Effects of radiation reabsorption on the flame speed and NO emission of NH3/H2/air flames at various hydrogen ratios

Zheng，Shu1; He，Yuzhen1; Hu，Bin1; Zhu，Jiajian2; Zhou，Bo3; Lu，Qiang1

2022-11-01

10.1016/j.fuel.2022.125176

FUEL   Impact Factor & Quartile

0016-2361

1873-7153

Ammonia has attracted extensive attention in the direct combustion applications due to its carbon–neutral properties. In this study, the numerical simulations of NH/H/air one-dimensional premixed laminar flame under the stoichiometric condition with different H ratios (η = X/(X + X) = 0.2–0.7) were conducted to explore the influence of radiation reabsorption on laminar flame speed and NO emission. Also the effect of radiation reabsorption on NO generation and emission in NH/H/air mixture when η = 0.6 with different equivalence ratios was discussed. The results showed that the radiation reabsorption effect on flame speed decreased monotonically with the H ratio increasing from 0.2 to 0.7, and the maximum effect was 17%. The effect on flame speed was regulated by the combination of direct radiation effect and chemical effect, which was influenced by reaction R257 NH + NO = NNH + OH via OH radical when η = 0.2–0.7 and ϕ = 1.0. The promotion effect of radiation reabsorption on NO generation and emission decreased monotonically with the increasing H proportion. The enhancement of NO generation caused by radiation reabsorption was mainly controlled by R222 N + OH<=>NO + H. On the other hand, R220 N + NO<=>N + O, R240 NH + NO = NO + H and R242 NH + NO = N + OH affected the NO emission in the post-flame zone. At η = 0.6 and ϕ = 0.65–1.5, the promotion of NO generation by radiation reabsorption was non-linear, which was mainly affected by R257, R241 NH + NO = NO + H and R222 reactions. The NO emission was mainly influenced by R241 and R233 in the post-flame zone at ϕ = 0.65–1.05. And R241, R242, R256 NH + NO = N + HO and R257 in the post-flame zone dominated the NO emission when ϕ > 1.05.

Ammonia Flame speed NO Radiation reabsorption

SCI ; EI

English

Others

National Natural Science Foundation of China["51976057","51922040"] ; Science and Technology Innovation Program of Hunan Province[2020RC5008] ; Fundamental Research Funds for the Central Universities["2020DF01","2021MS126"]

Energy & Fuels ; Engineering

Energy & Fuels ; Engineering, Chemical

WOS:000854043700003

ELSEVIER SCI LTD

20222712329132

Combustion ; Free radicals ; Hydrogen ; Radiation effects ; Speed

Chemical Products Generally:804 ; Inorganic Compounds:804.2

ENGINEERING

2-s2.0-85133483821

Scopus

1.National Engineering Research Center of New Energy Power Generation,North China Electric Power University,Beijing,102206,China
2.Science and Technology on Scramjet Laboratory,College of Aerospace Science and Engineering,National University of Defense Technology,Hunan,410073,China
3.Department of Mechanics and Aerospace Engineering,Southern University of Science and Technology,Shenzhen,518055,China

Zheng，Shu,He，Yuzhen,Hu，Bin,et al. Effects of radiation reabsorption on the flame speed and NO emission of NH3/H2/air flames at various hydrogen ratios[J]. FUEL,2022,327.

Zheng，Shu,He，Yuzhen,Hu，Bin,Zhu，Jiajian,Zhou，Bo,&Lu，Qiang.(2022).Effects of radiation reabsorption on the flame speed and NO emission of NH3/H2/air flames at various hydrogen ratios.FUEL,327.

Zheng，Shu,et al."Effects of radiation reabsorption on the flame speed and NO emission of NH3/H2/air flames at various hydrogen ratios".FUEL 327(2022).