Download or read book Development of Laser Absorption Sensors for Combustion Gases written by Xing Chao and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In situ sensors based on laser absorption spectroscopy are developed to monitor key species in combustion exhaust gases. Direct absorption (DA) and wavelength-modulation-spectroscopy (WMS) strategies are investigated for extended near-infrared and mid-infrared laser devices to detect target species in harsh environments at combustion exhaust temperatures in the presence of high moisture level and heavy particulate loading. A real time, in situ sensor for carbon monoxide (CO) was developed using DFB diode lasers near 2.3 æm, with selected transitions (R(10) near 4297.7 cm-1, R(11) near 4300.7 cm-1) in the first overtone band of CO. The sensor was studied in the controlled laboratory environments of a heated cell and a combustion exhaust rig. High temperature water vapor absorption spectra were first measured, and shown to produce

Download or read book Real time Laser Absorption Spectroscopy for Polyfuel Combustion Engines written by Kevin Schwarm and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation details the development and application of mid-infrared laser absorption spectroscopy sensing methods towards advancing low-carbon reciprocating engines for high-efficiency and low-emission power generation in a decarbonized energy sector. The scope of this work includes advancement in methods for fundamental spectroscopic studies, integration of advanced sensors into production reciprocating engines for characterization of combustion of low-carbon fuel blends, and computational methods advancement for high-speed real-time signal processing. A high-temperature, high-pressure optical gas cell is designed to enable controlled studies of molecular absorption spectra at high temperatures (>1200 K) and high pressures (>200 atm) to validate spectroscopic parameters at the elevated conditions in combustion engines. A novel optical approach provides access to the mid-wave infrared wherein lies the fundamental rovibrational absorption bands of combustion species critical to characterization of combustion process and emissions formation. Laser absorption sensors are developed and utilized for experimental measurements in the exhaust of a production Honda single-cylinder spark-ignition engine through design of an in-line exhaust sensor module to gain optical access to exhaust gases close-coupled to the exhaust valve. High-temperature opto-mechanical design and laser fiber-coupling assist in achieving robust measurements of cycle-resolved temperature and species (CO and NO) concentration at a rate of 10 kHz. The exhaust sensor is demonstrated by capturing cycle-to-cycle and intra-cycle emissions dynamics and characterizing emissions response to low-carbon fuel blends incorporating natural gas, hydrogen, and ammonia. To enable real-time measurement output at 10 kHz, computational time of the sensor data processing is reduced to sub-ms scales through the use of machine learning algorithms on an embedded processing platform. Compact neural network and ridge regression models are developed to calculate species concentration and temperature directly from transmitted laser signals, removing the need for computationally-intensive nonlinear fitting methods. The machine learning algorithms are deployed to a field-programmable gate array (FPGA) for further acceleration. Hardware-in-the-loop demonstration yields computational time and latency below 100 μs to expand use of the 10 kHz exhaust sensor for real-time sensing applications. Complementary to the sensor development work, a time-resolved chemical-kinetic model is constructed within Cantera to evaluate reciprocating engine performance and emissions during fueling with low- and non-carbon blends. The simulation model provides insights into strategies for optimization of low-carbon combustion and serves as a foundation for sensor interpretation and future work in engine optimization. Discussion of ongoing work includes the design and development of an electro-hydraulic camless valvetrain for future integration into a reciprocating engine architecture to enhance adaptability for fuel-flexible operation.

Download or read book State of the art Laser Gas Sensing Technologies written by Yufei Ma and published by MDPI. This book was released on 2020-03-05 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: Trace gas sensing technologies are widely used in many applications, such as environmental monitoring, life science, medical diagnostics, and planetary exploration. On the one hand, laser sources have developed greatly due to the rapid development of laser media and laser techniques in recent years. Some novel lasers such as solid-state, diode, and quantum cascade lasers have experienced significant progress. At present, laser wavelengths can cover the range from ultraviolet to terahertz, which could promote the development of laser gas sensing technologies significantly. On the other hand, some new gas sensing methods have appeared, such as photothermal spectroscopy and photoacoustic spectroscopy. Laser spectroscopy-based gas sensing techniques have the advantages of high sensitivity, non-invasiveness, and allowing in situ, real-time observation. Due to the rapid and recent developments in laser source as well as the great merits of laser spectroscopy-based gas sensing techniques, this book aims to provide an updated overview of the state-of-the-art laser gas sensing technologies.

