A unified equation of state for fluids of C-H-O-N-S-Ar composition and their mixtures up to very high temperatures and pressures

Abstract

A unified 3-parameter equation of state (EOS) for fluids of C-H-O-N-S-Ar composition based on molecular dynamical simulated data and on an approximation of intermolecular interaction with α-exponential-6 potential is shown to be valid at high pressure and temperature. The equation is parameterized for H 2O, CO 2, CH 4, CO, O 2, H 2, Ar, N 2, NH 3, H 2S, SO 2, COS, and S 2 in the ranges of temperature ( T) from 400 K (700 K for H 2O) to 4000 K and pressure from 5 kbar to 1000 kbar. The equation allows one to calculate any mixture of the fluid species in the system applying one-fluid approximation (i.e., using the α-exponential-6 parameters obtained by using mixing rules for the potentials of the pure species). The equation reproduces most of the available experimental data in the limits of experimental accuracy of volume ( V) measurements.