Wagner Equation Predicting Entire Curve for Pure Fluids from Limited VLE Data: Critical and Normal Boiling Points & Acentric Factor

Abstract

Wagner constants are estimated from VLE predictions based solely on the critical and normal boiling points, and acentric factor.  The predictions come from the standard forms of 1) Riedel and 2) Ambrose-Walton, 3) a modified Riedel equation resulting from forcing the value of K to provide zero error at the reduced temperature of 0.7, and 4) a modified Ambrose-Walton equation resulting from using a pseudo acentric factor that provides zero error at the normal boiling point.  Reduced vapor pressure values obtained using these Wagner constants are compared to those generated by using literature-reported Wagner constants that are applicable for the entire two-phase VLE curve for 72 species. It is shown that the Wagner equation parameterized using VLE predictions from such correlations can provide better accuracy than the underlying source correlations themselves, and it can exhibit less error than a parameterization using a limited interval of experimental data.

Keywords

• Vapor-liquid equilibrium,Wagner equation,Riedel equation,Ambrose-Walton equation

References

1. Dr. Ahmed Bellagi, U. R. Thermique et Thermodynamique des Procedes Industriels, Ecole Nationale d'ingenieurs de Monastir (E.N.I.M.), Avenue Ibn El Jazzar, 5060 Monastir, Tunisia, E-mail address: [e-mail]
2. Dr. Joachim Gross, Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, Pfaffenwaldring 9, D-70569 Stuttgart, Germany, E-mail: [e-mail]
3. Dr. Santiago Velasco, Departamento de Fisica Aplicada, Universidad de Salamanca, E-37008 Salamanca, Spain, E-mail: [e-mail]
4. Dr. Ehsan Sanjari, Department of Mechanics, Tiran Branch, Islamic Azad University, Isfahan, Iran, E-mail: [e-mail]