Accurate (p, ρ, T) data for two new (carbon dioxide + nitrogen) mixtures from (250 to 400) K at pressures up to 20 MPa

Abstract

Recently our group published a set of (p,ρ,T) data for two (carbon dioxide+nitrogen) mixtures with a low carbon dioxide content (xCO2=0.10,0.15). These data showed larger relative deviations from the GERG-2008 equation of state than expected, specially at low temperatures, high pressures, and for the mixture with higher carbon dioxide content (xCO2=0.15). In order to analyze whether the mentioned deviations from the equation of state increase with the carbon dioxide content, it was decided to measure the (p,ρ,T) behavior of two additional mixtures with higher carbon dioxide molar fractions (xCO2=0.20,0.50). The new experimental data show again an appreciable disagreement with the GERG-2008 equation of state at low temperatures and high pressures. Relative deviations, which depend on temperature, arise to 0.4% at 250K and 20MPa and to 0.24% at 275K and 20MPa for the xCO2=0.20 and xCO2=0.50 mixture, respectively. Second virial coefficients are calculated for the two new mixtures presented in this work and also for those presented in our previous paper.