A FIRST-PRINCIPLE CALCULATION OF THE BINARY DIFFUSION COEFFICIENTS PERTINENT TO KINETIC MODELING OF HYDROGEN/OXYGEN/HELIUM FLAMES

摘要

First-principle calculations were carried out to determine the binary diffusion coefficients of H-He, H-Ar, H-H_2, and He-H_2. Potential energy functions of pair interactions were critically reviewed for H-He and H-Ar and verified against molecular beam scattering and low-temperature diffusion cross-section data. Complementary quantum chemistry calculations were carried out for the interactions of H-He and H-Ar and CCSD(T)/AUG-cc-PV~*Z level of theory. The calculation of the H-He and H-Ar diffusion coefficients was performed by direct integration using literature potential functions. For H-H_2 and He-H_2, the diffusion cross-sections were determined using the close-coupling method, again using ab initio potential energy functions in recent literature. The computed diffusion coefficients of all pairs were compared with experimental data at room temperature, which showed very good agreement for all pairs. With the exception of H-Ar, the diffusion coefficients of the current study of all other pairs differ notably from those predicted by the Sandia TRANFIT and DRFM compilations. The implication of the current result in kinetic modeling of hydrogen-oxygen-helium flames is discussed.