Simulation of Soot Size Distribution in a Counterflow Flame

2015 ◽  
Vol 13 (1) ◽  
pp. 95-101 ◽  
Author(s):  
Z. He ◽  
K. Zhou ◽  
M. Xiao ◽  
F. Wei
Keyword(s):  
Size Distribution ◽  
Fossil Fuels ◽  
Soot Particle ◽  
Soot Formation ◽  
Health Hazard ◽  
Hydrogen Abstraction ◽  
Surface Growth ◽  
Narrow Region ◽  
Counterflow Flame ◽  
The Rich

Abstract Soot formed during the rich combustion of fossil fuels is an undesirable pollutant and health hazard. A newly developed Monte Carlo method is used to simulate the soot formation in a counterflow diffusion flame of ethylene. The simulation uses a new reaction mechanism available in literature, which focuses on modeling the formation of large polycyclic aromatic hydrocarbons (PAHs) up to coronene (C24H12). Nascent soot particles are assumed to form from the collision of eight different PAH molecules. Soot surface growth includes the hydrogen-abstraction-C2H2-addition mechanism and the condensation of the PAHs. Soot coagulation is in the free-molecular regime because particles are small (not more than a hundred nanometer). The coupling between vapor consumption and soot formation is handled by an interpolative moment method. Soot particle diffusion is found negligible throughout the counterflow flame, except for a very narrow region right around the stagnation plane. The soot particle size distribution (PSD) generally exhibits a bimodal shape. The first peak corresponds to a large number of nascent particles, while the second peak results from the competition between nucleation and coagulation. Surface growth affects the PSD quantitatively, but does not change the modality. A comparison with experimental data is also provided.

Soot Particle Evolution and Transport in a Direct Injection Diesel Engine

2015 ◽  
Vol 74 (3) ◽  
Author(s):  
Muhammad Ahmar Zuber ◽  
Wan Mohd Faizal Wan Mahmood ◽  
Zambri Harun ◽  
Zulkhairi Zainol Abidin
Keyword(s):  
Particle Size ◽  
Soot Particle ◽  
Soot Formation ◽  
Formation Rate ◽  
Soot Oxidation ◽  
Surface Growth ◽  
Number Density ◽  
Coagulation Rate ◽  
Particulate Emission ◽  
Soot Particles

Particle-based in-cylinder soot distribution study is becoming more important as the rules and regulations pertaining to particulate emission of diesel-powered vehicles have been increasingly more stringent. This paper focuses on the investigation of soot size evolution and its distribution and transport inside an engine cylinder. The overall process of soot formation includes soot nucleation, surface growth, oxidation, coagulation and agglomeration. The present study considers only soot surface growth, oxidation and coagulation to predict the in-cylinder soot particle size. The soot surface growth model was based on Hiroyasu’s soot formation model while soot oxidation was referred to Nagle & Strickland-Constable’s soot oxidation model. Coagulation rate was defined using Smoluchowski’s equation with constant proposed by Wersborg. From this study, it is demonstrated that soot particles with relatively larger size are gathered in the centre of the cylinder while smaller soot particles are found to be in the region near the wall. Soot number density is considerably high at the start of combustion and reduces sharply afterward while the soot particle size shows the opposite trend. Soot formation rate was found to be dominant at earlier crank angle and is overcome by soot oxidation and coagulation processes that caused lower soot number density but higher soot particle size.  

scholarly journals Fuel molecular structure effect on soot mobility size in premixed C6 hydrocarbon flames

2021 ◽  
Author(s):  
Shruthi Dasappa ◽  
Joaquin Camacho
Keyword(s):  
Size Distribution ◽  
Soot Particle ◽  
Volume Fraction ◽  
Soot Formation ◽  
Flame Structure ◽  
Flame Temperature ◽  
Similar Time ◽  
Mobility Diameter ◽  
Premixed Laminar ◽  
The Impact

