A Comparative Performance Study of Soot Formation Models in Methane Elevated Pressure Non-Premixed Flames

2011 ◽  
Vol 110-116 ◽  
pp. 18-22 ◽  
Author(s):  
A. Yunardi ◽  
B. Elwina ◽  
Sylvia Novi ◽  
D. Wusnah ◽  
Bindar Yazid
Keyword(s):  
Experimental Data ◽  
Soot Formation ◽  
Elevated Pressure ◽  
Single Step ◽  
Performance Study ◽  
Ethylene Flame ◽  
Step Model ◽  
Radial Profiles ◽  
Dissipation Model ◽  
Soot Model

This paper presents results obtained from the application of a computational fluid dynamics (CFD) code Fluent 6.3 to modeling of elevated pressure methane non-premixed sooting flames. The study focuses on comparing the two soot models available in the code for the prediction of the soot level in the flames. A standard k-ε model and Eddy Dissipation model are utilized for the representation of flow field and combustion of the flame being investigated. For performance comparison study, a single step soot model of Khan and Greeves and two-step soot model proposed by Tesner are tested. The results of calculations are compared with experimental data of methane sooting flame taken from literature. The results of the study show that a combination of the standard k-ε turbulence model and eddy dissipation model is capable of producing reasonable predictions of temperature both in axial and radial profiles; although further downstream of the flame over-predicted temperature is evidence. With regard to soot model performance study, it shows that the two-step model clearly performed far better than the single-step model in predicting the soot level in ethylene flame at both axial and radial profiles. With a modification in the constant α of the soot formation equation, the two-step model was capable of producing prediction of soot level closer to experimental data. In contrast, the single-step soot model produced very poor results, leading to a significant under-prediction of soot levels in both flames. Although the Tesner’s soot model is simpler than the current available models, this model is still capable of providing reasonable agreement with experimental data, allowing its application for the purpose of design and operation of an industrial combustion system.

scholarly journals Experimental and Numerical Investigation of Stepped Planing Hulls in Finding an Optimized Step Location and Analysis of Its Porpoising Phenomenon

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Sayyed Mahdi Sajedi ◽  
Parviz Ghadimi
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Three Dimensional ◽  
Single Step ◽  
Hydrodynamic Resistance ◽  
Resistance Reduction ◽  
Step Model ◽  
Volume Method ◽  
Mesh Technique ◽  
Good Agreement

Stability of a high-speed craft is an essential matter, and porpoising is one of the most critical instabilities that could occur in some planing hulls due to inappropriate design. In this paper, the porpoising phenomenon and variation of step location yielding resistance reduction are studied through experimental and numerical methods. The investigated models include a single-step model and a nonstep model with the same general shape, but with different step location. The nonstep model is previously tested, but the single-step model is examined in the present study. The nonstep model experiences porpoising at 8 m/s speed, but the single-step model remains stable at the same speed. A three-dimensional CFD analysis is conducted using the finite volume method (FVM). On the contrary, the volume of fluid (VOF) scheme is used for free surface modeling, and the overset mesh technique is implemented within StarCCM+ software. The CFD results of total hydrodynamic resistance and dynamic trim angle are compared against the experimental data. The numerical results are in good agreement with the experimental data. Subsequently, ten different stepped models are simulated to examine their effects. The longitudinal distance between steps and aft of these models are in the range of 19 to 50 percent of the length of models. The obtained results show that as steps are located farther than aft, the models become more stable, and resistance increases due to trim reduction. Finally, the optimum location of the step is extracted with the aim of minimizing the resistance through the design of experiment (DOE) method. Based on the DOE method, it is observed that the sensitivity of the drag value to the step location is higher than the speed.

Comparison of soot models for reacting sprays in diesel engine-like conditions

2021 ◽  
pp. 095440702110154
Author(s):  
Pavan Prakash Duvvuri ◽  
Rajesh Kumar Shrivastava ◽  
Sheshadri Sreedhara
Keyword(s):  
Experimental Data ◽  
Volume Fraction ◽  
Soot Volume Fraction ◽  
Modeling Framework ◽  
Aerosol Dynamics ◽  
Significant Difference ◽  
Polycyclic Aromatic ◽  
Order Of Magnitude ◽  
Detailed Kinetics ◽  
Soot Model

