Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

Accurate density data and a predictive Equation of State (EoS) for the CO2!VCH4 system are significantly important for the application of natural gas purification and Carbon Capture, Utilization and Storage (CCUS). In this work, densities of the CO2!VCH4 binary system with CO2 mole fractions ranging from 0.0998 to 0.8988 were measured at temperatures of 313!V353 K and pressures of 3!V18 MPa using a magnetic suspension balance, and the compressibility factors were calculated correspondingly. The expanded combined uncertainties of the measured densities ( ) / c u a a were in the range of 0.2% to 0.6%. The PC-SAFT EoS was employed for the density modeling, and the PR EoS was used for comparison. The measured density data in this work and experimental density data from the literatures, were used to optimize of the binary interaction parameter kij in PC-SAFT EoS and PR EoS. The predicting abilities of PC-SAFT and PR EoS with the optimized kij were compared to the case without binary interaction (kij = 0). The PC-SAFT EoS with the optimized kij had better performance than the PR EoS with optimized kij, and it could predict the density properties of the CO2!V CH4 system accurately, with an Average Absolute Deviation (AAD) of 1.16%. Modelings from PCSAFT with and without the optimized kij were then compared with the measured densities obtained in this work. The relative deviations for the calculation from PC-SAFT with the optimized kij were within the range of !V3.93% to 2.94%. Moreover, the CO2!VCH4 binary systems with CO2 mole fractions of 0.7985 and 0.8988 in this work can be regarded as CO2-rich fluids, and their density reductions compared with pure CO2 were evaluated for the measured density data and the values calculated from the modified PC-SAFT.