ReaxFF Study of Ethanol Oxidation in O2/N2 and O2/CO2 Environments at High Temperatures

The goal of this study was to investigate the reaction mechanisms linked with the oxy-fuel combustion of ethanol (C2H6O). The oxidation of ethanol in O-2/N-2 and O-2/CO2 environments was examined using reactive molecular dynamics in the temperature range from 2200 to 3000 K at constant density media and O-2/fuel ratio equals to 0.5. The main reactions were examined to supply a description of the ethanol oxidation behavior, the main product distribution, and the corresponding time evolution behavior in the atomic scale. It has been noted that the oxidation of C2H6O was initiated mainly from the same routes in both environments generating the same main species. However, the key reaction pathways were different depending on the media. We noticed an increase of CO formation when N-2 was replaced by CO2 molecules, increasing the net flux of the following reactions: by CO2 + H -> CO + OH and CO2 + CHO -> O=COH + CO. This work also studied the effect of increasing O-2 concentration (O-2/fuel ratio equals to 0.5, 1.0, and 2.0) in O-2/CO2 combustion. During the simulations, high oxygenated and unstable species were detected such as carbonates and carboxyl radicals. The change of the O-2/fuel ratio from 0.5 to 2.0 lead to an increase of CO2 formation mainly from O-2 + O=COH -> CO2 + HO2 and O-2 + CO -> CO2 + O reactions. In addition, the increase of O-2 concentration attenuated the effect of CO2 and could increase the occurrence of reactions that lead to flame cessation.