Thermodynamic modeling of PVTx properties for several water/hydrocarbon systems in near-critical and supercritical conditions

Both the equation of state-excess Gibbs energy (EoS/G ^E ) model and the cubic plus association (CPA) equation of state (EoS) are compared in this study with respect to their accuracy in the correlation of PVTx for systems such as water/methanol, water/ethanol, water/benzene, water/toluene, water/methane, water/n-butane, water/n-pentane, water/n-hexane, water/heptane, and water/octane, in supercritical conditions within temperature and pressure ranges of (573–698 K) and (7.0–276.0 MPa), respectively. In the proposed EoS/G ^E model, Peng-Robinson (PR) equation of state, linear combination Vidal-Michelsen (LCVM) and Wong-Sandler (WS) mixing rules in conjunction with UNIQUAC activity coefficient model were used. Correlation of both CPA and EoS/G ^E models was evaluated by comparing the results with the experimental data. Average absolute relative deviation (AARD) for WS, LCVM, and CPA was found to be 2.99, 11.11 and 5.14%, respectively, indicating better correlation of WS model with the experimental data.