College of Engineering,Peking University
2 State Key Laboratory of Clean and Efficient Coal Utilization,Taiyuan University of Technology
Marine Engineering College,Dalian Maritime University
School of Energy and Power Engineering,Huazhong University of Science and Technology

化石能源的利用推动了人类社会的进步,但也造成了全球气候变化,威胁人类的生存与发展。在此背景下,氨和氢作为零碳燃料引起了人们的重视,但其燃烧利用面临诸多问题。MILD燃烧是一种新型燃烧方式,有望实现氨/氢混合燃料的清洁高效燃烧,但目前研究非常有限。采用数值模拟方法对预混NH3/H2射流火焰的MILD燃烧和排放特性进行研究。改变了射流中的氢气比例(X(H2)F)和当量比(ΦJ),并详细分析了温升、反应域、抬升高度、自由基浓度以及氮氧化物(NOx)排放等。结果表明,添加少量H2可显著增强NH3火焰的稳定性,降低自着火温度并消除火焰抬升。此外,X(H2)F的增加能提高燃烧温度,加快H、O和OH自由基的产生,并使燃烧模式由MILD燃烧转变为高温燃烧。富燃料且氢气比例较低时,NH3在燃烧前大量分解为H2,导致燃烧温度较高。关于NOx排放,N2O和NO是最主要来源,NO2可忽略不计。整体上,N2O和NO的排放随X(H2)F的增加先升高再降低。当X(H2)F较低时,N2O的浓度峰值与排放量和NO相当。提高X(H2)F,温度升高,导致N2O转化为NO和N2,因此NO变为主要的NOx排放源。此外,富燃工况中,燃烧温度、OH浓度及射流对伴流中氧气的卷吸共同影响NO排放。

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.

国家自然科学基金资助项目(52206145,52076095)

刘祥涛,王国昌,司济沧,等.NH3/H2掺混MILD燃烧及NOx排放特性的数值模拟[J].洁净煤技术,2024,30(8):107-116.

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.