Effects of N2 dilution on laminar burning velocity, combustion characteristics and NOx emissions of rich CH4–air premixed flames

Chu, Huaqiang; Xiang, Longkai; Meng, Shun; Dong, Wei; Gu, Mingyan; Zhi-hu, LI

doi:10.1016/j.fuel.2020.119017

Cited by 46 publications

(16 citation statements)

References 53 publications

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“…Therefore, biomass gasification is considered as a more effective, promising and valuable application mode for biomass utilization (Cao et al, 2019). However, the composition of biogas is complex, especially the existence of inert gases such as CO 2 and N 2 will have a great impact on the combustion characteristics of flame and the formation of NO X (Chu et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

“…A small number of people have studied the effects of inert gas on combustion characteristics and NO X emission: The effects of N 2 dilution on laminar burning speed, adiabatic flame temperature, intermediate radicals and NO X emissions of methane were investigated under different equivalence ratio conditions. Results showed that under the same equivalence ratio, the mole fraction of NO X decreased as the N 2 doping ratio increased (Resende et al, 2019;Chu et al, 2021). The effect of CO 2 and N 2 dilution on CH 4 /air flame by flame temperature distribution measurement and flame calculation was analyzed.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Simulation of the Influence of CO2 on the Combustion Characteristics and NOX of Biogas

Luo

et al. 2022

Front. Energy Res.

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The existence of inert gases such as N2 and CO2 in biogas will reduce the proportion of combustible components in syngas and affect the combustion and NOX formation characteristics. In this study, ANSYS CHEMKIN-PRO software combined with GRI-MECH 3.0 mechanism was used to numerically simulate the effects of different CO2 concentrations (CO2 volume ratio in biogas is 0–41.6%) on flame combustion temperature, flame propagation speed and nitrogen oxide formation of complex biogas with low calorific value. The results showed that when the combustion reaches the chemical equilibrium, the flame combustion temperature and flame propagation speed decrease with the increase of CO2 concentration, and the flame propagation speed decreases even more slowly. Meanwhile, the molar fraction of NO at chemical equilibrium decreases with the increase of CO2 concentration and the decrease is decreasing, which indicates that the effect of CO2 concentration in biogas on NO is simpler. While the molar fraction of NO2 does not change regularly with the change of CO2 concentration, the effect of CO2 concentration in biogas on NO2 is complicated. The highest molar fraction of NO2 was found at chemical equilibrium when the CO2 concentration was 33.6%, when the target was a typical low calorific value biogas.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of the Influence of CO2 on the Combustion Characteristics and NOX of Biogas

Luo

et al. 2022

Front. Energy Res.

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“…The results showed that the spray flame's shape, temperature, and species distributions strongly depended on oxygen concentration. Chu et al 35 investigated the effects of N 2 dilution on laminar burning velocity (LBV), adiabatic flame temperature (AFT), intermediate radicals, and NOx emissions of rich methane/air premixed flames. Their results indicated the LBV, intermediate radicals, and NOx emissions first increased and then decreased as the equivalence ratio increased.…”

Section: Introductionmentioning

confidence: 99%

Suppression of thermoacoustic instability and NOx emissions of unsteady swirl premixed flame with upstream microjets

Zhou

2022

Asia-Pacific J Chem Eng

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Passive control methods are widely used in unsteady combustion systems due to their robustness and convenience. This paper used the upstream microjets method for the first time to control thermoacoustic instability and pollutant NOx emissions in unsteady swirl premixed flame. Three variables of CO 2 microjets flow rate, upstream microjets distance, and microjets number are investigated. Results demonstrate the upstream microjets distance plays a significant role in restraining the thermoacoustic instability and NOx emissions. The smaller the upstream microjets distance, the more completely the thermoacoustic instability is suppressed while the NOx emissions are the opposite, which means a compromise choice needs to be made between them. The damping ratio of pressure amplitude in the chamber can reach the maximum of 81.3%, and the damping ratio of CH* intensity can reach the maximum of 80.2%. Besides, the frequency of pressure and CH* will transit to a lower mode. NOx emissions can realize a maximum reduction of 12.2 ppm. Meanwhile, the flame mode switches from an enlarged Mode-A flame to a shrunk Mode-B flame, and the flame length shows a maximum reduction of 14 mm at the largest upstream distance. However, the specific control mechanism under upstream microjets still needs further study to clarify. This research proved the feasibility of suppressing combustion instability and NOx emissions with upstream microjets in unsteady swirl premixed flame, promoting its practical application in gas turbine systems.flame mode, NO x emissions, thermoacoustic instability, unsteady swirl premixed flame, upstream microjets | INTRODUCTIONAs a complex multidisciplinary problem, combustion instability was first proposed by scholar Rayleigh. 1 When combustion instability occurs, it is often accompanied by periodic large pressure oscillations. 2,3 The power engines in gas turbines, industrial furnaces, and rockets will face the threat of damage or even failure.To prevent the occurrence of combustion instability, researchers often implement control strategies from the two necessary factors of combustion instability, namely, acoustic oscillations and heat release oscillations. For

