The effect of temperature on the adiabatic burning velocities of diluted hydrogen flames: A kinetic study using an updated mechanism

On the role of excited species in hydrogen combustion

“…The rate expression for reaction (16) proposed by Kappel et al [66] and recently reconfirmed by Hong et al [67] was adopted by Konnov [56], Alekseev et al [40], and kept in the present work. Yield of hydrogen in reaction (-X3) was experimentally found negligible and below 1E−4 [68], while the branching ratio of the reaction path (X4) forming O 3 was determined to be less than 1E−3 [69] thus both channels can be safely ignored.…”

“…Reaction (X6) was included in the mechanism of Konnov [56] with the rate constant suggested in the review of the IUPAC [65] to investigate a possible role of the pressure dependence of the HO 2 self-reaction. Zhou et al [70] later found that the effect of pressure is negligible at all pressures below 10 atm and above 700 K. Therefore this reaction was not included in the updated model of Alekseev et al [40], and in the present mechanism. In the presence of singlet oxygen, initiation will be enhanced in reaction…”

“…The choice of the transport parameters implemented in the Chemkin package [50] for flame modeling was discussed by Alekseev et al [40]. Following recommendations of Brown et al [51] recently measured diffusion coefficients for OH, HO 2 , and ozone [52] are adopted in the present model.…”

“…Reactions comprising updated hydrogen combustion mechanism as well as ozone decomposition reactions and associated rate constants have been discussed recently [34,40], therefore they are only mentioned here if alternative product channels were proposed in in the most recent models of Starik et al [13,32], of Popov [5,29], and in the MSU mechanism [25,30]. The numbering of the reactions included in the present mechanism corresponds to Table 1, while reactions excluded from the model are listed in Table 2 with numbers (X1), (X2), etc.…”

“…In the present study recently updated hydrogen combustion mechanism [40] is combined with ozone decomposition reactions [34] and extended by reactions of excited species: O( 1 D), OH( 2 + ), O 2 (a¹ g). The goal of the present work was to evaluate the reliability and the accuracy of the rate constants pertinent to these excited species, and to validate and analyze kinetic mechanism predictions at high temperatures.…”