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Description: Experimental results are reviewed which demonstrate that combustion-generated soot particles can oxidize SO{sub 2} in both the absence ('dry' mechanism) and the presence ('wet' mechanism) of liquid water. The 'wet' mechanism is much more efficient than the 'dry' one, and is applicable to situations where the aerosol particles are covered with a liquid water layer. Calculations are presented which suggest that the soot-catalyzed oxidation of SO{sub 2} can be the dominant mechanism under realistic atmospheric conditions.
Date: May 1, 1978
Creator: Chang, S.G. & Novakov, T.
Partner: UNT Libraries Government Documents Department

Aerosol Mass Spectrometry via Laser-Induced Incandescence Particle Vaporization Final Report

Description: We have successfully developed and commercialized a soot particle aerosol mass spectrometer (SP-AMS) instrument to measure mass, size, and chemical information of soot particles in ambient environments. The SP-AMS instrument has been calibrated and extensively tested in the laboratory and during initial field studies. The first instrument paper describing the SP-AMS has been submitted for publication in a peer reviewed journal and there are several related papers covering initial field studies and laboratory studies that are in preparation. We have currently sold 5 SP-AMS instruments (either as complete systems or as SP modules to existing AMS instrument operators).
Date: October 20, 2011
Creator: Onasch, Timothy B.
Partner: UNT Libraries Government Documents Department

Chemical Bonding and Structural Information of Black Carbon Reference Materials and Individual Carbonaceous Atmospheric Aerosols

Description: The carbon-to-oxygen ratios and graphitic nature of a rangeof black carbon standard reference materials (BC SRMs), high molecularmass humic-like substances (HULIS) and atmospheric particles are examinedusing scanning transmission X-ray microscopy (STXM) coupled with nearedge X-ray absorption fine structure (NEXAFS) spectroscopy. UsingSTXM/NEXAFS, individual particles with diameter>100 nm are studied,thus the diversity of atmospheric particles collected during a variety offield missions is assessed. Applying a semi-quantitative peak fittingmethod to the NEXAFS spectra enables a comparison of BC SRMs and HULIS toparticles originating from anthropogenic combustion and biomass burns,thus allowing determination of the suitability of these materials forrepresenting atmospheric particles. Anthropogenic combustion and biomassburn particles can be distinguished from one another using both chemicalbonding and structural ordering information. While anthropogeniccombustion particles are characterized by a high proportion ofaromatic-C, the presence of benzoquinone and are highly structurallyordered, biomass burn particles exhibit lower structural ordering, asmaller proportion of aromatic-C and contain a much higher proportion ofoxygenated functional groups.
Date: April 25, 2007
Creator: Hopkins, Rebecca J.; Tivanski, Alexei V.; Marten, Bryan D. & Gilles, Mary K.
Partner: UNT Libraries Government Documents Department

An Inverted Co-Flow Diffusion Flame for Producing Soot

Description: We developed an inverted, co-flow, methane/air/nitrogen burner that generates a wide range of soot particles sizes and concentrations. By adjusting the flow rates of air, methane, and nitrogen in the fuel, the mean electric mobility diameter and number concentration are varied. Additional dilution downstream of the flame allows us to generate particle concentrations spanning those produced by spark-ignited and diesel engines: particles with mean diameters between 50 and 250 nm and number concentrations from 4.7 {center_dot} 10{sup 4} to 10{sup 7} cm{sup -3}. The range of achievable number concentrations, and therefore volume concentrations, can be increased by a factor of 30 by reducing the dilution ratio. These operating conditions make this burner valuable for developing and calibrating diagnostics as well as for other studies involving soot particles.
Date: June 21, 2005
Creator: Stipe, Christopher B.; Higgins, Brian S.; Lucas, Donald; Koshland, Catherine P. & Sawyer, Robert F.
Partner: UNT Libraries Government Documents Department

