Download or read book Fuel air Mixing Effect on NOx Emissions for a Lean Pre mixed Pre vaporized Combustion System written by Chi-Ming Lee and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Variable Fuel Composition on Emissions and Lean Blowoff Stability Performance written by Andrés Colorado and published by . This book was released on 2017 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fuel air Mixing and Nitrogen Oxide Formation in a Lean Premixed Gas Turbine Combustor written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental and Numerical Modeling of NOx Formation in Premixed Combustion of Pure and Renewable Liquid Fuels written by Arshiya Hoseyni Chime and published by . This book was released on 2018 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: A jet stirred reactor (JSR) is used to study the effects of fuel type and composition on NOx emissions. The reactor temperature is varied from 1700K to 1900K. Both pure and blended fuels are used in the experiments with the C/H ratio of fuels varying from 0.429 to 0.875. The fuels studied are: methane (as the baseline), n-hexane, n-octane, n-dodecane, isooctane, cyclo-hexane, toluene,1,3,5 tri-methyl benzene (135-TMB), jet-A, jet fuel made by Fischer-Tropsch processing of natural gas, and renewable jet fuel made from camelina, tallow, or bio-alcohol. The combustion of alternative and traditional commercial jet fuels show relatively minor differences in NOx. The trend observed at three different temperatures of the recirculation zone shows: HRJ-tallow

Download or read book Effect of fuel air ratio nonuniformity on emissions of nitrogen oxides written by Valerie J. Lyons and published by . This book was released on 1981 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Combustion Behavior Associated with Alternative Fuels in Lean Premixed High swirl Stabilized Distributed Reactions written by Amin Akbari and published by . This book was released on 2013 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lean blowoff, flashback and pollutant emission associated with lean premixed combustion of alternative fuels stabilized by high swirl are evaluated in this work. Alternative fuel compositions include blends of natural gas and hydrogen. Lean blowoff refers to events where the fuel-to-air ratio is not sufficient to sustain the reaction. Blowoff is often a dynamic process consisting of several stages. Correlations based on constant Damköhler (Da) number are able to estimate the impact of fuel composition on lean blowoff for the conditions studied. The accuracy of estimating initiation of blowoff is superior compared to estimation of subsequent stages of blowoff. Flashback refers to propagation of the reaction upstream into the premixing zone. In high swirl combustion applications, the concept of a quench criterion has been proposed for predicting flashback. For the present work, this concept only holds for some measured cases, which indicates multiple flashback modes even in high swirl combustion applications. The other major combustion challenge is pollutant emission. In this study NOx, CO, and N2O levels are experimentally measured. In addition, a chemical reaction network (CRN) was developed to study the details of emission formation. To develop a CRN, details of the reacting flow were needed. Hence, computational fluid dynamics (CFD) simulations were conducted. To validate CFD simulations, particle image velocimetry (PIV) and OH* chemiluminescence flame front imaging were applied. OH* chemiluminescence was also employed to visualize the flame structure and shape for different fuel compositions. The CRN simulations indicate that the NNH NOx formation pathway dominates the other formation pathways. Thus, conditions that enhance NNH NOx, such as an increase of hydrogen in fuel composition, and decrease of residence time, will result in more total NOx. The CRN also illustrates how the relative contribution of each NOx formation pathway to total NOx changes with adiabatic flame temperature (AFT). The NNH NOx formation pathway is dominant for AFT below 1900K; the Zeldovich mechanism is dominant for AFT above 1900K. In terms of N2O emissions measured and simulated results suggest the levels are negligible even for very low combustion temperatures.