Stringent emission legislations and growing health concerns have contributed to the evolution of soot modeling in diesel engines from simple empirical relations to methods involving detailed kinetics and complex aerosol dynamics. In this paper, four different soot models have been evaluated for the high temperature, high pressure combusting dodecane spray cases of engine combustion network (ECN) spray A which mimics engine-relevant conditions. The soot models considered include an empirical, a multistep, a method of moments based, and a discrete sectional method soot model. Two experimental cases with ambient oxygen volume of 21% and 15% have been modeled. A good agreement between simulations and experiments for vapor penetration and heat release rate has been obtained. Quasi-steady soot volume fraction contours for the four soot models have been compared with experiments. Contours of the species and source terms involved in soot modeling have also been compared for a better understanding of soot processes. The empirical soot model results in higher magnitude and spread of soot due to a lack of modeling framework for oxidation through OH species. Among the four models studied, the multistep soot model has been observed to provide the most promising agreement with the experimental data in terms of distribution of soot and location of peak soot volume fraction. Due to a two-way coupling of soot models, the detailed models predict an upstream location for soot as compared to the multi-step soot model which is one way coupled. A significant difference (of an order of magnitude) in the concentration of PAH (polycyclic aromatic hydrocarbons) precursor between multistep and detailed soot models has been observed because of precursor consumption due to the coupling of detailed soot models with chemical kinetics. It is recommended that kinetic schemes, especially those concerning PAH, be validated with experimental data with a kinetics-coupled soot model.

scholarly journals Modeling study of soot formation and oxidation in DI diesel engine using an improved soot model

2014 ◽  
Vol 62 (2) ◽  
pp. 303-312 ◽  
Author(s):  
Xiaobei Cheng ◽  
Liang Chen ◽  
Guang Hong ◽  
Fangqin Yan ◽  
Shijun Dong
Keyword(s):  
Diesel Engine ◽  
Soot Formation ◽  
Di Diesel Engine ◽  
Soot Model ◽  
Modeling Study

scholarly journals Equilibrium Modeling of Astaxanthin Extraction from Haematococcus pluvialis

2021 ◽  
Vol 21 (3) ◽  
pp. 554
Author(s):  
Putri Restu Dewati ◽  
Rochmadi Rochmadi ◽  
Abdul Rohman ◽  
Avido Yuliestyan ◽  
Arief Budiman
Keyword(s):  
Experimental Data ◽  
High Performance ◽  
Haematococcus Pluvialis ◽  
Equilibrium Constants ◽  
Extraction Methods ◽  
Single Step ◽  
Equilibrium Models ◽  
Extraction Equilibrium ◽  
Assisted Extraction ◽  
Solid Liquid

Astaxanthin is a natural antioxidant, and the highest content of this compound is found in Haematococcus pluvialis microalgae. Microwave-assisted extraction (MAE) is one of the environmentally friendly extraction methods and has many advantages. This study aims to investigate the extraction of astaxanthin through the MAE method using various solvents. Several equilibrium models were proposed to describe this solid-liquid equilibrium. The solid-liquid extraction equilibrium parameters were determined by minimizing the sum of squares of errors (SSE), in which equilibrium constants were needed for scaling up purposes. Previously, the microalgae were pretreated with HCl to soften their cell walls in order to improve the extraction recovery. In this study, dichloromethane, acetone, methanol, and ethanol were used as the solvents for extraction. The astaxanthin concentration was determined by high-performance liquid chromatography (HPLC) and spectrophotometry. Astaxanthin was found to attain equilibrium at 57.42% recovery in a single-step extraction. Thus, several steps were required in sequence to obtain an optimum recovery. The experimental data were fitted to three equilibrium models, namely, Henry, Freundlich, and Langmuir models. The experimental data were well fitted to all the models for the extraction in dichloromethane, methanol, ethanol and acetone, as evident from the almost same SSE value for each model.

scholarly journals Numerical analysis of pulverized biomass combustion

2021 ◽  
Vol 321 ◽  
pp. 01001
Author(s):  
Cansu Deniz Canal ◽  
Erhan Böke ◽  
Ali Cemal Benim
Keyword(s):  
Gas Phase ◽  
Radiative Heat ◽  
Particle Dispersion ◽  
Single Step ◽  
Biomass Combustion ◽  
Phase Conversion ◽  
Two Phase ◽  
Dissipation Model ◽  
Turbulent Particle Dispersion ◽  
Step Mechanism

Combustion of pulverized biomass in a laboratory swirl burner is computationally investigated. The two-phase flow is modelled by an Eulerian-Lagrangian approach. The particle size distribution and turbulent particle dispersion are considered. The radiative heat transfer is modelled by the P1 method. For modelling turbulence, different RANS modelling approaches are applied. The pyrolysis of the solid fuel is modelled by a single step mechanism. For the combustion of the volatiles a two-step reaction mechanism is applied. The gas-phase conversion rate is modelled by the Eddy Dissipation Model, combined with kinetics control. The results are compared with measurements.

scholarly journals Investigating the Effects of Chemical Mechanism on Soot Formation Under High-Pressure Fuel Pyrolysis

2021 ◽  
Vol 7 ◽  
Author(s):  
Nick J. Killingsworth ◽  
Tuan M. Nguyen ◽  
Carter Brown ◽  
Goutham Kukkadapu ◽  
Julien Manin
Keyword(s):  
High Pressure ◽  
Soot Formation ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Chemical Mechanism ◽  
Navier Stokes ◽  
Chemical Mechanisms ◽  
Constant Volume Combustion Chamber ◽  
Fuel Pyrolysis ◽  
Soot Model

