Soot and PAH Formation Characteristics in a Micro Flow Reactor With a Controlled Temperature Profile

2011 ◽  
Author(s):  
Ryu Tanimoto ◽  
Takuya Tezuka ◽  
Susumu Hasegawa ◽  
Hisashi Nakamura ◽  
Kaoru Maruta
Keyword(s):  
Flow Velocity ◽  
Temperature Profile ◽  
Mole Fraction ◽  
Equivalence Ratio ◽  
Flow Reactor ◽  
Volume Fraction ◽  
Soot Formation ◽  
Soot Volume Fraction ◽  
Low Flow ◽  
Micro Flow

To examine soot and PAH formation processes for rich methane/air and acetylene/air mixtures, a micro flow reactor with a controlled temperature profile was employed. In the experiment for a methane/air mixture, four kinds of responses to the variations of flow velocity and equivalence ratio were observed as follows: soot formation without a flame; a flame with soot formation; a flame without soot formation; and neither flame nor soot formation. Soot formations were observed in low flow velocity and high equivalence ratio. Starting point of soot formation shifted to the upstream side, i.e., low-temperature side, of the micro flow reactor with the decrease of flow velocity. One-dimensional steady-state computation was conducted by a flame code. In high flow velocity, low mole fraction of C2H2 and high mole fraction of OH were observed in the whole region of the micro flow reactor. Soot volume fraction did not increase in this case. On the other hand, in low flow velocity, high mole fraction of C2H2 and low mole fraction of OH were observed at the downstream side of the micro flow reactor. Soot volume fraction increased in this case. Since significant soot formation was observed at the low flow velocity and the high equivalence ratio, experiments with gas sampling were conducted for acetylene/air mixture to investigate temperature and equivalence ratio dependence of soot precursor production in such condition. Volume fractions of benzene increased with an increase of temperature. They were larger at higher equivalence ratio at the same temperature. Volume fractions of styrene increased with an increase of temperature. They were larger at higher equivalence ratio when the temperature is less than 1000 K. However the tendency was changed at 1000 K, styrene volume fraction at equivalence ratio of 7.0 was larger than that at equivalence ratio of 8.0.

scholarly journals Effect of the Preheated Oxidizer Temperature on Soot Formation and Flame Structure in Turbulent Methane-Air Diffusion Flames at 1 and 3 atm: A CFD Investigation

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3671
Author(s):  
Subrat Garnayak ◽  
Subhankar Mohapatra ◽  
Sukanta K. Dash ◽  
Bok Jik Lee ◽  
V. Mahendra Reddy
Keyword(s):  
Mole Fraction ◽  
Air Temperature ◽  
Reaction Rate ◽  
Volume Fraction ◽  
Diffusion Flames ◽  
Soot Formation ◽  
Flame Structure ◽  
Soot Volume Fraction ◽  
Computational Domain ◽  
Pressure Elevation

This article presents the results of computations on pilot-based turbulent methane/air co-flow diffusion flames under the influence of the preheated oxidizer temperature ranging from 293 to 723 K at two operating pressures of 1 and 3 atm. The focus is on investigating the soot formation and flame structure under the influence of both the preheated air and combustor pressure. The computations were conducted in a 2D axisymmetric computational domain by solving the Favre averaged governing equation using the finite volume-based CFD code Ansys Fluent 19.2. A steady laminar flamelet model in combination with GRI Mech 3.0 was considered for combustion modeling. A semi-empirical acetylene-based soot model proposed by Brookes and Moss was adopted to predict soot. A careful validation was initially carried out with the measurements by Brookes and Moss at 1 and 3 atm with the temperature of both fuel and air at 290 K before carrying out further simulation using preheated air. The results by the present computation demonstrated that the flame peak temperature increased with air temperature for both 1 and 3 atm, while it reduced with pressure elevation. The OH mole fraction, signifying reaction rate, increased with a rise in the oxidizer temperature at the two operating pressures of 1 and 3 atm. However, a reduced value of OH mole fraction was observed at 3 atm when compared with 1 atm. The soot volume fraction increased with air temperature as well as pressure. The reaction rate by soot surface growth, soot mass-nucleation, and soot-oxidation rate increased with an increase in both air temperature and pressure. Finally, the fuel consumption rate showed a decreasing trend with air temperature and an increasing trend with pressure elevation.

