Experimental and Theoretical Studies of Laminar Burning Speed and Flame Instability of Alternative Fuels and Refrigerants

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ISBN 13 :
Total Pages : 157 pages
Book Rating : 4.:/5 (123 download)

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Book Synopsis Experimental and Theoretical Studies of Laminar Burning Speed and Flame Instability of Alternative Fuels and Refrigerants by : Ziyu Wang

Download or read book Experimental and Theoretical Studies of Laminar Burning Speed and Flame Instability of Alternative Fuels and Refrigerants written by Ziyu Wang and published by . This book was released on 2020 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Alternative fuels and alternative refrigerants have attracted a lot of attention as many are deemed to be environmentally friendly. Consequently, the combustion behavior of fuels such as Syngas, Biogas, Liquified petroleum gas (LPG), and Gas to liquid (GTL) premixed flames were studied. In this investigation, the laminar burning speed and the flame instability of alternative fuels and refrigerants and different diluents (Exhaust gas recirculation (EGR), Helium, CO2) mixtures were evaluated both experimentally and numerically. Experiments were conducted using a spherical vessel to measure laminar burning speed and a cylindrical vessel to investigate flame instability. The cylindrical vessel is set up in a Z-shape Schlieren system, coupled with a high-speed CMOS camera that is used to capture evolutionary behavior of flames at up to 40,000 frames per second (around 2000 frames per second in general case). Upon ignition, the pressure rises as a function of time, during flame propagation in the spherical chamber, is the primary input of a multi-shell thermodynamic model, used to calculate the laminar burning speed for smooth flames. Power law correlations were developed for experimental burning speed results of different combustible mixtures over a wide range of equivalence ratios, temperatures, pressures, and diluent concentrations. For the onset of flame instability, a correlation for the ratio of critical pressure to initial pressure of syngas/air/diluent flames over a wide range of initial temperatures, initial pressures, equivalence ratios, diluent concentrations, and hydrogen percentages were developed. Kinetics simulations calculated by 1-D steady state flame code from CANTERA were compared with various experimental burning speed results"--Author's abstract.

On the Experimental and Theoretical Investigations of Lean Partially Premixed Combustion, Burning Speed, Flame Instability and Plasma Formation of Alternative Fuels at High Temperatures and Pressures

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ISBN 13 :
Total Pages : 271 pages
Book Rating : 4.:/5 (986 download)

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Book Synopsis On the Experimental and Theoretical Investigations of Lean Partially Premixed Combustion, Burning Speed, Flame Instability and Plasma Formation of Alternative Fuels at High Temperatures and Pressures by : Omid Askari

Download or read book On the Experimental and Theoretical Investigations of Lean Partially Premixed Combustion, Burning Speed, Flame Instability and Plasma Formation of Alternative Fuels at High Temperatures and Pressures written by Omid Askari and published by . This book was released on 2016 with total page 271 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation investigates the combustion and injection fundamental characteristics of different alternative fuels both experimentally and theoretically. The subjects such as lean partially premixed combustion of methane/hydrogen/air/diluent, methane high pressure direct-injection, thermal plasma formation, thermodynamic properties of hydrocarbon/air mixtures at high temperatures, laminar flames and flame morphology of synthetic gas (syngas) and Gas-to-Liquid (GTL) fuels were extensively studied in this work. These subjects will be summarized in three following paragraphs. The fundamentals of spray and partially premixed combustion characteristics of directly injected methane in a constant volume combustion chamber have been experimentally studied. The injected fuel jet generates turbulence in the vessel and forms a turbulent heterogeneous fuel-air mixture in the vessel, similar to that in a Compressed Natural Gas (CNG) Direct-Injection (DI) engines. The effect of different characteristics parameters such as spark delay time, stratification ratio, turbulence intensity, fuel injection pressure, chamber pressure, chamber temperature, Exhaust Gas recirculation (EGR) addition, hydrogen addition and equivalence ratio on flame propagation and emission concentrations were analyzed. As a part of this work and for the purpose of control and calibration of high pressure injector, spray development and characteristics including spray tip penetration, spray cone angle and overall equivalence ratio were evaluated under a wide range of fuel injection pressures of 30 to 90 atm and different chamber pressures of 1 to 5 atm. Thermodynamic properties of hydrocarbon/air plasma mixtures at ultra-high temperatures must be precisely calculated due to important influence on the flame kernel formation and propagation in combusting flows and spark discharge applications. A new algorithm based on the statistical thermodynamics was developed to calculate the ultra-high temperature plasma composition and thermodynamic properties. The method was applied to compute the thermodynamic properties of hydrogen/air and methane/air plasma mixtures for a wide range of temperatures (1,000-100,000 K), pressures (10−6-100 atm) and different equivalence ratios within flammability limit. In calculating the individual thermodynamic properties of the atomic species, the Debye-Huckel cutoff criterion has been used for terminating the series expression of the electronic partition function. A new differential-based multi-shell model was developed in conjunction with Schlieren photography to measure laminar burning speed and to study the flame instabilities for different alternative fuels such as syngas and GTL. Flame instabilities such as cracking and wrinkling were observed during flame propagation and discussed in terms of the hydrodynamic and thermo-diffusive effects. Laminar burning speeds were measured using pressure rise data during flame propagation and power law correlations were developed over a wide range of temperatures, pressures and equivalence ratios. As a part of this work, the effect of EGR addition and substitution of nitrogen with helium in air on flame morphology and laminar burning speed were extensively investigated. The effect of cell formation on flame surface area of syngas fuel in terms of a newly defined parameter called cellularity factor was also evaluated. In addition to that the experimental onset of auto-ignition and theoretical ignition delay times of premixed GTL/air mixture were determined at high pressures and low temperatures over a wide range of equivalence ratios.

