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Lundin, Eva. "Adaptive air-fuel ratio control for combustion engines." Thesis, Linköping University, Department of Electrical Engineering, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-56651.
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<p>Around the world, vehicle emission regulations become stricter, increasing exhaust emission demands. To manage these rules and regulations, vehicle manufacturers put a lot of effort into minimizing the exhaust emissions. The three-way catalytic converter was developed, and today it is the most commonly used device to control the exhaust emissions.</p><p>To work properly the catalytic converter needs to control the air-fuel mixture with great precision. This then increases the demands on the engine management systems, causing them to become more complex. With increased complexity, the time effort of optimizing parameters has grown drastically, hence increasing development costs. In addition to this, operating conditions change due to vehicles age, requiring further optimization of the parameters while running.</p><p>To minimize development cost and to control the air-fuel mixture with great precision during an engines full life span, this master thesis proposes a self-optimized system, i.e. an adaptive system, to control the air-fuel mixture.</p><p>In the suggested method, the fuel injection to the engine is controlled with help of a linear lambda sensor, which measures the air-fuel mixture. The mapping from injection to measured air-fuel mixture forms a nonlinear system. It can be approximated as a linear function at static engine operating points, allowing the system at each static point to be modelled as a first order system with long time delay. To enable utilization over full operating area, and not only in static point, the controller uses large maps, so called gain-scheduling maps, to change control parameters.</p><p>The tested controller is model based. It uses an Otto-Smith Predictor and a feed forward connection of target air-fuel. The model parameters in the controller are updated while driving and the adaptation method used is based on a least squares algorithm.</p><p>The performance of the adapted controller and the adaptation method is tested in both simulation environment and in vehicle, showing good potential.</p>
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Brandstetter, Markus. "Robust air-fuel ratio control for combustion engines." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627144.
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Kirtaş, Mehmet. "Large Eddy Simulation of a High Aspect Ratio Combustor." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14134.
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The present research investigates the details of mixture preparation and combustion in a two-stroke, small-scale research engine with a numerical methodology based on large eddy simulation (LES) technique. A major motivation to study such small-scale engines is their potential use in applications requiring portable power sources with high power density. The investigated research engine has a rectangular planform with a thickness very close to quenching limits of typical hydrocarbon fuels. As such, the combustor has a high aspect ratio (defined as the ratio of surface area to volume) that makes it different than the conventional engines which typically have small aspect ratios to avoid intense heat losses from the combustor in the bulk flame propagation period. In most other aspects, this engine involves all the main characteristics of traditional reciprocating engines. A previous experimental work has identified some major design problems and demonstrated the feasibility of cyclic combustion in the high aspect ratio combustor. Because of the difficulty of carrying out experimental studies in such small devices, resolving all flow structures and completely characterizing the flame propagation have been an enormously challenging task. The numerical methodology developed in this work attempts to complement these previous studies by providing a complete evolution of flow variables. Results of the present study demonstrated strengths of the proposed methodology in revealing physical processes occurring in a typical operation of the high aspect ratio combustor. For example, in the scavenging phase, the dominant flow structure is a tumble vortex that forms due to the high velocity reactant jet (premixed) interacting with the walls of the combustor. LES gives the complete evolution of this flow structure, from its beginning to its eventual decay after the scavenging period is over. In addition, LES is able to predict the interaction between the bulk flow at top dead center (TDC) and the turbulent flame propagation. The success of this depends on the ability of the model in predicting turbulent flow structure including its length and velocity scales.
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De, Zoysa Merrenna Manula. "Neural network estimation of air-fuel ratio in internal combustion engines." Thesis, University of Brighton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399048.
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This thesis presents an investigation into a novel method of estimating the air-fuel ratio of a gasoline-fuelled spark-ignition internal combustion engine. The measurement of the air-fuel ratio is important for controlling an engine to reduce exhaust emissions. In production vehicles, the air-fuel ratio is measured using an exhaust gas analyser and the exhaust emissions are reduced by using electronically controlled three-way catalytic converters, which are expensive and subject to operationallimitations such as, requiring the engine to operate with a stoichiometric air-fuel ratio. A micro-processor based engine management system monitors the engine performance and controls various engine parameters - the fuel pulse width, ignition timing, exhaust gas re-circulation etc. - to maintain strict control of the engine and ensure optimum engine performance. In the USA and UK the engine management system is also responsible for performing on-board diagnostics and warns the driver of any problems such as misfire, knocking combustion and failure of the catalytic converter. The method of measuring the air-fuel ratio presented in this thesis, termed Spark Voltage Characterization (SVC), uses neural networks to analyse the time varying spark voltage waveform to estimate the air-fuel ratio. The spark plug is in direct contact with the combustion itself, thus making it is an excellent candidate for use as a combustion sensor. As it is already installed in the engine, no modifications are required to the engine block itself. The method uses few external components making it cheaper to implement. Preliminary investigations on this method showed that it was possible to estimate the air-fuel ratio by neural network analysis of the spark voltage waveform. As different engines are equipped with different types of ignition systems, it is important that the sensor is independent of the ignition system thus ensuring that it is able to operate with any type of ignition system. The work presented in this thesis includes: i) an extensive review of other methods of measuring the air-fuel ratio, noting the advantages and disadvantages of each method and how the SVC sensor overcome these disadvantages; ii) a description of the theoretical operation of the sensor; iii) investigation of the effects of various engine parameters on the performance of the sensor; iv) suggestions for further work to improve the sensor performance.
