ReaxFF study on combustion mechanism of ethanol/nitromethane

Abstract

Abstract To gain an atomistic-level insight into the thermal and chemical responses of ethanol/nitromethane fuel, reactive molecular dynamics simulations were performed to investigate their high-temperature oxidation. The initial reaction scheme of ethanol/nitromethane oxidation was established by chemical trajectory analysis. The results showed that the unimolecular C-N bond cleavage of nitromethane is the dominant pathway to produce CH3 and NO2 fragments. The main initial decomposition of the ethanol molecule is dehydrogenation with the assistance of active groups. Active species (NO2, NO, OH, etc.) have a significant effect on the oxidation mechanism of ethanol. Alcohols are initiated and dehydrogenated mainly by the following reaction, NO2\xa0+\xa0R-H\xa0→\xa0R* + HNO2, HNO2\xa0→\xa0OH\xa0+\xa0NO, NO\xa0+\xa0R-H\xa0→\xa0R* + HNO, and OH\xa0+\xa0R-H\xa0→\xa0R* + H2O. The addition of nitromethane not only increases the oxygen contents of the fuel but also accelerates the decomposition of ethanol. In addition, the change of the nitromethane/ethanol ratio from 0.5 to 1.0 results in an increase of CO2 formation mainly via CHO2\xa0→\xa0CO2\xa0+\xa0H reaction. The results shed light on the complicated interplay of oxidation of ethanol/nitromethane and have potential applications in hypoxic combustion as in plateau areas.