Experimental Study of Laminar Burning Speed and Plasma-stabilized Flame

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ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (133 download)

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Book Synopsis Experimental Study of Laminar Burning Speed and Plasma-stabilized Flame by : Saeid Zare

Download or read book Experimental Study of Laminar Burning Speed and Plasma-stabilized Flame written by Saeid Zare and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since being discovered, combustion of fuels, especially fossil fuels in the last centuries, has been the dominant source of energy for human life. However, over the years, the adverse effects and shortcomings caused by the vast utilization of these energy sources have been observed; the three most important of which are unreliable resources, unfavorable natural outcomes, and limited performance. Using biofuels is one of the well-established proposed solutions to the scarcity and environmental issues of fossils as they are sustainable sources of energy with acceptable and even superior combustion characteristics. As a second-generation biofuel, anisole has shown promising results with high flame speed and high knock resistance. Therefore, the first chapter of this thesis is focused on experimental investigation of anisole laminar burning speed and stability properties so that it can be used as a benchmark for future kinetic mechanism validations. Stability is another important parameter in combustion systems, especially in diffusion jet flame combustion as used in many applications like thrusters or burners. Different methods are applied to improve the stability of such diffusion flames in propulsion systems, e.g., changing geometrical or flow characteristics of the burner. Most of these efforts have not been practically successful, due to the cost and compatibility issues. Another technique which minimizes such problems is to use electron impact excitation, dissociation and ionization and generate highly concentrated charged/excited species and active radicals. These methods include microwave, dielectric barrier, and repetitive nanosecond pulsed (RNP) discharge and the latter has shown promising results as one of the most effective low-temperature plasma (LTP) methods. In chapters 3 to 5, the benefits and issues associated with using RNP discharge in a single-element concentric methane-air inverse diffusion jet flame are discussed. It has been shown that RNP discharge with adequate discharge properties (voltage and repetition) can increase the stability of the flame and expand the flammability of the jet toward leaner compositions. However, the effectiveness is significant in a certain voltage-frequency ranges which results a non-thermal spark discharge mode. Hence, different modes of discharge were investigated and a parametric study on the transition between these modes were done.

Laminar Burning Speed Measurement, Autoignition and Flame Structure Study of Spherically Expanding Flames

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ISBN 13 :
Total Pages : 145 pages
Book Rating : 4.:/5 (952 download)

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Book Synopsis Laminar Burning Speed Measurement, Autoignition and Flame Structure Study of Spherically Expanding Flames by : Ali Moghaddas

