265104 Exploring Retrograde Vaporization and Derivative Properties of near-Critical Fluids Using Monte Carlo Simulations and Equations of State

Tuesday, October 30, 2012: 1:46 PM
412 (Convention Center )
Angel D. Cortés-Morales1, Nikolaos I. Diamantonis2,3, Ioannis G. Economou2,4, Cor J. Peters2 and J. Ilja Siepmann5, (1)Depts. of Chemistry and of Chemical Engineering & Materials Science and Chemical Theory Center, University of Minnesota, Minneapolis, MN, (2)Dept. of Chemical Engineering, The Petroleum Institute, Abu Dhabi, United Arab Emirates, (3)Molecular Thermodynamics and Modelling of Materials Laboratory, National Center for Scientific Research “Demokritos”, Aghia Paraskevi, Greece, (4)Molecular Thermodynamics and Modeling of Materials Laboratory, National Center for Scientific Research “Demokritos”, Aghia Paraskevi Attikis, Greece, (5)Depts. of Chemistry and of Chemical Engineering & Materials Science, University of Minnesota, Minneapolis, MN

Configurational-bias Monte Carlo simulations in the Gibbs, isobaric-isothermal, and canonical ensembles and various equations of state are applied to investigate two important phenomena found for near-critical fluids: (i) double retrograde vaporization in vapor-liquid phase equilibria of binary mixtures near the critical point of the lower-boiling compound, and (ii) non-monotonic behavior of thermodynamic derivative properties as function of density or pressure at temperatures above, but close to the critical temperature.  For the retrograde behavior, binary mixtures of methane/n-alkanes and carbon dioxide/(n-alkanes or alkylbenzenes) are discussed.  For the thermodynamic derivative properties, various butane-like models are investigated at a temperature of T/Tcrit = 1.1, where the critical temperature is determined from Gibbs ensemble simulations for each molecular model to allow for comparison of all models at the same reduced temperature.  The molecular simulations allow one to provide molecular-level understanding of these near-critical phenomena, whereas the equations of state serve as supporting data and as guide for the set-up of Gibbs ensemble simulations (i.e., by providing information on appropriate overall composition and volume/pressure to be used).

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See more of this Session: Thermophysical Properties and Phase Behavior I
See more of this Group/Topical: Engineering Sciences and Fundamentals