Description of phase equilibrium and volumetric properties for CO2+water and CO2+ethanol using the CPA equation of state

Abstract

Properties of fluids under high pressure is of interest for processes design. A literature survey was conducted on experimental vapor-liquid equilibrium (VLE) and density for CO2+water and CO2+ethanol. Phase equilibrium and density of pure water, ethanol and CO2 were evaluated considering 1868 data points. VLE and saturated liquid density data were collected: 544 data points for CO2+water and 859 data points for CO2+ethanol. Soave Redlich-Kwong (SRK) equation of state (EoS) with Cubic Plus Association (CPA) was applied for calculation of these properties. Peng-Robinson EoS was evaluated to demonstrate CPA improvement in properties description. The binary interaction parameters were estimated from VLE. For pure compounds, the results indicated suitable description for both phase behavior and density. For CO2+water, density calculations were accurate (Δρ = 0.5%) and VLE was adequately described (ΔxH2O = 0.49% and ΔyCO2 = 4.63%). CO2+ethanol volumetric behavior and VLE were also satisfactorily described in CO2 concentrations up to 30% (Δρ = 2.92%, ΔxEtOH = 1.37% and ΔyCO2 = 5.86%, respectively).