Download or read book Laminar Burning Speed Measurement, Autoignition and Flame Structure Study of Spherically Expanding Flames written by Ali Moghaddas and published by . This book was released on 2015 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laminar burning speed is a thermophysical property of a combustible mixture. It is a measure of the rate of energy released during combustion in quiescent gas mixtures and incorporates the effects of overall reaction rates, energy (heat) of combustion and energy and mass transport rates. There are several experimental techniques to measure laminar burning speed and they can be broadly categorized into two general categories of stationary flames methods and those that are based on propagating flames. Investigation of spherical flame propagation in constant volume vessels is recognized to be one of the most accurate approaches for laminar burning speed measurement and flame structure study. In this thesis flame structure, laminar burning speed and onset of autoignition are studied for different premixed combustible mixtures including n-decane, jet-fuels, and Hydrofluorocarbon (HFC) refrigerants in air at high temperatures and pressures over a wide range of fuel-air equivalence ratios. The experimental facilities consist of two spherical and cylindrical vessels. The spherical vessel is used to collect pressure data to measure the burning speed and cylindrical vessel is used to take pictures of flame propagation with a high speed CMOS camera located in a shadowgraph system. A thermodynamic model is employed that assumes unburned gases compress isentropically and that burned gases are in local thermodynamic equilibrium. Burning speed is derived from the time rate change of mass fraction of burned gases. The major advantages of this method are that it circumvents the need for any extrapolation due to having low stretch rates and that many data points can be collected along an isentrope in a single experiment. Flame structures are studied to determine the cell formation conditions. Critical pressures at which the flame becomes cellular are identified and the effects of important parameters on cell formation are studied. Autoignition experiments are carried out for JP-8 fuels with high initial pressures in the spherical chamber. Autoignition occurs at specific temperature and pressure during the compression of unburned gas due to flame propagation.

Combustion Properties of Biologically Sourced Alternative Fuels

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ISBN 13 : 9780494858479
Total Pages : pages
Book Rating : 4.8/5 (584 download)

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Book Synopsis Combustion Properties of Biologically Sourced Alternative Fuels by : Abhishek Barnwal

Download or read book Combustion Properties of Biologically Sourced Alternative Fuels written by Abhishek Barnwal and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Theoretical and Experimental Studies on Laminar Hybrid Combustion

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ISBN 13 :
Total Pages : 498 pages
Book Rating : 4.:/5 (318 download)

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Book Synopsis Theoretical and Experimental Studies on Laminar Hybrid Combustion by : Lakshminarayanan Krishnamurthy

Download or read book Theoretical and Experimental Studies on Laminar Hybrid Combustion written by Lakshminarayanan Krishnamurthy and published by . This book was released on 1972 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Measurement of Laminar Burning Speed and Investigation of Flame Stability of Syngas/air Mixture

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ISBN 13 :
Total Pages : 50 pages
Book Rating : 4.:/5 (915 download)

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Book Synopsis Measurement of Laminar Burning Speed and Investigation of Flame Stability of Syngas/air Mixture by : Bander Nafe Alhazmi

Download or read book Measurement of Laminar Burning Speed and Investigation of Flame Stability of Syngas/air Mixture written by Bander Nafe Alhazmi and published by . This book was released on 2015 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: Synthetic gas (Syngas) is a growing alternative fuel for fossil fuel used in power generation industries. It is cost effective and friendly with the ecosystem. In order to validate its capability as fuel supply, determination of syngas laminar burning speed is fundamental to understand its combustion behavior and kinetic model. Laminar burning speed of syngas with 5% of hydrogen and 95% carbon monoxide mixture has been measured using a constant volume cylindrical chamber and schlieren photography. The laminar burning speed has been measured in the range of temperature from 315 K to 490 K and range of pressure from 0.5 atm to 3.2 atm. The equivalence ratios for the combustible mixture ranged from 0.6 to 5. The thermodynamic model for calculating the laminar burning speed is based on the pressure rise method considering energy losses to the ignition source, unburned gas and chamber wall. The structure of the flame was studied through the shadowgraph method. Laminar burning speeds have only been reported for smooth flame. The results indicated that the laminar burning speed increases with increasing temperature and decreases as pressure increases. Flame cellularity was found to develop at early stage at high initial pressures. The measured burning speed has been compared with other researchers' data and the results were in a good agreement.

