Patterns of equilibria involving fluid phases and solid solutions

PORRAS GIRALDO, ANDRÉS F.; ZABALOY, MARCELO S; MOLINA, MATÍAS J.; RODRIGUEZ REARTES S. BELÉN

Itaici, Indaiatuba

Congreso; XII Iberoamerican Conference on Phase Equilibria and Fluid Properties for Process Design (Equifase 2022) and X Congresso Brasileiro de Termodinâmica Aplicada (CBTermo, 2022); 2022

University of Campinas

More than two decades ago, Garcia and Luks [1] used the van der Waals equation of state, together with an expression for the fugacity of a solid in pure state, for the partial computation of phase equilibrium characteristic maps (CMs) for binary ethane + n-alkane model systems. They [1] were specifically interested in studying the evolution of the form of the solid-liquid-vapor loci, and of the solid-liquid-liquid-vapor quadruple points, as the molecular difference between the solvent (ethane) and the solute (heavy n-alkane) was increased. The results in ref [1] have a qualitative nature since there was no attempt of matching experimental data, e.g., polymorphism was intentionally ignored. The results [1] suggested the potential existence of topologies richer than those previously envisioned. Later, Labadie et al [2] completed the work of ref [1] by adding the computed critical loci. The present work has the same spirit that the works of refs [1] and [2], being the main difference the added complexity of considering precipitation in solid-solution state rather than in pure state. The goal is to establish whether new topologies arise for the calculated three-phase lines involving solid phases, by performing a parametric study, analogous to the one in refs [1-2], also for the series n-ethane + heavy n-alkane. The comparison is performed by looking at computed binary CMs, in their pressure-temperature projections. Solid solutions are described in this work through the recent approach of ref [3]. [1] D.C. Garcia, K.D. Luks, Fluid Phase Equilib., 161 (1999) 91–106. [2] J.A. Labadie, D.C. Garcia, K.D. Luks, Fluid Phase Equilib. 171 (2000) 11–26. [3] A.F. Porras Giraldo, S.B. Rodriguez-Reartes, M.S. Zabaloy. Fluid Phase Equilib., 547 (2021) 113174.