Download or read book An Experimental Study of Soot Formation and Oxidation in Axisymmetric Counterflow Diffusion Flames written by Keunchul Lee and published by . This book was released on 1991 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental and Numerical Contributions to Soot Production in Laminar Axisymmetric Diffusion Flames written by Felipe Andrés Escudero Barros and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study was performed with the main objective of characterizing soot production for different oxygen indices (OIs) in normal (NDFs) and inverse (IDFs) diffusion flames. Specific absorption-emission based methods were developed, implemented and validated to measure soot volume fraction and temperature. It was found that for IDFs, an increase on the OI produces an enhancement of soot formation but does not affect oxidation processes, leading to an increase on soot volume fraction and radiant fraction. In addition, a scaling analysis based on the smoke point (SP) resulted on a unified behavior for ethylene, propane and butane fueled NDFs in terms of flame height, soot volume fraction and radiant fraction at SP. In a second step, a numerical study was performed with the main objective of evaluating the predictive capabilities of the sectional method (SM) and three methods of moments (MOMs) for the resolution of the population balance equation (PBE) for soot particle size distribution (PSD). For this purpose, the MOMs were added to an existing parallel code for simulating laminar axisymmetric diffusion flames. The SM was able to reproduce the available experimental data whereas the MOMs were not able to predict details of soot morphology with the same level of accuracy. An analysis on the main differences between the SM and MOMs was performed. The main issue identified for the MOMs was the inability to satisfy the assumption of conservation of number density of primary particles and number of primary particles per aggregate during soot surface processes.

Download or read book A Fundamental Study of Soot Formation in Diffusion Flames written by Richard L. Axelbaum and published by . This book was released on 1988 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulation of AxiSymmetric Laminar Diffusion Flames with Soot written by Adhiraj Dasgupta and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Detailed numerical modeling of combustion phenomena, soot formation, and radi-ation is an active area of research. In this work a general-purpose, pressure-based,finite volume code for modeling laminar diffusion flames has been incorporatedinto the CFD code OpenFOAM. The code uses a mixture-averaged model for thecalculation of transport coefficients, and can be used to perform detailed modelingof multi-dimensional laminar flames using realistic molecular transport, and withdetailed chemical mechanisms containing hundreds of chemical species and reac-tions. Two soot models have been incorporated into the code: a semi-empiricaltwo-equation model, as well as a detailed Method of Moments with InterpolativeClosure (MOMIC). An emission-only, optically-thin radiation model has also beenincluded in the code to account for the radiative heat loss, and sophisticated radia-tion models with detailed calculations of spectral properties and radiative intensityhave also been included. The flame code showed excellent scalability on massivelydistributed, high-performance computer systems. The code has been validated bymodeling four axisymmetric, co-flowing laminar diffusion flames, and the resultshave been found to be mostly within experimental uncertainty, and comparableto results reported in the literature for the same and similar configurations. Anumber of parametric studies to study the effects of detailed gas-phase chemistry,soot models and radiation have also been performed on these flame configurations.It has been found that the flames considered in this work are all optically thin,and so the simple, emission-only, optically-thin radiation model can be used tomodel these flames with good accuracy and a reasonable computational effort. Inparticular, the detailed radiation models increase the computational cost by twoorders of magnitude, and thus their applicability in a detailed calculation may belimited.It was found that the two-equation soot model used in conjunction with a gas-phase mechanism that adequately describes the combustion of C2 hydrocarbons produces results in close agreement with experimental data for a 1-bar ethylene-airflame, a 10 bar methane-air flame, as well as an ethane-air flame at 10 bar. Thedetailed MOMIC soot model requires the use of a larger, more detailed gas-phasechemical mechanism containing polycyclic aromatic hydrocarbons (PAH) with fourrings, and thus the computational cost associated with the MOMIC soot modelis significantly higher. The detailed model was used to model the flames, andcomputed soot levels were within a factor of two of the experimental values, whichis typically considered good agreement considering the complex physics involved.The last flame studied using both the soot models was a N2 -diluted ethylene-airflame, in which the predicted values of major gas-phase species were seen to be closeto the experimental values, but the soot levels were off by an order of magnitude.Notwithstanding the lack of agreement with measurements for this flame, the flamesolver with the soot models was demonstrated to be a robust, scalable, and generalcode with potential applications to a variety of laminar flames in the non-premixed,partially premixed and premixed regimes.

