CARBON-DIOXIDE WATER PHASE-EQUILIBRIA RESULTS FROM THE WONG-SANDLER COMBINING RULES

A model based upon the Peng-Robinson equation of state with the Wong-S andler mixture combining rule (W-S MCR) can correlate phase equilibria in CO2 + H2O. The W-S MCR requires two energy parameters for liquid b ehavior and one interaction parameter for gas behavior, k(ij). In this paper, we present expressions for the energy parameters which cover a wide temperature range, and we use a new procedure to obtain k(ij) by relating it to experimental cross second virial coefficients, B-ij. T he three-phase pressures calculated for this system using our proposed model agree with the experimental data within a fraction of 1 bar. Th e correlated phase behavior of CO2 + H2O appears to be accurate over t he ranges 1-1000 bar and 298.15-623.15 K. The proposed model also conf irms the advantage of using the W-S MCR for phase equilibrium calculat ions. (C) 1997 Elsevier Science B.V.