的缺点,即总是考虑b/T的符号和在低温下计算时,对于具有较大压缩因子的物质不适应;参数b的结合规则.总之,N-M方程的提出为纯物质的饱和液体及混合物的汽液相平衡计算提供了有价值的参考.
The Nasrifar-Moshfeghian（N M） equation of state （EOS） was evaluated and applied to predict the vapor-liquid equilibria （VI.E） of mixtures in this work. Combining with MHV1 mixing rule, the N-M EOS was tested for VLE of 17 polar/nonpolar systems, in which the NRTL activity coefficient model was used to calculate the excess Gibbs free energy. Comparisons between using the N M EOS with MHV1 mixing rule, and peng robinson （PR）,soave redlich kister（SRK） EOSs with MHV1 mixing rules showed that the correlation accuracy of the former was inferior to that of the latter. In order to improve the correlation accuracy further, two modifications were proposed to the original MHV1 mixing rule applying to the N-M EOS： 1） Introducing a new asymmetric parameter f ; 2） the parameter was in the non linear form. The average composition and pressure deviations of the systems were decreased after the modifications. The correlated accuracy using the N-M＋Modified MHV1 model is slightly superior to that of PR＋ MHV1,SRK＋MHVlmodels. But, there is less accuracy for some systems （acetone/water, methanol/water systems） in comparison with PR＋MHV1, SRK＋MHVlmodels. The reason may be considered from the following aspects： 1） The drawbacks of N-M EoS,that is, the sign of the derivative δb/δT should always be checked, and the substances with big acentric factor could be done at lower temperature： 2） the combining rule of N-M EoS dependent parameter b . However, the above results show that N M EOS can be conveniently applied to the predictions of VLE with a high accuracy for most systems. Therefore, it provides a new path not only for accurate predictions of liquid densities, but also for accurate predictions of VI.E for binary mixtures.
出处
《浙江大学学报（工学版）》
EI
CAS
CSCD
北大核心
2006年第4期684-688,共5页
Journal of Zhejiang University：Engineering Science
基金
浙江省自然科学基金资助项目(Z105034)
关键词
汽液相平衡
状态方程
混合规则
equation of state
vapor-liquid equilibrium
mixing rule
