Combustion Dynamics of NH3/H2 in a Jet-Stirred Reactor

As a highly promising zero-carbon fuel, NH3 has attracted widespread attention. Understanding the chemistry of NH3 combustion is now one of the challenges of combustion dynamics. In this work, experiments investigating NH3/H2 oxidation were conducted in a jet-stirred reactor at atmospheric pressure, covering H2 mole fractions (0–9000 ppm), equivalence ratios (0.6–1.4), and temperatures (800–1300 K). Key products (H2, N2, NO, and N2O) were quantified by gas chromatography. A refined kinetic model for NH3/H2 oxidation was developed by optimizing critical rate constants through the systematic integration of experimental data. The experimental results demonstrate that H2 addition enhances NH3 oxidation, manifesting reduced oxidization temperatures and elevated product mole fractions. Under fuel-lean conditions, NH3 exhibits strong oxidative reactivity, which diminishes with increasing equivalence ratios. At 1100–1300 K under fuel-rich conditions, NH3 pyrolysis becomes significant, marked by rising H2 mole fractions with temperature. Rate of production and sensitivity analyses reveal that the addition of H2 amplifies the H/OH radical pools, accelerating NH3 dehydrogenation. The suppression of HNO, NH, and H2NO intermediate formation under elevated equivalence ratios directly correlates with reduced NO and N2O mole fractions. The model was further validated against literature data for laminar flame speed, ignition delay time, and NH3 pyrolysis. This work establishes fundamental insights into NH3/H2 oxidation dynamics and offers reliable experimental data for modeling.