Download or read book Laser Absorption Spectroscopy Techniques for Determining Gas Properties in High Pressure Rocket Combustors written by Daniel D Lee and published by . This book was released on 2020 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Extended NIR Laser Diagnostics for Gas Sensing Applications written by Aamir Farooq and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of diagnostics based on laser-absorption spectroscopy for combustion applications has been an important and active field of research over the past two decades due to the advantages of this non-intrusive optical sensing technique compared to traditional sampling-based sensing methods. Tunable diode laser (TDL) sensors, in particular, have shown the ability to provide in situ, time-resolved, line-of-sight measurements of temperature, gas species concentration, velocity, density, mass flux, and pressure in a variety of combustion environments. This thesis explores three new areas of TDL research: (a) extended near-infrared (NIR) diagnostics, (b) sensing under high-pressures, and (c) applications to chemical kinetics. Water vapor (H2O) and carbon dioxide (CO2) are attractive sensing targets for hydrocarbon-fueled systems as they are primary combustion products and their concentrations can be interpretrated to indicate combustion progress and efficiency. Both these gases have absorption spectra in the infrared (IR) region. Most previous TDL absorption sensors were designed to exploit robust telecommunications diode lasers and optical fiber technology in the 1.3-1.6 [mu]m (NIR) wavelength region. Recent developments in semiconductor diode-laser technology have extended the range of continuous wave (CW) room-temperature single-mode diode lasers to 2.9 [mu]m, allowing access to stronger vibrational bands of H2O and CO2 in the extended-NIR region. The first combustion diagnostics in the extended-NIR wavelength were demonstrated as part of this thesis work. The sensors were designed by selecting optimal transitions and then measuring the pertinent spectroscopic parameters in controlled laboratory environements. These sensors were then tested in the combustion environments of a flat flame and shock tube to validate their performance. These new sensors provide enhanced sensitivity and improved accuracy compared to previous TDL diagnostics. As part of this work, a novel diagnostic based on wavelength modulation spectroscopy (WMS) of CO2 was developed to make precise measurements of temperature behind reflected shock waves. This temperature diagnostic achieved an unprecedented uncertainty of

Download or read book Spectroscopy and Optical Diagnostics for Gases written by Ronald K. Hanson and published by Springer. This book was released on 2015-10-26 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text provides an introduction to the science that governs the interaction of light and matter (in the gas phase). It provides readers with the basic knowledge to exploit the light-matter interaction to develop quantitative tools for gas analysis (i.e. optical diagnostics) and understand and interpret the results of spectroscopic measurements. The authors pair the basics of gas‐phase spectroscopy with coverage of key optical diagnostic techniques utilized by practicing engineers and scientists to measure fundamental flow‐field properties. The text is organized to cover three sub‐topics of gas‐phase spectroscopy: (1) spectral line positions, (2) spectral line strengths, and (3) spectral lineshapes by way of absorption, emission, and scattering interactions. The latter part of the book describes optical measurement techniques and equipment. Key subspecialties include laser induced fluorescence, tunable laser absorption spectroscopy, and wavelength modulation spectroscopy. It is ideal for students and practitioners across a range of applied sciences including mechanical, aerospace, chemical, and materials engineering.

