Effects of carbon dioxide on the combustion characteristics of the laminar premixed n-heptane/air flames at elevated pressures

Dong, Wei; Jin, Tao; Qiu, Bingbing; Chu, Huaqiang

doi:10.1016/j.joei.2021.08.011

Cited by 8 publications

(2 citation statements)

References 38 publications

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“…In order to further reveal the impact of blending CO 2 on intermediate radicals and NO x emissions, the maximum gradient point of temperature is chosen for sensitivity analysis of the effect of CO 2 addition on CH 4 combustion (Dong et al 2020(Dong et al , 2021. Armaco mech is used to analyze the effect of CO 2 addition on intermediate radicals and GRI 3.0 mech is used to analyze the effect of CO 2 addition on NO x .…”

Section: Sensitivity Analysismentioning

confidence: 99%

Effect of CO2 dilution on laminar burning velocities, combustion characteristics and NOx emissions of CH4/air mixtures

Dong,

Xiang,

Gao

et al. 2023

Int J Coal Sci Technol

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The laminar combustion characteristics of CH4/air premixed flames with CO2 addition are systemically studied. Experimental measurements and numerical simulations of the laminar burning velocity (LBV) are performed in CH4/CO2/Air flames with various CO2 doping ratio under equivalence ratios of 1.0–1.4. GRI 3.0 mech and Aramco mech are employed for predicting LBV, adiabatic flame temperature (AFT), important intermediate radicals (CH3, H, OH, O) and NOx emissions (NO, NO2, N2O), as well as the sensitivity analysis is also conducted. The detail analysis of experiment and simulation reveals that as the CO2 addition increases from 0% to 40%, the LBVs and AFTs decrease monotonously. Under the same CO2 doping ratio, the LBVs and AFTs increase first and then decrease with the increase of equivalence ratio, and the maximum of LBV is reached at equivalence ratio of 1.05. The mole fraction tendency of important intermediates and NOx with equivalence ratio and CO2 doping ratio are similar to the LBVs and AFTs. Reaction H + O2 ⇔ O + OH is found to be responsible for the promotion of the generation of important intermediates and NOx under the equivalence ratios and CO2 addition through sensitivity analysis. The sensitivity coefficients of elementary reactions that the increasing of CO2 doping ratio promotes or inhibits formation of intermediate radicals and NOx decreases. Graphical abstract

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Section: Sensitivity Analysismentioning

confidence: 99%

Effect of CO2 dilution on laminar burning velocities, combustion characteristics and NOx emissions of CH4/air mixtures

Dong,

Xiang,

Gao

et al. 2023

Int J Coal Sci Technol

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“…Wang et al studied the effect of sudden change of duct cross-sectional area on flame propagation of methane/air premixed gas. Compared to N 2 , CO 2 can participate in important chain reactions during combustion and compete with free radicals, leading to stronger inhibition of combustion. , Premixed combustion is unstable due to the influence of various flame instabilities. The presence of flame instability, equivalence ratio, oxygen concentration, and dilution have significant effects on flame structure and combustion characteristics.…”

Section: Introductionmentioning

confidence: 99%

Study of Methane Explosion Suppression Characteristics of N₂ and CO₂ in Variable Cross-Section Ducts

et al. 2022

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To investigate the effect of concentration of N 2 and CO 2 (0, 10, 20, 30, 40, and 50%) on the flame propagation characteristics of CH 4 /air premixed gases with stoichiometric ratios in variable cross-section ducts, experiments were conducted in four combinations of ducts at initial conditions of 298 K and 1 atm. The results show that the flame propagation velocity, propagation time, and overpressure are greater in the suddenly contracted duct than in the suddenly expanded duct if the dimensions of the ducts are kept constant. However, an increase in inert gas concentration leads to a decrease in flame propagation speed, an increase in flame propagation time, and changes in flame structure and pressure. "Tulip" flames appeared when a duct with a cross section of 100 mm × 100 mm was combined with a duct with a cross section of 70 mm × 70 mm, whether N 2 or CO 2 was added or what its concentration was. However, when a duct with a cross section of 140 mm × 140 mm was combined with a 70 mm × 70 mm duct, a "tulip" flame is formed only at a CO 2 concentration of 50%. As the concentration of inert gas increases, the explosion pressure first decreases and then stabilizes, while the rate of pressure increase showed a monotonically decreasing trend. The explosion pressure is minimized when the concentration of CO 2 and N 2 is 30 and 40%, respectively.

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Soot formation and laminar combustion characteristics of anisole: ReaxFF MD simulation and kinetic analysis

Dong,

Hong,

Yao

et al. 2024

Carb Neutrality

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The application of biomass energy is one of the important ways to achieve carbon neutrality and deal with global warming. The study on the combustion mechanism of anisole, an oxygen-containing fuel, is helpful for biofuel large-scale application. In this study, the soot formation and laminar combustion characteristics of anisole were analyzed by reactive force field molecular dynamics (ReaxFF MD) and kinetic simulation, respectively. ReaxFF MD simulation studies had shown that soot formation of anisole combustion occurred in three stages, stage 1 (0–1 ns), stage 2 (1–2.5 ns), stage 3 (2.5–6 ns). The three stages represented the pyrolysis of the fuel, the developmental stage of the soot, and the graphitization stage of the soot, respectively. During the combustion of anisole, primary mechanisms for the soot formation were as follows: H-abstraction-C2H2-addition, carbon-addition-hydrogen-addition, internal ring formation and long carbon chain link. The formation of soot graphitization exhibited different morphologically behaviors: from flakes to onions to spheres with fewer branched chains. From the study of the laminar combustion characteristics of anisole, it can be found that the laminar burning velocities increased along with the increase of temperature, while the opposite trend was shown along with the increase of pressure. The sensitivity coefficient of naphthalene, the main soot precursor, revealed that the main promotional reactions for soot formation were R5 (O2 + H < = > O + OH), R36 (CO + OH < = > CO2 + H).

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Effects of carbon dioxide on the combustion characteristics of the laminar premixed n-heptane/air flames at elevated pressures

Cited by 8 publications

References 38 publications

Effect of CO2 dilution on laminar burning velocities, combustion characteristics and NOx emissions of CH4/air mixtures

Effect of CO2 dilution on laminar burning velocities, combustion characteristics and NOx emissions of CH4/air mixtures

Study of Methane Explosion Suppression Characteristics of N₂ and CO₂ in Variable Cross-Section Ducts

Soot formation and laminar combustion characteristics of anisole: ReaxFF MD simulation and kinetic analysis

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Effects of carbon dioxide on the combustion characteristics of the laminar premixed n-heptane/air flames at elevated pressures

Cited by 8 publications

References 38 publications

Effect of CO2 dilution on laminar burning velocities, combustion characteristics and NOx emissions of CH4/air mixtures

Effect of CO2 dilution on laminar burning velocities, combustion characteristics and NOx emissions of CH4/air mixtures

Study of Methane Explosion Suppression Characteristics of N2 and CO2 in Variable Cross-Section Ducts

Soot formation and laminar combustion characteristics of anisole: ReaxFF MD simulation and kinetic analysis

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Product

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Study of Methane Explosion Suppression Characteristics of N₂ and CO₂ in Variable Cross-Section Ducts