Chemical kinetic analysis of H ₂ –NH ₃ addition on premixed natural gas flame at elevated pressures

Abstract The combustion of hydrocarbon fuels is a complex chemical reaction process. In this study, the effects of various H 2 –NH 3 blending ratio ( α ) in CH 4 /H 2 /NH 3 ternary fuel on laminar burning velocity (LBV), CO 2 , NOx, adiabatic flame temperature, and temperature sensitivity were investigated using Chemkin/Premix code. The results showed that α exerted more pronounced effects on LBVs of ternary fuel compared to the hydrogen volume fraction in the H 2 –NH 3 mixture ( β ). Fuel-rich combustion effectively reduced NOx emissions, compared to experiments of pure NH 3 blending, and the H 2 –NH 3 mixture significantly reduced NOx emissions in ternary premixed flames when equivalence ratios ( Φ ) exceeded 1.0. Temperature sensitivity analysis revealed that reaction R318 (NH 2 + O <=> HNO + H) exhibited temperature inhibition. This observation elucidated the initiation of the NH 2 → HNO → NO → N 2 O → N 2 pathway and demonstrated that C–N reactions were negligible in predicting laminar combustion characteristics of CH 4 /H 2 /NH 3 ternary fuel.