Diesel Engine Light Truck Application

Description: The Diesel Engine Light Truck Application (DELTA) program consists of two major contracts with the Department of Energy (DOE). The first one under DE-FC05-97-OR22606, starting from 1997, was completed in 2001, and consequently, a final report was submitted to DOE in 2003. The second part of the contract was under DE-FC05-02OR22909, covering the program progress from 2002 to 2007. This report is the final report of the second part of the program under contract DE-FC05-02OR22909. During the course of this contract, the program work scope and objectives were significantly changed. From 2002 to 2004, the DELTA program continued working on light-duty engine development with the 4.0L V6 DELTA engine, following the accomplishments made from the first part of the program under DE-FC05-97-OR22606. The program work scope in 2005-2007 was changed to the Diesel Particulate Filter (DPF) soot layer characterization and substrate material assessment. This final report will cover two major technical tasks. (1) Continuation of the DELTA engine development to demonstrate production-viable diesel engine technologies and to demonstrate emissions compliance with significant fuel economy advantages, covering progress made from 2002 to 2004. (2) DPF soot layer characterization and substrate material assessment from 2005-2007.
Date: December 31, 2007
Partner: UNT Libraries Government Documents Department


Description: Results obtained by means of x-ray photoelectron spectroscopy and internal reflection infrared spectroscopy demonstrate the feasibility of heterogeneous oxidation of sulfur dioxide on soot particles in air. Sulfuric acid formed in this process can be neutralized on basic surface sites of soot particles, resulting in the formation of carbonium and/or oxonium sulfate. Hydrolysis of these salts into cyclic hemiacetals and sulfuric acid is expected.
Date: December 1, 1975
Creator: Chang, S.G. & Novakov, T.
Partner: UNT Libraries Government Documents Department

An investigation of late-combustion soot burnout in a DI diesel engine using simultaneous planar imaging of soot and OH radical

Description: Diesel engine design continues to be driven by the need to improve performance while at the same time achieving further reductions in emissions. The development of new designs to accomplish these goals requires an understanding of how the emissions are produced in the engine. Laser-imaging diagnostics are uniquely capable of providing this information, and the understanding of diesel combustion and emissions formation has been advanced considerably in recent years by their application. However, previous studies have generally focused on the early and middle stages of diesel combustion. These previous laser-imaging studies do provide important insight into the soot formation and oxidation processes during the main combustion event. They indicate that prior to the end of injection, soot formation is initiated by fuel-rich premixed combustion (equivalence ratio > 4) near the upstream limit of the luminous portion of the reacting fuel jet. The soot is then oxidized at the diffusion flame around the periphery of the luminous plume. Under typical diesel engine conditions, the diffusion flame does not burn the remaining fuel and soot as rapidly as it is supplied, resulting in an expanding region of rich combustion products and soot. This is evident in natural emission images by the increasing size of the luminous soot cloud prior to the end of injection. Hence, the amount of soot in the combustion chamber typically increases until shortly after the end of fuel injection, at which time the main soot formation period ends and the burnout phase begins. Sampling valve and two-color pyrometry data indicate that the vast majority (more than 90%) of the soot formed is oxidized before combustion ends; however, it is generally thought that a small fraction of this soot from the main combustion zones is not consumed and is the source of tail pipe soot emissions.
Date: October 1, 1999
Creator: Dec, John E. & Kelly-Zion, Peter L.
Partner: UNT Libraries Government Documents Department


Description: The modifications to the SRT-RCFR facility described in the June report were completed. As a result of these changes, the furnace hot zone was increased in length from 7 cm to 15.5 cm. The injector region of the furnace, providing entrainment and sheath flows, was unchanged, while the flow path from the exit of the furnace to the sample collection section was shortened by approximately 10 cm. The modified facility was used to resume testing of Pittsburgh No. 8 coal at 10 atm. The first goal was to confirm that the facility now provides true secondary pyrolysis test conditions. That is, the tar product should be completely converted to soot even in the absence of oxygen in the gas stream. We have now performed four tests with pure argon carrier gas, and have consistently observed voluminous soot product with little or no evidence of tar. Thus, this objective was met. The clogging problems for Pittsburgh No. 8 coal under secondary pyrolysis test conditions may preclude achieving this data point. In that case, we will make measurements under oxidizing conditions, which are expected to eliminate the clogging, and to gradually reduce the oxygen content to the point where product yields can reliably be extrapolated to the zero oxygen case.
Date: October 28, 2002
Creator: Guenther, Chris
Partner: UNT Libraries Government Documents Department

