Combustion and NOx emission characteristics of dual-stage lean premixed flame

Zhao, Wenhua; Qiu, Penghua; Liu, Li; Shen, Wenkai; Lyu, Yajin

doi:10.1016/j.applthermaleng.2019.113951

Cited by 7 publications

(2 citation statements)

References 33 publications

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“…Compositional stratification is an integral part of new combustion technologies such as Low-Temperature Combustion (LTC), Homogeneous Charge Compression Ignition (HCCI), Moderate and Intense Low-oxygen Dilution (MILD), etc. The compositional stratification is generally achieved in engines using direct injection inside the combustion chamber [4][5][6] or by dilution of the fuel-air mixture [7][8][9]. With stratification, stoichiometric or slightly rich mixtures can be used near the ignition source, and ultra-lean mixtures can be used near the chamber walls.…”

Section: Introductionmentioning

confidence: 99%

A Detailed Analysis of Mixture Stratification on Flame Displacement Speed for Syngas Combustion

Patil,

Sreedhara

2024

Flow Turbulence Combust

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Gasoline direct injection (GDI) engines can provide higher thermal efficiency and lower emissions compared to conventional combustion techniques. The direct charge injection near the ignition source forms compositional stratification inside the combustion chamber.Compositional stratification inside the combustion chamber opens possibilities for ultra-lean and low-temperature combustion. In this paper, a 2D direct numerical simulation (DNS) has been performed to investigate the propagation of syngas flame in an equivalence ratio stratified medium. A spherically expanding flame has been initiated with a hotspot at the center of thedomain. An open-source PENCIL code [Babkovskaia, 2011] is used to analyse the effect of stratification by simulating cases with varying integral scales of mixing (lϕ) and fluctuations of equivalence ratio (ϕ´). Effects of differential diffusion of species on flame propagation have also been examined by comparing results with cases with unity Lewis number (Le=1). The results show that with an increase in lϕ, flame propagation shows a non-monotonic behavior.With an increase in lϕ, the flame speed and extent of burning increase first and then decrease.With an increase in ϕ´, the flame speed and extent of burning decreased consistently. The peak reaction rate of fuel species is also observed to be shifted to a higher reaction progress variable (c) with increased stratification. The effect of stratification and differential diffusion has been analysed for four identified components of flame displacement speed (Sd) viz. reaction (Sr), normal diffusion (Sn), tangential (St), and inhomogeneity (Sz). Sr and Sn are observed to be major contributors to Sd. The magnitude of Sr shows reductions with an increase in stratification. In comparison, Sn does not show significant change with increased stratification.The variation of the contribution of chemical reactions to heat release rate with stratification is also analysed in this study. The results show that shifting of peak reaction rate of fuel species to higher c values results in variation in heat release rate contribution for chemical reactions.

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Section: Introductionmentioning

confidence: 99%

A Detailed Analysis of Mixture Stratification on Flame Displacement Speed for Syngas Combustion

Patil,

Sreedhara

2024

Flow Turbulence Combust

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“…This combustion approach effectively reduces CO and NO emissions through MILD combustion, with further reductions achievable through air staging. Zhao et al [ 20 ] analyzed the combustion and NO x emission characteristics of dual‐stage lean premixed flames. The results highlighted that the secondary flame produces certain intermediates during the combustion process, leading to the reduction of NO x to N 2 .…”

Section: Introductionmentioning

confidence: 99%

Effects of Hydrogen Addition, Oxygen Level, and Strain Rate on Combustion Characteristics of CH₄/H₂ in Staged MILD Combustion

Zhang,

Liu,

Huang

et al. 2023

Energy Tech

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In this article, the effects of hydrogenation amount (0–80%), oxygen content (14–18%), and strain rate (10–1000 s−1) on the emission characteristics of NO and CO in moderate or intense low‐oxygen dilution (MILD) fractional combustion are studied under the actual working conditions of gas turbine (T = 723 K, P = 16.5 atm). The pathway of NO and CO production and the reaction with the greatest influence on their emissions are analyzed. In the findings, it is indicated that NO emissions are suppressed at lower hydrogen levels, while the addition of hydrogen leads to a decrease in CO emissions. Specifically, the key reaction for NO formation is H + NO + M = HNO + M, whereas CO emissions are primarily controlled by the direct reaction OH + CO = H + CO2. Furthermore, the reduction of oxygen levels effectively suppresses NO and CO emissions during MILD combustion. The variation in oxygen level exerts the greatest influence on the reaction rate of the NNH pathway. High concentrations of O2 are identified as the primary cause of elevated CO levels in MILD combustion. Finally, elevating the strain rate in MILD combustion demonstrates a mitigating effect on NO and CO emissions.

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Ultra-lean combustion mode

Nevrlý

Dostál

Klečka

et al. 2022

Fundamentals of Low Emission Flameless Combustion and Its Applications

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Combustion and NOx emission characteristics of dual-stage lean premixed flame

Cited by 7 publications

References 33 publications

A Detailed Analysis of Mixture Stratification on Flame Displacement Speed for Syngas Combustion

A Detailed Analysis of Mixture Stratification on Flame Displacement Speed for Syngas Combustion

Effects of Hydrogen Addition, Oxygen Level, and Strain Rate on Combustion Characteristics of CH₄/H₂ in Staged MILD Combustion

Ultra-lean combustion mode

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Combustion and NOx emission characteristics of dual-stage lean premixed flame

Cited by 7 publications

References 33 publications

A Detailed Analysis of Mixture Stratification on Flame Displacement Speed for Syngas Combustion

A Detailed Analysis of Mixture Stratification on Flame Displacement Speed for Syngas Combustion

Effects of Hydrogen Addition, Oxygen Level, and Strain Rate on Combustion Characteristics of CH4/H2 in Staged MILD Combustion

Ultra-lean combustion mode

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Effects of Hydrogen Addition, Oxygen Level, and Strain Rate on Combustion Characteristics of CH₄/H₂ in Staged MILD Combustion