Prediction of vapor–liquid equilibrium and PVTx properties of geological fluid system with SAFT-LJ EOS including multi-polar contribution. Part I: Application to H2O–CO2 system

Prediction of vapor–liquid equilibrium and PVTx properties of geological fluid system with SAFT-LJ EOS including multi-polar contribution. Part II: Application to H2O–NaCl and CO2–H2O–NaCl System

“…The SAFT-LJ EOS improved by Sun and Dubessy (2010) takes account of the energetic contribution of the main types of molecular interactions in the CO 2 -H 2 O system, such as the repulsion force, the dispersion force, the hydrogen-bonding force and the multi-polar forces. It can be extended to the CO 2 -H 2 O-NaCl system by adding a new term to account for the energetic contribution due to the long-range electrostatic force between ions considering that the Columbic force is the characteristic of electrolyte solution differing from non-electrolyte systems.…”

“…hydrocarbon, alkanol) and molecules with hydrogen bonding. A review on the state of the art of SAFT EOS has been given in our previous paper (Sun and Dubessy, 2010) and is omitted here. Many studies (Jin and Donohue, 1988;Wu and Prausnitz, 1998;Galindo et al, 1999;Liu et al, 1999;Tan et al, 2005) tried to model electrolyte solutions with SAFT EOS or other molecular-based EOS in the last two decades.…”

“…In the first companion paper (Sun and Dubessy, 2010), we improved the SAFT-LJ EOS proposed by Kraska and Gubbins (1996) and modeled the vapor-liquid equilibrium and PVTx properties of the H 2 O-CO 2 system over a wide P-T range. The purpose of this paper is to extend this EOS to the H 2 O-NaCl and CO 2 -H 2 O-NaCl systems below 573 K. Considering that the dissociation constant of NaCl in aqueous solution is greater than 1 at temperatures below 573 K (according to Mesmer et al, 1988) and the lower temperature limit of the EOS of Duan et al (1995) for the CO 2 -H 2 O-NaCl system is 573 K, we chose 573 K as the upper temperature limit of the new EOS.…”

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The SAFT-LJ equation of state improved by Sun and Dubessy (2010) can represent the vapor-liquid equilibrium and PVTx properties of the CO 2 -H 2 O system over a wide P-T range because it accounts for the energetic contribution of the main types of molecular interactions in terms of reliable molecular based models. Assuming that NaCl fully dissociates into individual ions (spherical Na + and Cl À ) in water and adopting the restricted primitive model of mean spherical approximation to account for the energetic contribution due to long-range electrostatic forces between ions, this study extends the improved SAFT-LJ EOS to the H 2 O-NaCl and the CO 2 -H 2 O-NaCl systems at temperatures below 573 K. The EOS parameters for the interactions between ion and ion and between ion and water were determined from the mean ionic activity coefficient data and the density data of the H 2 O-NaCl system.

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Modelling of phase equilibria in CH4–C2H6–C3H8–nC4H10–NaCl–H2O systems

“…Many studies have modified the SAFT model to generate improved versions such as SAFT-HS (Huang and Radosz, 1990), SAFT-SW (Gil-Villegas et al, 1997), SAFT1 (Adidharma and Radosz, 1998), SAFT-LJ (Kraska and Gubbins, 1996;Blas and Vega, 1997;Chen et al, 1998) and so on. Sun and Dubessy (2010), Sun and Dubessy (2012), and Sun et al (2014) successfully modelled CO 2 -H 2 O, CO 2 -H 2 O-NaCl and light hydrocarbon-H 2 O systems based on the SAFT-LJ model. Another class of EOS that considers the association compressibility factor based on cubic models was proposed by Kontogeorgis et al (1996;1999).…”