Numerical study of methane combustion under moderate or intense low-oxygen dilution regime at elevated pressure conditions up to 8 atm

Tu, Yaojie; Xu, Shunta; Xu, Minyi; Líu, Hao; Yang, Wenming

doi:10.1016/j.energy.2020.117158

Cited by 20 publications

(17 citation statements)

References 41 publications

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“…It should be mentioned that the reaction zone thickness for all test conditions thins linearly. Tu et al 63 reported that high operating pressure caused the reaction zone to move from the oxidant side to the fuel side. The chemical acceleration behavior of HCO + O 2 → HO 2 + CO, CH 2 + O 2 → 2H + CO 2 , and CH 2 + O 2 → OH + H + CO under high-pressure conditions enhanced the overall rate of O 2 consumption.…”

Section: Resultsmentioning

confidence: 99%

Numerical Simulation of Turbulent Non-premixed Combustion Processes for Methane and Dimethyl Ether Binary Fuels

Yuan

et al. 2021

ACS Omega

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The C 1ε = 1.6 standard k – ε equation combined with the steady flamelet model was applied to a methane/dimethyl ether swirl combustion field, and the effects of the dimethyl ether (DME) blending ratio and operating pressure on the flame behavior, including species variation, reaction zone behavior, and flame entrainment, were investigated. The results demonstrated that selected models could better reproduce the trends of the experimental measurements. The downstream reaction zone achieved better calculation accuracy than the outer shear layer of the first recirculation zone. The addition of DME accelerated the accumulation process of H 2 , O, H, and OH radicals. The intermediate radical CH 2 O was rapidly developed by the influence of the H extraction rate under a constant fuel volume flow rate. The reaction zone dimensions were approximately linearly and positively correlated with the DME blending ratio, whereas flame entrainment expressed a lower DME concentration dependence in the high-DME mass-dominated system. The operating pressure significantly impacted the distribution of reactive radicals in the turbulent flame; meanwhile, the flame and reaction zone length showed nonlinear inverse behavior with pressure variation, while the thickness of the reaction zone was always linearly and negatively correlated with pressure. Moreover, the peak flame entrainment rate also experienced a nonlinear decline with pressure elevation; however, the peak positions were not sensitive to pressure fluctuation. Concurrently, the response surface functions for the reaction zone dimensions were established covering the range of 0–1 for the DME blending ratio and 1–5 atm operating pressure, which could provide assistance for combustion condition optimization and combustion chamber design.

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Section: Resultsmentioning

confidence: 99%

Numerical Simulation of Turbulent Non-premixed Combustion Processes for Methane and Dimethyl Ether Binary Fuels

Yuan

et al. 2021

ACS Omega

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“…The related knowledge is critical for the MILD burner design. Since the early 1990s, there have been numerous experimental studies ,,,,− ,,,,,,,,,,− and numerical simulations ,− ,,,− that examined and tested various burner configurations of different types for both premixed and non-premixed combustion modes. Important to note, nearly all industrial applications use non-premixed burners typically of three patterns or arrangements of fuel and oxidant nozzles: i.e., a central fuel nozzle with annular oxidant nozzle or two or more oxidant nozzles aside; a central oxidant nozzle and two or more fuel nozzles aside; two or more pairs of fuel and oxidant nozzles distributed as a circle. …”

Section: Enclosed Furnace Mild Combustion and Its Nox Emissionsmentioning

confidence: 99%

“…The CFD modeling of MILD combustion in furnace has attracted much attention and produced a great number of publications, e.g., refs , − , and − . There are, at least, two reasons for this.…”

Section: Enclosed Furnace Mild Combustion and Its Nox Emissionsmentioning

confidence: 99%

Review on MILD Combustion of Gaseous Fuel: Its Definition, Ignition, Evolution, and Emissions

Wang

et al. 2021

Energy Fuels

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Combustion of fossil fuels has been continuously generating over 70% of the total energy for our human society, concurrently emitting vastly greenhouse gases and ecologically harmful pollutants. To mitigate the adverse issue, combustion technologies of a new type were successfully developed and debuted around 1990, associated with various terms of "flameless oxidation (FLOX)", "flameless combustion (FLC)", "high-temperature air combustion (HiTAC)", and "moderate and intense low-oxygen dilution (MILD) combustion". These combustion processes may be regarded as similar or the same class of combustion, because they all involve high preheat and deep dilution of individual reactants (nonpremixed) or the reactant mixture (premixed), prior to main combustion reactions, with high-temperature flue gases (burnt products) internally and/or externally. Very significantly, all of these combustion technologies can simultaneously achieve high efficiency and ultralow emissions of nitric oxides (NOx), light, and noise. This class of combustion has been frequently unified as "MILD combustion". Highly worthy to note, as a particular type of combustion, the MILD combustion has thus far been most extensively explored, resulting in many hundreds to 1000 academic articles published by various energy-related journals and conferences. The present review summarizes the research progress in the gaseous-fuel MILD combustion on its definition, ignition, evolution, and NOx emissions, specifically, through its aspects associated with open jet flames in hot coflow and industrial flames in combustion chamber or furnace. Also, discussions are provided on the relevant terminologies, existing problems, and further fundamental issues.

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“…It provided satisfactory results for computational fluid dynamics (CFD) of flameless combustion through previous studies. 3,11,[26][27][28] Therefore, it was chosen in present study for CH 4 combustion chemistry including CO and H 2 oxidation. The detailed mechanism was used to predict the major species and NO x emissions.…”

Section: Numerical Approachmentioning

confidence: 99%

Oxygen‐enriched flameless combustion of CH ₄ / H ₂ / CO mixtures

Kim

Park

Huh

et al. 2021

Intl J of Energy Research

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In the field of thermal energy, interest in carbon-free fuels, such as H 2 , is increasing to reduce greenhouse gas emissions; simultaneously, efforts are being made to reduce NO x emissions. In this study, experimental and numerical methodologies were applied to analyze the characteristics of flameless combustion under oxygen enrichment conditions for the simultaneous reduction of greenhouse gases and fine dust precursors. Flameless combustion was achieved under all conditions, and numerical simulations using GRI-mech 3.0

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Numerical study of methane combustion under moderate or intense low-oxygen dilution regime at elevated pressure conditions up to 8 atm

Cited by 20 publications

References 41 publications

Numerical Simulation of Turbulent Non-premixed Combustion Processes for Methane and Dimethyl Ether Binary Fuels

Numerical Simulation of Turbulent Non-premixed Combustion Processes for Methane and Dimethyl Ether Binary Fuels

Review on MILD Combustion of Gaseous Fuel: Its Definition, Ignition, Evolution, and Emissions

Oxygen‐enriched flameless combustion of CH ₄ / H ₂ / CO mixtures

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Numerical study of methane combustion under moderate or intense low-oxygen dilution regime at elevated pressure conditions up to 8 atm

Cited by 20 publications

References 41 publications

Numerical Simulation of Turbulent Non-premixed Combustion Processes for Methane and Dimethyl Ether Binary Fuels

Numerical Simulation of Turbulent Non-premixed Combustion Processes for Methane and Dimethyl Ether Binary Fuels

Review on MILD Combustion of Gaseous Fuel: Its Definition, Ignition, Evolution, and Emissions

Oxygen‐enriched flameless combustion of CH 4 / H 2 / CO mixtures

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Oxygen‐enriched flameless combustion of CH ₄ / H ₂ / CO mixtures