Soot formation characteristics and PAH formation process in a micro flow reactor with a controlled temperature profile

2014 ◽  
Vol 161 (2) ◽  
pp. 582-591 ◽  
Author(s):  
Hisashi Nakamura ◽  
Ryu Tanimoto ◽  
Takuya Tezuka ◽  
Susumu Hasegawa ◽  
Kaoru Maruta
Keyword(s):  
Temperature Profile ◽  
Formation Process ◽  
Flow Reactor ◽  
Soot Formation ◽  
Micro Flow

Modelling Soot Formation in Aviation Fuel Oxidation

2006 ◽  
Author(s):  
A. G. Kyne ◽  
M. Pourkashanian ◽  
C. W. Wilson
Keyword(s):  
Residence Time ◽  
Equivalence Ratio ◽  
Volume Fraction ◽  
Soot Formation ◽  
Soot Volume Fraction ◽  
Chemical Kinetic ◽  
Reaction Model ◽  
Aviation Fuel ◽  
Out Of Sample ◽  
The Impact

This study outlines the development of a new chemical kinetic surrogate aviation fuel air reaction mechanism which models up to four ring Polycyclic Aromatic Hydrocarbon (PAH) growth. A sensitivity analysis has been conducted to guide us in improving the correlation with modelled and measured species’ profiles in an n-decane – air combustion environment. It was reassuring that the mechanism could be successfully applied to an out of sample set of experimental profiles for acetylene combustion and showed a noticeable improvement over a previous reaction model. In order to calculate the soot volume fraction, a previously developed soot model was employed that accounts for soot particle coagulation, aggregation and surface growth. The impact of pressure, equivalence ratio and residence time on soot formation for a surrogate aviation fuel-air combustion in a Perfectly Stirred Reactor was also investigated. Generally speaking, the level of soot increased with increasing pressure, residence time and equivalence ratio.

Investigation of Soot Formation in Fuel-Rich Premixed Propane/Air Microcombustion at Low Temperatures

2020 ◽  
Author(s):  
Abdul H. Khalid ◽  
Jiashen Tian ◽  
Brent B. Skabelund ◽  
Ryan J. Milcarek
Keyword(s):  
Equivalence Ratio ◽  
Flow Reactor ◽  
Soot Formation ◽  
Inert Gas ◽  
Flow Rates ◽  
Soot Precursor ◽  
Before And After ◽  
Micro Flow ◽  
Gas Dilution ◽  
Lower Temperature

Abstract The advantage of micro/meso combustion includes higher efficiency, improved heat and mass transfer, swift startup and shutdown when compared with regular combustion. This study aims to investigate the critical sooting equivalence ratio and soot precursor formation in a micro-flow reactor with a controlled temperature profile of diameter 2.3mm and their dependence on the temperature ranging from 800–1250 °C. The equivalence ratio is varied from 1–13 and flow rates of 10 and 100sccm were investigated. Also, nitrogen is used to study the effect of inert gas dilution. A gas chromatograph is used to study the exhaust gas composition. The reactor is analyzed visually for the traces of soot particles before and after combustion, each time the temperature and/or equivalence ratio is varied. From 750–950°C, no soot is indicted at all equivalence ratios even up to 100. The inert gas dilution helped in raising the critical sooting equivalence ratio as expected because of the lower temperature. The results indicated an opposite trend to what has been well understood for the pre-mixed sooting flames, i.e., decreasing temperature decreases soot formation. The capability of the reactor to examine the effects of temperature on the critical sooting equivalence ratio at different flow rates has been successfully demonstrated.

scholarly journals A comparison of experimental results of soot production in laminar premixed flames

