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

Authors : Todd NİCHOLS, Vivek UTGİKAR

Pages : 158-172

Doi:10.5541/ijot.426202

View : 10 | Download : 7

Publication Date : 2018-09-01

Article Type : Research Paper

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. I t 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