Thermodynamic characterization of the ($CO_{2}$ + $O_{2}$) binary system for the development of models for CCS processes: Accurate experimental ($p$, $ρ$, $T$) data and virial coefficients

Continuing our study on ($CO_{2}$ + $O_{2}$) mixtures, this work reports new experimental($p$, $\rho$, $T$) data for two oxygen-rich mixtures with mole fractions $x$($O_{2}$) = (0.50 and 0.75) mol/mol, in the temperature range $T$ = (250-375) K and pressure range $p$ = (0.5-20) MPa, using a single-sinker densimeter. Experimental density data were compared to two well-established equation-of-state models: EOS-CG and GERG-2008. In the $p$, $T$-range investigated, the EOS-CG gave a better reproduction for the equimolar mixture $x$($O_{2}$) = 0.5, whereas the GERG-2008 performed significantly better for the oxygen-rich mixture $x$($O_{2}$) = 0.75. The EOS-CG generally overestimates the density, while the GERG-2008 underestimates it. This complete set of new experimental data, together with previous measurements, is used to calculate the virial coefficients $B$($T$, $x$) and $C$($T$, $x$), as well as the second interaction virial coefficient $B_{12}$($T$) for the ($CO_{2}$ + $O_{2}$) system.