Download or read book Flame Temperature Imaging of a Low NOx Burner Via Laser Rayleigh Scattering written by Nicholas A. Smith and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Federal and global legislation are requiring increasingly stringent emission regulation on household appliances and in particular water heater burners. Emissions like NOx (NO and NO2) are a growing concern due to their adverse health effects and contribution to tropospheric ozone, acid rain, and smog formation. As NOx is more closely controlled, appliance manufacturers are developing low emission burners for use in water heaters. Flame temperature is strongly correlated to NOx production. Hence, characterizing flame temperatures in new burners is a key part of improving upon burners used today and the development of future burners. Temperature measurements applied to a new, radiant, ultralow-NOx burner are thus the focus of this research. Laser Rayleigh scattering allows us to make near-instantaneous, 2-D measurements using an unobtrusive technique. The application of this technique resulted in flame temperature images in three locations, above and across the burner surface ranging from 800-1600 K in general with an uncertainty of 9.6%. The fluctuation of the flame temperature was also found ranging from 200-800 K, indicating the presence of large scale hot and cold gas mixing. Other temperature measuring techniques were applied to the burner as well. A type-K thermocouple 5 cm above the center of the burner measured a point gas temperature of 1508 K after an estimated radiative correction was applied. This measurement was within 5.3% of the laser Rayleigh scattering measurement of 1428 K at the same location. An IR camera did not provide quantitative temperature measurements, but the videos indicated similar flame structure and mixing behavior when compared to a series of single-shot laser Rayleigh scattering images. It was concluded that the large amount of excess air (equivalence ratio of 0.725) was primarily responsible for reducing the flame temperature by 436 K in comparison with the adiabatic flame temperature under stoichiometric conditions. The radiative emission by the burner was estimated from the thermocouple and laser Rayleigh scattering measurements to decrease the temperature further by an average of 420 K relative to the stoichiometric adiabatic flame temperature.
Download or read book Laser Diagnostics for Combustion Temperature and Species written by A. C. Eckbreth and published by Routledge. This book was released on 1988 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Springer Handbook of Experimental Fluid Mechanics written by Cameron Tropea and published by Springer Science & Business Media. This book was released on 2007-10-09 with total page 1570 pages. Available in PDF, EPUB and Kindle. Book excerpt: Accompanying DVD-ROM contains ... "all chapters of the Springer Handbook."--Page 3 of cover.
Download or read book The Development of a Combustion Temperature Standard for the Calibration of Optical Diagnostic Techniques written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the development and evaluation of a high-temperature combustion standard. This comprises a McKenna burner premixed flame, together with a full assessment of its temperature, stability and reproducibility. I have evaluated three techniques for high-accuracy flame thermometry: Modulated Emission in Gases (MEG), Rayleigh scattering thermometry and photo-acoustic thermometry. MEG: Analysis shows that MEG is not usable in this application because the sharp spectral features of the absorption coefficient of gases are represented within MEG theory as an average absorption coefficient over the optical detection bandwidth. A secondary difficulty arises from the lack of high power lasers operating at wavelengths that coincides with molecular absorption lines in the hot gas. Rayleigh Scattering: Applying corrections for the temperature-dependence of the scattering cross-section, it has been possible to determine the temperature of the combustion standard with an uncertainty of approximately 1%. The temperature dependence of the scattering cross-section arises from changes in the mean molecular polarisability and anisotropy and can amount to 2% between flame and room temperatures. Using a pulse Nd-YAG laser operating at 532 nm and high linearity silicon detectors, the Rayleigh scattering experimental system has been optimised. Temperatures measured over a three-month interval are shown to be reproducible to better than 0.4% demonstrating the suitability of the McKenna burner as a combustion standard. Photo-Acoustic: By measuring the transit time of a spark-induced sound wave past two parallel probe beams, the temperature has been determined with an uncertainty of approximate 1%. Flame temperatures measured by the photo-acoustic and Rayleigh scattering thermometry system show good agreement. For high airflow rates the agreement is better than 1% of temperature, but for low airflow rates, photo-acoustic temperatures are approximately 3.6% higher than the Ray.
