Laminar Flame Speed Measurement and Combustion Kinetic Mechanism Optimization of NH3/H2/Air Mixtures

To address the limitations of existing NH3/H2 combustion mechanisms, laminar flame speeds of NH3/H2/air mixtures were measured using the heat flux method over a range of equivalence ratios from 0.7 to 1.6 at different blending ratios. The results indicate that current mechanisms exhibit large prediction errors under fuel-rich conditions. Subsequently, based on the original mechanism, the pre-exponential factors of 13 key reactions were optimized using a particle swarm optimization algorithm, leading to the development of a new NH3/H2 chemical kinetic mechanism. The optimized mechanism not only improves the prediction of laminar flame speeds for NH3/H2/air mixtures but also significantly enhances accuracy in the fuel-rich region. In addition, it accurately predicts the ignition delay times of NH3/H2 and reliably reproduces the concentrations of H2O, NH3, NO, and N2O under low-equivalence-ratio conditions. Although the optimized mechanism was not specifically developed for pure NH3 or pure H2 fuels, it still performs well in describing their combustion characteristics. Overall, the optimized mechanism provides reliable predictions for both the laminar flame speeds and ignition delay times of NH3/H2 mixtures.