Laminar Flame Speed Measurement and Combustion Kinetic Mechanism Optimization of NH 3 /H 2 /Air Mixtures

To address the limitations of existing NH 3 /H 2 combustion mechanisms, laminar flame speeds of NH 3 /H 2 /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 NH 3 /H 2 chemical kinetic mechanism. The optimized mechanism not only improves the prediction of laminar flame speeds for NH 3 /H 2 /air mixtures but also significantly enhances accuracy in the fuel-rich region. In addition, it accurately predicts the ignition delay times of NH 3 /H 2 and reliably reproduces the concentrations of H 2 O, NH 3 , NO, and N 2 O under low-equivalence-ratio conditions. Although the optimized mechanism was not specifically developed for pure NH 3 or pure H 2 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 NH 3 /H 2 mixtures.