Automated discovery of influential chemically termolecular reactions in energetic material combustion: A case study for RDX

Toward a More Comprehensive Understanding of the Kinetics of a Common Biomass-Derived Impurity: NH3 Oxidation by N2O in a Jet-Stirred Reactor

“…Ammonia (NH 3 ) kinetics has received significant attention due to its broad relevance across many scientific and engineering domains. − Important applications include, for example, its proposed use as a carbon-free energy carrier, ,, its continued use as a nitrogen oxide reduction agent in the thermal DeNO x process − and similar processes using urea, its role as a decomposition fragment of many energetic materials, − and its presence in trace quantities as an impurity during biofuel and biomass combustion that influences overall system kinetics. ,− As the breadth of its applications continues to grow, there is an increasing need for comprehensive ammonia kinetic models that can accurately predict its kinetics across such highly varied domains with confidence. Even with the substantial previous attention devoted to ammonia kinetics, many researchers still believe that our understanding of ammonia chemistry is incomplete. ,− For example, Stagni et al note that “a comprehensive understanding of its kinetic behavior is still an open challenge, especially at low temperature ( T < 1200 K) and under diluted conditions.” Indeed, many submodels within NH 3 kinetic mechanisms rely on rate constant estimates that likely have not been tested/validated in previous theoretical and experimental studies.…”

“…Additionally, in some applications (e.g., during the combustion of nitrogen-rich energetic materials , ), ammonia is exclusively oxidized in an environment where nitrogen-containing oxidizers are present in much higher mole fractions than O 2 . Furthermore, NH 3 /N 2 O kinetics is also expected to be relevant to biomass combustion, where NH 3 and N 2 O are often present in sizable fractions, and to nitrogen oxide reduction strategies using ammonia, where N 2 O is both an undesirable byproduct in NO x reduction applications and itself among the major nitrogen oxide emissions in fluidized bed combustion .…”

“…41−43 Consequently, new experimental data for such reactant mixtures would be valuable for establishing ammonia kinetic models that can be broadly used across varied application domains by both evaluating untested reaction sets and accentuating different combinations of rate constants than previous data sets. Additionally, in some applications (e.g., during the combustion of nitrogen-rich energetic materials 14,15 ), ammonia is exclusively oxidized in an environment where nitrogencontaining oxidizers are present in much higher mole fractions than O 2 . Furthermore, NH 3 /N 2 O kinetics is also expected to be relevant to biomass combustion, where NH 3 and N 2 O are often present in sizable fractions, 21 and to nitrogen oxide reduction strategies using ammonia, where N 2 O is both an undesirable byproduct in NO x reduction applications 10 and itself among the major nitrogen oxide emissions in fluidized bed combustion.…”

Understanding and Representing the Distinct Kinetics Induced by Reactive Collisions of Rovibrationally Excited Ephemeral Complexes across Reactive Collider Mole Fractions and Pressures

“…Since then, the importance of several other chemically termolecular reactions in combustion has been recognized. − As examples, Barbet et al identified a handful of chemically termolecular reactions of potential importance to combustion using a rapid, automated procedure for identifying and estimating rate constants of chemically termolecular reactions. Lei and Burke have since demonstrated that H + C 2 H 2 + O 2 one of the reactions identified in the screening study of Barbet et alimpacts predicted ignition delay times by an order of magnitude.…”

“…Lei and Burke 10 have since demonstrated that H + C 2 H 2 + O 2  one of the reactions identified in the screening study of Barbet et al 9 impacts predicted ignition delay times by an order of magnitude. Cornell et al, 11 using the same screening procedure as Barbet et al, 9 identified yet more chemically termolecular reactions of potential importance to energetic materials combustion. Jasper et al 12 and Tao et al 13 have also found noticeable influences of H + CH 3 + X and H + OH + X (X = H, O, OH, O 2 ) on flame speeds.…”