Determination of the Phase Diagram of a Mixture of H2 + O2 Based on a Modified Van der Waals Model

Due to the absence of experimental data for constructing the phase diagram of a liquid and gaseous mixture of hydrogen and oxygen, it is determined by modeling. The model diagrams previously predicted (Deiters et al., 1993) by two methods (I and II) at pressures up to approximate to 100 MPa and a temperature up to approximate to 100 K have significant differences, which are considered by the authors as an approximate measure of the uncertainty of the knowledge of the real phase diagram of this mixture. In this paper, the phase diagram of a mixture of hydrogen and oxygen is determined using the previously proposed modified van der Waals model for individual and mixed compounds. Calculations were performed in two variants (A and B) differing in the binary interaction parameter. To control these variants, model diagrams were determined for mixtures of hydrogen with nitrogen, argon, and methane, for which there are experimental data in the range of pressures and temperatures comparable to those mentioned above for a mixture of hydrogen and oxygen. Variant B is more realistic as it is in better agreement with experiment than variant A. The phase diagram calculated by method B for a mixture of hydrogen and oxygen is close to the calculation by method I, which indicates that it is more realistic than method II.