Experimental study and kinetic model of propanal/H2/O2/Ar flames at low pressure

Propanal (C2H5CHO) is a crucial intermediate oxygenated species in hydrocarbons and oxygenates combustion, thus motivating a better understanding of its kinetics. In this study, two premixed flat flames of propanal/hydrogen/oxygen/argon, a stoichiometric one (φ = 1.1) and a rich one (φ = 1.72), are stabilized at low pressure (27 mbar) on a burner. Species mole fraction profiles have been measured by molecular beam mass spectrometry (M.B.M.S.) for the reactants, products, and intermediate species: C2H5CHO (propanal), H2, O2, Ar, H, OH, HO2, CO, CO2, H2O, CH3, CH4, CH2O (formaldehyde), CH2CO (ketene), CH3CO (acetyl radical), C2H2 (acetylene), C2H4 (ethylene) and C2H6 (ethane). The mechanism from the Universit ́e catholique de Louvain (UCL) has been extended to the kinetics of propanal and its reliability has been validated against both these propanal flames, at low pressure and up to 1530 K. According to the model, the main propanal consumption channel produces the ethyl radical (C2H5). This radical leads to hydrocarbons formation through C2H5 → C2H4 → C2H3 → C2H2 ; and also, to oxygenated compounds production through C2H5 → CH3CHO → CH3CO → CH2CO → CH2CHO. The presence of hydrogen, as a reactant, promotes the propanal consumption with the H radicals