Flame base structures of micro-jet hydrogen/methane diffusion flames

Gao, Jian; Hossain, Akter; Nakamura, Yuji

doi:10.1016/j.proci.2016.08.034

Cited by 37 publications

(17 citation statements)

References 22 publications

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“…However, further investigations will be necessary to increase the precision of the numerical results involving diffusion flames, especially at micro scales. [27]. They reported that flames with hydrogen as the base fuel would always attach to the burner, as opposed to flames with methane as the base fuel.…”

Section: Numerical Studies Of Micro-diffusion Flamesmentioning

confidence: 99%

“…Numerical study of micro-jet hydrogen/methane diffusion flames by Gao et al[27]. Top: Computed temperature contours and heat release rate (HRR) isopleths for CH4 flames at fuel jet velocity of 0.4 m/s for (a) T b = 1800 K (b) T b = 300 K, and for H 2 flames at 1.0 m/s for (c) Tb = 1800 K (d) T b = 300 K; Bottom: Computed temperature contours and HRR isopleths at the thermal conductive burner condition (the thermal conductivity of burner wall is 16 W/m-K) for (a) H 2 flame at 2.0 m/s, (b) H 2 /CH 4 80%/20% flame at 1.2 m/s, (c) H 2 /CH 4 20%/80% flame at 0.6 m/s, (d) CH 4 flame at 0.5 m/s.…”

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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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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%

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confidence: 99%

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

2019

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“…Hence, flame quenches at the tube wall for lower fuel flow velocities. Many studies [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] were conducted to analyze the flame structure and characteristics of micro diffusion flames, which were recently reviewed by Maruta [26] and Nakamura et al [27].…”

Section: Introductionmentioning

confidence: 99%

Effect of Burner Wall Material on Microjet Hydrogen Diffusion Flames near Extinction: A Numerical Study

et al. 2021

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Characteristics of microjet hydrogen diffusion flames stabilized near extinction are investigated numerically. Two-dimensional simulations are carried out using a detailed reaction mechanism. The effect of burner wall material, thickness, and thermal radiation on flame characteristics such as flame height and maximum flame temperature are studied. Results show that the flame stabilizes at lower fuel jet velocities for quartz burner than steel or aluminum. Higher flame temperatures are observed for low conductive burners, whereas the flame length increases with an increase in thermal conductivity of the burner. Even though thermal radiation has a minor effect on flame characteristics like flame temperature and flame height, it significantly influences the flame structure for low conductive burner materials. The burner tip and its vicinity are substantially heated for low conductive burners. The effect of burner wall thickness on flame height is significant, whereas it has a more negligible effect on maximum flame temperature. Variation in wall thickness also affects the distribution of H and HO2 radicals in the flame region. Although the variation in wall thickness has the least effect on the overall flame shape and temperature distribution, the structure near the burner port differs.

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“…With the rapid development of portable devices and micro-sized sensors, there is an increasing demand for small-scale power supplies and high-energy-density energy supply systems. Comparing with the current popular lithium battery products on the market, micro-scale burners based on hydrocarbon fuels have characteristics of high power density and high energy density [1][2][3][4][5][6]. With the advancement of science and technology, the micromotor system has the advantages of a high power density and a long energy supply time, providing sufficient power for micro-equipment.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study on the Characteristics of Methane Hedging Combustion in a Heat Cycle Porous Media Burner

Wang

Feng

et al. 2021

Processes

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With the rapid development of portable devices and micro-small sensors, the demand for small-scale power supplies and high-energy-density energy supply systems is increasing. Comparing with the current popular lithium batteries, micro-scale burners based on micro-thermal photoelectric systems have features of high power density and high energy density, the micro-scale burner is the most critical part of the micro-thermal photovoltaic system. In this paper, the combustor was designed as a heat cycle structure and filled with porous media to improve the combustion characteristics of the micro combustor. In addition, the influence of the porous media distribution on the burner center temperature and wall temperature distribution were studied through numerical simulation. Furthermore, the temperature distribution of the combustor was studied by changing the porous media parameters and the wall parameters. The research results show that the heat cycle structure can reduce heat loss and improve combustion efficiency. When the combustion chamber is filled with porous media, it makes the radial center temperature rise by about 50 K and the temperature distribution more uniform. When filling the heat cycle channel with porous media the wall temperature can be increased. Finally, the study also found that as methane is combusted in the combustor, the temperature of the outer wall gradually increases as the intake air velocity increases. The results of this study provide a theoretical and practical basis for the further design of high-efficiency combustion micro-scale burners in the future.

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Flame base structures of micro-jet hydrogen/methane diffusion flames

Cited by 37 publications

References 22 publications

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

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

Effect of Burner Wall Material on Microjet Hydrogen Diffusion Flames near Extinction: A Numerical Study

Numerical Study on the Characteristics of Methane Hedging Combustion in a Heat Cycle Porous Media Burner

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