Viscosity and density of aqueous solutions of carbon dioxide at temperatures from (274 to 449) K and at pressures up to 100 MPa

Abstract

The viscosity and density of aqueous solutions of carbon dioxide having mole fractions of CO2 of 0.0086, 0.0168, and 0.0271 are reported. The measurements were made in the single-phase compressed liquid region at temperatures between (294 and 449) K at pressures up to 100 MPa; additional density measurements were also made at T = 274 K in the same pressure range. The viscosity was measured with a vibrating-wire viscometer while the density was measured by means of a vibrating U-tube densimeter; both were calibrated with pure water and either vacuum or ambient air. The density data have an expanded relative uncertainty of 0.07 % with a coverage factor of 2. From the raw data, the partial molar volume of CO2 in aqueous solution has been determined and correlated as an empirical function of temperature and pressure. When combined with the IAPWS-95 equation of state of pure water, this correlation represents the measured densities of under-saturated solutions of CO2 in water within ± 0.04 %. The viscosity data have an expanded relative uncertainty of 1.4 % with a coverage factor of 2. A modified Vogel-Fulcher-Tamman equation was used to correlate the viscosity as a function of temperature, pressure, and mole fraction of CO2 with an absolute average relative deviation of 0.4 %. The viscosity and density of saturated aqueous solutions of CO2 may be calculated by combining the correlations presented in this work with a suitable model for the mole fraction of CO2 at saturation. (Figure Presented).