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Grant, Marcus Paul. "Computer control of air-gas ratio for nozzle mix systems." Thesis, Coventry University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390222.
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TEIXEIRA, RENATO NUNES. "INTERNAL COMBUSTION ENGINES WITH VARIABLE COMPRESSION RATIO: A THEORETICAL AND EXPERIMENTAL ANALYSIS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1992. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=19099@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO<br>É realizado um estudo teórico experimental sobre motores a combustão interna operando com taxa de compressão variável. É feita uma análise teórica sobre determinado mecanismo que permite variar a taxa de compressão. Para tal foi utilizado um programa de simulação para motores com ignição por centelha. No presente trabalho o modelo de simulação foi aprimorado, com a inclusão de previsão de detonação, de emissão de hidrocarbonetos, do cálculo da potencia de atrito, assim como a inclusão do dispositivo do mecanismo de taxa de compressão variável, entre outras alterações.
Uma parte experimental foi também realizada, como o objetivo de validar os resultados do modelo teórico e de quantificar os benefícios proporcionados pelo mecanismo em questão. Para tal um motor de pesquisa de combustível – motor CFR – foi utilizado.
Uma comparação dos resultados teóricos e experimentais obtidos no presente trabalho com os de outros pesquisadores é também apresentada.<br>The present work is concerned with a theoretical and expererimental study of variable compression ratio spark ignition internal combustion engines. A theoretical analysis of the engine, operating with a mechanism allows for variable compression ratio, is carried out. For that a simulation program is utilized. In the present work the simulation model was updated with the inclusion of friction, knocking and hidrocarbon emission models, among other things. An experimental work was also carried out, with a CFR engine. The objective was a wo-fold to validade the results of the theoretical model and to assens the benefits of running an engine with variable compression ratio. A comparison is also made between the rrsults of the present work and those from other authors.
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Alshuqaiq, Mohammad Abdullah. "An Analysis of Oil Combustion on Snow." Digital WPI, 2014. https://digitalcommons.wpi.edu/etd-theses/789.
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Several Arctic council reports conclude that oil spills are the most significant threat to the Arctic ecosystem. Some studies have shown that in-situ burning (ISB) of oil spills over water can remove more than 90% of the oil, and is the most promising technology for an efficient response to oil spills in the Arctic region. The definition of "In situ" is intentional, controlled burning of oil in place (i.e., without extracting or removing the oil first). Earlier studies [Bellino (WPI 2012), Farahani, (WPI 2014)] have investigated burning behavior of crude oil on ice, similar to what one would expect in sea-ice or bare lake ice conditions. The focus of the current study is to investigate the burning behavior of crude oil in snow, similar to oil spills in snow-covered land, or in snow covered sea ice in the Arctic. Understandably, due to the difference in packing density between ice/water and snow, the parameters that influence burning behavior of oil in snow are different compared to burning oil in the sea or ice conditions. The current experimental study shows that the snow behaves as a porous medium, and depending on the porosity and volume of the oil spill, two extreme behaviors are exhibited. In the case of an oil spill on snow with low porosity, the oil sinks easily to the bottom, and the burning involves, significant thermo capillary effects enabling the oil to rise up and burn. On the other hand, if the snow is less porous, most of the oil layer remains on the surface, approaching the case of an ice bed. However, the melting of snow due to flame heat flux causes a circulating flow pattern of the oil, whereby the hot layer at the surface moves down and comes back up due to capillary action. These processes, which have not been observed in the earlier studies, are physically explained in this study. The implications to overall efficiency of the burning process, which represents the amount of crude oil left in the snow after the burning process is discussed. The results will ultimately improve the strategies and the net environmental benefit of, and by it the success of, oil clean-up after an accidental spill on snow.
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Kamal, Rajit. "CFD simulation of mixing in a carbon black reactor : optimum geometry and momentum ratio." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/11254.
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Faulkner, Jason Christopher. "A study of ignition and flame propagation in a small, high surface-to-volume ratio combustor." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/12439.
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Petrolati, Andrea. "Fate of nitrogen/trace metals species during combustion and gasification of biomass." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/7011.
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This thesis focused on the fate of nitrogen and trace metals species from combustion and gasification of biomass. The effect of process parameters on the release of these species during pilot-scale combustion and gasification of biomass was investigated and the information used to identify methods for the reduction of these species. The investigation focused on Miscanthus and Dried distillers’ grains with solubles (DDGS). The pilot-scale test rigs used were a fluidised-bed combustor and a fixed-bed downdraft gasifier. The two fuels were analysed by means of proximate, ultimate and ash analysis. The process parameters monitored were temperatures, gas flow, gas composition and ash composition and the process parameters studied are bed temperature and equivalence ratio. The different nitrogen content of the two fuels plays an important role in the emission. Both bed temperature and air to fuel ratio have demonstrated to have an important influence in the release of nitrogen oxides in combustion and ammonia in gasification, therefore they can be used to mitigate the emission of these species in the flue gas. Both processes are affected by the high alkali metals content of the fuels for the tendency to form low melting composites. Differences have been highlighted in the metal distribution between combustion and gasification. The different nitrogen and ash content of the two fuels make the results of the present thesis applicable to predict the behaviour of other biomass fuels according to the fuel characteristics. The scale of the tests performed allowed highlighting which methods can be used to control the emission of nitrogen and trace metal species. Moreover, the investigation highlighted major drawbacks in the use of biomass fuels in both fluidised bed and fixed bed technology due to ash properties.
