Estimation and Correlation of Phase Equilibrium of CO₂- Hydrocarbon Systems with PRMHV2-UNIFAC and PRMHV2-NRTL Models

In this work, the Peng Robinson (PR) equation of state (EoS) and MHV2 mixing rule that were combined with UNIFAC and NRTL G(E) models were used to predict vapor liquid phase equilibrium (VLE) data for CO2-hydrocarbon systems. These systems included 12 binary systems and three ternary systems. The PRMHV2-UNIFAC model was used to calculate the bubble pressure, and the average absolute relative deviations (AARD %) were 17.49-32.20% for 12 binary systems. For the PRMHV2-NRTL model, the binary interaction parameters of the NRTL model dependent on temperature were regressed based on the binary VLE data. These new interaction parameters were used to estimate CO2 hydrocarbon VLE data for binary and ternary systems. The bubble pressure was predicted by the PRMHV2-NRTL model, and the AARD % values were 1.52-9.44% for binary systems, which were lower than the value of the PRMHV2-UNIFAC model. The PRMHV2-UNIFAC and PRMHV2-NRTL models were also used to calculate the liquid phase mole fraction of CO2-hydrocarbon ternary systems, and the average absolute deviations (AAD %) were less than 20.70 and 8.54%, respectively.