Download or read book Green Electronics written by Cristian Ravariu and published by BoD – Books on Demand. This book was released on 2018-06-20 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Compact Laser Based Sensors for Monitoring and Control of Gas Turbine Combustors written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-20 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research is reported on the development of sensors for gas turbine combustor applications that measure real-time gas temperature using near-infrared water vapor absorption and concentration in the combustor exhaust of trace quantities of pollutant NO and CO using mid-infrared absorption. Gas temperature is extracted from the relative absorption strength of two near-infrared transitions of water vapor. From a survey of the water vapor absorption spectrum, two overtone transitions near 1800 nm were selected that can be rapidly scanned in wavelength by injection current tuning a single DFB diode laser. From the ratio of the absorbances on these selected transitions, a path-integrated gas temperature can be extracted in near-real time. Demonstration measurements with this new temperature sensor showed that combustor instabilities could be identified in the power spectrum of the temperature versus time record. These results suggest that this strategy is extremely promising for gas turbine combustor control applications. Measurements of the concentration of NO and CO in the combustor exhaust are demonstrated with mid-infrared transitions using thermo-electrically cooled, quantum cascade lasers operating near 5.26 and 4.62 microns respectively. Measurements of NO are performed in an insulated exhaust duct of a C2H4-air flame at temperatures of approximately 600 K. CO measurements are performed above a rich H2-air flame seeded with CO2 and cooled with excess N2 to 1150 K. Using a balanced ratiometric detection technique a sensitivity of 0.36 ppm-m was achieved for NO and 0.21 ppm-m for CO. Comparisons between measured and predicted water-vapor and CO2 interference are discussed. The mid-infrared laser quantum cascade laser technology is in its infancy; however, these measurements demonstrate the potential for pollutant monitoring in exhaust gases with mid-IR laser absorption. Hanson, Ronald K. and Jeffries, Jay B. Ames Research Center

Download or read book Applied Laser Absorption Spectroscopy for Detonative Flows written by Kyle D. Thurmond and published by . This book was released on 2020 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: A great deal of interest lies in detonative combustion due to its destructive potential and the theoretical thermodynamic advantages over traditional deflagration devices used for propulsion and energy. High energy materials and explosives combustion products and temperature must be characterized to gain greater insight into the energy release mechanisms, allowing for more tailored deployment. Predictive models for detonations employ various types of state equations, and temperature can be used as a check on the equation validity. However, the extreme environment of explosives is incredibly challenging to evaluate temperature. Additionally, these reactions are extremely fast, taking place over microseconds, and have an extremely large dynamic range, with pressures and temperatures exceeding 30 bar and 3000 K, respectively. For harnessing detonations for energy and propulsion, rotating detonation engines (RDEs) have received much attention due to their simple design and ability to be fed continuously. Many of the same challenges faced in characterizing explosive detonation are encountered in the flowfield of RDEs. These devices require fast measurements (MHz) in extreme environments, which allow the development of better models. The work discussed in this dissertation presents the development and demonstration of laser absorption spectroscopy (LAS) sensors for the characterization of detonative flows in an RDE and high-explosive material's fireballs. The development cycle is discussed, including selecting the target gases, line selection, system design, validation, and demonstration. Temperature and H2O measurements within the detonation channel of a CH4/Air fired RDE are presented, which show incomplete detonation combustion and a secondary combustion mode from unreacted products.

Download or read book Advanced Diode Laser Absorption Sensor for In situ Combustion Measurements of CO2 H2O and Gas Temperature written by R. M. Mihalcea and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Environmental Application of High Sensitive Gas Sensors with Tunable Diode Laser Absorption Spectroscopy written by Xiaojuan Cui and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Applied Combustion Diagnostics written by KoHse-HoingHaus and published by CRC Press. This book was released on 2002-04-26 with total page 744 pages. Available in PDF, EPUB and Kindle. Book excerpt: The editors have assembled a world-class group of contributors who address the questions the combustion diagnostic community faces. They are chemists who identify the species to be measured and the interfering substances that may be present; physicists, who push the limits of laser spectroscopy and laser devices and who conceive suitable measurement schemes; and engineers, who know combustion systems and processes. This book assists in providing guidance for the planning of combustion experiments, in judging research strategies and in conceiving new ideas for combustion research. It provides a snapshot of the available diagnostic methods and thier typical applications from the perspective of leading experts in the field.

Download or read book Sensors and Measurement Techniques for Chemical Gas Lasers written by Mainuddin Gaurav Singhal and published by Lulu.com. This book was released on 2014-09-27 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sensing and Measurement is the key technology area in the development of these lasers. Advanced sensing and measurement technologies are required to acquire, analyze and transform data into information that is useful to enhance the performance and capabilities of these lasers systems.The goal of this book is therefore to enable scientists and technologists working in rather complex area of chemical lasers to achieve the best technical performances. Till now such topics havebeen covered scantly in open literature and that too in the research papers only.

