Numerical study on the influence of hydrogen addition on soot formation in a laminar ethylene–air diffusion flame

2006 ◽  
Vol 145 (1-2) ◽  
pp. 324-338 ◽  
Author(s):  
Hongsheng Guo ◽  
Fengshan Liu ◽  
Gregory J. Smallwood ◽  
Ömer L. Gülder
Keyword(s):  
Diffusion Flame ◽  
Soot Formation ◽  
Numerical Study ◽  
Hydrogen Addition ◽  
Air Diffusion

scholarly journals Numerical Study of Hydrogen Addition Fuel on Soot Formation in Axisymmetric Laminar Methane/Air Diffusion Flames

2020 ◽  
Vol 194 ◽  
pp. 04054
Author(s):  
Bencheng Zhu ◽  
Yuhan Zhu ◽  
Jiajia Wu ◽  
Kun Lu ◽  
Yang Wang ◽  
...  
Keyword(s):  
Diffusion Flames ◽  
Soot Formation ◽  
Numerical Study ◽  
Flame Temperature ◽  
Surface Growth ◽  
Chemical Effect ◽  
Oh Radicals ◽  
Phase Reaction ◽  
Hydrogen Addition ◽  
Air Diffusion

This article employs the CoFlame Code to investigate the effects of hydrogen addition to fuel on soot formation characteristics in laminar coflow methane/air diffusion flames at atmospheric pressure. Numerical calculations were carried out using a detailed C1-C2 gas phase reaction mechanism and a soot model consisting of two pyrene molecules colliding into a dimer as soot nucleation, hydrogen abstraction acetylene addition (HACA) and pyrene condensation as surface growth, and soot oxidation by O2, O and OH radicals. Calculations were conducted for five levels of hydrogen addition on volume basis. To quantify the chemical effect of hydrogen, additional calculations are performed for addition of inert pseudo-hydrogen (FH2). The addition of H2 or FH2 does not have a strong influence on flame temperature. The results confirm that hydrogen addition can inhibit soot formation in the methane/air diffusion flame by reducing both the nucleation and surface growth steps of soot formation process. The effect of FH2 addition on soot formation suppression is more remarkable than H2, indicating that the chemical effect of hydrogen added to methane prompts soot formation. The dilution effect of hydrogen addition on soot formation suppression is stronger than its chemical effect on soot formation enhancement the present findings are consistent with those of previous numerical studies.

Effects of Hydrogen and Helium Addition to Fuel on Soot Formation in Axisymmetric Coflow Laminar Methane-Air Diffusion Flame

2007 ◽  
Author(s):  
Fengshan Liu ◽  
Francesca Migliorini ◽  
Francesco Cignoli ◽  
Silvana De Iuliis ◽  
Giorgio Zizak
Keyword(s):  
Diffusion Flame ◽  
Volume Fraction ◽  
Soot Formation ◽  
Experimental Studies ◽  
Wide Band ◽  
Radiative Properties ◽  
Discrete Ordinates ◽  
Band Model ◽  
Hydrogen Addition ◽  
Air Diffusion

Numerical and experimental studies were conducted to investigate the effects of hydrogen and helium addition to fuel on soot formation in atmospheric axisymmetric coflow laminar methane-air diffusion flame. Soot temperature and volume fraction distributions were measured using a two-dimensional two-color technique. Numerically the conservation equations of mass, momentum, energy, and species in the limit of low-Mach number were solved. Detailed gas-phase chemistry and thermal and transport properties were accounted for. Radiative heat transfer by CO, CO2, H2O, and soot was calculated using the discrete-ordinates method with the radiative properties of the mixture obtained from a wide-band model. Soot was modeled using a two-equation semi-empirical model in which the mechanisms for inception and surface growth are assumed to be PAH coagulation and H-abstraction acetylene addition. Both experimental and numerical results show that helium addition is more efficient than hydrogen addition in reducing soot formation in the methane flame. These results are different from the previous investigations in ethylene flames where the hydrogen addition was found to be more effective in reducing soot formation than helium addition due to the additional chemical suppression of hydrogen on soot. It is suggested here that hydrogen chemically enhances soot formation when added to methane.

