A Comparison Study of Soot Precursor and Aggregate Property Between Algae-Based Aviation Biofuel and Aviation Kerosene RP-3 in Laminar Flame

Abstract Algae-based aviation biofuel shows the potential to reduce soot emission in flight. A comparison study of soot precursor and aggregate property between algae-based biofuel and aviation kerosene RP-3 in laminar flame was conducted to investigate the reason of biofuel’s less soot formation. The soot precursors were determined by the fringe lengths of soot particles. At a typical dimensionless height DH = 0.50 of both flames, the geometric mean fringe lengths of biofuel and RP-3 are measured to be 0.67 and 0.73 nm, respectively, approximating to the size of five-ringed (A5) and seven-ringed (A7) poly-aromatic hydrocarbon, respectively. An A5 growth mechanism was then added to biofuel surrogate mechanisms for soot formation simulation. Since the carbon number component of biofuel is wide and difficult for comprehensive mechanism development, two surrogate mechanisms were developed. One is based on the C8–C16 n-alkane that covers biofuel’s main components, and the other one is based on biofuel’s average carbon number to simplify the mechanism. Meanwhile, an A7 growth mechanism was added to a popular RP-3 mechanism. The soot formation simulation with the combination mechanisms for both fuels provides a better agreement with the measured primary particle diameter and suggests that the reason for less soot production by biofuel is its less soot precursor production that weakens soot nucleation and growth. Lastly, the soot fractal dimension of biofuel is smaller than that of RP-3, indicating that biofuel has a looser soot aggregate.

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

10.1115/gt2021-59203 ◽

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

10.1115/icef2021-67749 ◽

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.

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Ultrafine particulate matter in methane-air premixed flames with oxygen enrichment

10.31224/osf.io/6px2m ◽

2021 ◽

Author(s):

Shruthi Dasappa ◽

Joaquin Camacho

Keyword(s):

Particle Size ◽

Particulate Matter ◽

Equivalence Ratio ◽

Volume Fraction ◽

Soot Formation ◽

Flame Temperature ◽

Number Density ◽

Soot Precursors ◽

Soot Precursor ◽

Ultrafine Particulate Matter

A complementary computational and experimental study is carried out on the formation of ultrafine particulate matter in premixed laminar methane air flames. Specifically, soot formation is examined in premixed stretch-stabilized flames to observe soot inception and growth at relatively high flame temperatures common to oxygen enriched applications. Particle size distribution functions (PSDF) measured by mobility sizing show clear trends as the equivalence ratio increases from Φ = 2.2 to Φ = 2.4. For a given equivalence ratio, the measured distribution decreases in median mobility particle size as the maximum flame temperature increases from approximately 1950 K to 2050 K. The median mobility particle size is 20 nm or less for all flame conditions studied. The volume fraction decreases with increasing flame temperature for all equivalence ratio conditions. The Φ = 2.2 condition is close to the soot inception limit and both number density and volume fraction decrease monotonically with increasing flame temperature. The higher equivalence ratio conditions show a peak in number density at 2000 K which may indicate competing soot inception processes are optimized at this temperature. Flame structure computations are carried out using detailed gas-phase combustion chemistry of the Appel, Bockhorn, Frenklach (ABF) model to examine the connection of the observed PSDF to soot precursor chemistry. Agreement between measured and computed flame standoff distances indicates that the ABF model could provide a reasonable prediction of the flame temperature and soot precursor formation for the flames currently studied. To the first order, the trends observed in the measured PSDF could be understood in terms of computed trends for the formation of benzene, naphthalene and other soot precursors. Results of the current study inform particulate matter behavior for methane and natural gas combustion applications at elevated temperature and oxygen enriched conditions.

