A Numerical and Experimental Study of Soot Precursor and Primary Particle Size of N-Butylbenzene in Laminar Flame

2021 ◽  
Author(s):  
Mingshan Sun ◽  
Zhiwen Gan
Keyword(s):  
Soot Particle ◽  
Primary Particle ◽  
Volume Fraction ◽  
Soot Formation ◽  
Laminar Flame ◽  
Particle Diameter ◽  
Soot Volume Fraction ◽  
The Core ◽  
Soot Precursor ◽  
Combined Mechanism

Abstract The current study analyzed the soot precursor of the n-butylbenzene found in diesel and kerosene in laminar flame, and integrated the corresponding poly-aromatic hydrocarbon (PAH) growth mechanism with the popular n-butylbenzene oxidation mechanisms to improve the soot formation prediction of n-butylbenzene. The size of soot precursor was determined by the fringe length in the core of soot particle since the nanostructure of the core of soot particle is similar with that of nascent soot particle formed by soot precursor nucleation. The geometric mean fringe length in core of soot particles was measured to be 0.67 nm approximating to the size of five-ringed PAH (A5). An A5 growth mechanism was added on a popular n-butylbenzene mechanism, and the combined mechanism was further reduced. After validation by the ignition delay time in literature, the combined mechanism was then validated by the primary particle diameter in laboratory and soot volume fraction of n-propylbenzene in literature. The calculated soot precursor concentration and PAH condensation rate of the combined mechanism are smaller than that of the base mechanism. The simulated primary soot particle diameter of proposed combined mechanism agrees well with the measure primary soot particle diameter. Comparing to the simulated soot volume fraction of base n-butylbenzene mechanism, the simulated soot volume fraction of proposed combined n-butylbenzene-A5 mechanism agrees well with the measure soot volume fraction of n-propylbenzene in literature. This study provides certain support for further investigation of soot formation of n-butylbenzene and its relative fuel like diesel and kerosene.

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.

Mechanism of smokeless diesel combustion with oxygenated fuels based on the dependence of the equivalence ration and temperature on soot particle formation

2002 ◽  
Vol 3 (4) ◽  
pp. 223-248 ◽  
Author(s):  
T Kitamura ◽  
T Ito ◽  
J Senda ◽  
H Fujimoto
Keyword(s):  
Fine Particles ◽  
Volume Fraction ◽  
Soot Formation ◽  
Particle Diameter ◽  
Soot Volume Fraction ◽  
Diesel Combustion ◽  
Number Density ◽  
Particulate Size ◽  
Lower Temperature ◽  
Ultra Fine Particles

The equivalence ratio φ and temperature T are well known to have a significant effect on the quality of particulate formation, such as the soot volume fraction, particle diameter and number density. The purpose of this work is to clarify the φ-T dependence of soot formation for various kinds of fuels, including paraffinic hydrocarbon, aromatic hydrocarbon and oxygenated hydrocarbon, and to discuss a possibility for smokeless diesel combustion considering particulate size and number density. The sooting φ-T map, showing the tendency to generate soot particles as a function of φ-T and T, was made using a detailed soot kinetic model. The computational results show that oxygenated fuel reactions lead to a lower soot yield, smaller particle diameter, lower number density and narrower sooting φ-T region than those of aliphatic and aromatic fuels, due to the notable reduction in production of both acetylene and polycyclic aromatic hydrocarbons (PAHs). Furthermore, this lower sooting tendency is emphasized as the fuel oxygen content increases. It was also found that the leaner mixture side of the soot formation peninsula on the φ-T map, rather than the lower temperature side, should be utilized to suppress the formation of PAHs and ultra-fine particles together with a large reduction in particulate mass.

In-Situ Soot Measurements in an Operating Engine Gas Turbine Combustor

1991 ◽  
Author(s):  
R. Koch ◽  
S. Wittig ◽  
H.-J. Feld ◽  
H.-J. Mohr
Keyword(s):  
Gas Turbine ◽  
Soot Particle ◽  
Volume Fraction ◽  
Particle Diameter ◽  
Soot Volume Fraction ◽  
Light Extinction ◽  
Gas Turbine Combustor ◽  
Rotating Speed ◽  
Secondary Zone

The dispersion quotient method, an optical measuring technique for particles, has been applied to in situ measurements of the soot particle size and density in the secondary zone of a KHD GT-216 gas turbine combustor under operating engine conditions. The optical technique, which has been developed at the Institut of Thermische Strömungsmaschinen, is based on the light extinction at different wavelength by a particle cloud due to absorption and scattering. It is of particular advantage in applications, where particles of small size (d ≤ 1.0μ) and high density are to be investigated. In the present investigation, two idling running conditions of the turbine have been studied: 30.000 rpm and 47.000 rpm. The results show, that the dispersion quotient method is well suited for soot measurements in pressurized flames. In particular, it was found, that the soot particle diameter is not effected by the rotating speed of the turbine. The size of the soot particles was always in the range from 0.1 to 0.3 mircon. The soot volume fraction, however, was found to be strongly influenced by different rotating speeds, with higher rotating speed causing higher volume fraction of soot.

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