Soot formation in premixed laminar flames is examined for a canonical set of flames burning C6 hydrocarbon fuels. Particle mobility size and flame temperature measurements are complemented by flame structure calculations using detailed flame chemistry. Specifically, the evolution of the detailed soot particle size distribution (PSDF) is compared for n-hexane, n-hexene, 2-methylpentane, cyclohexane and benzene at a carbon-to-oxygen ratio of 0.69 and maximum flame temperature of 1800 K. Under this constraint, the overall sooting process is comparable as evidenced by similar time resolved bimodal PSDF. However, the first inception of particles and the persistence of nucleation-sized particles with time are depend upon the structure of the parent fuel. For the given conditions, the fastest onset of soot is observed in cyclohexane and benzene flames and the observed evolution of the PSDF also shows that nucleation-sized particles disappear sooner in cyclohexane and benzene flames. Flame structure computations incorporating detailed chemistry show a clear connection between the early onset of soot particles as fuel specific routes to PAH formation are predicted in the pre-flame region of the cyclohexane and benzene flames. These observations illustrate the impact of alkane, alkene, cycloalkane and aromatic fuel structure on soot formation in premixed flames. Analysis of soot particle morphology by atomic force microscopy indicates that most of size distribution is composed of aggregates. Simple aggregate mobility diameter analysis shows the spherical assumption taken to interpret the mobility diameter does not impact the PSDF number density result but the inferred volume fraction for aggregates deviates by up to an order of magnitude depending on the morphology assumptions adopted.

Soot Formation in Propane/Air Diffusion Flames

2013 ◽  
Vol 668 ◽  
pp. 123-127 ◽  
Author(s):  
Xue Sun ◽  
D.W. Zhang ◽  
G.L. Ning
Keyword(s):  
Particle Size ◽  
Soot Particle ◽  
Rate Coefficient ◽  
Diffusion Flames ◽  
Soot Formation ◽  
Surface Growth ◽  
Wide Range ◽  
Air Diffusion

Soot formation and growth in propane/air diffusion flames in a wide range of mole ratio of propane to air from 0.01 to 0.1 have been studied experimentally and theoretically. The concentration of acetylene, soot yield and particle size have been measured and the growth of soot particle has been simulated from surface growth and nucleation processes. The rate coefficient of surface growth has been correlated with the mole ratio of propane to air and the comparisons of particle size between measured and calculated results have been made.

scholarly journals Monte Carlo simulation for soot dynamics

2012 ◽  
Vol 16 (5) ◽  
pp. 1391-1394 ◽  
Author(s):  
Kun Zhou
Keyword(s):  
Particle Size ◽  
Monte Carlo ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Gas Phase ◽  
Volume Fraction ◽  
Soot Formation ◽  
Bimodal Distribution ◽  
Number Density ◽  
Stochastic Error

A new Monte Carlo method termed Comb-like frame Monte Carlo is developed to simulate the soot dynamics. Detailed stochastic error analysis is provided. Comb-like frame Monte Carlo is coupled with the gas phase solver Chemkin II to simulate soot formation in a 1-D premixed burner stabilized flame. The simulated soot number density, volume fraction, and particle size distribution all agree well with the measurement available in literature. The origin of the bimodal distribution of particle size distribution is revealed with quantitative proof.

Effect of mixing methane, ethane, propane and ethylene on the soot particle size distribution in a premixed propene flame

2018 ◽  
Vol 193 ◽  
pp. 54-60 ◽  
Author(s):  
Baiyang Lin ◽  
Hao Gu ◽  
Hong Ni ◽  
Bin Guan ◽  
Zhongzhao Li ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Soot Particle

scholarly journals Evolution of Soot Particle Number, Mass and Size Distribution along the Exhaust Line of a Heavy-Duty Engine Fueled with Compressed Natural Gas

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3993
Author(s):  
Elia Distaso ◽  
Riccardo Amirante ◽  
Giuseppe Calò ◽  
Pietro De Palma ◽  
Paolo Tamburrano
Keyword(s):  
Particle Size ◽  
Natural Gas ◽  
Size Distribution ◽  
Soot Formation ◽  
Distribution Data ◽  
Exhaust Pipe ◽  
Heavy Duty ◽  
Compressed Natural Gas ◽  
Soot Particles ◽  
Exhaust Line