Download or read book Soot Formation in Non premixed Laminar Flames at Subcritical and Supercritical Pressures written by Hyun Il Joo and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study was conducted using axisymmetric co-flow laminar diffusion flames of methane-air, methane-oxygen and ethylene-air to examine the effect of pressure on soot formation and the structure of the temperature field. A liquid fuel burner was designed and built to observe the sooting behavior of methanol-air and n-heptane-air laminar diffusion flames at elevated pressures up to 50 atm. A non-intrusive, line-of-sight spectral soot emission (SSE) diagnostic technique was used to determine the temperature and the soot volume fraction of methane-air flames up to 60 atm, methane-oxygen flames up to 90 atm and ethylene-air flames up to 35 atm. The physical flame structure of the methane-air and methane-oxygen diffusion flames were characterized over the pressure range of 10 to 100 atm and up to 35 atm for ethylene-air flames. The flame height, marked by the visible soot radiation emission, remained relatively constant for methane-air and ethylene-air flames over their respected pressure ranges, while the visible flame height for the methane-oxygen flames was reduced by over 50 % between 10 and 100 atm. During methane-air experiments, observations of anomalous occurrence of liquid material formation at 60 atm and above were recorded. The maximum conversion of the carbon in the fuel to soot exhibited a strong power-law dependence on pressure. At pressures 10 to 30 atm, the pressure exponent is approximately 0.73 for methane-air flames. At higher pressures, between 30 and 60 atm, the pressure exponent is approximately 0.33. The maximum fuel carbon conversion to soot is 12.6 % at 60 atm. For methane-oxygen flames, the pressure exponent is approximately 1.2 for pressures between 10 and 40 atm. At pressures between 50 and 70 atm, the pressure exponent is about -3.8 and approximately -12 for 70 to 90 atm. The maximum fuel carbon conversion to soot is 2 % at 40 atm. For ethylene-air flames, the pressure exponent is approximately 1.4 between 10 and 30 atm. The maximum carbon conversion to soot is approximately 6.5 % at 30 atm and remained constant at higher pressures.

Download or read book Soot Formation in Combustion written by Henning Bockhorn and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 595 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soot Formation in Combustion represents an up-to-date overview. The contributions trace back to the 1991 Heidelberg symposium entitled "Mechanism and Models of Soot Formation" and have all been reedited by Prof. Bockhorn in close contact with the original authors. The book gives an easy introduction to the field for newcomers, and provides detailed treatments for the specialists. The following list of contents illustrates the topics under review:

Download or read book Effects of Pressure on the Mechanisms of Soot Formation and Oxidation in Laminar Diffusion Flames written by Chul Han Kim and published by . This book was released on 2005 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Soot Formation in Non premixed Laminar Flames at Subcritical and Supercritical Pressures written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study was conducted using axisymmetric co-flow laminar diffusion flames of methane-air, methane-oxygen and ethylene-air to examine the effect of pressure on soot formation and the structure of the temperature field. A liquid fuel burner was designed and built to observe the sooting behavior of methanol-air and n-heptane-air laminar diffusion flames at elevated pressures up to 50 atm. A non-intrusive, line-of-sight spectral soot emission (SSE) diagnostic technique was used to determine the temperature and the soot volume fraction of methane-air flames up to 60 atm, methane-oxygen flames up to 90 atm and ethylene-air flames up to 35 atm. The physical flame structure of the methane-air and methane-oxygen diffusion flames were characterized over the pressure range of 10 to 100 atm and up to 35 atm for ethylene-air flames. The flame height, marked by the visible soot radiation emission, remained relatively constant for methane-air and ethylene-air flames over their respected pressure ranges, while the visible flame height for the methane-oxygen flames was reduced by over 50 % between 10 and 100 atm. During methane-air experiments, observations of anomalous occurrence of liquid material formation at 60 atm and above were recorded. The maximum conversion of the carbon in the fuel to soot exhibited a strong power-law dependence on pressure. At pressures 10 to 30 atm, the pressure exponent is approximately 0.73 for methane-air flames. At higher pressures, between 30 and 60 atm, the pressure exponent is approximately 0.33. The maximum fuel carbon conversion to soot is 12.6 % at 60 atm. For methane-oxygen flames, the pressure exponent is approximately 1.2 for pressures between 10 and 40 atm. At pressures between 50 and 70 atm, the pressure exponent is about -3.8 and approximately -12 for 70 to 90 atm. The maximum fuel carbon conversion to soot is 2 % at 40 atm. For ethylene-air flames, the pressure exponent is approximately 1.4 between 10 and 30 atm. The maximu.

Download or read book A Study of the Fuel Oxygen Effect on Soot Formation in Counterflow Diffusion Flames written by Harjit Singh Hura and published by . This book was released on 1988 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Detailed Modeling of Soot Formation Oxidation in Laminar Coflow Diffusion Flames written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: PhD.

