Download or read book Laser based Diagnostics and Modeling of Nitric Oxide and Its Precursor Ammonia in Low Specific Energy Gas Flames written by Denise Charlston Goch and published by . This book was released on 2000 with total page 796 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Detailed Modeling and Laser induced Fluorescence Imaging of Nitric Oxide in a NH i seeded Non premixed Methane written by and published by . This book was released on 2001 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper we study the formation of NO in laminar, nitrogen diluted methane diffusion flames that are seeded with ammonia in the fuel stream. We have performed numerical simulations with detailed chemistry as well as laser-induced fluorescence imaging measurements for a range of ammonia injection rates. For comparison with the experimental data, synthetic LIF images are calculated based on the numerical data accounting for temperature and fluorescence quenching effects. We demonstrate good agreement between measurements and computations. The LIF corrections inferred from the simulation are then used to calculate absolute NO mole fractions from the measured signal. The NO formation in both doped and undoped flames occurs in the flame sheet. In the undoped flame, four different mechanisms including thermal and prompt NO appear to contribute to NO formation. As the NH3 seeding level increases, fuel-NO becomes the dominant mechanism and N2 shifts from being a net reactant to being a net product. Nitric oxide in the undoped flame as well as in the core region of the doped flames are underpredicted by the model; we attribute this mainly to inaccuracies in the NO recycling chemistry on the fuel-rich side of the flame sheet.

Download or read book Laser Induced Fluorescence Measurements and Modeling of Nitric Oxide in High pressure Premixed Flames written by and published by . This book was released on 1994 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser Diagnostics and Modeling of Combustion written by Kazuo Iinuma and published by Springer. This book was released on 1987 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser based Investigation of Gas and Solid Fuel Combustion under Oxy Fuel Atmosphere written by Sebastian Bürkle and published by BoD – Books on Demand. This book was released on 2019-03-04 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oxy-fuel combustion has the potential to reduce the atmospheric CO2-emissions of fossil fuel power plants by burning gaseous or solid fuels under an atmosphere of carbon dioxide and oxygen. The combustion under oxy-fuel operating conditions, however, is accompanied by major changes in the combustion behavior. The underlying chemical and physical processes are complex and highly coupled, which impedes investigations and modeling. Since tactile and most of the optical measurement techniques fail under the sensitive and simultaneously harsh environments of oxy-fuel combustion, an optical in-situ measurement system based on tunable diode laser absorption spectroscopy is developed in this work. This system allows to investigate the thermochemical state of combustion gases with respect to the quantitative concentrations of multiple combustion-relevant gases and the gas temperature. In combination with a newly developed and applied measurement strategy, the system even allows for a measurement of the gas residence time distribution. To improve the measurement accuracy, multiple absorption line parameters are experimentally determined. The measurement system is applied to three oxy-fuel combustion systems. First, the thermochemical state of the laminar, non-premixed methane combustion under oxy-fuel atmosphere is studied. The turbulent, premixed combustion of the same fuel under air and two oxy-fuel atmospheres is studied in a 20 kWth swirled combustor. Measurements of the residence time distribution of fluids in the combustion chamber provide insights into mixing and transport properties of the flow. The thermochemical state reveals insights into the reaction progess and flow mixing. Co-firing of three different solid fuels in an assisting gas flame is investigated for a combined thermal power up to 40 kWth. Here, the char burnout of the particles is investigated. The thermochemical state of the combustion of pure torrefied biomass under air and oxy-fuel combustion atmosphere is investigated in a 60 kWth close-to-application facility and compared to equillibrium calculations.

Download or read book Mixture Preparation and Nitric Oxide Formation in a GDI Engine Studied by Combined Laser Diagnostics and Numerical Modeling written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Through the combination of advanced imaging laser diagnostics with multi-dimensional computer models, a new understanding of the performance of direct-injection gasoline engines is pursuit. The work focuses on the fuel injection process, the breakup of the liquid into a fine spray and the mixing of the fuel with the in-cylinder gases. Non-intrusive laser diagnostics will be used to measure the spatial distribution of droplets and vaporized fuel with very high temporal resolution. These data along with temperature measurements will be used to validate a new spray breakup model for gasoline direct-injection. Experimental data on near wall fuel distributions will be used for comparison with a model that predicts the spray-wall interaction and the dynamics of the liquid film on the surface. Quantitative measurements of local nitric oxide concentrations inside the combustion chamber will provide a critical test for a numerical simulation of the nitric oxide formation process. This model is based on a modified flamelet approach and will be used to study the effects of exhaust gas recirculation.

