Experimental and numerical study of soot formation in laminar coflow diffusion flames of gasoline/ethanol blends

Khosousi, Ali; Liu, Fengshan; Dworkin, Seth B.; Eaves, Nick A.; Thomson, Murray J.; He, Xiangming; Dai, Yujie; Gao, Yunkai; Liu, Fushui; Shuai, Shijin; Wang, Jianxin

doi:10.1016/j.combustflame.2015.07.029

Cited by 118 publications

(44 citation statements)

References 53 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%

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%

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 governing equations and the solution method have been given in previous studies [7,19,20] and will be described only briefly. The numerical model solves the conservation equations for mass, momentum, gas-phase species mass fraction, and energy in the low Mach number formulation and in axisymmetric coordinates by using a finite volume method and the SIMPLE algorithm.…”

Section: Numerical Modelmentioning

confidence: 99%

“…The incipient soot particles are assumed to be spherical and belong to the first section. As in previous studies [7,[19][20][21], 35 sections were used with a spacing factor of 2.35. Coagulation terms are calculated using the same method given in Ref.…”

Section: Numerical Modelmentioning

confidence: 99%

“…The numerical model solves the conservation equations for mass, momentum, gas-phase species mass fraction, and energy in the low Mach number formulation and in axisymmetric coordinates by using a finite volume method and the SIMPLE algorithm. Additional transport equations for sectional soot aggregate and primary particle number densities are solved to describe the soot particle dynamics [7]. The divergence of the radiative flux was computed by the discrete ordinate method coupled to a statistical narrow-band-correlated k-based wide-band model for properties of CO, CO 2 , and…”

Section: Numerical Modelmentioning

confidence: 99%

“…Although it is important to investigate the effects of these factors on soot emissions from GDI engines, it is challenging to isolate the influence of a particular factor, such as fuel chemistry, on soot formation, as the high sensitivity of soot emissions from a GDI engine to various engine parameters can mask the effect of this particular factor on soot formation. In order to circumvent this drawback, well-controlled laminar diffusion flames have been often used [3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

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Numerical study of soot formation in laminar coflow methane/air diffusion flames doped by n- heptane/toluene and iso-octane/toluene blends

Consalvi

Liu

Kashif

et al. 2017

Combustion and Flame

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Abstract:The laminar coflow nitrogen-diluted methane/air diffusion flames doped with a small amount of n-heptane/toluene and iso-octane/toluene binary mixtures, investigated experimentally by Kashif et al. [Combust. Flame 162 (2015) 1840-18476], were simulated numerically by using a detailed reaction mechanism and a sectional polycyclic aromatic hydrocarbon (PAH)-based soot model. The numerical model provides results in reasonable qualitative agreement with the experimental data by using the same chemical mechanism, the same soot model, and the same set of constants employed successfully in a previous study to model the effects of nheptane/iso-octane doping, demonstrating that this overall model is promising to model soot formation in gasoline flames. Soot production is enhanced monotonically with increasing the 2 toluene content in either the n-heptane/toluene or iso-octane/toluene doping fuel mixture. The increase in benzene and pyrene production displays a non-monotonic and synergistic response to the increase in toluene content. These numerical results are consistent with available experimental results as far as the trends in the effects of increasing the toluene content are concerned. Model results show that the dominant pathways responsible for the synergistic effects on benzene and pyrene production are respectively C 6 H 5 CH 3 (n-heptane) + H ↔ A1 (benzene) + CH 3 and A3-(C 14 H 9 ) + C 2 H 2 ↔ A4 (pyrene) + H.

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Effect of Alcohol Addition to Gasoline on Soot Distribution Characteristics in Laminar Diffusion Flames

Liu

Hua

et al. 2018

Chem Eng & Technol

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Alcohols are widely used as alternative fuel for spark ignition engines to reduce soot emission. 2D soot distributions of alcohols‐gasoline blends were studied in laminar diffusion flames by two‐color laser‐induced incandescence technique. The soot volume fraction decreases significantly with the alcohol blending ratio. At the same blending ratio, the soot‐reducing ability declined with the carbon length of the alcohol, but the reducing effect for short‐chain alcohols, i.e., methanol and ethanol, deteriorated at high blending ratio while it remained constant for the long‐chain alcohol n‐butanol. At fixed oxygen content, the soot‐reducing ability of a short‐chain alcohol is still higher than that of a long‐chain alcohol, i.e., not only the oxygen content but also the molecular structure dominates the soot‐reducing ability.

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Experimental and numerical study of soot formation in laminar coflow diffusion flames of gasoline/ethanol blends

Cited by 118 publications

References 53 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

Numerical study of soot formation in laminar coflow methane/air diffusion flames doped by n- heptane/toluene and iso-octane/toluene blends

Effect of Alcohol Addition to Gasoline on Soot Distribution Characteristics in Laminar Diffusion Flames

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