Combined Catalyzed Soot Filter and SCR Catalyst System for Diesel Engine Emission Reduction

Description: Substantially reduces particulate emission for diesel vehicles Up to 90% effective against carbonaceous particulate matter Significantly reduces CO and HC Filter regenerates at normal diesel operation temperatures Removable design for easy cleaning and maintenance.
Date: August 20, 2000
Creator: Kakwani, R.M.
Partner: UNT Libraries Government Documents Department

Development of Detection Techniques and Diagnostics for Airborne Carbon Nanoparticles

Description: We have recorded time-resolved LII signals from a laminar ethylene diffusion flame over a wide range of laser fluences at 532 nm. We have performed these experiments using an injection-seeded Nd:YAG laser with a pulse duration of 7 ns. The beam was spatially filtered and imaged into the flame to provide a homogeneous spatial profile. These data were used to aid in the development of a model, which will be used to test the validity of the LII technique under varying environmental conditions. The new model describes the heating of soot particles during the laser pulse and the subsequent cooling of the particles by radiative emission, sublimation, and conduction. The model additionally includes particle heating by oxidation, accounts for the likelihood of particle annealing, and incorporates a mechanism for nonthermal photodesorption, which is required for good agreement with our experimental results. In order to investigate the fast photodesorption mechanism in more detail, we have recorded LII temporal profiles using a regeneratively amplified Nd:YAG laser with a pulse duration of 70 ps to heat the particles and a streak camera with a temporal resolution of {approx}65 ps to collect the signal. Preliminary results confirm earlier indications of a fast mechanism leading to signal decay rates of much less than a nanosecond. Parameters to which the model is sensitive include the initial soot temperature, the temperature of the ambient gas, and the partial pressure of oxygen. In order to narrow the model uncertainties, we have developed a source of soot that allows us to determine and control these parameters. Soot produced by a burner is extracted, diluted, and cooled in a flow tube, which is equipped with a Scanning Mobility Particle Sizer (SMPS) for characterization of the aggregates.
Date: November 1, 2003
Creator: Michelsen, Hope Andrea
Partner: UNT Libraries Government Documents Department

The role of pore structure on char reactivity. Quarterly progress report, [January--March 1993]

Description: Studies will be conducted on coal chars in the electrodynamic balance to examine the role of mesopore structure on reactivity. Larger particles will also be examined using a fluidized bed to examine diffusion control reactions. Soots will also be investigated to examine the role of meso- and micro-pores without macro-pore interference. These studies will allow a full range of particles sizes and temperatures to be investigated and eventually modelled.
Date: April 1, 1993
Creator: Sarofim, A. F.
Partner: UNT Libraries Government Documents Department

Autothermal Reforming of Natural Gas to Synthesis Gas

Description: This Project Final Report serves to document the project structure and technical results achieved during the 3-year project titled Advanced Autothermal Reformer for US Dept of Energy Office of Industrial Technology. The project was initiated in December 2001 and was completed March 2005. It was a joint effort between Sandia National Laboratories (Livermore, CA), Kellogg Brown & Root LLC (KBR) (Houston, TX) and Süd-Chemie (Louisville, KY). The purpose of the project was to develop an experimental capability that could be used to examine the propensity for soot production in an Autothermal Reformer (ATR) during the production of hydrogen-carbon monoxide synthesis gas intended for Gas-to-Liquids (GTL) applications including ammonia, methanol, and higher hydrocarbons. The project consisted of an initial phase that was focused on developing a laboratory-scale ATR capable of reproducing conditions very similar to a plant scale unit. Due to budget constraints this effort was stopped at the advanced design stages, yielding a careful and detailed design for such a system including ATR vessel design, design of ancillary feed and let down units as well as a PI&D for laboratory installation. The experimental effort was then focused on a series of measurements to evaluate rich, high-pressure burner behavior at pressures as high as 500 psi. The soot formation measurements were based on laser attenuation at a view port downstream of the burner. The results of these experiments and accompanying calculations show that soot formation is primarily dependent on oxidation stoichiometry. However, steam to carbon ratio was found to impact soot production as well as burner stability. The data also showed that raising the operating pressure while holding mass flow rates constant results in considerable soot formation at desirable feed ratios. Elementary reaction modeling designed to illuminate the role of CO2 in the burner feed showed that the conditions in the ...
Date: April 13, 2007
Creator: Rice, Steven F. & Mann, David P.
Partner: UNT Libraries Government Documents Department

The effect of oxygenate molecular structure on soot production in direct-injection diesel engines.