Download or read book Laser Induced Fluorescence Measurements and Modeling of Nitric Oxide in Counterflow Diffusion Flames written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-27 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: The feasibility of making quantitative nonintrusive NO concentration ([NO]) measurements in nonpremixed flames has been assessed by obtaining laser-induced fluorescence (LIF) measurements of [NO] in counterflow diffusion flames at atmospheric and higher pressures. Comparisons at atmospheric pressure between laser-saturated fluorescence (LSF) and linear LIF measurements in four diluted ethane-air counterflow diffusion flames with strain rates from 5 to 48/s yielded excellent agreement from fuel-lean to moderately fuel-rich conditions, thus indicating the utility of a model-based quenching correction technique, which was then extended to higher pressures. Quantitative LIF measurements of [NO] in three diluted methane-air counterflow diffusion flames with strain rates from 5 to 35/s were compared with OPPDIF model predictions using the GRI (version 2.11) chemical kinetic mechanism. The comparisons revealed that the GRI mechanism underpredicts prompt-NO by 30-50% at atmospheric pressure. Based on these measurements, a modified reaction rate coefficient for the prompt-NO initiation reaction was proposed which causes the predictions to match experimental data. Temperature measurements using thin filament pyrometry (TFP) in conjunction with a new calibration method utilizing a near-adiabatic H2-air Hencken burner gave very good comparisons with model predictions in these counterflow diffusion flames. Quantitative LIF measurements of [NO] were also obtained in four methane-air counterflow partially-premixed flames with fuel-side equivalence ratios (phi(sub B)) of 1.45, 1.6, 1.8 and 2.0. The measurements were in excellent agreement with model predictions when accounting for radiative heat loss. Spatial separation between regions dominated by the prompt and thermal NO mechanisms was observed in the phi(sub B) = 1.45 flame. The modified rate coefficient proposed earlier for the prompt-NO initiation reaction improved agreement between code predictions and measurements in the re

Download or read book Laser Induced Fluorescence Measurements and Modeling of Nitric Oxide in High Pressure Premixed Flames written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-25 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laser-induced fluorescence (LIF) has been applied to the quantitative measurement of nitric oxide (NO) in premixed, laminar, high-pressure flames. Their chemistry was also studied using three current kinetics schemes to determine the predictive capabilities of each mechanism with respect to NO concentrations. The flames studied were low-temperature (1600 less than T less than 1850K) C2H6/O2/N2 and C2H6/O2/N2 flames, and high temperature (2100 less than T less than 2300K) C2H6/O2/N2 flames. Laser-saturated fluorescence (LSF) was initially used to measure the NO concentrations. However, while the excitation transition was well saturated at atmospheric pressure, the fluorescence behavior was basically linear with respect to laser power at pressures above 6 atm. Measurements and calculations demonstrated that the fluorescence quenching rate variation is negligible for LIF measurements of NO at a given pressure. Therefore, linear LIF was used to perform quantitative measurements of NO concentration in these high-pressure flames. The transportability of a calibration factor from one set of flame conditions to another also was investigated by considering changes in the absorption and quenching environment for different flame conditions. The feasibility of performing LIF measurements of (NO) in turbulent flames was studied; the single-shot detection limit was determined to be 2 ppm. Reisel, John R. and Laurendeau, Normand M. Unspecified Center NASA-CR-195404, E-9248, NAS 1.26:195404 NAG3-1038; RTOP 537-02-20...