An experimental study has been conducted to provide a characterization of the transformations that particle size distributions and the number density of soot particles can encounter along the exhaust line of a modern EURO VI compliant heavy-duty engine, fueled with compressed natural gas. Being aware of the particles history in the exhausts can be of utmost importance to understand soot formation and oxidation dynamics, so that, new strategies for further reducing these emissions can be formulated and present and future regulations met. To this purpose, particle samples were collected from several points along the exhaust pipe, namely upstream and downstream of each device the exhaust gases interact with. The engine was turbocharged and equipped with a two-stage after-treatment system. The measurements were carried out in steady conditions while the engine operated in stoichiometric conditions. Particle emissions were measured using a fast-response particle size spectrometer (DMS500) so that size information was analyzed in the range between 5 and 1000 nm. Particle mass information was derived from size distribution data using a correlation available in the literature. The reported results provide more insight on the particle emission process related to natural gas engines and, in particular, point out the effects that the turbine and the after-treatment devices produce on soot particles. Furthermore, the reported observations suggest that soot particles might not derive only from the fuel, namely, external sources, such as lubricant oil, might have a relevant role in soot formation.

scholarly journals WdStuAp, an APSES Transcription Factor, Is a Regulator of Yeast-Hyphal Transitions in Wangiella (Exophiala) dermatitidis

2007 ◽  
Vol 6 (9) ◽  
pp. 1595-1605 ◽  
Author(s):  
Qin Wang ◽  
Paul J. Szaniszlo
Keyword(s):  
Transcription Factor ◽  
Agar Medium ◽  
Hyphal Growth ◽  
Surface Growth ◽  
Yeast Growth ◽  
Amino Terminal ◽  
Yeast Extract Peptone Dextrose ◽  
Development And Differentiation ◽  
Colony Surface ◽  
The Rich

ABSTRACT APSES transcription factors are well-known regulators of fungal cellular development and differentiation. To study the function of an APSES protein in the fungus Wangiella dermatitidis, a conidiogenous and polymorphic agent of human phaeohyphomycosis with yeast predominance, the APSES transcription factor gene WdSTUA was cloned, sequenced, disrupted, and overexpressed. Analysis showed that its derived protein was most similar to the APSES proteins of other conidiogenous molds and had its APSES DNA-binding domain located in the amino-terminal half. Deletion of WdSTUA in W. dermatitidis induced convoluted instead of normal smooth colony surface growth on the rich yeast maintenance agar medium yeast extract-peptone-dextrose agar (YPDA) at 37°C. Additionally, deletion of WdSTUA repressed aerial hyphal growth, conidiation, and invasive hyphal growth on the nitrogen-poor, hypha-inducing agar medium potato dextrose agar (PDA) at 25°C. Ectopic overexpression of WdSTUA repressed the convoluted colony surface growth on YPDA at 37°C, and also strongly repressed hyphal growth on PDA at 25°C and 37°C. These new results provide additional insights into the diverse roles played by APSES factors in fungi. They also suggest that the transcription factor encoded by WdSTUA is both a positive and negative morphotype regulator in W. dermatitidis and possibly other of the numerous human pathogenic, conidiogenous fungi capable of yeast growth.

scholarly journals Advancing predictive models for particulate formation in turbulent flames via massively parallel direct numerical simulations

2014 ◽  
Vol 372 (2022) ◽  
pp. 20130324 ◽  
Author(s):  
Fabrizio Bisetti ◽  
Antonio Attili ◽  
Heinz Pitsch
Keyword(s):  
Internal Combustion Engines ◽  
Fossil Fuels ◽  
Soot Formation ◽  
Model Development ◽  
Turbulent Flames ◽  
Pollutant Emissions ◽  
Combustion Model ◽  
Carbon Abatement ◽  
Physico Chemical ◽  
Combustion Modelling

Combustion of fossil fuels is likely to continue for the near future due to the growing trends in energy consumption worldwide. The increase in efficiency and the reduction of pollutant emissions from combustion devices are pivotal to achieving meaningful levels of carbon abatement as part of the ongoing climate change efforts. Computational fluid dynamics featuring adequate combustion models will play an increasingly important role in the design of more efficient and cleaner industrial burners, internal combustion engines, and combustors for stationary power generation and aircraft propulsion. Today, turbulent combustion modelling is hindered severely by the lack of data that are accurate and sufficiently complete to assess and remedy model deficiencies effectively. In particular, the formation of pollutants is a complex, nonlinear and multi-scale process characterized by the interaction of molecular and turbulent mixing with a multitude of chemical reactions with disparate time scales. The use of direct numerical simulation (DNS) featuring a state of the art description of the underlying chemistry and physical processes has contributed greatly to combustion model development in recent years. In this paper, the analysis of the intricate evolution of soot formation in turbulent flames demonstrates how DNS databases are used to illuminate relevant physico-chemical mechanisms and to identify modelling needs.

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