Description: A combined experimental and kinetic modeling study of soot formation in diesel engine combustion has been used to study the addition of oxygenated species to diesel fuel to reduce soot emissions. This work indicates that the primary role of oxygen atoms in the fuel mixture is to reduce the levels of carbon atoms available for soot formation by fixing them in the form of CO or COz. When the structure of the oxygenate leads to prompt and direct formation of CO2, the oxygenate is less effective in reducing soot production than in cases when all fuel-bound 0 atoms produce only CO. The kinetic and molecular structure principles leading to this conclusion are described.
Date: June 1, 2003
Creator: Westbrook, Charles K. (Lawrence Livermore National Laboratory, Livermore, CA); Pitz, William J. (Lawrence Livermore National Laboratory, Livermore, CA); Mueller, Charles J.; Martin, Glen M. & Pickett, Lyle M.
Partner: UNT Libraries Government Documents Department

Soot properties and species measurements in a two-meter diameter JP-8 pool fire : 2003 test series.

Description: A tunable diode laser absorption spectroscopy probe was used to measure in situ soot properties and species concentrations in a two-meter diameter JP-8 pool fire. Thirty-five tests were performed at the Lurance Canyon Burn Site operated by Sandia in Albuquerque, New Mexico. The axial profile of the fire was characterized with a series of tests with the probe located on the centerline at heights ranging from 0.5 m to 2.0 m in 0.25 m increments. The radial profile of the fire was characterized with a series of tests with the probe 1.0 m above the fuel surface at radial positions ranging from 0.0 m to 0.6 m, in 0.1 m increments. Experiments were also performed with variation of the air flow into the facility. Soot concentration was determined using a light extinction measurement based on the transmission of a solid-state red laser (635 nm) through the 3.7 cm long probe volume. Soot temperature and a second estimate of soot concentration were measured using two-color optical pyrometry at 850 nm and 1000 nm. The effective data rate for these measurements was 10 kHz. Finally, tunable diode laser absorption spectroscopy was used to estimate the concentrations of water vapor, acetylene, and methane. The results presented include the statistics, probability density functions, and spectral density functions of soot concentration, soot temperature, and approximate species concentrations at the different measurement locations throughout the fire.
Date: March 1, 2004
Creator: Shaddix, Christopher R. & Murphy, Jeffrey J.
Partner: UNT Libraries Government Documents Department

Biodiesel Fuel Property Effects on Particulate Matter Reactivity

Description: Controlling diesel particulate emissions to meet the 2007 U.S. standard requires the use of a diesel particulate filter (DPF). The reactivity of soot, or the carbon fraction of particulate matter, in the DPF and the kinetics of soot oxidation are important in achieving better control of aftertreatment devices. Studies showed that biodiesel in the fuel can increase soot reactivity. This study therefore investigated which biodiesel fuel properties impact reactivity. Three fuel properties of interest included fuel oxygen content and functionality, fuel aromatic content, and the presence of alkali metals. To determine fuel effects on soot reactivity, the performance of a catalyzed DPF was measured with different test fuels through engine testing and thermo-gravimetric analysis. Results showed no dependence on the aromatic content or the presence of alkali metals in the fuel. The presence and form of fuel oxygen was the dominant contributor to faster DPF regeneration times and soot reactivity.
Date: June 1, 2010
Creator: Williams, A.; Black, S. & McCormick, R. L.
Partner: UNT Libraries Government Documents Department