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 A Linear Array for Rayleigh Scattering written by L. Talbot and published by . This book was released on 1985 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gas density under combustion conditions can be obtained by measuring the intensity of the molecular (Rayleigh) scattering of light from a laser beam. A system which obtains an essentially continuous record of the density along a length of the laser beam is described. The temperature and degree of combustion can thus be determined for a number of interesting combustion configurations, which will ultimately lead to a better description and understanding of combustion flow flame field phenomena. An image of Rayleigh scattered light from the combustion region is projected onto a monolithic self scanning linear photodiode array by means of a lens, bandpass filter, slit, image intensifier, and fiber optic reducer. The video output of the linear array is digitized and stored, creating a space-time map of the density which can be visualized and manipulated as an image. Analysis of these images by image processing techniques gives qualitative and quantitative information about such features of the combustion zone as flame wrinkling and periodicity, flame thickness and continuity, and other structural and time dependent properties in the combustion region. Following a brief introduction, the components are described, the system performance characteristics are discusssed, and an example of a processed image from a simple turbulent flame is presented. Keywords: Rayleigh scattering; Premixed turbulent flames; Laser imaging.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1995 with total page 988 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dynamics of the Flame Flowfields in a Low swirl Burner written by Robert Cheng and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The concept of using low swirl to stabilize lean premixed turbulent flame was introduced in 1992. Since then, the low-swirl burner (LSB) has become a useful laboratory tool for the study of detailed flame structures as well as turbulent burning speeds. Its main attribute is that the flame is freely propagating and is locally normal to the turbulent approach flow (Figure 1). Therefore, the turbulent flame brush is not influence by physical boundaries. The capability of LSB to support very lean flames and very turbulent flames [1, 2] was further exploited in recent studies to test the validity of the flame regime concept. Using 2D imaging diagnostics (e.g. planar laser induced fluorescence, PLIF, and planar laser induced Rayleigh scattering) our analysis showed that the wrinkled flame regime to be valid at a turbulence intensity level much higher than previously thought [3-5]. This provided experimental verification of a new 'thin reaction zone' regime for the Kalovitz number range of 1
Download or read book Crossed Plane Imaging of Premixed Turbulent Combustion Processes written by and published by . This book was released on 2003 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the last several years we have developed and applied advanced imaging methods - crossed-plane laser tomography and crossed-plane laser Rayleigh imaging -- for high-resolution studies of scalar fields in premixed combustion. Laser tomography with micron sized, silicone oil droplets marks 650 K isothermal surfaces, and we have used crossed-plane tomography to measure for the first time in three dimensions the instantaneous orientation of these surfaces and to determine the probability density function of the surface normal vector, a statistical measure of surface wrinkling. Rayleigh scattering from premixed flames can be used for temperature imaging, and we have developed crossed-plane Rayleigh imaging in order to measure with high-resolution instantaneous temperature fields, temperature gradient vectors and isothermal surface densities in premixed reacting flows. Most recently we have combined crossed-plane tomography with stereo particle image velocimetry to measure for the first time reactant flow velocities and the components of this velocity both perpendicular and tangent to the reaction sheet. In this report progress from the inception of Grant number DAAD 19-99-1-0324 is summarized, and relevant information regarding publications and participants in the research is presented.
Download or read book The Effect of Strain Rate on the Temperature Field Structure in a Turbulent Non premixed Flame Using Planar Rayleigh Scattering written by David Alan Everest and published by . This book was released on 1994 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Temperature Mapping of an Acoustically Forced Laminar Diffusion Flame Using Planar Laser Rayleigh Scattering written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Laser saturated Fluorescence Measurements in Laminar Sooting Diffusion Flames written by Changlie Wey and published by . This book was released on 1993 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: The hydroxyl radical is known to be one of the most important intermediate species in the combustion processes. The hydroxyl radical has also been considered a dominant oxidizer of soot particles in flames. In this investigation the hydroxyl concentration profiles in sooting diffusion flames were measured by the laser-saturated fluorescence (LSF) method. The temperature distributions in the flames were measured by the two-line LSF technique and by thermocouple. In the sooting region the OH fluorescence was too weak to make accurate temperature measurements. The hydroxyl fluorescence profiles for all four flames presented herein show that the OH fluorescence intensities peaked near the flame front. The OH fluorescence intensity dropped sharply toward the dark region of the flame and continued declining to the sooting region. The OH fluorescence profiles also indicate that the OH fluorescence decreased with increasing height in the flames for all flames investigated. Varying the oxidizer composition resulted in a corresponding variation in the maximum OH concentration and the flame temperature. Furthermore, it appears that the maximum OH concentration for each flame increased with increasing flame temperature.
