Download or read book Study of Morphology of Soot Particles in a Diffusion Flame Using the Discrete Dipole Approximation written by Amar Mahadeviah and published by . This book was released on 1991 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS)* at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dis semination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volumes were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 38 (thesis year 1993) a total of 13,787 thesis titles from 22 Canadian and 164 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this impor tant annual reference work. While Volume 38 reports theses submitted in 1993, on occasion, certain uni versities do report theses submitted in previous years but not reported at the time.

Download or read book Morphology of Diesel Soot Residuals from Supercooled Water Droplets and Ice Crystals written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Freshly emitted soot particles are fractal-like aggregates, but atmospheric processing often transforms their morphology. Morphology of soot particles plays an important role in determining their optical properties, life cycle and hence their effect on Earth's radiative balance. However, little is known about the morphology of soot particles that participated in cold cloud processes. Here we report results from laboratory experiments that simulate cold cloud processing of diesel soot particles by allowing them to form supercooled droplets and ice crystals at -20 and -40°C, respectively. Electron microscopy revealed that soot residuals from ice crystals were more compact (roundness~0.55) than those from supercooled droplets (roundness ~0.45), while nascent soot particles were the least compact (roundness~0.41). Optical simulations using the discrete dipole approximation showed that the more compact structure enhances soot single scattering albedo by a factor up to 1.4, thereby reducing the top-of-the-atmosphere direct radiative forcing by ~63%. Lastly, these results underscore that climate models should consider the morphological evolution of soot particles due to cold cloud processing to improve the estimate of direct radiative forcing of soot.

Download or read book Investigation of Light Scattering as a Technique for Detecting Discrete Soot Particles in a Luminous Flame written by David R. Schryer and published by . This book was released on 1978 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Theoretical and Experimental Studies on the Hygroscopic Properties of Soot Particles Sampled from a Kerosene Diffusion Flame written by Junteng Wu and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Freshly emitted soot particles from combustion processes are hydrophobic. However, the aging process in the atmosphere can modify their size, morphology and surface chemistry and turn them into efficient cloud condensation (CCN) and ice nuclei (IN) that significantly contribute to the indirect radiative forcing of climate. For spherical and monodisperse aerosols, k-Köhler theory is often used in the literature to quantify the hygroscopic properties of aerosols. In this work, a combined theoretical and experimental approach is proposed to add to the theory the contributions of the particle size distribution and morphology. Hygroscopic properties of the particles are derived by measuring their activated fraction as a function of the water supersaturation using a CCN counter. The model developed in this work is first tested on dry ammonium sulfate particles (quasi spherical and non aggregating). Then, it is applied to soot particles that are complex aggregates of primary particles. Soot particles are generated from a laboratory diffusion jet flame supplied with kerosene, and aged with ozone and sulfur dioxide in controlled conditions of temperature, pressure and relative humidity to simulate their permanence in the atmosphere. The electrical mobility, morphology and chemical composition of fresh and aged soot are measured by scanning mobility particle sizing, electron microscopy and secondary ion mass spectrometry, respectively, before and after the aging and related to the activation process. From the comparison of the experimental activation curves and the model, the values of the hygroscopicity parameter k could be determined for a large variety of operating conditions.

Download or read book Heat Transfer in Fire and Combustion Systems written by A. Murty Kanury and published by . This book was released on 1992 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of Light Scattering as a Technique for Detecting Discrete Soot Particles in a Luminous Flame written by and published by . This book was released on 1978 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Study of Soot Formation in an Iron seeded Isooctane Diffusion Flame Using in Situ Light Scattering written by Kathryn Allida Masiello and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Elastic light scattering and transmission measurements were performed on a laboratory isooctane diffusion flame seeded with 4000 ppm iron pentacarbonyl. These measurements allowed the determination of the size, number density, and volume fraction of soot particles in the seeded flame. Comparison to an unseeded flame allowed the determination of the effects of the metallic additive on soot particle inception, growth, and oxidation. It was shown that while the additive may have had a slight soot-enhancing effect at early residence times, the growth of the soot particles was unaffected by the addition of iron to the flame. The greatest effect of the additive on soot perturbation is concluded to occur in the oxidation regime of the flame. In addition, confocal micro-Raman spectroscopy performed on the stainless steel mesh flame holders of the seeded and unseeded flames showed that the state of the iron present was the oxide Fe2O3.