Download or read book Effects of the Fuel Air Mixing on Combustion Instabilities and NOx Emissions in Lean Premixed Combustion written by Wessam Estefanos and published by . This book was released on 2016 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study was conducted to investigate the effects of the fuel-air mixing on combustion instabilities and NO x emissions in lean premixed combustion. High speed PIV measurements in water were conducted to capture the mean and dynamic behavior of the cold flow generated by a 3X model of the tested premixer. High speed PLIF in water measurements were conducted to quantify the mean and unsteady fuel-air mixing at different momentum flux ratios. Atmospheric combustion tests using the original premixer, were conducted using natural gas and propane at the same momentum flux ratios of the PLIF mixing tests. An emissions analyzer was used to measure the emissions from combustion tests. Dynamic pressure transducers were used to measure the amplitude and the frequency of the dynamic pressure oscillations associated with the combustion instabilities. CHEMKIN-PRO was used to model the atmospheric combustion and predict NO x emissions at different conditions. Results showed that unsteady fuel-air mixing was concentrated at the center and near the outer edges of the premixer. These regions were characterized by high fuel concentration gradients. With the increase in the momentum flux ratio, the concentration gradient and the level of unsteady mixing increased, indicating that the fuel-air spatial unmixedness was the source of the unsteady mixing. It was found that local flow turbulence tended to decrease the concentration gradient through enhancing the fuel-air mixing, which resulted in decreasing the level of unsteady mixing. NO x emissions from atmospheric combustion increased with the increase in the momentum flux ratio due to the increase in the flame temperature and the fuel-air spatial and temporal unmixedness. The intensity of the combustion dynamics increased with the increase in the level of unsteady mixing. Axial injection of the fuel into the regions of strong unsteady mixing eliminated the combustion dynamics through damping the unsteady mixing. Results of CHEMKIN-PRO agreed very well with the experimental results and showed that the spatial and temporal unmixedness have a significant effect on NO x emissions for very lean combustion (F = 0.4). With the increase in the equivalence ratio, their relative contribution decreased.

Download or read book ASME Technical Papers written by and published by . This book was released on 2001 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Paper written by and published by . This book was released on 2001 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Influence of Fuel Structure on CO and NOx Formation in Lean Premixed Hydrocarbon Flames written by and published by . This book was released on 1909 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A study is made of the influence chemical structure of fuel has upon combustion performance through tracing the generation of carbon monoxide and oxides of nitrogen in lean, premixed, hydrocarbon-air flames. The study includes both analytical and experimental investi- gations. On the analytical side, a kinetic model is developed to predict both CO and NO time-histories in one-dimensional, premixed flames. The model is based upon the assumption of partial equilibrium in the post-flame zone while the fuel oxidation in the main reaction zone is allowed for by using a global oxidation rate equation. NO formation is assumed to be entirely via the Zeldovitch mechanism and to start in the post-flame zone. The utility of the model is judged through comparison between theoretical results and experimental data. On the experimental side, a simple burner system, supporting a one-dimensional premixed flame was designed and built. All fuels selected for investigation were pure hydrocarbons representing the main hydrocarbon types usually found in practical fuels; namely paraffins, olefins, naphthenes and aromatics. The hydrogen-to-carbon ratio ranged from 1 to 2.67 and the carbon number from 3 to 12. The experiments were performed at 1,2 and 3 atm pressure levels and 140°C inlet temperature, while the equivalence ratio was in the range 0.6 to 0.9. Flames were sampled for most stable species by a water- cooled stainless steel sampling probe. The experimental results show that the fuel structure signifi- cantly affects CO time-histories in the investigated flames mainly through influencing its generation rather than its burnout. CO burnout is shown to be mainly controlled by radical recombination processes, and the experimentally derived CO global oxidation rate equations are found not to be universally applicable. The results also show that the fuel structure influences prompt NOx formation within, and very near, the main reaction zone but that it does not influence post-equilibriu.

Download or read book NOx Formation in Lean Premixed Hydrocarbon Combustion written by Robert A. Corr (II.) and published by . This book was released on 1990 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NOx Formation in Lean premixed Combustion of Liquid Hydrocarbons written by Scott A. Capehart and published by . This book was released on 1995 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Lean Premixed prevaporized Combustion written by and published by . This book was released on 1977 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Combustion Flames and Explosions of Gases written by Bernard Lewis and published by Academic Press. This book was released on 2013-10-22 with total page 754 pages. Available in PDF, EPUB and Kindle. Book excerpt: Combustion, Flames, and Explosions of Gases, Second Edition focuses on the processes, methodologies, and reactions involved in combustion phenomena. The publication first offers information on theoretical foundations, reaction between hydrogen and oxygen, and reaction between carbon monoxide and oxygen. Discussions focus on the fundamentals of reaction kinetics, elementary and complex reactions in gases, thermal reaction, and combined hydrogen-carbon monoxide-oxygen reaction. The text then elaborates on the reaction between hydrocarbons and oxygen and combustion waves in laminar flow. The manuscript tackles combustion waves in turbulent flow and air entrainment and burning of jets of fuel gases. Topics include effect of turbulence spectrum and turbulent wrinkling on combustion wave propagation; ignition of high-velocity streams by hot solid bodies; burners with primary air entrainment; and description of jet flames. The book then takes a look at detonation waves in gases; emission spectra, ionization, and electric-field effects in flames; and methods of flame photography and pressure recording. The publication is a valuable reference for readers interested in combustion phenomena.

