The utilization of fossil fuels has propelled the advancement of human society; however, it has also caused globalclimate change, posing a threat to the survival and development of humanity. In this context, ammonia and hydrogen, as zero-carbon fuels, have attracted much attention. However, their combustion utilization faces numerous challenges. MILD combustion is a new combustion technology that may achieve clean and efficient combustion of NH / H blended fuel, but research in this area is currently very limited. The combustion and emission characteristics of a premixed NH / H jet flame was thoroughly investigated by numerical simulation. Specially, the hydrogen proportion (X(H)) and jet equivalence ratio (Φ) were varied, and a detailed analysis on temperature rise, reaction zone size, lift-off height, radical concentrations, and NO emissions was conducted. Results indicate that the addition of a small amount of H significantly enhances the stability of ammonia flame, lowers the auto-ignition temperature, and eliminates flame lift phenomenon. Moreover, an increase in X(H) elevates the combustion temperature, accelerates the production of H,O, and OH radicals, thereby leading to a transition in the combustion regime from MILD to high-temperature combustion. Under fuel -rich conditions and lowX(H), significant amounts of NH decompose into H prior to main combustion reactions, resulting in high combustion temperatures. Asfor NO emissions, NO and NO are the dominant sources, while NO is negligible. Generally, the emissions of NO and NO first increaseand then decrease with increasing X. Moreover, when X(H) is low, the peak concentrations and emissions of NO and NO are comparable. However, as X(H) increases, the temperature rises, leading to the decomposition of N O, with NO becoming the primarysource of NO emissions. Furthermore, under fuel-rich conditions, the combustion temperature, OH concentration, and the entrainment ofjet to the coflow O collectively influence the NO emission.

刘祥涛(1995—),男,山东济宁人,博士研究生。E-mail:liuxtcoe@stu.pku.edu.cn

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LIU Xiangtao, WANG Guochang, SI Jicang, et al. Numerical study on the combustion and emission characteristics ofpremixed NH3 / H2 jet flame[J].Clean Coal Technology,2024,30(8):107-116.