Effect of water content on the equilibrium pressure of (carbon dioxide + decane and + decalin) from T = (313.15 to 333.15) K

• Phase transition pressures for ternary systems with a hydrocarbon (decane or decalin) water and carbon dioxide were measured.
• Phase transitions were easily identified at poor CO2 compositions compared to rich CO2 compositions.
• The phase behaviour of the systems containing decalin was more complicated than that containing decane as a hydrocarbon.

Phase behaviour of mixtures containing hydrocarbons, water and carbon dioxide are of great interest to the petroleum and related industries. However, to describe the effect of water on phase equilibria remains a challenge from theoretical and experimental point of view. Phase transitions for the {decane (C10H22) + water + CO2} and {decalin (C10H18) + water + CO2) system were measured using an apparatus based on the visual synthetic method. The experimental work was carried out in a high-pressure equilibrium cell. Using this apparatus, temperatures ranging from 313 K to 333 K and pressures up to 15 MPa can be handled. Phase transitions were mainly affected by critical points of miscibility and also by the vicinity of the CEP.