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Structure and propagation of n-heptane/air premixed flame in low temperature ignition regime

Zhong, Shenghui LU ; Zhang, Fan LU ; Jangi, Mehdi LU ; Bai, Xue Song LU ; Yao, Mingfa and Peng, Zhijun (2020) In Applied Energy 275.
Abstract

This paper presents a large eddy simulation of n-heptane/air turbulent premixed combustion in a reactor assisted turbulent slot (RATS) burner under different preheating conditions. N-heptane/air mixture at an equivalence ratio of 0.6, pressure of 1 atm and temperature of 600, 650 and 700 K is considered to investigate the effect of low temperature chemistry on turbulent burning velocities and flame regimes, including chemically frozen (CF) regime where the fuel/air mixture inside the burner is chemically frozen, low temperature ignition (LTI) regime where the fuel/air mixture inside the burner undergoes LTI reactions, and transition regime from CF to LTI. The results show that the flame in the LTI regime exhibits the highest turbulent... (More)

This paper presents a large eddy simulation of n-heptane/air turbulent premixed combustion in a reactor assisted turbulent slot (RATS) burner under different preheating conditions. N-heptane/air mixture at an equivalence ratio of 0.6, pressure of 1 atm and temperature of 600, 650 and 700 K is considered to investigate the effect of low temperature chemistry on turbulent burning velocities and flame regimes, including chemically frozen (CF) regime where the fuel/air mixture inside the burner is chemically frozen, low temperature ignition (LTI) regime where the fuel/air mixture inside the burner undergoes LTI reactions, and transition regime from CF to LTI. The results show that the flame in the LTI regime exhibits the highest turbulent burning velocity. Differential diffusion is found to play an important role in the LTI regime whereas it is less important in the CF regime. To investigate the effect of LTI reactions on the flame, a series of two-dimensional laminar flames are simulated, in which the effect of turbulence on the flames is eliminated. The results show that in the LTI regime, the laminar burning velocity is drastically enhanced and the heat release zone is broadened. Budget term analysis shows that the enhanced rate of production and diffusion towards the preheat zone of the flames and the smaller gradient of reactant mass fraction are the main reasons behind the increased laminar burning velocity in the LTI regime.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Burning velocity, Differential diffusion, Fuel reactivity, Low temperature ignition, Turbulent premixed flame
in
Applied Energy
volume
275
article number
115320
publisher
Elsevier
external identifiers
  • scopus:85086928698
ISSN
0306-2619
DOI
10.1016/j.apenergy.2020.115320
language
English
LU publication?
yes
id
8c8c3f65-8ced-447c-ae13-eea90adb74b9
date added to LUP
2020-07-07 09:06:10
date last changed
2022-04-18 23:20:34
@article{8c8c3f65-8ced-447c-ae13-eea90adb74b9,
  abstract     = {{<p>This paper presents a large eddy simulation of n-heptane/air turbulent premixed combustion in a reactor assisted turbulent slot (RATS) burner under different preheating conditions. N-heptane/air mixture at an equivalence ratio of 0.6, pressure of 1 atm and temperature of 600, 650 and 700 K is considered to investigate the effect of low temperature chemistry on turbulent burning velocities and flame regimes, including chemically frozen (CF) regime where the fuel/air mixture inside the burner is chemically frozen, low temperature ignition (LTI) regime where the fuel/air mixture inside the burner undergoes LTI reactions, and transition regime from CF to LTI. The results show that the flame in the LTI regime exhibits the highest turbulent burning velocity. Differential diffusion is found to play an important role in the LTI regime whereas it is less important in the CF regime. To investigate the effect of LTI reactions on the flame, a series of two-dimensional laminar flames are simulated, in which the effect of turbulence on the flames is eliminated. The results show that in the LTI regime, the laminar burning velocity is drastically enhanced and the heat release zone is broadened. Budget term analysis shows that the enhanced rate of production and diffusion towards the preheat zone of the flames and the smaller gradient of reactant mass fraction are the main reasons behind the increased laminar burning velocity in the LTI regime.</p>}},
  author       = {{Zhong, Shenghui and Zhang, Fan and Jangi, Mehdi and Bai, Xue Song and Yao, Mingfa and Peng, Zhijun}},
  issn         = {{0306-2619}},
  keywords     = {{Burning velocity; Differential diffusion; Fuel reactivity; Low temperature ignition; Turbulent premixed flame}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Applied Energy}},
  title        = {{Structure and propagation of n-heptane/air premixed flame in low temperature ignition regime}},
  url          = {{http://dx.doi.org/10.1016/j.apenergy.2020.115320}},
  doi          = {{10.1016/j.apenergy.2020.115320}},
  volume       = {{275}},
  year         = {{2020}},
}