Combustion characteristics and emissions of nitrogen oxides (NO, NO2 , N2O) from spherically expanding laminar flames of ammonia-hydrogen blends

While ammonia (NH3) and hydrogen (H-2) are promising carbon-free fuels, there are significant challenges presented by their combustion properties. Blending them can help mitigate some of these issues; however, the fundamental behaviors of these blends need to be well understood. A constant volume combustion chamber (CVCC) is used to study the emissions of nitrogen oxides (NO, NO2, N2O), laminar burning velocity (LBV), and intrinsic instabilities for H-2-NH3 blends across a wide range of equivalence ratios (Phi = 0.5 to 1.5) and volume fractions of H-2 in the blends (0% to 50%). Measurements of LBV are consistent with existing data where available. The largest NOx and N2O emissions are found at lean conditions and decrease significantly for rich mixtures. NOx emissions tend to increase with H-2 fractions in fuel for lean mixtures. Intrinsic instabilities are more prominent at lean conditions and heavily influenced by the amount of H-2 in the blend.