A numerical study on heat-recirculation assisted combustion for small scale jet diffusion flames at near-extinction condition

Gao, Jian; Hossain, Akter; Matsuoka, Tsuneyoshi; Nakamura, Yuji

doi:10.1016/j.combustflame.2016.12.028

Cited by 32 publications

(18 citation statements)

References 36 publications

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“…Gao et al continued their investigations by conducting a numerical study of micro-jet diffusion flames using different fuels for several operating conditions by varying the inlet jet velocities and burners proprieties. The objective of this study was to prove the importance of the heat-recirculation impact on the flame stabilization at near-extinction conditions [28]. They used different fuels such as hydrogen, methane and dimethyl ether (DME), and employed a chemical kinetics mechanism with 17 species and 58 reactions.…”

Section: Numerical Studies Of Micro-diffusion Flamesmentioning

confidence: 99%

“…Numerical study on heat-recirculation assisted combustion for small scale jet diffusion flames at near-extinction condition by Gao et al[28].Left: Effective excess-enthalpies (a) and flame temperatures (b) over fuel jet velocities range from the extinction limits to 3.2 m/s for different burners: Burner-A with c b = 0.2 mm and k b = 1 W/(m-K), Burner-B with c b = 0.2 mm and k b = 6 W/(m-K) and Burner-C with c b = 0.8 mm and k b = 6 W/(m-K); Right: Effective excess-enthalpies (a) and flame temperatures (b) as a function of Re number for H 2 , CH 4 , and DME flames. The burner wall thickness is and the thermal conductivity is c b = 0.2 mm and k b = 6 W/(m-K).…”

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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%

“…Gao et al [25] conducted a numerical study on methane/air jet diffusion flames over a wide range of fuel jet velocities by varying the burner wall material and thickness to understand the physical mechanism in flame stabilization. The effect of heat recirculation on the stabilization of micro-jet diffusion flames was analyzed by performing detailed heat flux calculations.…”

Section: Introductionmentioning

confidence: 99%

“…Based on the existing literature, it can be inferred that most of the studies were conducted to explore the effect of fuel jet velocity and burner tube diameter on micro diffusion flame characteristics. Even though Cheng et al [17] and Gao et al [25] investigated the effect of burner tube material on micro flame behavior, the chemical structure and the rate of reactions in the flame standoff region remain to be analyzed. Additionally, the flame stability and structure of micro diffusion hydrogen flame were not studied close to the extinction limit.…”

Section: Introductionmentioning

confidence: 99%

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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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Partially-Premixed Combustion Characteristics and Thermal Performance of Micro Jet Array Burners with Different Nozzle Spacings

Yang

Zeng

et al. 2021

J. Therm. Sci.

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A numerical study on heat-recirculation assisted combustion for small scale jet diffusion flames at near-extinction condition

Cited by 32 publications

References 36 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

Partially-Premixed Combustion Characteristics and Thermal Performance of Micro Jet Array Burners with Different Nozzle Spacings

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