Libro de resúmenes - Facultad de Ciencias Exactas, Físicas y ...

I JORNADA DE DIFUSIÓN DE INVESTIGACIÓN Y EXTENSIÓN EN INGENIERÍA QUÍMICA FCEFyN – UNC“Ideas y perspectivas para construir futuros distintos”5 de Mayo de 2010THE INFLUENCE OF TERNARY INTERACTION PARAMETERS ON THEREPRESENTATION OF THE HIGH-PRESSURE FLUID PHASE EQUILIBRIA OFTERNARY SYSTEMSGerardo Pisoni 1,2 , Martín Cismondi 2 , Marcelo S. Zabaloy 11 PLAPIQUI-Planta Piloto de Ingeniería Química, Universidad Nacional del Sur-CONICET,Bahía Blanca, Argentina. Ce: gpisoni@plapiqui.edu.ar2 Cátedra de Termodinámica Química, FCEFyN-UNC. Ce: mcismondi@plapiqui.edu.ar,mzabaloy@plapiqui.edu.arKeywords: model, asymmetric systems, high pressure, cubic mixing rules.Models of the equation of state (EOS) type are customary used to describe the phaseequilibria of mixtures in liquid, vapor and supercritical states, over wide ranges of conditions.These models typically assume that the system behavior can be described from binarycontributions only. Conventionally, the binary interaction parameters of the model are fit frombinary fluid phase equilibrium data. Once this is done, all the predicted ternary and higherequilibria become determined by both, the pure compound parameters and the previously fitbinary interaction parameters. It is well documented in the literature that the high-pressurephase equilibria of ternary highly non ideal systems is not well predicted from binarycontributions. Sometimes the binary interaction parameters are fit from both, binary andternary data, which implies a poorer description of the binary data for the sake of improvingthe reproduction of the ternary experimental information. It is clear that we need more flexiblemodels. One possibility is to couple the EOS model to mixing rules written as triplesummations of terms which depend on the product of three mole fractions. These are cubicmixing rules (CMRs). CMRs depend on three-index binary interaction parameters and onthree-index ternary interaction parameters. For a given binary system, CMRs provide fourindependent interaction parameters. Thus, highly asymmetric binary systems can berepresented more accurately by CMRs than by quadratic mixing rules (QMRs). For a giventernary system, CMRs provide two ternary interaction parameters: one of them influences themixture attractive energy parameter while the other affects the mixture covolume parameter.By fitting both ternary parameters, it is possible to improve the reproduction of ternaryexperimental data while leaving invariant the description of the three constituent binarysubsystems. In this work, we test this approach by studying the system Carbon Dioxide + n-Hexadecane + 1,8-Octanediol, for which we have available both, binary an ternary phaseequilibrium data. For such system, we show the influence of the ternary parameters on thesize of ternary two-phase and three-phase immiscibility regions. We also discuss a techniqueto predict the values of the ternary parameters in the absence of ternary data. We compare inthis study the behavior of the two-parameter Peng-Robinson EOS and of the three-parameterRK-PR EOS, both coupled to CMRs.Resumen presentado en II Iberoamerican Conference on Supercritical Fluids PROSCIBA2010.72