Download or read book Laser Induced Fluorescence Measurements and Modeling of Nitric Oxide in Counterflow Diffusion Flames written by and published by . This book was released on 2000 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dimensionally Reduced Modeling of Nitric Oxide Formation for Premixed Methane air Flames with Ammonia Content written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Application of Laser based Diagnostics for Nanomaterials Synthesis written by Xiaofei Liu and published by . This book was released on 2009 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spectroscopic laser-based diagnostics are applied in the gas-phase synthesis of nanostructrued materials to make non-intrusive, in-situ, spatially-precise measurements of gas-phase temperatures and relevant chemical species. For the nanomaterials themselves, a novel application of Raman spectroscopy is developed to characterize nanoparticles in-situ, during flame and plasma synthesis. As result, the local conditions for gas-phase synthesis can be determined for a given nanomaterial property, so that fundamental mechanisms can be revealed and process conditions can be optimized. The synthesis configurations investigated in this work are (i) the inverse co-flow diffusion flame (IDF), (ii) the counter-flow diffusion flame (CDF), (iii) the low-pressure burner-stabilized premixed stagnation-point flame, and (iv) the inductively-coupled plasma (ICP) impinging on a cold substrate. Spontaneous Raman spectroscopy (SRS) is used to measure local gas-phase conditions in the 2-D axi-symmetric IDF and the quasi 1-D CDF, where nanomaterials are grown on inserted substrates of various compositions. Nitrogen-diluted methane-air flames are examined. Carbon nanotubes (CNTs) are grown catalytically on metal-alloy substrates, and their morphologies are correlated with the local gas-phase temperature and the concentrations of carbon-based precursor species (e.g. C2H2, CO). Zinc oxide (ZnO) nanostructures are grown directly on zinc-plated steel substrates, and their morphologies are correlated with the local gas-phase temperature and the concentrations of oxidative (e.g. O2, H2O, and CO2) and reducing (e.g. H2) species. Computational simulations in 1-D, involving detailed chemical kinetics and transport properties, and in 2-D, using simplified kinetics and transport, are used to validate and improve the measurements. Laser-induced fluorescence (LIF) is employed to measure the gas-phase temperature profile and OH radical species concentration distribution in a low-pressure, premixed, nitrogen-diluted hydrogen-oxygen, burner-stabilized, stagnation-point flame. Titania nanoparticles are synthesized using a metalorganic precursor. The LIF measurements are compared with computational simulations with detailed chemical kinetics and transport, to affirm the quasi 1-D flow field, as well as to investigate the effects of precursor addition and uniform electric-field application. SRS is utilized to characterize in-situ the composition and crystallinity of nanoparticles, in aerosol form, produced in the aforementioned low-pressure premixed flame and in the ICP synthesis setup. The Stokes spectra are identified for crystalline phases of TiO2 (and Al2O3 in a different flame setup) and c-BN based on ex-situ-taken spectra from the literature. The in-situ technique is able to delineate the phase conversion of nanoparticles (including amorphous to crystalline) as they evolve in the flow field.

Download or read book Laser Diagnostics for Combustion Temperature and Species written by Alan C. Eckbreth and published by CRC Press. This book was released on 1996-10-10 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt: Focusing on spectroscopically-based, spatially-precise, laser techniques for temperature and chemical composition measurements in reacting and non-reacting flows, this book makes these powerful and important new tools in combustion research

Download or read book Measurements and Modeling of Nitric Oxide Formation in Counterflow Premixed Ch4 O2 N2 Flames written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-27 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laser-induced fluorescence (LIF) measurements of NO concentration in a variety of CH4/O2/N2 flames are used to evaluate the chemical kinetics of NO formation. The analysis begins with previous measurements in flat, laminar, premixed CH4/O2/N2 flames stabilized on a water-cooled McKenna burner at pressures ranging from 1 to 14.6 atm, equivalence ratios from 0.5 to 1.6, and volumetric nitrogen/oxygen dilution ratios of 2.2, 3.1 and 3.76. These measured results are compared to predictions to determine the capabilities and limitations of the comprehensive kinetic mechanism developed by the Gas Research Institute (GRI), version 2.11. The model is shown to predict well the qualitative trends of NO formation in lean-premixed flames, while quantitatively underpredicting NO concentration by 30-50%. For rich flames, the model is unable to even qualitatively match the experimental results. These flames were found to be limited by low temperatures and an inability to separate the flame from the burner surface. In response to these limitations, a counterflow burner was designed for use in opposed premixed flame studies. A new LIF calibration technique was developed and applied to obtain quantitative measurements of NO concentration in laminar, counterflow premixed, CH4/O2/N2 flames at pressures ranging from 1 to 5.1 atm, equivalence ratios of 0.6 to 1.5, and an N2/O2 dilution ratio of 3.76. The counterflow premixed flame measurements are combined with measurements in burner-stabilized premixed flames and counterflow diffusion flames to build a comprehensive database for analysis of the GRI kinetic mechanism. Pathways, quantitative reaction path and sensitivity analyses are applied to the GRI mechanism for these flame conditions. The prompt NO mechanism is found to severely underpredict the amount of NO formed in rich premixed and nitrogen-diluted diffusion flames. This underprediction is traced to uncertainties in the CH kinetics as well as in the nitrogen oxidation chemistry. S