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“…10,11 As one of the most common gaseous fuels, the research of laminar burning velocity of CH 4 is of great interest in the community. Chu et al 12 measured the laminar burning velocity of methane, and the effects of equivalence ratio and N 2 doping on it were numerically analyzed. The laminar flame speeds of NH 3 −air premixed flames have been investigated by Han et al, 13 Li et al, 14 and Hayakawa et al 15 According to their results, the laminar flame speed of NH 3 −air premixed flames is lower than that of hydrocarbon flames, such as CH 4 −air flames and H 2 −air flames, and decreases with an increase in the initial pressure.…”

Section: ■ Introductionmentioning

confidence: 99%

Effect of CH₄, Pressure, and Initial Temperature on the Laminar Flame Speed of an NH₃–Air Mixture

et al. 2021

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Ammonia (NH 3 ) is not only expected to be used as a hydrogen energy carrier but also expected to become a carbon-free fuel. Methane (CH 4 ) can be used as a combustion enhancer for improving the combustion intensity of NH 3 . In addition, it is important to understand the flame characteristics of NH 3 –air at elevated pressures and temperatures. The laminar flame speed of NH 3 –CH 4 –air is numerically investigated, where the mole fraction of CH 4 ranges from 0 to 50% in binary fuels and the pressure and initial temperature are up to 10 atm and 1000 K, respectively. The calculated value from the Okafor mechanism is in excellent agreement with experimental data. The CH 4 in the fuel affects the flame speed by changing the main species of free radicals in the flame; the high pressure not only increases the rate-limiting reaction rate in the flame but also reduces the amount of H, O, and OH radicals in the flame, so as to restrain the propagation of the flame. At a higher initial temperature, the faster flame speed is mainly due to the higher adiabatic flame temperature. The laminar flame speed correlation equation has a consistent trend with the simulation results, though with a slight underestimation at higher pressures and temperatures. It is a more effective way to calculate the laminar flame speeds of NH 3 –air for a given pressure and temperature.

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Effects of N2 dilution on laminar burning velocity, combustion characteristics and NOx emissions of rich CH4–air premixed flames

Cited by 46 publications

References 53 publications

Numerical Simulation of the Influence of CO2 on the Combustion Characteristics and NOX of Biogas

Numerical Simulation of the Influence of CO2 on the Combustion Characteristics and NOX of Biogas

Suppression of thermoacoustic instability and NOx emissions of unsteady swirl premixed flame with upstream microjets

Effect of CH₄, Pressure, and Initial Temperature on the Laminar Flame Speed of an NH₃–Air Mixture

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Effects of N2 dilution on laminar burning velocity, combustion characteristics and NOx emissions of rich CH4–air premixed flames

Cited by 46 publications

References 53 publications

Numerical Simulation of the Influence of CO2 on the Combustion Characteristics and NOX of Biogas

Numerical Simulation of the Influence of CO2 on the Combustion Characteristics and NOX of Biogas

Suppression of thermoacoustic instability and NOx emissions of unsteady swirl premixed flame with upstream microjets

Effect of CH4, Pressure, and Initial Temperature on the Laminar Flame Speed of an NH3–Air Mixture

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Effect of CH₄, Pressure, and Initial Temperature on the Laminar Flame Speed of an NH₃–Air Mixture