Ammonia combustion is offset by long ignition delays, low burning velocities, and high NOx. This study probes H2 enrichment and H2O addition to jointly tune reactivity and emissions, assessing effects on ignition delay time (IDT), laminar burning velocity (LBV), flame thickness, heat release rate (HRR), and NO/N2O. Using validated 0D/1D simulations plus sensitivity and pathway analyses, and data-driven surrogates (polynomial-Lasso, HGB), we achieve reduced-order models with R2: IDT 0.999, LBV 0.997, NO 0.981, N2O 0.972. H2 markedly shortens IDT; a blend with 20% H2 and 20% H2O highlights synergy via coupled dissociation. H2O suppresses LBV, flame thickness, and HRR through thermal/dilution effects, while lowering NOx by cooling and promoting NO reduction (NH2 + NO → NNH + OH; NH2 + NO → H2O + N2) and N2 formation via N2H2/N2H. Sensitivity shows H2 boosts LBV via H + O2 ⇌ O + OH; H2O moderate via H + O2 (+M) ⇌ HO2(+M).
Water-moderated combustion and NOx emissions in ammonia/hydrogen blends: Detailed kinetics with supporting data-driven correlations
Mehdi G.
;De Giorgi M. G.;
2026-01-01
Abstract
Ammonia combustion is offset by long ignition delays, low burning velocities, and high NOx. This study probes H2 enrichment and H2O addition to jointly tune reactivity and emissions, assessing effects on ignition delay time (IDT), laminar burning velocity (LBV), flame thickness, heat release rate (HRR), and NO/N2O. Using validated 0D/1D simulations plus sensitivity and pathway analyses, and data-driven surrogates (polynomial-Lasso, HGB), we achieve reduced-order models with R2: IDT 0.999, LBV 0.997, NO 0.981, N2O 0.972. H2 markedly shortens IDT; a blend with 20% H2 and 20% H2O highlights synergy via coupled dissociation. H2O suppresses LBV, flame thickness, and HRR through thermal/dilution effects, while lowering NOx by cooling and promoting NO reduction (NH2 + NO → NNH + OH; NH2 + NO → H2O + N2) and N2 formation via N2H2/N2H. Sensitivity shows H2 boosts LBV via H + O2 ⇌ O + OH; H2O moderate via H + O2 (+M) ⇌ HO2(+M).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