Description: Combustion-produced soot (carbonaceous) particles have been found to be efficient catalysts for SO{sub 2} oxidation, especially in the presence of liquid water. A kinetic study of the catalytic oxidation of SO{sub 2} on carbon particles suspended in solution has been carried out. The reaction was found to be first order with respect to the concentration of carbon particles, 0.69th order with respect to dissolved oxygen, between zero and second order with respect to S(IV) concentrations, and independent of the pH. Temperature studies were carried out, and an activation energy for this reaction was determined. A four-step mechanism is proposed for this carbon-catalyzed oxidation reaction.
Date: February 1, 1980
Creator: Brodzinsky, R.; Chang, S.G.; Markowitz, S.S. & Novakov, T.
Partner: UNT Libraries Government Documents Department

Diagnostic development for determining the joint temperature/soot statistics in hydrocarbon-fueled pool fires : LDRD final report.

Description: A joint temperature/soot laser-based optical diagnostic was developed for the determination of the joint temperature/soot probability density function (PDF) for hydrocarbon-fueled meter-scale turbulent pool fires. This Laboratory Directed Research and Development (LDRD) effort was in support of the Advanced Simulation and Computing (ASC) program which seeks to produce computational models for the simulation of fire environments for risk assessment and analysis. The development of this laser-based optical diagnostic is motivated by the need for highly-resolved spatio-temporal information for which traditional diagnostic probes, such as thermocouples, are ill-suited. The in-flame gas temperature is determined from the shape of the nitrogen Coherent Anti-Stokes Raman Scattering (CARS) signature and the soot volume fraction is extracted from the intensity of the Laser-Induced Incandescence (LII) image of the CARS probed region. The current state of the diagnostic will be discussed including the uncertainty and physical limits of the measurements as well as the future applications of this probe.
Date: September 1, 2009
Creator: Casteneda, Jaime N.; Frederickson, Kraig; Grasser, Thomas W.; Hewson, John C.; Kearney, Sean Patrick & Luketa, Anay Josephine
Partner: UNT Libraries Government Documents Department

Particle Formation from Pulsed Laser Irradiation of SootAggregates studied with scanning mobility particle sizer, transmissionelectron microscope and near-edge x-ray absorption fine structure.

Description: We investigated the physical and chemical changes induced in soot aggregates exposed to laser radiation using a scanning mobility particle sizer, a transmission electron microscope, and a scanning transmission x-ray microscope to perform near-edge x-ray absorption fine structure spectroscopy. Laser-induced nanoparticle production was observed at fluences above 0.12 J/cm(2) at 532 nm and 0.22 J/cm(2) at 1064 nm. Our results indicate that new particle formation proceeds via (1) vaporization of small carbon clusters by thermal or photolytic mechanisms, followed by homogeneous nucleation, (2) heterogeneous nucleation of vaporized carbon clusters onto material ablated from primary particles, or (3) both processes.
Date: February 20, 2007
Creator: Michelsen, Hope A.; Tivanski, Alexei V.; Gilles, Mary K.; vanPoppel, Laura H.; Dansson, Mark A.; Buseck, Peter R. et al.
Partner: UNT Libraries Government Documents Department

Weathering of Roofing Materials-An Overview

Description: An overview of several aspects of the weathering of roofing materials is presented. Degradation of materials initiated by ultraviolet radiation is discussed for plastics used in roofing, as well as wood and asphalt. Elevated temperatures accelerate many deleterious chemical reactions and hasten diffusion of material components. Effects of moisture include decay of wood, acceleration of corrosion of metals, staining of clay, and freeze-thaw damage. Soiling of roofing materials causes objectionable stains and reduces the solar reflectance of reflective materials. (Soiling of non-reflective materials can also increase solar reflectance.) Soiling can be attributed to biological growth (e.g., cyanobacteria, fungi, algae), deposits of organic and mineral particles, and to the accumulation of flyash, hydrocarbons and soot from combustion.
Date: March 30, 2006
Creator: Berdahl, Paul; Akbari, Hashem; Levinson, Ronnen & Miller, William A.
Partner: UNT Libraries Government Documents Department

Modified thermal-optical analysis using spectral absorption selectivity to distinguish black carbon from pyrolized organic carbon

