Numerical investigation on mixing performance and diffusion combustion characteristics of H2 and air in planar micro-combustor

Li, Linhong; Yuan, Zili; Xiang, Ying; Fan, Aiwu

doi:10.1016/j.ijhydene.2018.04.194

Cited by 46 publications

(12 citation statements)

References 26 publications

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“…Such behavior was the opposite for fuels with Sc < 1.0, such as methane (Sc = 0.7) and hydrogen (Sc = 0.2), where the chemical kinetics is dominant in the flame base structure, and higher values of H are expected. Li et al investigated the mixing performance and the diffusion combustion characteristics in a 2D planar micro-combustor using hydrogen and air separated by a plate [7]. This study was conducted through numerical simulations and consisted of various boundary conditions and burner geometries.…”

Section: Numerical Studies Of Micro-diffusion Flamesmentioning

confidence: 99%

“…In premixed combustion, researchers have concluded that combustion characteristics and flame behavior are very sensitive to the dimensional and thermo-physical parameters [3][4][5][6]. Other than premixed combustion at micro scales, non-premixed or diffusion combustion at such scales has also been under great attention due to the fact that diffusion combustion is a more typical combustion regime to use in practical systems [7]. By comprehending the effects of the complex transport phenomena associated with the chemical kinetics of such flames, researchers can further investigate complex phenomena such as flame ignition and extinction and pollution formations and eventually improve the efficiency of combustion-oriented devices such as combustion engines [8].…”

Section: Introductionmentioning

confidence: 99%

“…Numerical investigation on mixing performance and diffusion combustion characteristics of H 2 and air in planar micro-combustor by Li et al[7]. (Left): Required mixing distance versus inlet air velocity for micro-combustors with different heights; (Right): Variations in combustion efficiency versus inlet air velocity in three micro-combustors with different heights.…”

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Numerical Investigations of Micro-Scale Diffusion Combustion: A Brief Review

2019

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With the increasing global concerns about the impacts of byproducts from the combustion of fossil fuels, researchers have made significant progress in seeking alternative fuels that have cleaner combustion characteristics. Such fuels are most suitable for addressing the increasing demands on combustion-based micro power generation systems due to their prominently higher energy density as compared to other energy resources such as batteries. This cultivates a great opportunity to develop portable power devices, which can be utilized in unmanned aerial vehicles (UAVs), micro satellite thrusters or micro chemical reactors and sensors. However, combustion at small scales—whether premixed or non-premixed (diffusion)—has its own challenges as the interplay of various physical phenomena needs to be understood comprehensively. This paper reviews the scientific progress that researchers have made over the past couple of decades for the numerical investigations of diffusion flames at micro scales. Specifically, the objective of this review is to provide insights on different numerical approaches in analyzing diffusion combustion at micro scales, where the importance of operating conditions, critical parameters and the conjugate heat transfer/heat re-circulation have been extensively analyzed. Comparing simulation results with experimental data, numerical approaches have been shown to perform differently in different conditions and careful consideration should be given to the selection of the numerical models depending on the specifics of the cases that are being modeled. Varying different parameters such as fuel type and mixture, inlet velocity, wall conductivity, and so forth, researchers have shown that at micro scales, diffusion combustion characteristics and flame dynamics are critically sensitive to the operating conditions, that is, it is possible to alter the flammability limits, control the flame stability/instability or change other flame characteristics such as flame shape and height, flame temperature, and so forth.

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Section: Numerical Studies Of Micro-diffusion Flamesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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Numerical Investigations of Micro-Scale Diffusion Combustion: A Brief Review

2019

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“…Ansari and Amani [26] numerically examined a novel planar microcombustion chamber with a combined bluff and baffle structure for micro-TPV systems and found that this new combustor outperforms a combustor with only one baffle or cylinder in terms of flame stability and combustion efficiency. Li et al [27] numerically studied the effects of channel height and inlet velocity on combustion characteristics in a 2D planar microcombustion chamber with a separating plate and found that the mixing effect can be improved by reducing the inlet velocity and channel height. Tang et al [28] numerically and experimentally studied the propane/air premixed combustion performance of a new cross-plate microplanar combustor and found that the crossplate enhances the heat transfer and increases the average wall temperature by more than 90 K. e new structure also extended the blowout limit of the cross-plate combustor.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of the Combustion in an Improved Microcombustion Chamber with Rib

Chen

Liu

2019

Journal of Chemistry

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This study proposes an improved microcombustor with a rectangular rib to improve the temperature level of the combustor wall. Moreover, the OH mass fraction, temperature distribution, and outer wall temperature of the original and improved combustors of premixed hydrogen/air flames are numerically investigated under various inlet velocities and equivalence ratios. Results show that the improved microcombustor enhances heat transfer between the mixture and wall because its recirculation zone is larger than that of the original, thereby resulting in high wall temperature. Conversely, thermal resistance in the horizontal direction increases with upstream and downstream step lengths. Consequently, the outer wall temperature decreases with step length in the improved combustor. A high equivalence ratio (e.g., 0.6) may result in the destruction of the combustor because the wall temperature has exceeded the acceptable temperature of wall material quartz. Therefore, the improved microcombustor is recommended for micro-thermo-photovoltaic systems.

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“…Due to high energy density, long life, and instantly rechargeable power supplies, the micro power systems based on hydrocarbon fuels combustion have attracted the extensive attention [1][2][3][4][5][6][7][8] in recent two decades. Consequently, the micro power systems possess a great application potential in energy supplies of military and civilian portable devices.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation on ignition intensification of n‐butane with tert‐butyl hydroperoxide (TBHP) addition

et al. 2019

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Summary Aimed to intensify the ignition and combustion process of n‐butane fuel in micro internal combustion (IC) engines, ignition delay characteristics of n‐butane/air mixtures with tert‐butyl hydroperoxide (TBHP) addition ratios below 10% were investigated numerically by CHEMKIN‐PRO software. Results show that ignition delay times of n‐butane can be shortened nonlinearly with TBHP addition at initial temperatures of 650 K to 1000 K, namely, the reduction rate of ignition delay times rises slowly as the TBHP addition ratio increases. In addition, the negative temperature coefficient (NTC) behavior can be weakened significantly with TBHP addition at 650 K to 1000 K. Especially, the ignition delay time of n‐butane can be reduced about 32 times with 10% TBHP addition at 750 K. However, the ignition intensification effect of TBHP addition is slight when the initial temperature is above 1000 K. The acting mechanism of TBHP addition was investigated in detail by the rate of production and consumption (ROP), sensitivity, and reaction pathway analysis. The ROP analysis shows that the released and quickly consumed OH radicals with TBHP addition play an important role in promoting n‐butane ignition at the lower initial temperature. However, the relatively slow consumption rate of OH radicals at higher temperature weakens the intensification effect. Furthermore, the sensitivity analysis and reaction pathway analysis indicate that the dominated elemental reactions and reaction pathway vary significantly with TBHP addition at lower initial temperature.

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Numerical investigation on mixing performance and diffusion combustion characteristics of H2 and air in planar micro-combustor

Cited by 46 publications

References 26 publications

Numerical Investigations of Micro-Scale Diffusion Combustion: A Brief Review

Numerical Investigations of Micro-Scale Diffusion Combustion: A Brief Review

Numerical Investigation of the Combustion in an Improved Microcombustion Chamber with Rib

Numerical investigation on ignition intensification of n‐butane with tert‐butyl hydroperoxide (TBHP) addition

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