We performed Computational Fluid Dynamics (CFD) simulations using a Reynolds-Averaged Navier-Stokes (RANS) turbulence model of high-pressure spray pyrolysis with a detailed chemical kinetic mechanism encompassing pyrolysis of n-dodecane and formation of polycyclic aromatic hydrocarbons. We compare the results using the detailed mechanism and those found using several different reduced chemical mechanisms to experiments carried out in an optically accessible, high-pressure, constant-volume combustion chamber. Three different soot models implemented in the CONVERGE CFD software are used: an empirical soot model, a method of moments, and a discrete sectional method. There is a large variation in the prediction of the soot between different combinations of chemical mechanisms and soot model. Furthermore, the amount of soot produced from all models is substantially less than experimental measurements. All of this indicates that there is still substantial work that needs to be done to arrive at simulations that can be relied on to accurately predict soot formation.

Prediction of Soot Formation Trends in Turbulent Kerosene-Air Diffusion Jet Flames With Elevated Operating Pressure

2017 ◽  
Author(s):  
Pravin Nakod ◽  
Saurabh Patwardhan ◽  
Ishan Verma ◽  
Stefano Orsino
Keyword(s):  
Environmental Protection Agency ◽  
Volume Fraction ◽  
Soot Formation ◽  
Mixture Fraction ◽  
Soot Volume Fraction ◽  
Operating Pressure ◽  
Jet Flames ◽  
Emission Standard ◽  
Radial Profiles ◽  
Air Diffusion

Emission standard agencies are coming up with more stringent regulations on soot, given its adverse effect on human health. It is expected that Environmental Protection Agency (EPA) will soon place stricter regulations on allowed levels of the size of soot particles from aircraft jet engines. Since, aircraft engines operate at varying operating pressure, temperature and air-fuel ratios, soot fraction changes from condition to condition. Computation Fluid Dynamics (CFD) simulations are playing a key role in understanding the complex mechanism of soot formation and the factors affecting it. In the present work, soot formation prediction from numerical analyses for turbulent kerosene-air diffusion jet flames at five different operating pressures in the range of 1 atm. to 7 atm. is presented. The geometrical and test conditions are obtained from Young’s thesis [1]. Coupled combustion-soot simulations are performed for all the flames using steady diffusion flamelet model for combustion and Mass-Brookes-Hall 2-equation model for soot with a 2D axisymmetric mesh. Combustion-Soot coupling is required to consider the effect of soot-radiation interaction. Simulation results in the form of axial and radial profiles of temperature, mixture fraction and soot volume fraction are compared with the corresponding experimental measured profiles. The results for temperature and mixture fraction compare well with the experimental profiles. Predicted order of magnitude and the profiles of the soot volume fraction also compare well with the experimental results. The correct trend of increasing the peak soot volume fraction with increasing the operating pressure is also captured.

Simulation of Particle Synthesis by Premixed Laminar Stagnation Flames

2013 ◽  
Vol 1506 ◽  
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.

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.

scholarly journals Experimental and computational investigation of temperature effects on soot mechanisms

2014 ◽  
Vol 79 (7) ◽  
pp. 881-895 ◽  
Author(s):  
Xiaojie Bi ◽  
Maoyu Xiao ◽  
Xinqi Qiao ◽  
Chia-Fon Lee ◽  
Liu Yu
Keyword(s):  
Ambient Temperature ◽  
Soot Formation ◽  
Oxidation Mechanism ◽  
Soot Oxidation ◽  
Ambient Temperatures ◽  
Operation Conditions ◽  
Constant Volume Chamber ◽  
Soot Mass ◽  
Soot Measurement ◽  
Soot Model

Effects of initial ambient temperatures on combustion and soot emission characteristics of diesel fuel were investigated through experiment conducted in optical constant volume chamber and simulation using phenomenological soot model. There are four difference initial ambient temperatures adopted in our research: 1000 K, 900 K, 800 K and 700 K. In order to obtain a better prediction of soot behavior, phenomenological soot model was revised to take into account the soot oxidation feedback on soot number density and good agreement was observed in the comparison of soot measurement and prediction. Results indicated that ignition delay prolonged with the decrease of initial ambient temperature. The heat release rate demonstrated the transition from mixing controlled combustion at high ambient temperature to premixed combustion mode at low ambient temperature. At lower ambient temperature, soot formation and oxidation mechanism were both suppressed. But finally soot mass concentration reduced with decreasing initial ambient temperature. Although the drop in ambient temperature did not cool the mean in-cylinder temperature during the combustion, it did shrink the total area of local high equivalence ratio, in which soot usually generated fast. At 700 K initial ambient temperature, soot emissions were almost negligible, which indicates that sootless combustion might be achieved at super low initial temperature operation conditions.

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