(59c) Learning Fugacity, Fugacity Coefficient and the Phase Equilibrium Criteria through 3D Phase Diagrams for Pure Components

Authors: 
Flores-Tapia, J., Universidad de las Américas, Puebla
Gómez-Tena, M., Universidad de las Américas, Puebla
Ríos-Casas, L. G., Universidad de las Américas, Puebla
Alarcon-Garcia, A., Ciba, S.A. de C.V. (part of the BASF Group)


In undergraduate Chemical Engineering programs, it is evident the complexity that students have to handle when the professor starts the study of thermodynamic properties and phase equilibrium criteria, but a deeper understanding could be attained by adding a visual approach.This work is related to a previous one regarding the representation of analysis of Gibbs Free Energy in 3D diagrams. The thermodynamic properties data for water were plotted in 3D to represent the resulting equations for G (Gibbs free energy).The database was taken from Haar et. al. (1984). The 3D diagrams obtained were used to generate projections in 2 dimensions: P-G, G-P, T-G, G-T, for homogeneous fluid phases and vapor-liquid equilibrium. This time it is focused on the behavior of concepts like fugacity and fugacity coefficient, as additional equilibrium criteria. These thermodynamic definitions are obtained from the Gibbs Free Energy and are calculated with an equation of state. The 3D diagrams for ln f as a function of P and T, are presented. The mesh is constructed with values at constant temperature and pressure and the curves for constant vapor fraction are included inside the vapor-liquid region. The 3D diagrams obtained can be used to generate projections in 2 dimensions ln f-P.In the last few years, this methodology has been applied in the Thermodynamics course for undergraduate Chemical Engineering students. The professor has perceived that students show good acceptance of this educational material and the evaluations have revealed a better understanding of these concepts.