Measurement on CO2 Solution Density by Optical Technology

The optical technology based on Mach-Zehnder interferometry was successfully applied to a high-pressure liquid CO2 and water system to measure CO2 solution density. Experiments were carried out at a pressure range of from 5.0 to 12.5 MPa, temperatures from 273.25 to 284.15 K, and CO2 mass fraction in solution up to 0.061. CO2 solution density data were obtained from two sets of experiments. These data were calculated through the fringe shifts induced by density changes inside of the high-pressure vessel, which were directly recorded during the experiments, and a modified version of Lorentz-Lorenz formulation. The experimental results indicated that the density ratio of CO2 solution to that of pure water at the same pressure and temperature is monotonically linear with the CO2 concentration in the solution. The slope of this linear function, calculated by the experimental data fitting, is 0.275.