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Author: R. K. Hanson Publisher: ISBN: Category : Languages : en Pages : 9
Book Description
Applications of tunable infrared diode lasers for combustion gas measurements are described. The diode laser serves as a source of narrow-linewidth infrared radiation whose wavelength can be rapidly modulated to perform fast, high-resolution absorption spectroscopy. Measurements of fully resolved vibration-rotation lines in the fundamental band of CO are used to infer temperature, CO species concentrations and CO collisions halfwidths in the post-flame gases of a flat flame burner. The feasibility of diode laser measurements in fluctuating and particle-laden combustion flows is also demonstrated. (Author).
Author: R. K. Hanson Publisher: ISBN: Category : Languages : en Pages : 9
Book Description
Applications of tunable infrared diode lasers for combustion gas measurements are described. The diode laser serves as a source of narrow-linewidth infrared radiation whose wavelength can be rapidly modulated to perform fast, high-resolution absorption spectroscopy. Measurements of fully resolved vibration-rotation lines in the fundamental band of CO are used to infer temperature, CO species concentrations and CO collisions halfwidths in the post-flame gases of a flat flame burner. The feasibility of diode laser measurements in fluctuating and particle-laden combustion flows is also demonstrated. (Author).
Author: Susan M. Schoenung Publisher: ISBN: Category : Absorption spectra Languages : en Pages : 21
Book Description
The initial work in a program at Stanford to develop laser-based combustion diagnostics has focused on tunable laser absorption spectroscopy using an infrared diode laser. An important aspect of this program is the validation of the laser technique under controlled conditions and by comparison with established probe-based methods. This paper reports preliminary results from such experiments, which consisted of CO concentration measurements in a flat premixed flame using a tunable diode laser, and both CO and CO2 measurements in a similar flame using an uncooled, aerodynamically quenched quartz sampling probe. CO was chosen for this study for several reasons: it is an important flame species whose concentration can be predicted under equilibrium conditions which prevail in the post-flame region of fuel-rich flames; its concentration in combustion products can be easily varied from 10 ppm to greater than 10%, a range which is compatible with commercial NDIR instruments; and it has a well-understood infrared absorption spectrum which simplifies analysis of the absorption measurements.
Author: Xiaojuan Cui Publisher: ISBN: Category : Technology Languages : en Pages :
Book Description
Due to the fact of global warming, air quality deterioration and health concern over the past few decades, great demands and tremendous efforts for new technology to detect hazard gases such as CH4, CO2, CO, H2S, and HONO have been performed. Tunable diode laser absorption spectroscopy (TDLAS) is a kind of technology with advantages of high sensitivity, high selectivity, and fast responsivity. It has been widely used in the applications of greenhouse gas measurements, industrial process control, combustion gas measurements, medicine, and so on. In this chapter, we will briefly summarize the most recent progress on TDLAS technology and present several kinds of gas sensors developed mainly by our group for various field applications. These could expand from energy, environment, and public safety to medical science.
Author: Cristian Ravariu Publisher: BoD – Books on Demand ISBN: 1789233046 Category : Technology & Engineering Languages : en Pages : 254
Book Description
The Green Electronics book is intended to stimulate people's thinking toward the new concepts of an environment-friendly electronics - the main challenge in the future. The book offers multiple solutions to push the classical electronic industry toward green concepts, aided by nanotechnologies, with revolutionary features that provide low power consumption in electronics, use biomaterials for integrated structures, and include environmental monitoring tools. Based on organic semiconductors/insulators without toxic precursors, green electronic technologies launched promising devices like OLED, OTFT, or nano-core-shell transistors. The Green Electronics book successfully presents the recent directions collected worldwide and leaves free space for continuing year by year with new subtopics.
Author: Sebastian Bürkle Publisher: BoD – Books on Demand ISBN: 3748145144 Category : Science Languages : en Pages : 190
Book Description
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.
