Determination of the Rate Parameters of N/H/O Elementary Reactions based on H2/O2/NOx Combustion Experiments

A mechanism for the description of the H2/O2/NOx combustion systems was optimized via the method developed in our laboratory using computer framework code Optima++. In total, 5073 experimental data points (ignition delay times, concentration profiles and burning velocity measurements) were collected from the literature and were reproduced using 17 recent NOx mechanisms. The performance of the Glarborg-2018 mechanism was the best. Ten elementary reactions were selected based on local sensitivity analysis and the Arrhenius parameters of them were fitted to indirect experimental data, and direct experimental and theoretical determinations of the rate coefficients. This way more accurate rate parameters of these reactions were obtained and the temperature dependent uncertainties of the rate coefficients were calculated. Introduction Environmental regulations of industrial processes require the exploration of the behaviour of nitrogen oxides in combustion systems. Several detailed reaction mechanisms [1-17] were published in the last decades to describe the generation of NOx in combustion systems. These mechanisms are also applicable to facilitate the development of technologies for lowering NOx emission from combustion systems. In a recent review, Glarborg et al. [1] state that for all NOx formation routes and all major non-catalytic NO removal methods good reaction schemes are available, but the simulation results still have high uncertainty. In this work, concentration profiles measured in jet stirred reactors, ignition delay times determined in shock tubes, concentration profiles measured in flow reactors, laminar burning velocity measurements and concentration profiles measured in burner stabilized flames (indirect measurements) related to hydrogenoxygen combustion systems doped with NO, NO2 or N2O, and H2/N2O combustion systems were considered. These data, together with direct experimental and theoretical determinations of the rate coefficients were used to obtain the rate parameters of ten selected N/H/O elementary reactions with low uncertainty. A methodology was developed by Turányi et al. [18] for the determination of rate parameters based on direct and indirect measurements, and theoretical determinations. The method provides rate parameters which are in accordance with the considered indirect measurements and the literature information related to the investigated elementary reactions. Collection of experimental data Our aim was to collect all experimental data on hydrogen combustion influenced with nitrogen oxides related to measurements in homogenous reactors and flames. The summary of the experimental conditions and the number of the collected data is given in Table 1. * Corresponding author: turanyi@chem.elte.hu Proceedings of the European Combustion Meeting 2019 Table 1 List of the considered hydrogen combustion experiments. Exp. type Data sets Data points T / K p / atm  JSR 19 945 700– 1150 1– 10 0.1– 2.5 IDT 65 775 738– 2712 0.14– 35.9 0.3– 5.0 LFR 43 1538 780– 1382 0.5– 12.5 0.25– 3.77 LBV 7 88 297– 299 0.197– 1.02 0.15– 1.79 BSF 81 1727 293– 970 0.026– 1 0.45– 1.74 Exp. type: experiment type; Date sets.: number of datasets; Data points: number of data points; JSR: concentration profiles measured in jet stirred reactors; IDT: ignition delay time measured in shock tubes; LFR: concentration profiles measured in laminar flow reactors; LBV: laminar burning velocity measurements; BSF: concentration profiles measured in burner stabilized flames All collected indirect experimental data (5073 data points in 215 data sets of 36 experimental articles) were stored in ReSpecTh Kinetics Data (RKD) files. The RKD-format [19,20] was developed from the PrIMe kinetics data format [21,22] by adding several new keywords. These data formats are XML based and can be well read by both humans and computer codes. The RKD-format files were created with our Optima++ code [23]. Optima++ was also used for reading the data files, running the FlameMaster simulation code [24] and comparing the simulation results with the experimental data.