Download or read book Crossed Plane Laser Imaging of Premixed Turbulent Combustion Processes written by F. C. Gouldin and published by . This book was released on 2001 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of our research is to measure, using crossed-plane imaging, normal vectors and the instantaneous thermal structure of flamelets in premixed turbulent flames. Data for surface normal vectors can be used to calculate important quantities such as Sigma, the flamelet surface density. Sigma is a measure of the wrinkling of the flamelet surface and is proportional to the rate of product formation per unit volume in the flame, w, which appears as an unclosed term in premixed flame models and is related to the burning intensity. Flamelet thermal structure data can be used to estimate the constant of proportionality between w and Sigma. Instantaneous flamelet normals have been measured in three dimensions using crossed-plane imaging via either laser tomography or planar laser induced acetone fluorescence. We are now exploiting crossed-plane imaging for flamelet normal measurements in different burners and over a range of conditions. In additional we are developing crossed-plane Rayleigh imaging in order to measure temperature gradients within flamelets and thereby to determine their thermal structure. Through measurements of flamelet normal and thermal structure we can estimate w.
Download or read book Interpretation of Rayleigh Scattering in a Flame written by and published by . This book was released on 1980 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rayleigh scattering has become an accepted technique for the determination of total number density during the combustion process. The interpretation of the ratio of total Rayleigh scattering signal as a ratio of densities or temperatures is hampered by the changing composition and mean molecular weight through a flame. Typical values of correction factors as a function of degree of reaction, fuel, and equivalence ratio are calculated for an idealized one-dimensional flame front. The fuels considered are H{{u2082}, CH4, C2H4, C2H6, and C3H. Errors of up to 30% can occur in the interpretation of the Rayleigh scattering as gas density for the heavier hydrocarbon fuels due, primarily, to the presence of CO as an intermediate combustion product. Conversely, using H2 as a fuel will result in a maximum error of 3%, which is within the expected experimental accuracy of a typical Rayleigh scatterinq system. The interpretation of Rayleigh scattering as temperature was found to have larger errors than the interpretation as density. Nevertheless, when corrections are applied for changes in gas composition, Rayleigh scattering provides an excellent measure of total gas density and temperature in flames.
Download or read book Technical Report written by and published by . This book was released on 2015 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: A laser Rayleigh scattering (LRS) temperature diagnostic was developed over 8 weeks with the goal of studying oxy-combustion of pulverized coal char in high temperature reaction environments with high concentrations of carbon dioxide. Algorithms were developed to analyze data collected from the optical diagnostic system and convert the information to temperature measurements. When completed, the diagnostic will allow for the kinetic gasification rates of the oxy-combustion reaction to be obtained, which was previously not possible since the high concentrations of high temperature CO2 consumed thermocouples that were used to measure flame temperatures inside the flow reactor where the combustion and gasification reactions occur. These kinetic rates are important for studying oxycombustion processes suitable for application as sustainable energy solutions.
Download or read book Burner Design Criteria for NOX Control from Low BTU Gas Combustion Volume I written by Donald R. Shoffstall and published by . This book was released on 1977 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research program was initiated to characterize problems associated with retrofitting existing utlity boilers with low- and medium-Btu gases manufactured from commercially available coal conversion processes. All the experimental results were gathered from a pilot-scale furnace fired with a movable-vane boiler burner at a heat input of 0.66 MW (2,250,000 Btu/h). The low- and medium-Btu gases tested ranged in heating value from 3.7 to 11.2 MJ/m3 (100 to 300 Btu/SCF). They were synthetically produced with a natural gas reformer system. Data were collected to permit a comparison between natural gas and low-Btu gases in the areas of flame stability, flame length, flame emissivity, furnace efficiency, and NOx emissions. Flame stability was found to be very sensitive to fuel jet volocity. An injection velocity of 30.5 m/s (100 ft/s) was found to be optimum. Flame length decreased with increasing movable vane angle (swirl of the combustion air), and the low- and medium-Btu gases tested were generally shorther than those of natural gas. Good agreement was obtained between measured and calculated flame emissivities. Some boiler modifications would be necessary to maintain rating when burning gases of less thatn 7.5 MJ/m3 (200 Btu/SCF) heating value. NO emissions were ordered by adiabatic flame temperature. The NO emission data yielded an activation energy of 153 k-cal/mole compared to kinetic model predictions of 135 k-cal/mole. The use of adiabatic flame temperature provided a good empirical method of predicting NO emissions for the fuels tested.
Download or read book Burner design criteria NOX control from low BTU gas combustion written by Donald R. Shoffstall and published by . This book was released on 1977 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
