Stability limits and NO emissions of technically-premixed ammonia-hydrogen-nitrogen-air swirl flames
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ArticleAuthors
Khateeb, Abdulrahman A.
Guiberti, Thibault
Zhu, Xuren

Younes, Mourad
Jamal, Aqil
Roberts, William L.

KAUST Department
Clean Combustion Research CenterMechanical Engineering Program
Physical Science and Engineering (PSE) Division
high-pressure combustion (HPC) Research Group
Date
2020-07-07Online Publication Date
2020-07-07Print Publication Date
2020-08Embargo End Date
2022-08-06Submitted Date
2020-03-03Permanent link to this record
http://hdl.handle.net/10754/664592
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Hydrogen is a promising carbon-free fuel for power generation in gas turbines. However, this raises some challenges associated with the storage and distribution of pure hydrogen. Storing hydrogen chemically in the form of ammonia is a safe and efficient alternative. However, ammonia as a fuel features a low chemical reactivity compared to hydrogen and natural gas and, as a consequence, stabilizing turbulent ammonia-air flames is challenging. Offsetting this low reactivity by enriching ammonia with some amount of hydrogen, which is much more reactive, is a promising strategy. In this study, the stability limits of technically-premixed ammonia-hydrogen-air flames are measured in a laboratory-scale swirl combustor for a wide range of ammonia fractions in the ammonia-hydrogen fuel blend. Results are compared to that obtained in the same combustor for reference methane-hydrogen-air mixtures. Data show that increasing the ammonia fraction in the fuel blend promotes lean blowout but reduces the flames’ propensity to flashback. The latter effect is even more pronounced if the volume fraction of ammonia in the fuel blend exceeds 0.7. In that case, increasing the equivalence ratio at a fixed bulk velocity does not yield flashback and rich blowout occurs instead, yielding a much wider range of stable equivalence ratios. This study also reports exhaust NO mole fractions, measured for large ranges of equivalence ratio and ammonia fraction in the fuel blend. Regardless of the ammonia fraction, data show that competitively low NO emissions occur for slightly rich equivalence ratios of φ ≥ 1.05, which is consistent with earlier studies. Stable flames and good NO performance are also found for very lean ammonia-hydrogen-air mixtures with φ ≤ 0.50, demonstrating the strong potential of fueling gas turbines with ammonia-hydrogen blends.Citation
Khateeb, A. A., Guiberti, T. F., Zhu, X., Younes, M., Jamal, A., & Roberts, W. L. (2020). Stability limits and NO emissions of technically-premixed ammonia-hydrogen-nitrogen-air swirl flames. International Journal of Hydrogen Energy, 45(41), 22008–22018. doi:10.1016/j.ijhydene.2020.05.236Sponsors
This work is supported by Saudi Aramco Research and Development Center under research agreement number RGC/3/3837-01-01 and by the King Abdullah University of Science and Technology under grant number BAS/1/1370-01-01.Publisher
Elsevier BVAdditional Links
https://linkinghub.elsevier.com/retrieve/pii/S0360319920320917ae974a485f413a2113503eed53cd6c53
10.1016/j.ijhydene.2020.05.236