Modeling the phase equilibria of a H₂O–CO₂ mixture with PC-SAFT and tPC-PSAFT equations of state

Abstract

Water–carbon dioxide binary mixtures are important for a number of industrial and environmental applications. Accurate modeling of the thermodynamic properties is a challenging task due to the highly non-ideal intermolecular interactions. In this work, two models based on the Statistical Associating Fluid Theory (SAFT) are used to correlate reliable experimental vapor–liquid equilibria (VLE) and liquid–liquid equilibria (LLE) data in the temperature range 298–533 K. CO₂ is modeled as a non-associating or associating component within the Perturbed Chain-SAFT (PC-SAFT) and as a quadrupolar component within the truncated PC-Polar SAFT (tPC-PSAFT). It is shown that PC-SAFT with explicit account of H₂O–CO₂ cross-association and tPC-PSAFT with explicit account of CO₂ quadrupolar interactions are the most accurate of the models examined. Saturated liquid mixture density data are accurately predicted by the two models.

Keywords:

• Carbon capture and storage
• carbon dioxide transport
• polar fluids
• water

Acknowledgements

The authors acknowledge the financial support of the 7th European Commission Framework Program for Research and Technological Development for the project “Quantitative failure consequence hazard assessment for next generation CO₂ pipelines” (project No. 241346) and from the Petroleum Institute Research Initiation Funding Program for the project “An in-house general-purpose simulator for multiscale multiphase flows in heterogeneous porous media for enhanced oil recovery and carbon capture and storage processes”. Also, The Petroleum Institute is acknowledged for a visiting PhD scholarship to N.I.D.