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Ultrafine Particulate Matter in Methane-Air Premixed Flames With Oxygen Enrichment

Frontiers in Mechanical Engineering ◽

10.3389/fmech.2021.739914 ◽

2021 ◽

Vol 7 ◽

Author(s):

Shruthi Dasappa ◽

Joaquin Camacho

Keyword(s):

Particle Size ◽

Particulate Matter ◽

Equivalence Ratio ◽

Volume Fraction ◽

Soot Formation ◽

Flame Temperature ◽

Number Density ◽

Soot Precursors ◽

Soot Precursor ◽

Ultrafine Particulate Matter

A complementary computational and experimental study is carried out on the formation of ultrafine particulate matter in premixed laminar methane air flames. Specifically, soot formation is examined in premixed stretch-stabilized flames to observe soot inception and growth at relatively high flame temperatures common to oxygen enriched applications. Particle size distribution functions (PSDF) measured by mobility sizing show clear trends as the equivalence ratio increases from Φ = 2.2 to Φ = 2.4. For a given equivalence ratio, the measured distribution decreases in median mobility particle size as the maximum flame temperature increases from approximately 1,950–2,050 K. The median mobility particle size is 20 nm or less for all flame conditions studied. The volume fraction decreases with increasing flame temperature for all equivalence ratio conditions. The Φ = 2.2 condition is close to the soot inception limit and both number density and volume fraction decrease monotonically with increasing flame temperature. The higher equivalence ratio conditions show a peak in number density at 2,000 K which may indicate competing soot inception processes are optimized at this temperature. Flame structure computations are carried out using detailed gas-phase combustion chemistry of the Appel, Bockhorn, Frenklach (ABF) model to examine the connection of the observed PSDF to soot precursor chemistry. Agreement between measured and computed flame standoff distances indicates that the ABF model could provide a reasonable prediction of the flame temperature and soot precursor formation for the flames currently studied. To the first order, the trends observed in the measured PSDF could be understood in terms of computed trends for the formation of benzene, naphthalene and other soot precursors. Results of the current study inform particulate matter behavior for methane and natural gas combustion applications at elevated temperature and oxygen enriched conditions.

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Simulation of Particle Synthesis by Premixed Laminar Stagnation Flames

MRS Proceedings ◽

10.1557/opl.2013.1049 ◽

2013 ◽

Vol 1506 ◽

Cited By ~ 1

Author(s):

Abhijit Modak ◽

Karthik Puduppakkam ◽

Chitralkumar Naik ◽

Ellen Meeks

Keyword(s):

Experimental Data ◽

Particle Size ◽

Particle Production ◽

Soot Formation ◽

Laminar Flame ◽

Practical Importance ◽

Batch Reactors ◽

Size Distributions ◽

Particle Size Distributions ◽

Premixed Laminar

ABSTRACTA sectional method for determining particle size distributions has been implemented within the particle tracking module included with CHEMKIN-PRO. The module is available for use with many types of reactor models, ranging from 0-D batch reactors to laminar flame simulations. Coupled with the Burner-stabilized Stagnation Flame (BSSF) Model, the sectional model offers a high-fidelity, robust, and efficient computational framework for simulating flame synthesis of particles in a laminar, premixed stagnation flame environment. The CHEMKIN-PRO coupling allows inclusion of detailed gas-phase chemistry that determines key particle-formation precursors, along with physical processes such as nucleation and coagulation of particles. These capabilities are demonstrated for two flame-particle systems of practical importance, viz. nanocrystalline titania synthesis and soot formation. The results are compared with experimental data obtained at the University of Southern California (USC) flame facility. Computed particle size distributions show good agreement with experimental data. Simulations have led to exploration of the parameter space for particle production and particle-size influences.

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Spray Combustion Characteristics of Single/Multi-Component Surrogate Fuel for Aviation Kerosene

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4052782 ◽

2022 ◽

Author(s):

Wenjin Qin ◽

Dengbiao Lu ◽

Lihui Xu

Keyword(s):

Soot Formation ◽

Mean Field ◽

Combustion Characteristics ◽

Spray Combustion ◽

Aviation Kerosene ◽

Eddy Simulation ◽

Air Mixing ◽

Flow Field Characteristics ◽

Lift Off ◽

Surrogate Fuel

Abstract In this research, n-dodecane and JW are selected as single and multi-component surrogate fuel of aviation kerosene to study the Jet-A spray combustion characteristics. The spray combustion phenomena are simulated using large eddy simulation coupled with detailed chemical reaction mechanism. Proper orthogonal decomposition method is applied to analyze the flow field characteristics, and the instantaneous velocity field are decomposed into four parts, namely the mean field, coherent field, transition field and turbulent field, respectively. The four subfields have their own characteristics. In terms of different fuels, JW has a higher intensity of coherent structures and local vortices than n-dodecane, which promotes the fuel-air mixing and improves the combustion characteristics, and the soot formation is significantly reduced. In addition, with the increase of initial temperature, the combustion is more intense, the ignition delay time is advanced, the flame lift-off length is reduced, and soot formation is increased accordingly.

