Effects of CO2 addition on soot formation of ethylene non-premixed flames under oxygen enriched atmospheres

Hoerlle, Cristian Alex; Pereira, Fernando M.

doi:10.1016/j.combustflame.2019.02.016

Cited by 41 publications

(8 citation statements)

References 69 publications

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“…Therefore, for a quantitative prediction of soot formation, many existing soot inception models are typically developed based on the dimerization of different-sized PAHs [72][73][74][75]. In particular, the present work utilized the wellestablished models based on dimerization of large PAHs (4 rings and larger), which has been used widely by various research groups [34,76,77] and successful in explaining many experimental observations. We nevertheless note more work needs to be done to improve the model to account for most recent fundamental development in soot inception mechanisms.…”

Section: Numerical Modelingmentioning

confidence: 99%

“…Note, although several studies have attempted to introduced the reversibility in modeling the PAH addition processes [66,79,80], however, rate parameters were still not fully established for many PAHs involved in the present model. Therefore, the addition of PAH was modelled as an irreversible process for simplicity, an assumption that has also been adopted by other researchers [15,77] to explain, for examples, the effects of CO2 addition on soot formation. Particle coagulation was assumed to occur in the free-molecular regime with a collision efficiency of 2.2 (after multiplying the van der Waals enhancement factor) [81].…”

Section: Numerical Modelingmentioning

confidence: 99%

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Chemical effects of hydrogen addition on soot formation in counterflow diffusion flames: Dependence on fuel type and oxidizer composition

Yan

Wang

et al. 2020

Combustion and Flame

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We experimentally studied and kinetically modeled the effects of hydrogen addition on soot formation in methane and ethylene counterflow diffusion flames (CDFs). To isolate the chemical effects of hydrogen in such flames, we also ran a set of experiments on flames of the same base fuels but with the addition of helium. Specifically, we measured the soot volume fractions of the flames using the planar laser-induced incandescence technique. We simulated detailed sooting structures by coupling the gas-phase chemistry with the polycyclic aromatic hydrocarbon (PAH)-based soot model, using a sectional method to resolve the soot particle dynamics. Our experimental and numerical results show that hydrogen chemically inhibits soot formation in ethylene CDFs. While in methane flames, it is interesting to observe that the difference in soot production between the hydrogen-and helium-doped cases became much smaller when the oxygen concentration in the oxidizer stream (XO) was reduced.This suggests that for methane CDFs the chemical soot-inhibiting effects of hydrogen was highly dependent on oxidizer composition (i.e., XO). Explanations are provided through detailed kinetic analysis concerning the effects of hydrogen addition on the growth of PAH, soot inception, and soot surface growth processes. Our results suggest that hydrogen's chemical role in soot formation not only depends on fuel type (ethylene or methane), it also may be sensitive to oxidizer composition.

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Section: Numerical Modelingmentioning

confidence: 99%

Section: Numerical Modelingmentioning

confidence: 99%

Chemical effects of hydrogen addition on soot formation in counterflow diffusion flames: Dependence on fuel type and oxidizer composition

Yan

Wang

et al. 2020

Combustion and Flame

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“…The soot mass is reduced by 50% with the presence of 6.22% CO 2 and 3.63% H 2 O in the ambient gases. Figure 6b presents the comparison between the total soot mass for both conditions with the results obtained in [7], named "SNL CVP vessel". The soot mass fraction for the ECN condition with pre-burn constituents in the ambient gases is around half of 51 lg, obtained in reference conditions.…”

Section: Effect Of Pre-burn Productsmentioning

confidence: 99%

“…As, in modern internal combustion engines, one way to strongly reduce NO X is the recirculation of exhaust gas, the presence of CO 2 or H 2 O in the combustion chamber is now usual and can impact soot formation. Several numerical and experimental studies about their effects on ethylene (both premixed and diffusion flames) [5][6][7][8] concluded that they have an effect on soot reduction, due especially to chemical effects.…”

Section: Introductionmentioning

confidence: 99%

Effect of exhaust gas recirculation composition on soot in ECN spray A conditions

Patel

Hespel

Nguyen

et al. 2020

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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Due to its strong impact on health, particulate matter is increasingly regulated by government emission standards for vehicles. As one of the sources of particulate matter is the soot produced by internal combustion engines, it remains a challenge to improve advanced combustion modes to reduce it. There is still, however, some lack of understanding about the formation and oxidation processes of soot, especially in “realistic” conditions, such as for example at high temperature and pressure conditions with or without the presence of exhaust gases. The objective of this study is to investigate soot formation in the case of n-Dodecane spray flames at conventional Diesel engine conditions generated in the New One Shot Engine by using diffused back-illumination extinction with different CO2 and water vapour contents. It was found that CO2 addition reduces the soot mass fraction if its volumetric concentration in ambient mixtures is at least 4.5% while 1% of water is sufficient to significantly reduce the soot mass fraction. The impact of the ambient mixture obtained in ECN spray A pre-burn vessels was also investigated to assess the accuracy against soot measurements available in the literature.

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“…The present study shows, under some simplified assumptions, the expected effects on soot predictions when frequently used models for transport properties and radiation are chosen. In a more advanced model [24] based on pyrene (a 4-aromatic ring species, A 4 ) as the soot precursor and taking the particle size distribution into account, it is shown that the changes in C 2 H 2 are well correlated with the changes in A 4 when the fuel or oxidant-diluent species changes from N 2 to CO 2 , which consequently affects the mass diffusivities of C 2 H 2 and A 4 . Although not linear, the qualitative trend is the same for both species.…”

Section: Soot Modelmentioning

confidence: 99%

Limitations of simplified models to predict soot formation in laminar flames

Zimmer

Pereira

2020

J Braz. Soc. Mech. Sci. Eng.

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Soot formation and radiation are important aspects for combustion problems. In this work, numerical simulations of ethylene coflow laminar flames are used to evaluate soot formation and radiation processes under different modeling approximations. Priority was given for models that were capable of producing detailed information with reduced computational requirements. So, the objective of this work is to show and quantify the importance of heat loss by gas and soot radiation and to quantitatively show the impact of different transport models (a detailed and a simplified) in soot predictions. For soot modeling, a semiempirical two-equation model is chosen for predicting soot mass fraction and number density. The model describes particle nucleation, surface growth and oxidation. For flame radiation, the radiant heat losses (gas and soot) are modeled by using the gray-gas approximation with optically thin approximation. For the chemical kinetics, a detailed approach is employed. It is found that gas and soot components of the radiative heat loss are comparable, with the gas radiation being larger (65%). To capture 99.9% of the total heat loss, the numerical domain has to be extended to 2.4 times the flame length based on the stoichiometric mixture fraction. Radiation modeling has a large impact on soot predictions. An error of 19% in the peak soot volume fraction is found when radiation is neglected. Errors due to simplified transport properties are also around 21%.

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Effects of CO2 addition on soot formation of ethylene non-premixed flames under oxygen enriched atmospheres

Cited by 41 publications

References 69 publications

Chemical effects of hydrogen addition on soot formation in counterflow diffusion flames: Dependence on fuel type and oxidizer composition

Chemical effects of hydrogen addition on soot formation in counterflow diffusion flames: Dependence on fuel type and oxidizer composition

Effect of exhaust gas recirculation composition on soot in ECN spray A conditions

Limitations of simplified models to predict soot formation in laminar flames

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