Detailed Kinetic Modeling of Soot-Particle and Key-Precursor Formation in Laminar Premixed and Counterflow Diffusion Flames of Fossil Fuel Surrogates

This study reports a chemical kinetics soot model for combustion of engine-relevant fuels. The scheme accounts for both low- and high-temperature oxidation, considering their crucial role in engine combustion process. The mechanism is validated against several ignition delay times and laminar burning velocities data sets for single and mixtures of hydrocarbons. To assess the mechanism ability to predict soot precursors, formation of aromatic and aliphatic species with critical effects on soot formation is investigated for several laminar premixed and diffusion flames. The model includes soot particle inception, surface growth, coagulation, and aggregation based on the method of moments. The performance of the model is evaluated by predicting the amount of produced soot during heavy alkanes and aromatic species mixtures pyrolysis. The results are encouraging, proving this methodology to be a suitable tool to simulate the all-round combustion features of engine fuel surrogates by a single reaction model.

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Development and Application of a Reversible PAH Formation Model for Soot Prediction in Complex Fuel CFD Applications

Volume 4A: Combustion, Fuels, and Emissions ◽

10.1115/gt2020-14692 ◽

2020 ◽

Author(s):

Florian Eigentler ◽

Peter Gerlinger ◽

Manfred Aigner ◽

Ruud Eggels

Keyword(s):

Diffusion Flames ◽

Soot Formation ◽

Hydrogen Abstraction ◽

Equation Model ◽

General Validity ◽

Mixing Ratios ◽

Ignition Delay Times ◽

Soot Precursors ◽

Wide Range ◽

Soot Model

Abstract An improved modelling approach for polycyclic aromatic hydrocarbons (PAHs) and soot formation in complex fuels is presented. The introduction of PAH radicals allows a reversible growth by hydrogen abstraction and carbon addition. Emphasis is placed on the model’s general validity with respect to fuel flexibility and operating condition using one set of model constants. A detailed gas phase mechanism describes the decomposition of fuel species as well as the formation and growth of PAHs and soot precursors. PAHs and PAH radicals are described by a sectional approach. Soot particle dynamics are modeled either by a two-equation model or alternatively by a sectional approach. All models take the processes of growth, collision, oxidation and agglomeration into account. The introduction of a temperature-dependent collision coefficient enhances the PAH and soot interaction. The differences between the two-equation model and the sectional approach are investigated. An extensive set of shock tube experiments is examined to verify the developed PAH and soot model over a wide range of temperatures, pressures, fuels and mixing-ratios. Thereby, the pyrolysis and oxidation of ethylene, benzene, kerosene and its major components are examined. In addition, ignition delay times and laminar diffusion flames are used for further validation. The overall agreement to experimental data demonstrates the applicability of the presented PAH and soot model even for complex fuels.

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Soot Formation in Propane/Air Diffusion Flames

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.668.123 ◽

2013 ◽

Vol 668 ◽

pp. 123-127 ◽

Cited By ~ 1

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.

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In-situ Combustion Simulation from Laboratory to Field Scale

Geofluids ◽

10.1155/2021/8153583 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Zhouyuan Zhu ◽

Canhua Liu ◽

Yajing Chen ◽

Yuning Gong ◽

Yang Song ◽

...

Keyword(s):

Combustion Process ◽

Reaction Model ◽

Field Scale ◽

Arrhenius Kinetics ◽

Kinetics Parameters ◽

In Situ Combustion ◽

Temperature Oxidation ◽

Reservoir Volume ◽

Combustion Simulation

In-situ combustion simulation from laboratory to field scale has always been challenging, due to difficulties in deciding the reaction model and Arrhenius kinetics parameters, together with erroneous results observed in simulations when using large-sized grid blocks. We present a workflow of successful simulation of heavy oil in-situ combustion process from laboratory to field scale. We choose the ongoing PetroChina Liaohe D block in-situ combustion project as a case of study. First, we conduct kinetic cell (ramped temperature oxidation) experiments, establish a suitable kinetic reaction model, and perform corresponding history match to obtain Arrhenius kinetics parameters. Second, combustion tube experiments are conducted and history matched to further determine other simulation parameters and to determine the fuel amount per unit reservoir volume. Third, we upscale the Arrhenius kinetics to the upscaled reaction model for field-scale simulations. The upscaled reaction model shows consistent results with different grid sizes. Finally, field-scale simulation forecast is conducted for the D block in-situ combustion process using computationally affordable grid sizes. In conclusion, this work demonstrates the practical workflow for predictive simulation of in-situ combustion from laboratory to field scale for a major project in China.

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Effects of aromatic on soot characteristics of aviation fuel surrogates in diffusion flames

Science and Technology Development Journal ◽

10.32508/stdj.v18i4.986 ◽

2015 ◽

Vol 18 (4) ◽

pp. 55-64

Author(s):

Thong Duc Hong ◽

Osamu Fujita

Keyword(s):

Diffusion Flames ◽

Soot Formation ◽

Linear Functions ◽

Aviation Fuel ◽

Light Extinction ◽

Flame Height ◽

Aircraft Engines ◽

Mass Consumption ◽

Function Of Two Variables ◽

Fuel Surrogates

Co-annular smoke-free laminar diffusion wick-fed flames of dodecane and its blended with various amounts of propylbenzene of 10, 20, 25 vol.% have been used to study soot formation characteristics. Dodecane and propylbenzene are selected as the surrogates for paraffin class and aromatic class of aviation fuel. A light extinction method is adopted to determine the total soot volume (TSV) as a function of flame height (Hf) and fuel mass consumption rate (FMCR). An empirical model has been built to predict soot formation of dodecane and propylbenzene (Do/PB) mixtures as the function of two variables of FMCR and concentration of propylbenzenet (%PB). TSVs of Do/PB mixtures increase with increasing Hf, FMCR and %PB. The effect of Hf, FMCR and %PB on soot formation are respectively expressed as the quadratic, power law and linear functions. The result of current work creates a database for optimizing the trade-off impacts of aromatic in aviation fuel. This information is of high importance when blending aromatic to bioparaffins, which is produced from triglycerides and fatty acids in the vegetable by hydrotreating process, for using as a fuel in aircraft engines.

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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 ◽

10.3390/en14123671 ◽

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.

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Isothermal Kinetic Analysis of the Thermal Decomposition of Wood Chips from an Apple Tree

Processes ◽

10.3390/pr9020195 ◽

2021 ◽

Vol 9 (2) ◽

pp. 195

Author(s):

Ivan Vitázek ◽

Martin Šotnar ◽

Stella Hrehová ◽

Kristína Darnadyová ◽

Jan Mareček

Keyword(s):

Thermal Decomposition ◽

Apple Tree ◽

Combustion Process ◽

Reaction Model ◽

Wood Chips ◽

Small Scale ◽

Exponential Factor ◽

Air Atmosphere ◽

First Order Chemical Reaction ◽

Isothermal Kinetic

The thermal decomposition of wood chips from an apple tree is studied in a static air atmosphere under isothermal conditions. Based on the thermogravimetric analysis, the values of the apparent activation energy and pre-exponential factor are 34 ± 3 kJ mol−1 and 391 ± 2 min−1, respectively. These results have also shown that this process can be described by the rate of the first-order chemical reaction. This reaction model is valid only for a temperature range of 250–290 °C, mainly due to the lignin decomposition. The obtained results are used for kinetic prediction, which is compared with the measurement. The results show that the reaction is slower at higher values of degree of conversion, which is caused by the influence of the experimental condition. Nevertheless, the obtained kinetic parameters could be used for the optimization of the combustion process of wood chips in small-scale biomass boilers.

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