Download or read book Detailed Modeling of Soot Formation oxidation in Laminar Coflow Diffusion Flames written by Qingan Zhang and published by . This book was released on 2009 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first goal of this thesis is to develop and validate a modeling tool into which fundamental combustion chemistry and aerosol dynamics theory are implemented for investigating soot formation/oxidation in multi-dimensional laminar coflow diffusion flames taking into account soot polydispersity and fractal-like aggregate structure. The second goal is to use the tool to study soot aggregate formation/oxidation in experimentally studied laminar coflow diffusion flames to advance the understanding of soot aggregate formation/oxidation mechanism.The first part of the thesis deals with the large CPU time problem when detailed models are coupled together. Using the domain decomposition method, a high performance parallel flame code is successfully developed. An advanced sectional aerosol dynamics model which can model fractal-like aggregate structure is successfully implemented into the parallel flame code. The performance of the parallel code is demonstrated through its application to the modeling of soot formation/oxidation in a laminar coflow CH4/air diffusion flame. The parallel efficiency reaches as high as 83%.In the third part of the thesis, the effects of oxidation-driven soot aggregate fragmentation on aggregate structure and soot oxidation rate are studied. Three fragmentation models with different fragmentation patterns are developed and implemented into the sectional aerosol dynamics model. The implementation of oxidation-driven aggregate fragmentation significantly improves the prediction of soot aggregate structure in the soot oxidation region.The second part of the thesis numerically explores soot aggregate formation in a laminar coflow C2H4/air diffusion flame using detailed PAH-based combustion chemistry and a PAH-based soot formation/oxidation model. Compared to the measured data, flame temperature, axial velocity, C2 H2 and OH concentrations, soot volume fraction, the average diameter and the number density of primary particles are reasonably well predicted. However, it is very challenging to predict effectively the average degree of particle aggregation. To do so, particle-particle and fluid-particle interactions that may cause non-unitary soot coagulation efficiency need to be considered. The original coagulation model is enhanced in this thesis to accommodate soot coagulation efficiency. Different types of soot coagulation efficiency are numerically investigated. It is found that a simple adjustment of soot coagulation efficiency from 100% to 20% provides good predictions on soot aggregate structure as well as flame properties.

Download or read book High pressure Soot Formation and Diffusion Flame Extinction Characteristics of Gaseous and Liquid Fuels written by Ahmet Emre Karatas and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Study of NOx Production in Sooty Radiating Counterflow Diffusion Flames written by Han-Kyoo Kim and published by . This book was released on 1998 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Experimental Study of the Processes Involved in the Formation of Soot Particles in Diffusion Flames written by Uri Vandsburger and published by . This book was released on 1986 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanisms Controlling Soot Formation in Diffusion Flames written by and published by . This book was released on 1997 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: Arclength continuation methods were incorporated into a code for predicting the structure of sooting, opposed-jet flames. The code includes complex chemistry, detailed particle dynamics, particle chemistry and radiation. The code was used to predict soot production over a wide variation in strain rates for both ethylene/air and methane/air diffusion flames. Predicted values (both peak and spatial distributions) agree well with experimental measurements in ethylene flames. Particle size distributions are also predicted using the aerosol equations from MAEROS, but no data is available for comparison. Also, the soot dynamical equations were imbedded into a separate code to describe soot production in a coflow, laminar, diffusion flame which includes treatment of detailed, gas phase chemistry. Predictions were compared to measurements made in a methane, coflow flame. Reasonable agreement between the predictions and measurements was obtained, although a factor of three underprediction of the soot volume fractions is likely due to uncertainties in inlet conditions and an inability to match closely bulk flame parameters such as temperature. Predicted peak soot production occurred around 1720K and particle oxidation was dominated by superequilibrium concentrations of hydroxyl radicals. Several PAH-forming sequences were examined and compared to the traditional acetylene-addition sequence. A sequence involving benzyl-propargyl combination was found to compete with the traditional mechanism and it should be included in future analyses. The algorithms for treating sectional soot dynamics and growth/oxidation rates were modified to include effects at high pressure. Continuum effects and limitations to gaseous diffusion were included in the opposed jet code. Predicted variations in soot production due to pressure changes from 4 to 10 atmospheres were made for an ethylene-air,

Download or read book The Effects of Unsteady Hydrodynamics on Soot Formation in a Counterflow Diffusion Flame written by Michele Elaine Riggen-DeCroix and published by . This book was released on 1998 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Detailed Studies of Soot Formation in Laminar Diffusion Flames for Application to Modeling Studies written by and published by . This book was released on 1993 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation of soot formation in laminar diffusion flames has shown that soot particle surface growth under laminar diffusion flame conditions ceases because of the depletion of hydrocarbon species, in particular acetylene and benzene, and not due soot particle reactivity loss due to thermal aging of the particles. This results has been obtained through direct species concentration measurements under well controlled conditions while the particle reactivity effects were calculated based on premixed flame results along with particle temperature/time information available from earlier laminar diffusion flame studies. Comparisons with a soot formation model which incorporated detailed chemistry effects showed good agreement in terms of predicted and measured species concentration and soot particle field evolution. In addition, a novel technique for measuring soot volume fraction has been developed based on laser-induced incandescence and applied to similar laminar diffusion flame, studies with good success. This technique represents a major development in terms of its ability to make soot volume fraction measurements in unsteady inhomogeneous combusting flows. Soot formation, Soot particles, Diffusion flames.