Calculation of thermodynamic properties of CO2 using the combined thermal equation of state with a small number of adjustable parameters
Petr P. Bezverkhy and Victor G. Martynets
The new combined equation of state including regular and scaling parts was applied for calculation of thermodynamic properties of CO2 in intervals 0 < ρ/ρc < 2, 217 K< T <430 K, 0< p ≤ 25 MPa, including the critical region. The total number of system-specific constants is 14. The description of PρT-data was achieved with an Rms error on pressure ±0.63%. The heat capacity Cv calculated on isochores and isotherms including the critical region with using constants of the combined equation of state. Also single-phase heat capacities Cv, Cp and sound velocity w calculated at T < Tc along binodal. The calculating Cv -values describe the known experimental Cv data with an accuracy of ±8%. The comparison is made with known tabulated referenced data.
Keywords: Carbon dioxide, equation of state, scaling, critical point, calculation of heat capacities.