Formation of NO in High-Temperature N₂/O₂/H₂O Mixtures: Re-evaluation of Rate Coefficients

Abstract

A re-evaluation of the flow reactor experiments of Abián et al. (Formation of NO from N2/O2 Mixtures in a Flow Reactor: Toward an Accurate Prediction of Thermal NOAbiánM.AlzuetaM. U.GlarborgP. Abián, M. Alzueta, M. U. Glarborg, P. Int. J. Chem. Kinet.201547518532) is presented. In these experiments, nitrogen oxide formation was measured at atmospheric pressure in the temperature range of 1700–1810 K using several mixtures containing different ratios of oxygen, nitrogen, and water vapor. On the basis of the mechanism of Abián et al., the two most important reaction steps for NO formation (reaction R1, NO + N = N2 + O; reaction R2, N2O + O = 2 NO) were identified by local sensitivity analysis. For the optimization of the Arrhenius parameters of these reaction steps, 25 data points measured by Abián et al., two direct rate coefficient measurements (73 data points), and one theoretical calculation were used. The obtained mechanism with the optimized Arrhenius parameters (reaction R1, A = 1.176 × 1010 cm3 mol–1 s–1, n = 0.935, and E/R = −693.68 K; reaction R2, A = 1.748 × 1016 cm3 mol–1 s–1, n = −0.557, and E/R = 14 447 K) described the results of the flow reactor experiments, direct measurements, and theoretical calculations much better compared to the Abián et al. mechanism and also several recent NOx mechanisms. The rate coefficients of these elementary reactions were obtained with low uncertainty in the temperature range of 1600–2200 K.

Combustion Chemistry of Unsaturated Hydrocarbons Mixed with NOx: A Review with a Focus on Their Interactions

“…With the re-evaluated rate, thermal NO formation was accurately predicted. The rate coefficients mentioned above are plotted in Figure 20; it was found that the rate coefficient provided by Buczko et al [93] was about an order of magnitude larger than that of Baber and Dean [92].…”

“…Baber and Dean [92] conducted shock tube experiments for the dissociation of N2O/Ar mixtures over a temperature range of 1850-2540 K and proposed the rate coefficient of N2O + O = NO + NO by fitting the experimental results using a complex mechanism. Recently, Buczko et al [93] re-evaluated the rate coefficient of N2O + O = NO + NO based on direct rate coefficient measurements and theoretical calculations. With the re-evaluated rate, thermal NO formation was accurately predicted.…”

“…In most nitrogen chemistry models, the one-step conversion pathways between the three NO x species can be summarized as shown in Figure 19 20; it was found that the rate coefficient provided by Buczko et al [93] was about an order of magnitude larger than that of Baber and Dean [92]. As for the second N 2 O to NO conversion reaction (N 2 O + H = NO + NH), Baldwin et al [94] first recommended a rate coefficient at 863 K by studying the reaction between H 2 and N 2 O.…”

Comparison of Methane Combustion Mechanisms Using Shock Tube and Rapid Compression Machine Ignition Delay Time Measurements

“…Note that due to the squaring in the definition of E , a twice as high deviation of the simulated and experimental values leads to a four times higher value of E . This objective function has been used in our previous studies for assessing the performance of combustion mechanisms in the estimation of rate parameters from experimental data, comparison of reaction mechanisms, and mechanism optimization. − ,− …”

Analysis of methane combustion mechanisms using large amount of indirect measurement data

“…Ei belonging to dataset i, and E belonging to all considered N datasets are expected to be near unity if the chemical kinetic model is accurate, and the deviations of the measured and simulated results are caused by the scatter of the experimental data only. Note that due to the squaring in the definition of E, a twice as high deviation of the simulated and experimental values leads to a four times higher value of E. This objective function has been used in our previous studies for assessing the performance of combustion mechanisms in the estimation of rate parameters from experimental data, comparison of reaction mechanisms and mechanism optimization[3][4][5][6]11,[72][73][74][75][76][77][78][79].In contrast to E, the sign of the difference 𝑌 sim,𝑖𝑗 − 𝑌 exp,𝑖𝑗 is maintained in the definition of D, therefore trends such as systematic under-or over-prediction are captured in the D values. This is meaningful, if the investigated model results are all of the same type, like ignition delay time.…”