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Simulations of vapor–liquid phase equilibrium and interfacial tension in the CO 2 –H 2 O–NaCl system
Author(s) -
Liu Yang,
Lafitte Thomas,
Panagiotopoulos Athanassios Z.,
Debenedetti Pablo G.
Publication year - 2013
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.14042
Subject(s) - molality , thermodynamics , surface tension , solubility , chemistry , bar (unit) , phase (matter) , work (physics) , vapor pressure , aqueous solution , organic chemistry , physics , meteorology
Direct interfacial molecular dynamics simulations are used to obtain the phase behavior and interfacial tension of CO 2 –H 2 O–NaCl mixtures over a broad temperature and pressure range (50°C ≤ T ≤ 250°C, 0 ≤ P ≤ 600 bar) and NaCl concentrations (1–4 mol/kg H 2 O). The predictive ability of several existing water (SPC and TIP4P2005), carbon dioxide (EPM2 and TraPPE), and sodium chloride (SD and DRVH) models is studied and compared, using conventional Lorentz–Berthelot combining rules for the unlike‐pair parameters. Under conditions of moderate NaCl molality (∼1 mol/kg H 2 O), the predictions of the CO 2 solubility in the water‐rich and CO 2 ‐rich phase resemble those in the CO 2 –H 2 O system [Liu et al., J Phys Chem B. 2011;115:6629–6635]. Consistent with our previous work, the TraPPE/TIP4P2005 model combination gives the best overall performance in predicting coexistence composition and pressure in the water‐rich phase. Critical assessments are also made on the ranges of temperature and pressure where particular model combinations work better. The dependence of the interfacial tension on temperature and pressure is better predicted by the TraPPE/TIP4P2005 and EPM2/SPC models, whereas the EPM2/TIP4P2005 model overestimates this property by 10–20%, possibly due to the inadequacy of the combining rules. It is also found that the interfacial tension increases with salt concentration, consistent with experimental observations. © 2013 American Institute of Chemical Engineers AIChE J , 59: 3514–3522, 2013