Main sources of uncertainty in recent methanol/NOx combustion models

Abstract

AbstractThe performance of 17 recent detailed reaction mechanisms describing the interactions of methanol and formaldehyde with nitrogen oxides in combustion systems was investigated based on large number of literature experimental data covering a wide range of conditions. This data collection consists of 2552 data points of concentration profiles in 243 datasets measured in jet stirred reactors, tubular flow reactors, and shock tubes. The two best mechanisms were found to be the Shrestha‐2019 and Glarborg‐2018 mechanisms, which were selected for further investigations. Two additional mechanisms were created via the replacement of the hydrogen, syngas, methanol submechanisms, and the parameters of nine N/H/O reactions to ones from our previous mechanism optimization studies. Local sensitivity analysis of the kinetic and thermodynamic parameters (Arrhenius A‐factors, heat capacities, standard enthalpies of formation, and standard molar entropies) of these four mechanisms was carried out. The results were in good agreement and the most sensitive reactions belong to the neat hydrogen, syngas, or methanol oxidation. The most important reactions of the interaction between C1 species and NOx are hydrogen‐abstraction reactions CH3OH + NO2 = HONO + CH2OH and CH2O + NO2 = HONO + HCO. The most sensitive thermodynamic properties are the molar heat capacities of species OH, NO, HONO, and NO2, and the standard enthalpies of formation and entropies of these species have also significant sensitivities. According to the local uncertainty analysis of the kinetic and thermodynamic parameters, the rate coefficients of the NOx chemistry have the highest contribution to the overall uncertainty of the simulation results, especially those of the two reactions above. The highest uncertainty caused by the thermodynamic parameters is due to the heat capacity of HNO, OH, HO2, and NO2 and some other species, whereas the uncertainty contributions of all enthalpies of formation and entropies were negligible.