Experimental and Theoretical Investigation of Low-Temperature Ignition in a Laminar Flow Reactor

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Publisher : Cuvillier Verlag
ISBN 13 : 3736939302
Total Pages : 224 pages
Book Rating : 4.7/5 (369 download)

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Book Synopsis Experimental and Theoretical Investigation of Low-Temperature Ignition in a Laminar Flow Reactor by : Tomoya Wada

Download or read book Experimental and Theoretical Investigation of Low-Temperature Ignition in a Laminar Flow Reactor written by Tomoya Wada and published by Cuvillier Verlag. This book was released on 2011-11-29 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main purpose of this dissertation is to investigate low-temperature ignition in detail. In the previous findings with conventional fuels such as diesel, gasoline, or jet fuels, first- and second-stage ignitions are observed in the negative temperature coefficient regime due to high- and low-temperature chemistry (LTC and HTC). As results from these investigations have shown, it is well-known that this temperature regime has high potential to reduce emission in applications. In general, these ignitions are observed sequentially (i.e., two ignition processes are observed as the overall-ignition). On the other hand, the importance of first-stage ignition due to low-temperature chemistry has been noted as one of the dominant phenomena in the overall-ignition process. In order to observe the ignition at low temperatures, a laminar flow reactor (LFR) has been developed. This LFR allows the experimental observations of only low-temperature ignition (i.e., first-stage ignition (FSI)). In other words, LFR extracts only FSI from the overall-ignition process. N-heptane, dimethyl ether and their mixtures are chosen as fuels. The entire LFR remains at isothermal conditions. Temperature increase due to the FSI in LFR and the products from FSI are experimentally measured. Numerical calculations are conducted to simulate the experiments. Based on the experimentally and numerically determined results theoretical models are established. Combustion and flame http://www.journals.elsevier.com/combustion-and-flame//a Combustion Science and Technology http://www.tandf.co.uk/journals/titles/00102202.html Combustion Theory and Modeling http://www.tandf.co.uk/journals/titles/13647830.asp Journal of combustion http://www.hindawi.com/journals/jc//a International Journal of Chemical Kinetics http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1097-4601 Proceedings of Combustion Institute http://www.journals.elsevier.com/proceedings-of-the-combustion-institute//a

Theory of Laminar Flames

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Publisher : Cambridge University Press
ISBN 13 : 9780521091923
Total Pages : 0 pages
Book Rating : 4.0/5 (919 download)

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Book Synopsis Theory of Laminar Flames by : J. D. Buckmaster

Download or read book Theory of Laminar Flames written by J. D. Buckmaster and published by Cambridge University Press. This book was released on 2008-12-04 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph deals with the structure, generation and stability of flames from a mathematical point of view. It uses a specific mathematical approach to provide a unified theoretical description of fundamental flame phenomena. Its importance stems from the fact that it provides the first clear evidence that combustion can be legitimately treated as a mathematical science as well as an empirical one. The book will be of interest to researchers in combustion, fluid mechanics and applied mathematics, as well as to graduate students taking advanced courses in these areas.

Laminar Flame Speed of Jet Fuel Surrogates and Second Generation Biojet Fuel Blends

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ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (922 download)

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Book Synopsis Laminar Flame Speed of Jet Fuel Surrogates and Second Generation Biojet Fuel Blends by : Jeffrey Munzar

Download or read book Laminar Flame Speed of Jet Fuel Surrogates and Second Generation Biojet Fuel Blends written by Jeffrey Munzar and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "An understanding of the fundamental combustion properties of alternative fuels is essential for their adoption as replacements for non-renewable sources. In the aviation industry, a promising candidate is hydrotreated renewable jet fuel (HRJF). HRJF can be synthesized in a sustainable and economically viable manner from long chain fatty-acid methyl esters found in jatropha and camelina seed, and the laboratory-scale characterization of the combustion properties of HRJF is an active area of research. Such research is motivated, in part, by the chemical complexity of biojet fuels which are composed of hundreds of hydrocarbon species, similar to conventional aviation grade fuels. The laminar flame speed has been identified as an important combustion parameter for many combustion applications, and is especially relevant to the aviation community. The laminar flame speed is also an important parameter in the validation of chemical kinetic mechanisms, as it is representative of the chemical reactivity of the fuel. In this study, laminar, atmospheric pressure, premixed stagnation flames were used to determine the laminar flame speed of HRJF blended in varying ratios with Jet A-1 aviation fuel, requiring a combination of experimental and numerical methods. Jet A-1 was also studied to allow for comparative benchmarking of the biojet blends. Experiments were carried out in a jet-wall stagnation flame geometry at a pre-heated temperature of 400 K. Centerline velocity profiles were obtained using particle image velocimetry, from which the strained reference flame speeds were determined. Simulations of each experiment were carried out using the CHEMKIN-PRO software package together with a detailed chemical kinetic mechanism, with the specification of necessary boundary conditions taken entirely from experimental measurements. A direct comparison method was used to infer the true laminar flame speed from the experimental and numerical strained reference flame speeds. In order to model the chemical kinetics of Jet A-1 and the biojet blends, it was necessary to identify a surrogate blend that emulates the reactivity of the biojet fuels, while consisting of a much smaller number of pure compounds. Published data shows significant discrepancies for many jet fuel surrogate components, motivating their inclusion in this study. Thus, laminar flame speeds were also obtained for three candidate jet fuel surrogate components: n-decane, methylcyclohexane and toluene, which are representative of the alkane, cycloalkane and aromatic components of conventional aviation fuel, respectively. Results for the pure surrogate components were used to generate a suitable surrogate blend for the biojet blends. The results form this work resolve conflicting laminar flame speed data for the surrogate components, which is essential for the further development of chemical kinetic mechanisms and contributes to the surrogate modelling of jet fuel combustion. The laminar flame speeds of the biojet blends are compared to the Jet A-1 benchmark over a wide range of equivalence ratios. The biojet blends are found to behave similarly to Jet A-1 for low to moderate levels of blending, but show a marked disagreement otherwise." --

