Molecular‐based virial coefficients of CO₂‐H₂O mixtures

Abstract

We report second and third virial coefficients for the system CO2‐H2O, calculated via cluster integrals using quantitative molecular models taken from the literature. Considered models include (1) fits to highly accurate ab initio calculations of the potential energy surfaces, and (2) semiempirical Gaussian Charge Polarizable Models (GCPM). Three‐body effects are found to be essential for obtaining quantitative results. Good agreement with experiment is obtained for the pure‐component coefficients, and for the cross second virial coefficient. For the two cross third virial coefficients, the few experimental data available do not agree well with the calculations; it is not clear whether this is due to problems with the data or deficiencies in the three‐body potentials. The uncertain state of the experimental data, and the relative mutual consistency of values computed from ab initio and GCPM models, suggest that calculated mixture third virial coefficients could be more accurate than values from experiment. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3029–3037, 2015

Nonadditive three-body potential and third to eighth virial coefficients of carbon dioxide

“…The calculated values for the third virial coefficient agree very well with those of Schultz et al, 53 which were calculated using the same pair potential as in the present work 9 and a very simple nonadditive three-body potential. Agreement with experimental data is, for the most part, satisfactory.…”

“…Third virial coefficient B 3 as a function of temperature obtained in this work at three different levels of theory as well as B 3 values calculated by Schultz et al, 53 B 3 values derived from the experimentally based SWEOS, 45 and selected experimental B 3 data. [54][55][56][57][58][59][60] Schultz et al 53 obtained their B 3 values using the same pair potential as in the present work 9 including the QFH correction. To account for nonadditive three-body interactions, they used an isotropic ATM term and a single polarizable site with isotropic polarizability.…”

“…In Fig. 3 53 B 3 values derived from the experimentally based SWEOS, 45 and selected experimental B 3 data. [54][55][56][57][58][59][60] The values of Vukalovich and Masalov 54 are those quoted in Ref.…”

“…The figure shows that the differences between the additive and nonadditive values are dramatic, whereas the QFH correction for nuclear quantum effects is almost negligible, confirming observations from previous studies. 15,53,62 FIG. 3.…”

Structural and dynamical properties predicted by reactive force fields simulations for four common pure fluids at liquid and gaseous non-reactive conditions

“…Several approaches can be employed to calculate B2 for either pure compounds or mixtures. The Mayer sampling method, based on free energy perturbation approaches [65], was implemented to calculate virial coefficients for a variety of potentials [66][67]. B2 for small alkanes and inert gases can be extracted from the simulated pair correlation functions [68][69] or from analytic equations of state [70][71].…”