ScholarWorks@성균관대학교

초록

The detailed reaction mechanism for NOx formation under high-temperature conditions was generated using the Reaction Mechanism Generator (RMG). The mechanism was generated over 2000-5000 K at 1 bar and included pressure-dependent reactions. The final mechanism consists of 33 species and 292 reactions, including neutral and electronically excited species. To evaluate the generated mechanism, it was implemented in a reduced-order chemical reactor network model that accounts for the flow characteristics of a microwave plasma reactor, and the predicted NOx concentrations were compared with measurements. The simulations predicted that the NOx concentration reaches a maximum at N-2:O-2 = 6:4 and 5:5 and decreases with increasing flow rate, consistent with the experimental observations. However, the discrepancy between the simulations and experiments increased as the flow rate increased, which is attributed not to missing reaction pathways but to simplifications in the reactor model that do not fully capture the actual temperature gradient. Reaction path analysis showed that Zeldovich reactions and three-body dissociation of O-2 and NO dominate in the plasma stream. In the surrounding stream, reactions involving O atoms diffusing from the plasma stream are dominant, with O-atom recombination to form O-2 and NO-NO(2 )interconversion as the main pathways. Additionally, reactions involving electronically excited species derived from the pressure-dependent reactor were also identified. However, these excited species did not contribute to NOx formation and instead relaxed back to their ground state via collisional relaxation.

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