Experimental and Analytical Examination of Spherical Flame Instabilities

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ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (111 download)

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Book Synopsis Experimental and Analytical Examination of Spherical Flame Instabilities by : Carl Regis Bauwens

Download or read book Experimental and Analytical Examination of Spherical Flame Instabilities written by Carl Regis Bauwens and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "From the standpoint of industrial safety, explosions present a major hazard, particularly for chemical plants and refineries, where accidental releases of large quantities of flammable material can often occur. When an explosion does take place at one of these facilities, the greatest hazards are often large-scale deflagrations, which can result in significant damage to individual buildings or even widespread damage over a large area, as in the case of unconfined vapor cloud explosions. At these scales, the formation of flame instabilities significantly increase the overall burning rate of the flame and the severity of the event.Without an adequate understanding of the mechanisms which govern the growth of these flame instabilities, and how they interact, existing modeling techniques are unable to accurately predict the consequences of these events. This creates considerable uncertainty in the protection requirements for these facilities. To improve our understanding of the mechanisms behind the development of large-scale flame instabilities, a comprehensive experimental study was performed examining the onset and growth of spherical-flame instabilities for propane-air, methane-air, and hydrogen-air flames at large scale. Across these fuels, a range of concentrations were studied, allowing for the growth of these instabilities to be evaluated for both thermal-diffusively stable and unstable flames. In addition, the interaction between weak initial turbulence and the growth of these instabilities was also examined. From the experimental work, it was shown that the critical radius for onset of instability varies linearly with mixture Markstein length, consistent with smaller-scale studies seen in the literature. For mixtures with positive Markstein length, an oscillatory rate of flame acceleration was observed that had not been previously identified. These oscillations were consistent with the fractal theory of spherical-flame acceleration and the formation of discrete length scales of instability. In the case of thermal-diffusively unstable mixtures, with negative Markstein length, no oscillations were observed; however, the rate of flame acceleration was consistent with a 4/3 power law exponent described in the literature. When weak initial turbulence was introduced, it was found that thermal-diffusively stable flames, with positive Markstein length, behave similar to mixtures with negative Markstein length under quiescent conditions. Specifically, initial turbulence significantly reduced the critical radius for onset of instability and increased the overall rate of spherical-flame acceleration in these mixtures. Using a number of assumptions inferred from the experimental work, an analytical model was developed to describe the growth of flame instabilities on a spherical flame, considering a fractal approach where multiple length scales grow on the flame surface simultaneously. This model shows how the growth of these instabilities can have a significant impact on the flame speed and overall rate of fuel consumption, and why they must be accounted for in the development of models describing large-scale flames. In particular, this work shows how turbulence plays a key role in determining the onset of instability and the rate of spherical- flame acceleration that occurs. This analytical model can be used to provide insight into the development of new engineering correlations or provide a basis for the development of sub-grid CFD models that quantify the effect of flame instabilities at large scale." --

Laminar Burning Velocities and Laminar Flame Speeds of Multi-component Fuel Blends at Elevated Temperatures and Pressures

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ISBN 13 :
Total Pages : 332 pages
Book Rating : 4.:/5 (731 download)

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Book Synopsis Laminar Burning Velocities and Laminar Flame Speeds of Multi-component Fuel Blends at Elevated Temperatures and Pressures by : Jung Joo Byun