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Parametric Study of Moss-Brookes (MB) and Moss-Brookes-Hall (MBH) Model Constants for Prediction of Soot Formation in a Turbulent Hydrocarbon Flames

ASME 2013 Gas Turbine India Conference ◽

10.1115/gtindia2013-3689 ◽

2013 ◽

Cited By ~ 3

Author(s):

Pravin Rajeshirke ◽

Pravin Nakod ◽

Rakesh Yadav ◽

Stefano Orsino

Keyword(s):

Reaction Mechanism ◽

Chemical Reaction ◽

Parametric Study ◽

Soot Formation ◽

Hydrocarbon Flames ◽

Oxidation Rates ◽

Numerical Predictions ◽

Chemical Reaction Mechanism ◽

Soot Precursors ◽

Original Works

In the present work, two equation soot models proposed by Moss-Brookes (MB) and Moss-Brookes-Hall (MBH), available in ANSYS FLUENT14.5, are used to study the soot formation in a turbulent kerosene-air flame. The model constants in the original works of MB and MBH model were primarily tuned for the methane-air or other lower hydrocarbon flames. In this work, the emphasis has been given on the applicability of these models in modeling the soot formation in heavy hydrocarbon fuels. The current work is primarily focused on the parametric study of the various modeling constants for calculating the soot inception and oxidation rates. A parametric study is performed to calculate the soot inception rates by considering different soot precursors like C2H2, C2H4, C6H6 and C6H5. Steady laminar flamelet approach with a detailed chemical reaction mechanism (Jet_SurF_2.0), is used for modeling gas phase combustion. The current numerical predictions are compared with experimental results of Young et al. [1] and earlier published numerical results of Wen et al. [2]. The study is further extended to understand the role of chemical reaction mechanism on soot predictions considering detailed versus reduced (JP10revC) chemical mechanisms.

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Investigation of the Early Soot Formation Process in a Transient Spray Flame Via Spectral Measurements of Laser-Induced Emissions

International Journal of Engine Research ◽

10.1243/146808705x60825 ◽

2006 ◽

Vol 7 (2) ◽

pp. 93-101 ◽

Cited By ~ 7

Author(s):

T Aizawa ◽

H Kosaka

Keyword(s):

Formation Process ◽

Soot Formation ◽

Yttrium Aluminium Garnet ◽

Two Dimensional ◽

Spectral Measurements ◽

Cross Sectional ◽

Soot Particles ◽

Nozzle Orifice ◽

Spray Flame ◽

Soot Precursors

In order to investigate the early soot formation process in a diesel spray flame, two-dimensional imaging and spectral measurements of laser-induced emission from soot precursors and soot particles in a transient spray flame achieved in a rapid compression machine (2.8 MPa, 710 K) were conducted. The 3rd harmonic (355 nm) and 4th harmonic (266 nm) Nd: YAG (neodymium-doped yttrium aluminium garnet) laser pulses were used as the light source for laser-induced fluorescence (LIF) from soot precursors and laser-induced incandescence (LII) from soot particles in the spray flame. The two-dimensional imaging covered an area between 30 and 55 mm downstream from the nozzle orifice. The results of two-dimensional imaging showed that strong laser-induced emission excited at 266 nm appears only on the laser incident side of the spray flame, in contrast to an entire cross-sectional distribution of the emission excited at 355 nm, indicating that 266 nm-excited emitters are stronger absorbers and more abundant than 355 nm-excited emitters in the spray flame. The spectral measurements were conducted at three different positions, 35, 45, and 55 mm downstream from the nozzle orifice, along the central axis of the spray, where LIF from soot precursors was observed in a previous two-dimensional imaging study. The spectra measured in upstream positions showed that broad emission peaked at around 400–500 nm, which is attributable to LIF from polycyclic aromatic hydrocarbons (PAHs). The spectra measured in downstream positions appeared very much like grey-body emission from soot particles.

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