PREDICTION OF THE THERMODYNAMIC PROPERTIES OF HYDROGEN-OXYGEN MIXTURES FROM 80-K TO 373-K AND TO 100-MPA

The equations of state of Deiters and of Christoforakos and Franck, together with appropriate mixing rules, have been used to predict fluid phase equilibria, the critical curve, molar volumes and excess enthalpies of the binary hydrogen-oxygen system between 80 and 373 K and to pressures of 100 MPa. The applicability of the equations of state has been tested with experimental data which exist for the hydrogen-nitrogen system and, to some extent, for the systems neon-nitrogen and neon-oxygen. Binary interaction parameters for the hydrogen-oxygen system have been derived from these systems. Results from both equations of state have been compared. Numerical values for the thermodynamic properties of the hydrogen-oxygen system are given. The calculated critical line is of the interrupted type; the upper branch begins at the critical point of oxygen (154.6 K) and tends to approximately 83 - 99 K at 100 MPa, depending on the calculation method. Hydrogen appears to be considerably less miscible with oxygen than with nitrogen at high pressures. Predicted pressures for oxygen-hydrogen solid-gas equilibria at 49.8 K agree well with experimental data to 12 MPa.