Characteristics of ammonia/N2/O2 laminar flame in oxygen-enriched air condition

Abstract

Ammonia is regarded as one of the alternative fuels and regarded as a “hydrogen carrier”. Ammonia is an easily-liquefiable fuel. Therefore, it is a suitable fuel for transportation and storage. Also, ammonia can be produced in large quantities by using the Haber-Bosch process with low price. It is known that the laminar burning velocity of ammonia/air mixture is about 10 cm/s at near stoichiometric condition. This laminar burning velocity is very low compared with that of other fossil fuels. Therefore, in order to use ammonia as the alternative fuel, it is necessary to improve the laminar burning velocity of ammonia mixture. In this study, the oxygen-enriched combustion was applied to an ammonia/N2/O2 premixed flame and the effects of the oxygen-enriched combustion on the flammable range, the laminar burning velocity and the flame temperature were evaluated. Also, laminar burning velocity was calculated by using CHEMKIN-Pro. The chemical reaction set about ammonia oxidation, which reported by Lindstedt, was applied as the detailed elementary reactions. Results showed that oxygen concentration was necessary at least 26% to maintain ammonia flame stable. The laminar burning velocity was increased with the increase of O2 concentration in both experimental results and numerical results. At 30% O2 concentration and stoichiometric condition, the laminar burning velocity was 27.4 cm/s. Also, Ammonia flame temperature was around 2167 K under 30% O2 concentration.

Keywords

• renewable energy
• ammonia fuel
• alternative fuel
• carbon free
• oxygen-enriched combustion