Description: Black carbon (BC), a main component of combustion-generated soot, is a strong absorber of sunlight and contributes to climate change. Measurement methods for BC are uncertain, however. This study presents a method for analyzing the BC mass loading on a quartz fiber filter using a modified thermal-optical analysis method, wherein light transmitted through the sample is measured over a spectral region instead of at a single wavelength as the sample is heated. Evolution of the spectral light transmission signal depends on the relative amounts of light-absorbing BC and char, the latter of which forms when organic carbon in the sample pyrolyzes during heating. Absorption selectivities of BC and char are found to be distinct and are used to apportion the amount of light attenuated by each component in the sample. Light attenuation is converted to mass concentration based on derived mass attenuation efficiencies (MAE) of BC and char. The fraction of attenuation due to each component are scaled by their individual MAE values and added together as the total mass of light absorbing carbon (LAC). An iterative algorithm is used to find the MAE values for both BC and char that provide the best fit to the carbon mass remaining on the filter (derived from direct measurements of thermally evolved CO{sub 2}) at temperatures higher than 480 C. This method was applied to measure the BC concentration in precipitation samples collected from coastal and mountain sites in Northern California. The uncertainty in measured BC concentration of samples that contained a high concentration of organics susceptible to char ranged from 12 to 100 percent, depending on the mass loading of BC on the filter. The lower detection limit for this method was approximately 0.35 {micro}g BC and uncertainty approached 20 percent for BC mass loading greater than 1.0 {micro}g BC.
Date: April 14, 2008
Creator: Hadley, Odelle; Hadley, O.L.; Corrigan, C.E. & Kirchstetter, T.W.
Partner: UNT Libraries Government Documents Department

A joint computational and experimental study to evaluate Inconel-sheathed thermocouple performance in flames.

Description: A joint experimental and computational study was performed to evaluate the capability of the Sandia Fire Code VULCAN to predict thermocouple response temperature. Thermocouple temperatures recorded by an Inconel-sheathed thermocouple inserted into a near-adiabatic flat flame were predicted by companion VULCAN simulations. The predicted thermocouple temperatures were within 6% of the measured values, with the error primarily attributable to uncertainty in Inconel 600 emissivity and axial conduction losses along the length of the thermocouple assembly. Hence, it is recommended that future thermocouple models (for Inconel-sheathed designs) include a correction for axial conduction. Given the remarkable agreement between experiment and simulation, it is recommended that the analysis be repeated for thermocouples in flames with pollutants such as soot.
Date: September 1, 2005
Creator: Brundage, Aaron L.; Nicolette, Vernon F.; Donaldson, A. Burl; Kearney, Sean Patrick & Gill, Walter
Partner: UNT Libraries Government Documents Department

Soot particle disintegration and detection using two laserELFFS

Description: A two laser technique is used to study laser-particle interactions and the disintegration of soot by high power UV light. Two separate 20 ns laser pulses irradiate combustion generated soot nanoparticles with 193 nm photons. The first laser pulse, from 0 to 14.7 J/cm{sup 2}, photofragments the soot particles and electronically excites the liberated carbon atoms. The second laser pulse, held constant at 13 J/cm{sup 2}, irradiates the remaining particle fragments and other products of the first laser pulse. The atomic carbon fluorescence at 248 nm produced by the first laser pulse increases linearly with laser fluence from 1 to 6 J/cm{sup 2}. At higher fluences, the signal from atomic carbon signal saturates. The carbon fluorescence from the second laser pulse decreases as the fluence from the first laser increases, ultimately approaching zero as first laser fluence approaches 10 J/cm{sup 2}, suggesting that the particles fully disintegrate at high laser fluences. We use an energy balance parameter, called the photon-atom ratio (PAR), to aid in understanding laser-particle interactions. These results help define the regimes where photofragmentation fluorescence methods quantitatively measure total soot concentrations.
Date: November 17, 2004
Creator: Stipe, Christopher B.; Lucas, Donald; Koshland, Catherine P. & Sawyer, Robert F.
Partner: UNT Libraries Government Documents Department