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Nattan R. Caetano ◽  
Diego Soares ◽  
Roger P. Nunes ◽  
Fernando M. Pereira ◽  
Paulo Smith Schneider ◽  
...  
Keyword(s):  
Equivalence Ratio ◽  
Computational Models ◽  
Volume Fraction ◽  
Soot Formation ◽  
Measurement Techniques ◽  
Soot Volume Fraction ◽  
Light Extinction ◽  
Burner Surface ◽  
Experimental Database ◽  
Premixed Laminar

AbstractSoot emission has been the focus of numerous studies due to the numerous applications in industry, as well as the harmful effects caused to the environment. Thus, the purpose of this work is to analyze the soot formation in a flat flame burner using premixed compressed natural gas and air, where these quasi-adiabatic flames have one-dimensional characteristics. The measurements were performed applying the light extinction technique. The air/fuel equivalence ratiowas varied to assess the soot volume fractions for different flame configurations. Soot production along the flamewas also analyzed by measurements at different heights in relation to the burner surface. Results indicate that soot volume fraction increases with the equivalence ratio. The higher regions of the flamewere analyzed in order to map the soot distribution on these flames. The results are incorporated into the experimental database for measurement techniques calibration and for computational models validation of soot formation in methane premixed laminar flames, where the equivalence ratio ranging from 1.5 up to 8.

Effect of radical quenching on CH4/air flames in a micro flow reactor with a controlled temperature profile

2015 ◽  
Vol 35 (3) ◽  
pp. 3389-3396 ◽  
Author(s):  
Yuta Kizaki ◽  
Hisashi Nakamura ◽  
Takuya Tezuka ◽  
Susumu Hasegawa ◽  
Kaoru Maruta
Keyword(s):  
Temperature Profile ◽  
Flow Reactor ◽  
Micro Flow

Analytical Formulation-Based Soot Modelling in Ethylene Laminar Jet Diffusion Flames

2021 ◽  
Author(s):  
Amit Makhija ◽  
Krishna Sesha Giri
Keyword(s):  
Volume Fraction ◽  
Diffusion Flames ◽  
Soot Formation ◽  
Mixture Fraction ◽  
Soot Volume Fraction ◽  
Smoke Point ◽  
Computational Time ◽  
Detailed Model ◽  
Conservation Equations ◽  
Oxidation Rates

Abstract Soot volume fraction predictions through simulations carried out on OpenFOAM® are reported in diffusion flames with ethylene fuel. A single-step global reaction mechanism for gas-phase species with an infinitely fast chemistry assumption is employed. Traditionally soot formation includes inception, nucleation, agglomeration, growth, and oxidation processes, and the individual rates are solved to determine soot levels. However, in the present work, the detailed model is replaced with the soot formation and oxidation rates, defined as analytical functions of mixture fraction and temperature, where the net soot formation rate can be defined as the sum of individual soot formation and oxidation rates. The soot formation/oxidation rates are modelled as surface area-independent processes. The flame is modelled by solving conservation equations for continuity, momentum, total energy, and species mass fractions. Additionally, separate conservation equations are solved to compute the mixture fraction and soot mass fraction consisting of source terms that are identical and account for the mixture fraction consumption/production due to soot. As a consequence, computational time can be reduced drastically. This is a quantitative approach that gives the principal soot formation regions depending on the combination of local mixture fraction and temperature. The implemented model is based on the smoke point height, an empirical method to predict the sooting propensity based on fuel stoichiometry. The model predicts better soot volume fraction in buoyant diffusion flames. It was also observed that the optimal fuel constants to evaluate soot formation rates for different fuels change with fuel stoichiometry. However, soot oxidation strictly occurs in a particular region in the flame; hence, they are independent of fuel. The numerical results are compared with the experimental measurements, showing an excellent agreement for the velocity and temperature. Qualitative agreements are observed for the soot volume fraction predictions. A close agreement was obtained in smoke point prediction for the overventilated flame. An established theory through simulations was also observed, which states that the amount of soot production is proportional to the fuel flow rate. Further validations underscore the predictive capabilities. Model improvements are also reported with better predictions of soot volume fractions through modifications to the model constants based on mixture fraction range.

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