Validation of classical mixing rule coupled with a van der Waals–type equation of state for supercritical mixture system of oxygen and hydrogen using molecular simulation

抄録

We have validated the classical mixing rule (CMR) applied to the Soave–Redlich–Kwong (SRK) equation of state (EOS) as one of the van der Waals–type EOSs for the thermodynamic properties (pressure–volume–temperature relationship, specific heat at constant pressure) of oxygen–hydrogen mixture in supercritical state using molecular dynamics (MD) simulations. As for oxygen and hydrogen, effect of the intramolecular orientation on the intermolecular interaction is very small; therefore, we employed the Lennard–Jones (L–J) potential between each molecule. The intermolecular interaction between the different molecular species was given by modified Lorentz–Berthelot (L–B) rules, which improved the accuracy of the well–applied original L–B rules in accordance with the more accurate combining rules proposed for the L–J potential. We have validated the CMR applicability through the comparison of thermodynamic variables obtained by MD simulations with those obtained by CMR coupled with the SRK EOS. As a result, the thermodynamic variables by MD simulations corresponded with those from the SRK EOS employing CMR. Further, the relative difference in thermodynamic variables between the MD simulations and SRK EOS hardly increased against single–component fluids. Therefore, we conclude that the CMR can be applied to the oxygen–hydrogen mixture system in supercritical condition.