A numerical study of catalytic combustion of methane-air in excess oxygen and deficient oxygen environments with increasing initial pressure: A molecular dynamic approach

In the low-temperature range, catalytic combustion results in few emissions of nitrogen oxide and happens without a visible flame. This work explored the effect of initial pressure (IP) on catalytic methane-air combustion (CMAC) in a microchannel using the molecular dynamics (MD) method. Palladium particles with an atomic ratio of 4% were used as a catalyst in this study. The study also examined the CMAC in two environments: excess oxygen (EO) and deficient oxygen (DO). The research analyzed the changes in density (Den), velocity (Velo), temperature (Temp) profiles, heat flux (HF), thermal conductivity (TC), and combustion efficiency (CE). The results of the MD simulation indicate that the utmost values of Den and Velo decreased as the IP increased to 10 bar. This reduction was more pronounced in the EO medium than in the DO medium. The maximal values of density and Velo decreased to 0.105 atom/Å and 0.17 Å/ps, respectively, in the EO medium. These values decreased to 0.080 atom/Å and 0.20 Å/ps, respectively, in the DO medium. Additionally, the HF and TC values decreased in both mediums, with the EO medium showing values of 1839 W/m2 and 1.01 W/m.K, and the DO medium showing values of 1869 W/m2 and 1.04 W/m.K. If there was a DO medium, the atoms and particles of the system had a greater ability to transfer heat and energy to different parts. Therefore, TC and HF was more in this case.