Accurate prediction of the thermodynamic properties of fluids in the system H2O-CO2-CH4-N-2 up to 2000 K and 100 kbar from a corresponding states/onefluid equation of state

Previously, we reported an equation of state (EOS) modeling approach that s uccessfully calculated the PVTX properties of supercritical fluid mixtures. The model is based on a corresponding states assumption applied to a highl y accurate EOS for the reference CH4 system. The CH4 EOS was parameterized from 273 to 723 K and 1 to 3000 bar by using experimental PVT data. Molecul ar dynamics simulated PVT data were used to extend the parameterization in the CH4 system to 2000 K and 20 kbar. Mixing in the H2O-CO2-CH4-N-2 system was successfully described by using a simple empirical mixing rule with onl y two temperature- and pressure-independent parameters for each binary mixt ure. Results indicated that PVTX properties in higher order systems could b e reliably calculated without additional parameters. In this paper, by usin g experimental PVTX data in the H2O-CO2-CH4-N-2 system that were not used i n the EOS parameterization, we show that the model predictions are accurate from just above the critical temperature for the least volatile component to 2000 K and from 0 to 100 kbar. We also show that our modeling approach c an be extended to reliably calculate supercritical phase equilibria and oth er thermodynamic properties, such as fugacity and enthalpy, under high-temp erature and -pressure conditions. Copyright (C) 2000 Elsevier Science Ltd.