An investigation of important gas-phase reactions of nitrogenous species from the simulation of experimental measurements in combustion systems

Abstract

Simulated results from a detailed elementary reaction mechanism for nitrogen-containing species in flames consisting of hydrogen, C 1 or C 2 fuels are presented, and compared with bulk experimental measurements of nitrogen-containing species in a variety of combustion systems including flow reactors, perfectly stirred reactors, and low pressure laminar flames. Sensitivity analysis has been employed to highlight the important reactions of nitrogenous species in each system. The rate coefficients for these reactions have been compared against the expressions used in three other recent reaction mechanisms: version 3.0 of the GRI mechanism, the mechanism of Glarborg, Miller and co-workers, and that of Dean and Bozzelli. Such comparisons indicate that there are still large discrepancies in the reaction mechanisms used to describe nitrogen chemistry in combustion systems. Reactions for which further measurements and evaluations are required are identified and the differences between the major mechanisms available are clearly demonstrated.

Unimolecular and Bimolecular Calculations for HN2

“…[1][2][3][4][5][6] It is also relevant in the understanding of noncatalytic radical mechanisms leading to the ammonia production. 7 Although the experimental detection of HN 2 is still to be accomplished (see ref 8), a long-standing conclusion from theoretical methods based on ab initio calculations is that such a species should be metastable with a very short lifetime.…”

Uncertainty analysis of NO production during methane combustion

“…The agreement is getting worse with increasing equivalence ratio, and the simulated concentrations underpredict the measured NO concentration. Note that the GRI 2.11 mechanism provided a good agreement [44,49,50] with the Bartok et al data, but the latter 3.0 version [50] strongly overpredicted the NO concentration. Monte Carlo analysis is an accurate method for the determination of the uncertainty of model results.…”

“…In Case I, the enthalpies of formation of all species were updated to reflect the development in the accuracy of thermodynamic data since the publication [44] of the mechanism. There is an accumulating body of evidence that the major intermediate of the prompt NO formation is not HCN, as it was previously assumed, but NCN.…”

“…In this paper, the investigations are based on the Leeds methane oxidation mechanism [43] with the NO x reaction block extension [44]. The published works of Hughes et al [43,44] contain results of comprehensive testing of the mechanism against experimental data. Two different versions of the Leeds mechanism were used.…”

“…[48] is that the applied domain of pressure, temperature, residence time, and equivalence ratio is close to the conditions of an industrial furnace. This experiment is widely used (see, e.g., publications [44,49,50]) for testing mechanisms of NO formation during methane oxidation.…”