Measurement and Modeling of the Densities for CO2 + Dodecane System from 313.55 K to 353.55 K and Pressures up to 18 MPa

Abstract

Densities of binary mixtures of CO2 and dodecane were measured by a magnetic suspension balance (MSB) at temperatures ranging from 313.55 K to 353.55 K under pressures from (8 to 18) MPa at five different CO2 mole fractions: x1 = 0, 0.2497, 0.5094, 0.7576, and 0.8610. Densities of the binary mixture increase with increasing pressure and decrease with increasing temperature. A crossover phenomenon is observed at high CO2 concentrations, and the crossover pressure increases with increasing temperature. The experimental densities increase with the CO2 mole fraction at first and then decrease at high CO2 concentrations. The excess molar volumes are negative over the whole range of CO2 concentrations and are more negative with increasing temperature and less negative with increasing pressure. The Benedict–Webb–Rubin–Starling (BWRS) and the improved Perturbed Hard-Sphere Chain (PHSC) equations of state were used to calculate the densities of the CO2–dodecane mixtures. The improved PHSC model has fewer parameters and shows little loss of overall calculation accuracy compared to BWRS.