Download or read book Analysis of Fuel Vaporization Fuel air Mixing and Combustion in Lean Premixed prevaporized Combustors written by J. M. Deur and published by . This book was released on 1995 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Fuel Composition on Combustion Stability and NO Emissions for Traditional and Alternative Jet Fuels written by Shazib Z. Vijlee and published by . This book was released on 2014 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: Synthetic jet fuels are studied to help understand their viability as alternatives to traditionally derived jet fuel. Two combustion parameters - flame stability and NOX emissions - are used to compare these fuels through experiments and models. At its core, this is a fuels study comparing how chemical makeup and behavior relate. Six 'real', complex fuels are studied in this work - four are synthetic from alternative sources and two are traditional from petroleum sources. Two of the synthetic fuels are derived from natural gas and coal via the Fischer Tropsch catalytic process. The other two are derived from Camelina oil and tallow via hydroprocessing. The traditional military jet fuel, JP8, is used as a baseline as it is derived from petroleum. The sixth fuel is derived from petroleum and is used to study the effects of aromatic content on the synthetic fuels. The synthetic fuels lack aromatic compounds, which are an important class of hydrocarbons necessary for fuel handling systems to function properly. Several single-component fuels are studied (through models and/or experiments) to facilitate interpretation and understanding. Methane is used for detailed modeling as it has a relatively small and well-understood chemical kinetic mechanism. Toluene, iso-octane, n-octane, propylcyclohexane, and 1,3,5-trimethylbenzene are included as they are all potential surrogates for jet fuel components. The flame stability study first compares all the `real', complex fuels for blowout. A toroidal stirred reactor is used to try and isolate temperature and chemical effects. The reactor has a volume of 250 mL and a residence time of approximately 8.0 ms. The air flow rate is held constant such that the inlet jets are sonic and turbulent mixing is present throughout the reactor. The fuel flow rate (hence equivalence ratio) is slowly lowered until the flame cannot sustain itself and it extinguishes. The results show that there is very little variation in blowout temperature and equivalence ratio for the synthetic fuels when compared to JP8 with low levels (0, 10, and 20%) of the aromatic additive. However, the 100% aromatic fuel behaved significantly differently and showed a lower resistance to blowout (i.e., it blew out at a higher temperature and equivalence ratio). The modeling study of blowout in the toroidal reactor is the key to understanding any fuel-based differences in blowout behavior. A detailed, reacting CFD model of methane is used to understand how the reactor stabilizes the flame and how that changes as the reactor approaches blowout. A 22 species reduced form of GRI 3.0 is used to model methane chemistry. The model shows that the reactor is quite homogenous at high temperatures, far away from blowout, and the transport of chain-initiating and chain-branching radical species is responsible for stabilizing the flame. Particularly, OH radical is recirculated around the reactor with enough concentration and at a high enough rate such that the radicals interact with the incoming fuel/air and initiate fuel decomposition. However, as equivalence ratio decreases, the reactor begins to behave in a more zonal nature and the radical concentration/location is no longer sufficient to initiate or sustain combustion. The knowledge of the radical species role is utilized to investigate the differences between a highly aliphatic fuel (surrogated by iso-octane) and a highly aromatic fuel (surrogated by toluene). A perfectly stirred reactor model is used to study the chemical kinetic pathways for these fuels near blowout. The differences in flame stabilization can be attributed to the rate at which these fuels are attacked and destroyed by radical species. The slow disintegration of the aromatic rings reduces the radical pool available for chain-initiating and chain-branching, which ultimately leads to an earlier blowout. The NOX study compares JP8, the aromatic additive, the synthetic fuels with and without an aromatic additive, and an aromatic surrogate (1,3,5-trimethylbenzene). A jet stirred reactor is used to try and isolate temperature and chemical effects. The reactor has a volume of 15.8 mL and a residence time of approximately 2.5 ms. The fuel flow rate (hence equivalence ratio) is adjusted to achieve nominally consistent temperatures of 1800, 1850, and 1900K. Small oscillations in fuel flow rate cause the data to appear in