The replacement of hydrocarbon fuels by ammonia in industrial systems is challenging due to its low burning velocity, its narrow flammability range, and a large production of nitric oxide and nitrogen dioxide when burned close to stoichiometric conditions. Cracking a fraction of ammonia into hydrogen and nitrogen prior to injection in the combustion chamber is considered a promising strategy to overcome these issues. This paper focuses on evaluating how different levels of ammonia cracking affect the overall burning velocity, the lean blow-off limit, the concentration of nitric oxide and nitrogen dioxide, and the flame response to acoustic perturbations. Swirl stabilized premixed flames of pure ammonia–air and ammonia–hydrogen–nitrogen–air mixtures mimicking 10%, 20%, and 28% of cracking are experimentally investigated. The results show that even though ammonia cracking is beneficial for enhancing the lean blow-off limit and the overall burning velocity, its impact on pollutant emissions and flame stability is detrimental for a percentage of cracking as low as 20%. Based on an analysis of the flame dynamics, reasons for these results are proposed.
|Original language||English (US)|
|State||Published - Jan 27 2023|
Bibliographical noteKAUST Repository Item: Exported on 2023-02-02
Acknowledged KAUST grant number(s): URF/1/4051-01-01
Acknowledgements: This research was funded by the King Abdullah University of Science and Technology through the CRG project “Tailoring Flame Dynamics in Carbon Free Combustors,” grant number URF/1/4051-01-01. The authors would like to thank Thibault Guiberti for the interesting discussions on ammonia swirling flames and the technical staff of the Clean Combustion Research Center, more specifically Et-touhami Es-sebbar. The authors also sincerely thank Amit Katoch, Samir Rojas Chavez, Daniel Vigarinho de Campos, and Vigneshwaran Sankar for their help during the measurement campaign.
ASJC Scopus subject areas
- Computer Science(all)