Download or read book Laminar Burning Velocities and Laminar Flame Speeds of Multi-component Fuel Blends at Elevated Temperatures and Pressures written by Jung Joo Byun and published by . This book was released on 2011 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: Iso-octane, n-heptane, ethanol and their blends were tested in a constant volume combustion chamber to measure laminar burning velocities. The experimental apparatus was modified from the previous version to an automatically-controlled system. Accuracy and speed of data acquisition were improved by this modification. The laminar burning velocity analysis code was also improved for minimized error and fast calculation. A large database of laminar burning velocities at elevated temperatures and pressures was established using this improved experimental apparatus and analysis code. From this large database of laminar burning velocities, laminar flame speeds were extracted. Laminar flame speeds of iso-octane, n-heptane and blends were investigated and analysed to derive new correlations to predict laminar flame speeds of any blending ratio. Ethanol and ethanol blends with iso-octane and/or n-heptane were also examined to see the role of ethanol in the blends. Generally, the results for iso-octane and n-heptane agree with published data. Additionally, blends of iso-octane and n-heptane exhibited flame speeds that followed linear blending relationships. A new flame speed model was successfully applied to these fuels. Ethanol and ethanol blends with iso-octane and/or n-heptane exhibited a strongly non-linear blending relationship and the new flame speed model was not applied to these fuels. It was shown that the addition of ethanol into iso-octane and/or n-heptane accelerated the flame speeds.

Experiments on the Effect of Exhaust Gas Recirculation Diluent on the Laminar Burning Speed and Stability of Syngas/air Flames

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Publisher :
ISBN 13 :
Total Pages : 37 pages
Book Rating : 4.:/5 (972 download)

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Book Synopsis Experiments on the Effect of Exhaust Gas Recirculation Diluent on the Laminar Burning Speed and Stability of Syngas/air Flames by : Kevin Vien

Download or read book Experiments on the Effect of Exhaust Gas Recirculation Diluent on the Laminar Burning Speed and Stability of Syngas/air Flames written by Kevin Vien and published by . This book was released on 2016 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: Important intrinsic properties of a combustible mixture that adequately characterizes a fuel. It is important to understand the laminar burning speed's dependence on various parameters such as the fuel, pressure and temperature, fuel/oxidizer equivalence ratio and diluent. The laminar burning speed of synthetic gas (syngas), which is a gaseous mixture of H2 and CO, that is diluted with inert exhaust gas recirculation (EGR) is presented in this thesis as well as a study of flame stability. Experiments were performed in a spherical chamber and a cylindrical chamber. The cylindrical chamber is installed in a Schlieren/shadowgraph setup that captures the density variations of a propagating flame using a high-speed CMOS camera, which are used to track any deviations from a smooth, spherical, and laminar flame, such as cellularity or buoyancy. The combustible mixture is centrally ignited in the vessel using extended spark plugs and the pressure rise resulting from combustion is recorded by a pressure transducer fitted to the wall of the chamber, which is the primary input to the thermodynamic model used to calculate the laminar burning speed. The conditions presented in this work are for 5:95, 10:90, and 25:75 H2 o CO fuel ratios, over equivalence ratios that ranged from 0.6 to 3.0, pressures of 0.5-3 atm, and temperaures of 298-400K, which were diluted by 5% and 10% EGR that has a composition of 14% CO2 and 86% N2. A power law correlation is presented for the laminar burning speeds of H2/CO/air/EDG.

A Theoretical and Experimental Study of Preferential-diffusion/stretch Interactions of Laminar Premixed Flames

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Publisher :
ISBN 13 :
Total Pages : 536 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis A Theoretical and Experimental Study of Preferential-diffusion/stretch Interactions of Laminar Premixed Flames by : Oh Chae Kwon

Download or read book A Theoretical and Experimental Study of Preferential-diffusion/stretch Interactions of Laminar Premixed Flames written by Oh Chae Kwon and published by . This book was released on 2000 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Measurement of Laminar Burning Speed and Flame Instability Study of Syngas/oxygen/helium Premixed Flame

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ISBN 13 :
Total Pages : 50 pages
Book Rating : 4.:/5 (98 download)

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Book Synopsis Measurement of Laminar Burning Speed and Flame Instability Study of Syngas/oxygen/helium Premixed Flame by : Ziyu Wang