bands, which facilitated Arrhenius-type NOX-temperature correlations for direct comparison between fuels. The fuel comparisons are somewhat inconsistent, especially when the aromatic fuel is blended into the synthetic fuels. In general, the aromatic surrogate (1,3,5-trimethylbenzene) produces the most NOX, followed by JP8. The synthetic fuels (without aromatic additive) are always in the same ranking order for NOX production (HP Camelina > FT Coal > FT Natural Gas > HP Tallow). The aromatic additive ranks differently based on the temperature, which appears to indicate that some of the differences in NOX formation are due to the Zeldovich NOX formation pathway. The aromatic additive increases NOX for the HP Tallow and decreases NOX for the FT Coal. The aromatic additive causes increased NOX at low temperatures but decreases NOX at high temperatures for the HP Camelina and FT Natural Gas. A single perfectly stirred reactor model is used with several chemical kinetic mechanisms to study the effects of fuel (and fuel class) on NOX formation. The 27 unique NOX formation reactions from GRI 3.0 are added to published mechanisms for jet fuel surrogates. The investigation first looked at iso-octane and toluene and found that toluene produces more NOX because of a larger pool of O radical. The O radical concentration was lower for iso-octane because of an increased concentration of methyl (CH3) radical that consumes O radical readily. Several surrogate fuels (iso-octane, toluene, propylcyclohexane, n-octane, and 1,3,5-trimethylbenzene) are modeled to look for differences in NOX production. The trend (increased CH3→ decreased O → decreased NOX) is consistently true for all surrogate fuels with multiple kinetic mechanisms. It appears that the manner in which the fuel disintegrates and creates methyl radical is an extremely important aspect of how much NOX a fuel will produce.

Download or read book The Influence of Fuel Structure on CO and NOx Formation in Lean Premixed Hydrocarbon Flames written by H. S. M. Saleh and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A study is made of the influence chemical structure of fuel hasupon combustion performance through tracing the generation of carbonmonoxide and oxides of nitrogen in lean, premixed, hydrocarbon-airflames. The study includes both analytical and experimental investi-gations. On the analytical side, a kinetic model is developed to predictboth CO and NO time-histories in one-dimensional, premixed flames. The model is based upon the assumption of partial equilibrium in thepost-flame zone while the fuel oxidation in the main reaction zone isallowed for by using a global oxidation rate equation. NO formationis assumed to be entirely via the Zeldovitch mechanism and to startin the post-flame zone. The utility of the model is judged throughcomparison between theoretical results and experimental data. On the experimental side, a simple burner system, supporting aone-dimensional premixed flame was designed and built. All fuelsselected for investigation were pure hydrocarbons representing themain hydrocarbon types usually found in practical fuels; namelyparaffins, olefins, naphthenes and aromatics. The hydrogen-to-carbonratio ranged from 1 to 2.67 and the carbon number from 3 to 12. Theexperiments were performed at 1,2 and 3 atm pressure levels and 140?Cinlet temperature, while the equivalence ratio was in the range 0.6to 0.9. Flames were sampled for most stable species by a water-cooled stainless steel sampling probe. The experimental results show that the fuel structure signifi-cantly affects CO time-histories in the investigated flames mainlythrough influencing its generation rather than its burnout. COburnout is shown to be mainly controlled by radical recombinationprocesses, and the experimentally derived CO global oxidation rateequations are found not to be universally applicable. The resultsalso show that the fuel structure influences prompt NOx formationwithin, and very near, the main reaction zone but that it does notinfluence post-equilibrium NOx formation if account is taken ofdifferences in the flame temperatures. N02 is found to constitute alarge percentage of total NOx measured especially at lower temperatureand equivalence ratios. Comparison between experimental and theoretical results showthat the prescribed kinetic model can satisfactorily predict CO levelsfor different fuels and under different conditions if the fuel oxidationglobal rate equation is correctly defined for different fuels. On theother hand, agreement between predicted and measured NO profiles hasbeen obtained at atmospheric pressure only. At high pressure, thepredicted levels were much smaller than those measured experimentally, and this disagreement is attributed to the fact that proper account isnot taken of the NO and N02 formation kinetics in the main reactionzone.