Download or read book Laser and Fiber Optic Gas Absorption Spectroscopy written by George Stewart and published by Cambridge University Press. This book was released on 2021-04-08 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: An invaluable text for the teaching, design, and development of gas sensor technology. This excellent resource synthesizes the fundamental principles of spectroscopy, laser physics, and photonics technology and engineering to enable the reader to fully understand the key issues and apply them in the design of optical gas absorption sensors. It provides a straightforward introduction to low-cost and highly versatile near-IR systems, as well as an extensive review of mid-IR systems. Fibre laser systems for spectroscopy are also examined in detail, especially the emerging technique of frequency comb spectroscopy. Featuring many examples of real-world application and performance, as well as MATLAB computer programs for modeling and simulation, this exceptional work is ideal for postgraduate students, researchers, and professional engineers seeking to gain an in-depth understanding of the principles and applications of fibre-optic and laser-based gas sensors.

Download or read book Combustion Control Using a Multiplexed Diode Laser Sensor System written by and published by . This book was released on 1996 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A multiplexed diode-laser sensor system, comprised of two InGaAsP diode lasers and fiber-optic components, has been developed to non-intrusively measure temperature and species concentration over a single path for closed-loop process control using laser absorption spectroscopy techniques. The system was applied to measure and control the gas temperature in the post-flame gases 6 mm above the surface of a Hencken burner. The wavelengths of the lasers were independently current-tuned H2O Transitions near 1343 nm and 1392 nm. Temperature was determined from the ratio of measured peak absorption coefficients. H2O concentration was determined from the measured absorption coefficient of one transition set at the measured temperature. The mean temperatures recorded compared well with those measured by a thermocouple. Temperature fluctuations up to 250 Hz were accurately measured with the sensor system, demonstrating the high bandwidth of the measurement technique.

Download or read book Mid infrared Laser Diagnostics for Chemical Kinetics Study of Oxygenates written by Wei Ren and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Biofuels are classified as renewable because the carbon present in the vegetable oil or animal fat feedstocks originates from carbon dioxide already present in the atmosphere. One of the current focuses on biofuel-based combustion research is the design of advanced energy conversion devices using complex reaction mechanisms. The development of these mechanisms requires a large experimental database to ensure accuracy of computational predictions. Infrared laser-absorption diagnostics are widely used in combustion research for fast, sensitive, and non-intrusive measurements of species concentration, temperature, and pressure. This thesis explores three new areas of laser diagnostic research: (a) mid-infrared diagnostics, (b) sensing in multiphase flows, and (c) applications to shock tube chemical kinetics. A novel distributed-feedback quantum-cascade laser (DFB-QCL) near 4.7 um was investigated to develop a new mid-infrared absorption sensor for in situ measurements of carbon monoxide (CO) and temperature in combustion gases. The laser provides convenient access to the stronger vibrational bands of CO than was possible previously, enabling ppm-level detectivity with an optical path length of 10 cm at high temperatures between 1000-2000 K. Wavelength modulation spectroscopy with 1f-normalized 2f detection (WMS-2f/1f) of CO2 was developed for accurate temperature sensing in multiphase combustion flows. In this method, two tunable diode lasers with wavelengths near 2.7 um were used to measure time-varying gas temperature during the evaporation of shock-heated fuel aerosols. These recently developed mid-IR laser absorption diagnostics were then applied in studying the thermal decomposition of oxygenates (biofuel surrogates) by measuring species concentration time-histories behind reflected shock waves. In a particular study of methyl formate (the simplest biodiesel surrogate), the reaction rate constants of methyl formate unimolecular decomposition were measured using the mid-IR CO absorption behind reflected shock waves. Detailed comparisons of the measured methanol and CO time-histories with the model predictions were made. Sensitivity and reaction pathway analyses for these oxygenated fuel components were performed, leading to rate recommendations with improved model performance.

Download or read book Combustor Exhaust Temperature Nonuniformity Sensing Using Diode Laser Absorption written by Tudor Ioan Palaghita and published by . This book was released on 2007 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the development of a sensing technique for temperature nonuniformity along the line of sight through combustion exhaust. Tunable diode laser absorption spectroscopy is used to measure three absorption lines and compute a variable to characterize the level of temperature nonuniformity along the laser path.