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 1996 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation of soot formation in laminar diffusion flames showed that soot particle surface growth under laminar diffusion flame conditions ceases because of the depletion of hydrocarbon species and not soot particle reactivity loss due to thermal aging of the particles. This result was 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 was developed based on laser-induced incandescence and was successfully applied to similar laminar diffusion flame studies. This technique was extended to droplet and turbulent diffusion flame conditions where a two-dimensional imaging approach was employed to measure soot volume fraction. Finally, the complete data set from these studies was assembled in a form suitable for dissemination on computer diskettes throughout the research community for comparison with modeling efforts.

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 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fuel Structure and Pressure Effects on the Formation of Soot Particles in Diffusion Flames written by Robert J. Santoro and published by . This book was released on 1988 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the first year of the present grant, efforts have concentrated on examining the effects of fuel molecular structure on soot formation in diffusion flames. Studies involving alkane, alkene, alkyne and aromatic fuel species have been studied with specific attention given to the surface growth process. Analysis of these studies has demonstrated a strong fuel structure dependence for the amount of soot formed, the conversion percentage of fuel carbon to soot, and the soot particle surface area present in these diffusion flames. However, when surface area taken into account, similar specific surface growth rate coefficients are observed for all the fuels studied. These results point to a similar surface growth process for all the fuels. Consistent with premixed flame results, the present studies show a continual decrease in this specific surface growth rate coefficient with time. Other effects of fuel structure observed include an acceleration of the inception of soot particles to lower locations and, thus, earlier times in the flame as soot conversion percentage increases. These results also point to the importance of the initial particle inception process which appears to control subsequent soot particle evolution. Keywords: Soot formation; Soot particles; Diffusion flames.

Download or read book Soot Formation in the Buoyancy dominated Ethene Diffusion Flame written by Haran Subramaniasivam and published by . This book was released on 1992 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: The intense particle inception region, characterized by a large concentration of liquid-like microdroplets, is contained within the low part of the flame. These microdroplets form on the fuel side of the flame front where the temperature is the highest. Above the inception region aggregates of increasing size are observed, i. e., increasing the number of primary particles, while the primary particles ceases to exist above the vortex region of the flame, i. e., above Z=15 cm. Since there is very little evidence of oxidation taking place within this buoyancy-dominated flame, it is concluded that most of the soot formed in this flame is released into the surroundings. Observations being made here have been compared to similar soot morphology studies previously made on laminar ethene diffusion flames, both non-sooting, and laser diagnostic tests.

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 Master s Theses Directories written by and published by . This book was released on 1992 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Evolution of Soot Morphology in Laminar Co Flow Diffusion Flames of the Surrogates for Jet A 1 and a Synthetic Kerosene written by Mohammad Reza Kholghy and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Soot Morphology in Unsteady Counterflow Diffusion Flames written by William Roberts and published by . This book was released on 2001 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: As Diesel engines consume the majority of the injected fuel in diffusion controlled combustion processes compared to the relatively short initial premixed phase, and diffusion flames have a greater propensity to form soot, particulate matter emission from Diesel engines can considerable. These particles have a much stronger thermal signature compared to gas phase products, water and carbon dioxide, and render Diesel-powered vehicles susceptible to tracking and targeting via IR sensors. This IR signature will decay with time as the particles cool, and this temporal profile is a function of the morphology of the soot. Therefore, it is important to understand, and eventually control, not only the soot volume fraction of the particulate matter, but also its morphology.