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

Abstract

In the low-temperature range, catalytic combustion results in few emissions of nitrogen oxide and happens without a visible flame. This work investigates 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. The study also investigates the CMAC in two environments: excess oxygen (EO) and deficient oxygen (DO). The research investigates 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 maximum values of Den and velocity decrease as the IP increases to 10 bar. This reduction was more pronounced in the EO medium than in the DO medium. The maximum values of density and velocity decrease to 0.105 atom/Å and 0.17 Å/ps, respectively, in the EO medium. These values decrease to 0.080 atom/Å and 0.20 Å/ps, respectively, in the DO medium. Additionally, the HF and TC values decrease 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 heat transfer to different parts. Therefore, TC and HF are more in this case.