A Numerical Study of the Influence of Hydrogen Addition on Soot Formation in a Laminar Counterflow Ethylene/Oxygen/Nitrogen Diffusion Flame

2004 ◽  
Author(s):  
Hongsheng Guo ◽  
Fengshan Liu ◽  
Gregory J. Smallwood
Keyword(s):  
Diffusion Flame ◽  
Volume Fraction ◽  
Diffusion Flames ◽  
Soot Formation ◽  
Numerical Study ◽  
Soot Volume Fraction ◽  
Phase Reaction ◽  
Nitrogen Diffusion ◽  
Atom Concentration ◽  
Hydrogen Addition

The influence of hydrogen addition to the fuel on soot formation in an ethylene/oxygen/nitrogen diffusion flame was numerically studied by simulation of three counterflow laminar diffusion flames at atmosphere pressure. The fuel mixtures for the three flames are pure ethylene, ethylene/hydrogen and ethylene/helium, respectively, while the oxidant is a mixture of oxygen and nitrogen. A detailed gas phase reaction mechanism including species up to benzene and complex thermal and transport properties were used. The soot inception and surface growth rates were, respectively, calculated based on benzene and HACA (H-abstraction and C2H2-addition) mechanisms. The predicted results for the three flames were compared and analyzed. It is indicated that although the addition of either hydrogen or helium to the fuel can reduce the soot volume fraction, the addition of hydrogen is more efficient. While the addition of helium reduces soot formation only through dilution, the addition of hydrogen suppresses soot formation through both dilution and chemical reaction effects. This conclusion is qualitatively consistent with available experiments. The simulations revel that the chemically inhibiting effect is caused by the decrease of hydrogen atom concentration in soot formation region, due to the displacement of the primary reaction zone, when hydrogen is added to the fuel.

The influence of nitrogen and hydrogen addition/dilution on soot formation in coflow ethylene/air diffusion flames

Fuel ◽  
2022 ◽  
Vol 309 ◽  
pp. 122244
Author(s):  
Andisheh Khanehzar ◽  
Francisco Cepeda ◽  
Seth B. Dworkin
Keyword(s):  
Diffusion Flames ◽  
Soot Formation ◽  
Hydrogen Addition ◽  
Air Diffusion

A Numerical Study on the Influence of Hydrogen Addition on Soot Formation in a Laminar Aviation Kerosene (Jet A1) Flame at Elevated Pressure

2021 ◽  
Author(s):  
Mingshan Sun ◽  
Zhiwen Gan
Keyword(s):  
Volume Fraction ◽  
Soot Formation ◽  
Laminar Flame ◽  
Numerical Study ◽  
Soot Volume Fraction ◽  
Elevated Pressure ◽  
Condensation Process ◽  
Hydrogen Addition ◽  
Aviation Kerosene ◽  
Soot Precursor

Abstract The hydrogen addition is a potential way to reduce the soot emission of aviation kerosene. The current study analyzed the effect of hydrogen addition on aviation kerosene (Jet A1) soot formation in a laminar flame at elevated pressure to obtain a fundamental understanding of the reduced soot formation by hydrogen addition. The soot formation of flame was simulated by CoFlame code. The soot formation of kerosene-nitrogen-air, (kerosene + replaced hydrogen addition)-nitrogen-air, (kerosene + direct hydrogen addition)-nitrogen-air and (kerosene + direct nitrogen addition)-nitrogen-air laminar flames were simulated. The calculated pressure includes 1, 2 and 5 atm. The hydrogen addition increases the peak temperature of Jet A1 flame and extends the height of flame. The hydrogen addition suppresses the soot precursor formation of Jet A1 by physical dilution effect and chemical inhibition effect, which weaken the poly-aromatic hydrocarbon (PAH) condensation process and reduce the soot formation. The elevated pressure significantly accelerates the soot precursor formation and increases the soot formation in flame. Meanwhile, the ratio of reduced soot volume fraction to base soot volume fraction by hydrogen addition decreases with the increase of pressure, indicating that the elevated pressure weakens the suppression effect of hydrogen addition on soot formation in Jet A1 flame.

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