Download or read book Development of All Solid State Sensors for Measurement of Nitric Oxide and Ammonia Concentrations by Optical Absorption in Particle Laden Combustion Exhaust Streams written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An all-solid-state continuous-wave (cw) laser system for ultraviolet absorption measurements of the nitric oxide (NO) molecule has been developed and demonstrated. For the NO sensor, 250 nW of tunable cw ultraviolet radiation is produced by sum-frequency-mixing of 532-nm radiation from a diode-pumped Nd:YAG laser and tunable 395-nm radiation from an external cavity diode laser (ECDL). The sum-frequency-mixing process occurs in a beta-barium borate crystal. The nitric oxide absorption measurements are performed by tuning the ECDL and scanning the sum-frequency-mixed radiation over strong nitric oxide absorption lines near 226 nm. In Year 1 of the research, the nitric oxide sensor was used for measurements in the exhaust of a coal-fired laboratory combustion facility. The Texas A & M University boiler burner facility is a 30 kW (100,000 Btu/hr) downward-fired furnace with a steel shell encasing ceramic insulation. Measurements of nitric oxide concentration in the exhaust stream were performed after modification of the facility for laser based NOx diagnostics. The diode-laser-based ultraviolet absorption measurements were successful even when the beam was severely attenuated by particulate in the exhaust stream and window fouling. Single-laser-sweep measurements were demonstrated with an effective time resolution of 100 msec, limited at this time by the scan rate of our mechanically tuned ECDL system. In Year 2, the Toptica ECDL in the original system was replaced with a Sacher Lasers ECDL. The mode-hop-free tuning range and tuning rate of the Toptica ECDL were 25 GHz and a few Hz, respectively. The mode-hop-free tuning range and tuning rate of the Sacher Lasers ECDL were 90 GHz and a few hundred Hz, respectively. The Sacher Lasers ECDL thus allows us to scan over the entire NO absorption line and to determine the absorption baseline with increased accuracy and precision. The increased tuning rate is an advantage in that data can be acquired much more rapidly and the absorption measurements are less susceptible to the effects of transient fluctuations in the properties of the coal combustor exhaust stream. Gas cell measurements were performed using the NO sensor with the new ECDL, and a few spectra were acquired from the coal exhaust stream. However, the laser diode in the new ECDL failed during the coal combustor tests. In Year 3, however, we obtained a new GaN laser diode for our ECDL system, installed it, and completed an extensive series of measurements in the Texas A & M coal-fired laboratory combustion facility. The combustor was operated with coal and coal/biomass as fuels, with and without reburn, and with and without ammonia injection. Several different fuel equivalence ratios were investigated for each operating condition. A series of spectral simulations was performed using the HITRAN code to investigate the potential sensitivity of absorption measurements of ammonia in different spectral regions. It was concluded that ammonia absorption features in the 3000-nm spectral region would be hard to measure due to water vapor interferences. We will concentrate on the spectral region near 1530 nm, where other researchers have had some success in measuring ammonia.

