Calculation of Isothermal Vapor-Liquid Equilibrium Data for Binary Mixtures from Heats of Mixing
Calculation of Isothermal Vapor-Liquid Equilibrium Data for Binary Mixtures from Heats of Mixing
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DOI：
10.1021/i160039a025
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发表时间：
1971-08
期刊：
影响因子：
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通讯作者：
R. W. Hanks;Avinash C. Gupta;J. J. Christensen-J.
中科院分区：
文献类型：
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作者：
R. W. Hanks;Avinash C. Gupta;J. J. Christensen-J.
将Gibbs-Helmholtz关系和两个流行的超额自由能半理论关系式(Wilson方程和NRTL方程)用于计算六个高度非理想二元体系的等温汽液平衡(XY)数据。这种方法可以直接从测量的混合热(/)数据和纯组份蒸汽压中产生可靠的XY曲线，而不需要测量任何XY数据。这种方法与滴定量热技术相结合，可以方便、快速地测量AHM，在相平衡工作中具有相当大的实用潜力。虽然使用了威尔逊方程和NRTL方程，但该计算方法对任何超额自由能函数都是有效的。计算的XY数据的精度似乎仅受AHM和蒸汽压数据的精度以及所选择的半理论过剩自由能模型的限制。Zapor-Liquid平衡数据具有相当重要的工业和学术意义。虽然这些数据可以很容易地计算出理想解，但大多数感兴趣的解在行为上并不理想。人们已经对非理想解进行了大量的研究，但目前还不存在能够从理论上准确预测偏离理想解的方法。因此，人们必须求助于实验测量来确定给定系统的非理想性。本文讨论了一种估算等温汽-液平衡的方法，这种方法不涉及对汽液平衡混合物中汽相或液体组成的实验测量，这一过程通常是相当繁琐的。该方法包括使用测量的混合热来评估半理论热力学方程中的常数，而半理论热力学方程又被用来计算纯组分蒸汽的平衡数据。
The Gibbs-Helmholtz relation is used together withtwo popular semitheoretical excess free energy relations (Wilson’s equation and the NRTL equation) to calculate isothermal vapor-liquid equilibrium (xy) data for six highly nonidealbinary systems. This method is shown to produce reliable xy curves directly from measured heat of mixing (/) data and pure component vapor pressures without the necessity of measuring any xy data. This method, coupled with titration calorimetry techniques for measuring AhM easily and quickly, has considerable practical potential for phase equilibrium work. Although Wilson’s equation and the NRTL equation were used, the calculation method is valid for any excess free energy function. The accuracy of the calculated xy data appears to be limited only by the accuracy of the AhM and vapor pressure data and the semitheoretical excess free energy model chosen.\Zapor-liquid equilibrium data are of considerable industrial and academic importance. Although these data can readily be calculated for ideal solutions, most solutions of interest are not ideal in behavior. A great deal of study has been performed on nonideal solutions, but at present no way exists which will permit the accurate theoretical prediction of deviations from ideality. Therefore, one must turn to experimental measure-ment to determine nonidealities for a given system. In this paper, we discuss a method of estimating isothermal vapor-liquid equilibriumwhich does not involve the experi-mental measurement of the composition of either the vapor or liquid in a vapor-liquid equilibrium mixture, a procedure which is often quite laborious. The method consists of using measured heats of mixing to evaluate the constants in semi-theoretical thermodynamic equations which in turn are used to calculate equilibrium data from pure component vapor