Ultra-lean combustion characteristics of premixed methane flames in a micro flow reactor with a controlled temperature profile

Okuno, Tomoya; Nakamura, Hisashi; Tezuka, T.; Hasegawa, Susumu; Maruta, Kaoru

doi:10.1016/j.proci.2016.06.137

Cited by 21 publications

(2 citation statements)

References 25 publications

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“…The ability of the system to operate under fuel-lean conditions can expected to be beneficial, since it could reduce unwanted combustion products such as coke, nitric oxide, and carbon monoxide (Hernández-Pérez et al, 2015). It could also reduce the operating temperature, which in turn could increase the lifetime of the system (Okuno et al, 2017). There are two regimes of low and high Reynolds number.…”

Section: Temperature Profilesmentioning

confidence: 99%

CFD Modeling of the Combustion Characteristics and Stability in Catalytic Micro-Channels

Junjie¹,

Xu²

2017

AJHMT

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Combustion characteristics and stability of premixed methane-air mixtures in catalytic micro-channels is studied numerically, using CFD (computational fluid dynamics). The characteristics of the fluid mechanics are also analyzed. A two-dimensional CFD model with detailed reaction mechanisms and multicomponent transport is developed to evaluate the effect of operating conditions on the combustion stability. The laminar flow is assumed, and steady-steady simulations are performed. The fuel-lean equivalence ratio operation limit for the system is determined by the analysis of Reynolds number. The primary focus is on CFD as a means of understanding thermal management at small scales. It is shown that an appropriate choice of the flow velocity is crucial in achieving the self-sustained operation. Large gradients in temperature and species concentration are observed, despite the small scales of the system under certain conditions. The flow velocity is very important as it determines the flame location. Furthermore, the flow velocity plays a dual, competing role in the stability of the system. Low flow velocities reduce the heat generation, whereas high flow velocities reduce the convective time-scale. There is a narrow regime of flow velocities that allows self-sustained operation. When a low-power system is desired, highly insulating materials should be preferred, whereas a high-power system would favor highly conductive materials. Engineering maps that delineate combustion stability are constructed. In order to gain further insight into the combustion characteristics of the system, the optimum Reynolds number is determined. Finally, design recommendations are made.

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Section: Temperature Profilesmentioning

confidence: 99%

CFD Modeling of the Combustion Characteristics and Stability in Catalytic Micro-Channels

Junjie¹,

Xu²

2017

AJHMT

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“…A large number of intermediate components are produced during the combustion process, and some components are of great significance for the study of the flame formation and development process [33][34][35]. It is generally believed that the distribution of OH radicals and CH radicals can show flame-peak surfaces [36][37][38]. Therefore, the free radicals generated during the combustion process and their concentration distribution can reflect information such as the fine structure of the combustion flame, partial combustion-reaction mechanism, and combustion speed [39,40].…”

Section: Introductionmentioning

confidence: 99%

Effect of Surface Reaction on the Distribution Characteristics of Temperature and OH Radicals in Microchannel Combustion

Li,

Kang,

Zhang

et al. 2024

Fire

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Microchannel burners suffer from low combustion efficiency and poor stability in applications. In order to explore the effect of wall reaction on methane/air premixed combustion performances in the microchannel, the effects of wall activity, inlet velocity, pressure, and equivalence ratio on the temperature and radical distribution characteristics were studied by CFD computational simulations. It is found that as the reaction pressure increases, there are more free-radical collisions, causing the reaction temperature to rise. The OH radicals participate in the reaction at the active near wall so that the mass fraction of the OH radical on the active wall is lower than that on the inert wall. As the equivalence ratio increases from 0.6 to 1.2, the high-temperature regions increase but the maximum temperature decreases. The mass fraction of OH radical increases with the increase of the equivalence ratio, and the increase of OH radical near the inert wall is larger than that of the active wall. As the flow rate increases, the disturbance increases, and the combustion reaction becomes more intense, resulting in an increase in the temperature and the mass fraction of OH radicals. The mass fraction of H, O, OH, and CH3 radicals in the inert wall was slightly higher than that in the active wall, in which the peak mass fraction of CH3 radical appeared at the axial position closest to the entrance, while the other three radicals reached the peak at about the same axial position. This study provides a reference for combustion stability in microcombustors.

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Enhancement of flame stability by a short Pt segment for CH4/H2 blended fuels in a micro-flow reactor

Wang,

Du,

Fan

2024

Chemical Engineering and Processing - Process Intensification

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Ultra-lean combustion characteristics of premixed methane flames in a micro flow reactor with a controlled temperature profile

Cited by 21 publications

References 25 publications

CFD Modeling of the Combustion Characteristics and Stability in Catalytic Micro-Channels

CFD Modeling of the Combustion Characteristics and Stability in Catalytic Micro-Channels

Effect of Surface Reaction on the Distribution Characteristics of Temperature and OH Radicals in Microchannel Combustion

Enhancement of flame stability by a short Pt segment for CH4/H2 blended fuels in a micro-flow reactor

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