Download or read book Measurement of Laminar Burning Speed and Flame Instability Study of Syngas/oxygen/helium Premixed Flame written by Ziyu Wang and published by . This book was released on 2016 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:

The Effects of Differential Diffusion in Counter-flow Premixed Flames with Dilution and Enrichment

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ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (111 download)

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Book Synopsis The Effects of Differential Diffusion in Counter-flow Premixed Flames with Dilution and Enrichment by : Ehsan Abbasi Atibeh

Download or read book The Effects of Differential Diffusion in Counter-flow Premixed Flames with Dilution and Enrichment written by Ehsan Abbasi Atibeh and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "The continued combustion of fossil fuels to fulfill global energy demand is being questioned because of the well-known problem of greenhouse-gas (GHG) emissions, which introduces new carbon, in the form of carbon dioxide, into the environment causing climate change. However, the inherent advantages of combustion-based engines, e.g., energy and power densities, make it hard for other power systems to compete; hence, a leading strategy is to avoid burning fossil fuels by using alternative renewable fuels, such as hydrogen and renewable biofuels. Adaptability with alternative renewable fuels that have variable compositions is referred to as fuel flexibility, which is an important parameter of next-generation combustor design. However, fuel flexibility significantly affects combustor operability properties, such as blowout, flashback, and dynamic stability, mainly due to variations in turbulent burning rates. Changing the fuel and oxidizing-gas mixture composition affects flame characteristics and burning rates through changing: (1) mixture reactivity, which is represented by unstretched laminar flame speed, and (2) mixture diffusivity, i.e., the diffusivity of the deficient reactant and diffusivity of heat. The disparity between thermal and mass diffusivities at the flame front is known as "differential diffusion", which causes stretch sensitivity, and thermal-diffusive instabilities, in flame-front propagation, and is represented by Lewis number, a ratio of thermal-to-mass diffusivities.This thesis investigates the effects of differential diffusion and stretch sensitivity on propagation, stabilization, and structure of lean turbulent premixed flames in the thin reaction zone regime. In the context of fuel flexibility, various fuels and oxidizer-inert mixtures are used to form mixtures with distinct effective Lewis numbers, through changing both fuel diffusivity and thermal diffusivity of the mixture. In these experiments, the unstretched laminar flame speed is kept constant during mixture dilution, and hydrogen enrichment of hydrocarbon flames, through changing the mixture equivalence ratio, in order to minimize the effects of chemistry. Furthermore, bulk-flow properties and the temperature boundary condition are kept constant; hence, the study highlights the effects of differential diffusion. The experiments are carried out using strained counter-flow flames, in order to study the effects of both components of the flame stretch, i.e., hydrodynamic strain and curvature. Local instantaneous statistics of various flame parameters within the imaged plane are quantified using high-speed particle image velocimetry (PIV) and Mie scattering flame tomography at various levels of turbulence intensity. These statistics include flame location, flame velocity, and flame-front topology, such as flame stretch, flame-front curvature, and flame surface area.The statistics of various parameters of turbulent flames with distinct effective Lewis number show that the effects of differential diffusion on the burning rates and the structure of turbulent premixed flames are important in highly turbulent flames in the thin reaction zone of combustion. Furthermore, these results are not dependent on the fuel or oxidizing-gas mixture and can be described fully by the effective Lewis number and turbulence intensity. In addition, at constant turbulence intensities, differential diffusion increases the burning rate of turbulent flames in thermo-diffusively unstable mixtures through two main mechanisms: (1) increasing the local flamelet displacement velocity, and (2) increasing the flame surface area. This thesis shows the need to advance the combustion theory to produce models that can capture the effects of differential diffusion for flames in real-world combustion systems, in order to predict the performance of future fuel-flexible combustors. The experimental results of this thesis provide a valuable dataset for the validation of such theories." --

Experimental Studies of the Effect of Gravity on the Stability of Premixed Laminar Flames

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ISBN 13 :
Total Pages : 642 pages
Book Rating : 4.:/5 (33 download)

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Book Synopsis Experimental Studies of the Effect of Gravity on the Stability of Premixed Laminar Flames by : Corey Martin Dunsky

Download or read book Experimental Studies of the Effect of Gravity on the Stability of Premixed Laminar Flames written by Corey Martin Dunsky and published by . This book was released on 1991 with total page 642 pages. Available in PDF, EPUB and Kindle. Book excerpt: