Predictive model for the intra-diffusion coefficients of H₂ and O₂ in vapour H₂O based on data from molecular dynamics simulations

Abstract

Available data from experiments and molecular simulations for the intra-diffusivities of H (Formula presented.) and O (Formula presented.) in H (Formula presented.) O, and for the self-diffusivity of pure H (Formula presented.) O (at pressure and temperature conditions in which the solvent is in the vapour phase) are compared against calculations based on the Chapman-Enskog theory or other semi-empirical/semi-theoretical methods. A novel methodology is proposed to extrapolate the intra-/self-diffusivities data computed from molecular dynamics simulations at low pressures. The extrapolated values are used to further refine the recently-proposed [Tsimpanogiannis et al., J. Chem. Eng. Data, 66, 3226-3244, (2021)], molecular simulation based correlation of intra-/self-diffusivities as a function of pressure and temperature with the solvent being in the vapour phase.