Investigation and Optimization of Existing Laminar Flame Velocity Reaction Mechanisms in NH3 and NH3/H2 Flames
2025
Shaowen Xu | Zhigang Liu | Huiming Chen | Yun Chao | Liang Xu
With the increasing greenhouse effect and energy crisis, ammonia is one of the most promising alternative fuels. However, the research on the combustion characteristics of ammonia needs to be further improved. In this paper, the combustion characteristics of two kinds of ammonia and ammonia&ndash:hydrogen amino fuels (laminar flame velocity) are investigated through experimental data and kinetic mechanism analysis, and the laminar flame predictions are calculated for 20 kinds of ammonia mechanisms with different equivalence ratios, oxygen contents, and hydrogen doping ratios, after which MAPE and sensitivity analysis are used to determine the applicability of the mechanisms. The results indicate that the incorporation of hydrogen and the augmentation of oxygen concentration induce exponential and linear increases in the laminar flame speed of ammonia, respectively. The laminar flame speed of ammonia reaches its maximum at an equivalence ratio of approximately 1.1, with a value ranging from 6 to 7 cm/s. Under a hydrogen addition ratio of 0.4, the laminar flame speed of ammonia even reaches 29&ndash:30 cm/s. The Otomo and Zhang mechanisms are recommended for ammonia fuels with different equivalence ratios and oxygen contents. For different equivalence ratios and hydrogen doping ratios of ammonia&ndash:hydrogen combustion, the Gotama and Stagni mechanisms are more suitable. For the overall conditions, the Zhang mechanism is recommended in this paper to simulate the laminar flame velocity for ammonia and ammonia&ndash:hydrogen mechanisms. Based on the Glarborg mechanism, an optimized mechanism is proposed to simulate the laminar flame velocity for both fuels, which reduces to 9.55% compared to 43% for the average calculation error of the original mechanism.
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