Author: Gordon S. Humphries Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
In-situ optical techniques offer one of the most attractive options for measuring species concentration and spatial distribution profiles in reacting environments, such as flames. The generally non-intrusive nature and spatial resolution of these techniques are now preferred over on extractive sampling, followed by analysis using techniques such as gas chromatography. In this thesis two laser absorption measurement techniques are applied to measure the soot distribution, and acetylene concentration profiles in a flat-flame burner. The in-situ measurement of the distribution of particulate matter in flames is a key step in understanding the mechanism of its formation. Most in-situ measurement systems for this purpose are based on laser induced incandescence where particles are heated using high power laser sources and the increased incandescence emission of the soot particles is detected. However as the soot cools by heat transfer to the surrounding gas, following laser heating, the pressure of the gas is increased creating an acoustic effect. Photoacoustic detection has been applied to quantify low concentrations of particulate matter in ambient air but there have been few applications of photoacoustic detection to the in-situ measurement of particulate matter formation in combustion processes. A novel simple approach using a modulated continuous wave diode laser is presented in this thesis. The measurements taken using this new technique are compared to measurements of the visible emission from the flame, and previous soot distribution measurements using laser induced incandescence. Absorption spectroscopy using near-infrared tunable diode lasers has been applied to measure species in several harsh environments such as aero-engine exhaust plumes, flames, and other industrial processes. Simple single pass absorption techniques are not always suitable for this purpose due to the low absorption of the target species, either due to low concentration or weak absorption line-strength at high temperatures. One method to increase the sensitivity of such techniques is by using cavity enhanced methods which increase the effective path length of the laser through the absorbing medium. One such cavity enhanced method is Cavity Ring-Down Spectroscopy (CRDS). CRDS uses a cavity constructed of highly reflecting mirrors, laser light is then coupled into this cavity and absorption measurements can be evaluated from the decay rate of light from the cavity. The design and, novel application of continuous wave CRDS to measure the concentration profile of acetylene in the flat-flame burner is presented. Difficulties in deriving an absolute acetylene concentration from the measured ringdown times were encountered due to the large number of interfering features. Serveral fitting and extraction techniques are applied and compared to attempt to overcome these difficulties.
Author: Daniel D Lee Publisher: ISBN: Category : Languages : en Pages : 161
Book Description
This dissertation describes laser absorption spectroscopy methods developed for temperature and carbon oxide (CO and CO2) sensing in high-pressure, fuel-rich combustion conditions of hydrocarbon-fueled bipropellant rockets. The scope of the work includes fundamental studies of spectroscopic interactions at high gas density, development of unique laser tuning and signal processing methods, and application of prototype sensors to rocket combustion devices under investigation at the Air Force Research Laboratory in Edwards, CA. Infrared vibrational spectra of CO and CO2 were probed using tunable semi-conductor lasers to infer gas properties. Initial sensor design targeted the absorption spectra of CO near 4.98 m, selected to minimize spectral interference with other combustion gas species at the extreme temperatures (> 3000 K) and pressures (> 50 atm) of a kerosene-fueled rocket combustion environment. Successful measurements were conducted up to 70 bar utilizing a scanned wavelength modulation spectroscopy technique, creating a new pressure-limit for quantitative in situ species sensing in a combustion device. At higher pressures (which were tested), collisional-broadening effects blended the targeted absorption transitions, causing differential absorption to diminish and reducing the signal-to-noise ratio of the measurements. To overcome the pressure-constraints, a more advanced laser absorption sensing strategy was developed, targeting the vibrational bandheads of CO near 2.3 m and CO2 near 4.2 m and exploiting the band narrowing effects of collisional line mixing to counter collisional broadening. Spectral line mixing--typically observed at high gas densities in which intermolecular collisions are sufficiently frequent and strong to cause a shift in energy level populations--corresponds to a transfer of absorption intensity from weak to strong absorption regions, inducing a narrowing of spectral features. This non-ideal phenomenon is more prominent in spectrally dense regions, such as bandheads. Targeting infrared bandheads to exploit line mixing, measurements of CO and CO2 concentration were demonstrated over a range of high pressures up to 105 bar in a single-element-injector RP-2/CH4-GOx rocket combustor. To make such measurements quantitative,spectroscopic models accounting line mixing effects have been developed utilizing a high-enthalpy shock tube; these models are then employed for interpretation of measured absorption signals for quantitative temperature and species sensing.
Author: R. K. Hanson
Author: R. K. Hanson
Author: Reynolds Reed Skaggs
Author: Susan M. Schoenung
Author: Xiaojuan Cui
Author: Susan Marie Schoenung
Author: Cristian Ravariu
Author: Sebastian Bürkle
Author: Gordon S. Humphries
Author: Patricia Kuntz Falcone
Author: Daniel D Lee