Download or read book Development of a Quantum Cascade Laser Based Detector for Ammonia and Nitric Acid written by and published by . This book was released on 2005 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have developed a compact, robust, atmospheric trace gas detector based on mid-infrared absorption spectroscopy using pulsed quantum cascade (QC) lasers. The spectrometer is suitable for airborne measurements of ammonia, nitric acid, formaldehyde, formic acid, methane, nitrous oxide, carbon monoxide, nitrogen dioxide and other gases that have line-resolved absorption spectra in the mid-infrared spectral region. The QC laser light source operates near room temperature with thermal electric cooling instead of liquid nitrogen which has been previously required for semiconductor lasers in the mid-infrared spectral region. The QC lasers have sufficient output power so that thermal electric cooled detectors may be used in many applications with lower precision requirements. The instrument developed in this program has been used in several field campaigns from both the Aerodyne Mobile Laboratory and from the NOAA WP3 aircraft. The Phase II program has resulted in more than 10 archival publications describing the technology and its applications. Over 12 instruments based on this design have been sold to research groups in Europe and the United States making the program both a commercial as well as a technological success. Anticipated Benefits The development of a sensitive, cryogen-free, mid-infrared absorption method for atmospheric trace gas detection will have wide benefits for atmospheric and environmental research and broader potential commercial applications in areas such as medical diagnostic and industrial process monitoring of gaseous compounds. Examples include air pollution monitoring, breath analysis, combustion exhaust diagnostics, and plasma diagnostics for semi-conductor fabrication. The substitution of near-room temperature QC lasers for cryogenic lead salt TDLs and the resulting simplifications in instrument design and operation will greatly expand the range of applications.

Download or read book Development of All Solid State Sensors for Measurement of Nitric Oxide and Ammonia Concentrations by Optical Absorption in Particle Laden Combustion Exhaust Streams written by Robert P. Lucht and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An all-solid-state continuous-wave (cw) laser system for ultraviolet absorption measurements of the nitric oxide (NO) molecule has been developed and demonstrated. For the NO sensor, 250 nW of tunable cw ultraviolet radiation is produced by sum-frequency-mixing of 532-nm radiation from a diode-pumped Nd:YAG laser and tunable 395-nm radiation from an external cavity diode laser (ECDL). The sum-frequency-mixing process occurs in a beta-barium borate crystal. The nitric oxide absorption measurements are performed by tuning the ECDL and scanning the sum-frequency-mixed radiation over strong nitric oxide absorption lines near 226 nm. In Year 1 of the research, the nitric oxide sensor was used for measurements in the exhaust of a coal-fired laboratory combustion facility. The Texas A & M University boiler burner facility is a 30 kW (100,000 Btu/hr) downward-fired furnace with a steel shell encasing ceramic insulation. Measurements of nitric oxide concentration in the exhaust stream were performed after modification of the facility for laser based NOx diagnostics. The diode-laser-based ultraviolet absorption measurements were successful even when the beam was severely attenuated by particulate in the exhaust stream and window fouling. Single-laser-sweep measurements were demonstrated with an effective time resolution of 100 msec, limited at this time by the scan rate of our mechanically tuned ECDL system. In Year 2, the Toptica ECDL in the original system was replaced with a Sacher Lasers ECDL. The mode-hop-free tuning range and tuning rate of the Toptica ECDL were 25 GHz and a few Hz, respectively. The mode-hop-free tuning range and tuning rate of the Sacher Lasers ECDL were 90 GHz and a few hundred Hz, respectively. The Sacher Lasers ECDL thus allows us to scan over the entire NO absorption line and to determine the absorption baseline with increased accuracy and precision. The increased tuning rate is an advantage in that data can be acquired much more rapidly and the absorption measurements are less susceptible to the effects of transient fluctuations in the properties of the coal combustor exhaust stream. Gas cell measurements were performed using the NO sensor with the new ECDL, and a few spectra were acquired from the coal exhaust stream. However, the laser diode in the new ECDL failed during the coal combustor tests. In Year 3, however, we obtained a new GaN laser diode for our ECDL system, installed it, and completed an extensive series of measurements in the Texas A & M coal-fired laboratory combustion facility. The combustor was operated with coal and coal/biomass as fuels, with and without reburn, and with and without ammonia injection. Several different fuel equivalence ratios were investigated for each operating condition.

Download or read book The Yield of Nitric Oxide from Premixed Flames of Hydrogen and Hydrocarbons with Nitrous Oxide written by Burton Davis Fine and published by . This book was released on 1963 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: