Thermodynamics of the carbon dioxide plus argon (CO2 + Ar) system: An improved reference mixture model and measurements of vapor-liquid, vapor-solid, liquid-solid and vapor-liquid-solid phase equilibrium data at the temperatures 213–299 K and pressures up to 16 MPa

• Published in: Fluid phase equilibria 2018-06, Vol.466, p.48-78
• Main Authors: Løvseth, Sigurd Weidemann, Austegard, Anders, Westman, Snorre Foss, Stang, Hans Georg Jacob, Herrig, Stefan, Neumann, Tobias, Span, Roland
• Format: Article
• Language: English
• Subjects: Argon; Carbon dioxide; CO2 capture and storage; Fundamental equation of state; Measurements; Phase equilibrium
• ISSN: 0378-3812; 1879-0224
• DOI: 10.1016/j.fluid.2018.02.009

Phase equilibrium behavior of the carbon dioxide and argon system has been investigated at the temperatures 213, 223, 243, 263, 273, 283, and 299 K. The full vapor-liquid equilibria phase envelope has been measured at all temperatures using an analytical technique where the compositions of both the liquid and vapor phase have been measured. In addition, the fluid compositions at the three-phase line and phase equilibria involving solids at 213 K have been measured. The three-phase line was determined at 213 K with an estimated uncertainty of 2 kPa. Otherwise, the estimated uncertainty is better than 13 mK for the temperature measurements, 3.2 kPa for the pressure measurements, and 0.12% in total combined uncertainty in terms of mole fraction for all the 107 measured data points. The new data have been compared with existing models, and estimates for the critical points of the 7 isotherms have been made. Together with recently established experimental results for homogeneous density, speed of sound, and dew-point pressure, the vapor-liquid-equilibrium data were used to develop an improved Helmholtz-energy-explicit mixture model. This new model enables the calculation of highly-accurate data for all types of thermodynamic properties. Its development is part of the ongoing work on setting up an extended multi-fluid mixture model for the description of carbon-dioxide-rich mixtures with various impurities as relevant for CCS applications. [Display omitted] •The thermodynamics of the CO2+Ar system has been thoroughly examined.•7 new phase equilibrium isotherms were accurately measured from 213 to 299 K.•At 213 K, both liquid-vapor and liquid/vapor-solid equilibria were investigated.•A critical review of thermodynamic literature data has been performed.•A new Helmholtz-energy-explicit mixture model based on available data is presented.