Modeling Vapor Liquid Equilibrium of Binary and Ternary Systems of CO₂ + Hydrocarbons at High-Pressure Conditions

Abstract

In this work, binary and ternary systems composed by hydrocarbons and CO2 in liquid-vapor equilibrium conditions (LV) were thermodynamically modeled using Peng-Robinson (PR) and Patel-Teja (PT) equations of state (EoS) in combination with van der Waals mixing rule with two adjustable parameters (vdW -2, kij and lij). The model was formulated as a minimization of the Mean Absolute Deviation (%AAD) between the predicted and experimental values for liquid and vapor phases using the simplex algorithm, through the software Phase- Equilibrium 2000 (PE-2000). Low deviations, %AAD = 2.33% for PR EoS and %AAD = 3.06% for PT EoS were observed for binary systems in the evaluation of 160 experimental points (EP). Ternary systems were modeled with low deviations too, %AAD = 1.12% for EoS PR and %AAD = 1.18% for EoS PT were observed in the evaluation of 69 EP. Both tested EoS proved to be useful to represent LV equilibrium in this kind of system.