Solid Phase I of Carbon Dioxide: A New Gibbs Energy Equation of State and Its Application for the Calculation of Solid–Fluid Equilibria

A new Gibbs energy Equation of State (EoS) has been developed to describe solid phase I of carbon dioxide (“dry ice”) for use in phase equilibrium calculations. Its functional form, which uses temperature and pressure as independent variables, is inspired by the work of Stringari ( J. Chem. Eng. Data 2021, 66(2), 1157–1171)and is valid up to 400 K and 1.2 GPa. The model parameters were fitted to literature data for molar volume, isothermal compressibility, isobaric heat capacity, and the sublimation and melting pressures. Melting and sublimation lines were determined by coupling the new solid-phase EoS with the reference fluid-phase EoS of Span; ; Wagner( J. Phys. Chem. Ref. Data 1996, 25, 1509–1596). As illustrative applications, the new EoS was coupled with the default Helmholtz energy EoS implemented in REFPROP v10 to predict the solubility of CO2 in methane and nitrogen. For comparison, similar calculations were performed using alternative solid-phase EoSs from the literature, namely those of (i) Jäger; ; Span ( J. Chem. Eng. Data 2012, 57, 590–597), (ii) Trusler ( J. Phys. Chem. Ref. Data 2011, 40(4), 043105), and the (iii) Classical Approach (Prausnitz et al. 1999).