Counterflow flame extinction of ammonia and its blends with hydrogen and C1-C3 hydrocarbons

Ammonia as a fuel offers the potential to avoid carbon emissions, but its combustion is hindered by low reactivity. Here, extinction limits of NH3 and plus reactivity enhancers were measured in counterflow laminar non-premixed flames. A stable NH3-N2 flame was established with an oxygen-enriched oxidizer stream, when blended CH4, C2H6, C3H8, H2. For mixtures, results showed that CH4 has least enhance stability flames compared other additives. The C2H6 C3H8 are nearly identical. At percentage addition, H2-blended extinguish earlier than those C1-C3 hydrocarbons, this trend reversed at higher H2 blends. Experimental conditions simulated using Okafor et al. 2018 model extended Zhang al 2021 developed here. models captured trends, including crossover between NH3-H2 NH3-C2/C3 hydrocarbon fuels. Quantitatively, both under-predicted NH3-N2/enriched flame. Better quantitative agreement observed for fuels Discrepancies have been reported rates reactions involving HNO (+OH, H), if addressed, could improve models' capability predicting behavior Numerical analyses carried out understand kinetic coupling H2/C2-C3 counter-flow Extinction NH3-C2-C3/H2 shown be affected H abstraction related chain termination reactions, heat producing branching reactions. It also high blending ratios, C2H6/C3H8 addition reduced peak OH concentration via recombination which compete pathways. mostly influenced active radicals.