A deep study on the phase behavior of the mixture CO2 – n-Hexadecane at 298.15 K: Miscibility window, mass barotropy, volumetric/saturation data, and separability of the phases

Abstract

This paper investigates the phase behavior of the CO₂ - n-Hexadecane mixture at a temperature of 298.15 K for high CO₂ concentrations. Under these conditions, the systems exhibit liquid-liquid equilibria at high pressures, accompanied by interesting phenomena, including a miscibility window and mass barotropy. The idea was to scrutinize the phase behavior of a simple compositional system displaying intricacies inherent to more complex CO₂-dominant fluids. The literature gap addressed in this paper is the generated volumetric data, accompanied by a discussion of the results concerning the composition and density of the phases indirectly calculated using the volumetric method. The generated phase equilibrium (saturation and volumetric) and density data can be used in basic projects as a model mixture of CO₂-rich phases for feeding porous or pipe multi-phase flow software simulations. The present investigation observed the separability of the phases under different conditions. The results suggest that interfacial tension is the main factor determining the degree of separability between these high-pressure liquid phases. Slight differences in density display a secondary, less pronounced impact on dispersibility; however, the interface tends not to resolve when the densities are similar, resulting in large stationary drops in this region.