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Disseau, Mael Leo David Soliman. "Development and investigation of a small, high aspect ratio, two-stroke engine." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/12485.
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Postma, Marius. "Air-fuel ratio control in spark ignition internal combustion engines using switching LPV techniques." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/30499.
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The Three-Way Catalytic Converter (TWC) is a critical component for the mitigation of tailpipe emissions of modern Internal Combustion (IC) engines. Because the TWC operates effectively only when a stoichiometric ratio of air and fuel is combusted in the engine, accurate control of the air-fuel ratio is required. To track the desired ratio, a switching Linear Parameter Varying (LPV) air-fuel ratio feedback controller, scheduled based on engine speed and air flow, and providing guaranteed L2 performance, is introduced. The controller measures the air-fuel ratio in the exhaust flow using a Universal Exhaust Gas Oxygen (UEGO) sensor and adjusts the amount of fuel injected accordingly.
A detailed model of the air-fuel ratio control problem is developed to demonstrate the non-linear and parameter-dependent nature of the plant, as well as the presence of pure delays. The model’s dynamics vary considerably with engine speed and air flow. A simplified model, widely used in literature and known as a First Order Plus Dead Time (FOPDT) model, is then derived. It effectively captures the control problem using a model which is linear but parameter-varying with engine speed and air flow.
Large variation of the FOPDT model across the engine’s operating range has led to conservative LPV controllers in previous literature. For this reason, the operating range is divided into smaller subregions, and an individual LPV controller is designed for each subregion. The LPV controllers are then switched based on the current engine speed and air flow and are collectively referred to as a switching LPV controller. The controller design problem is expressed as a Linear Matrix Inequality (LMI ) convex optimization problem which can be efficiently solved using available LMI techniques.
Simulations are performed and the air-fuel ratio tracking performance of the switching LPV controller is compared with that of conventional controllers including, H∞ and LPV, as well as a novel adaptive controller. The switching LPV controller achieves improved performance over the complete operating range of the engine.
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Aivaz, Balian Razmik. "The effect of compression ratio on the performance of a direct injection diesel engine." Thesis, Brunel University, 1990. http://bura.brunel.ac.uk/handle/2438/11249.
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This thesis considers the effect of compression ratio on the performance of a direct injection diesel engine. One aspect of engine performance is considered in great detail, namely the combustion performance at increased clearance volume. This aspect was of particular interest because variable compression ratio (VCR) systems normally operate by varying the clearance volume. The investigation relied upon results obtained both from experimental and computer simulating models. The experimental tests were carried out using a single-cylinder direct-injection diesel engine, under simulated turbocharged conditions at a reduced compression ratio. A number of one-dimensional computer models were developed; these simulate the induction and compression strokes, and the fuel spray trajectories in the presence of air swirl. The major objectives of the investigation were: to assess the benefits of VCR in terms of improvements in output power and fuel economy; to assess the effects on combustion of increased clearance volume, and investigate methods for ameliorating resulting problems; develop computational models which could aid understanding of the combustion process under varying clearance volume conditions. It was concluded that at the reduced compression ratio of 12.9:1 (compared to the standard value of 17.4:1 for the naturally-aspirated engine), brake mean effective pressure (BMEP) could be increased by more than 50%, and the brake specific fuel consumption (BSFC) could be reduced by more than 20%. These improvements were achieved without the maximum cylinder pressure or engine temperatures exceeding the highest values for the standard engine. Combustion performance deteriorated markedly, but certain modifications to the injection system proved successful in ameliorating the problems. These included: increase in the number of injector nozzle holes from 3 to 4, increase in injection rate by about 28%, advancing injection timing by about 6°CA. In addition, operation with weaker air fuel ratio, in the range of 30 to 40:1 reduced smoke emissions and improved BSFC. Use of intercooling under VCR conditions provided only modest gains in performance. The NO emission was found to be insensitive to engine operating conditions (fixed compression ratio of 12.9:1), as long as the peak cylinder pressure was maintained constant. Engine test results were used in order to assess the accuracy of four published correlations for predicting ignition delay. The best prediction of ignition delay with these correlations deviated by up to 50% from the measured values. The computer simulation models provided useful insights into the fuel distribution within the engine cylinder. It also became possible to quantify the interaction between the swirling air and the fuel sprays, using two parameters: the crosswind and impingement velocities of the fuel spray when it impinges on the piston-bowl walls. Tentative trends were identified which showed that high crosswind velocity coincided with lower smoke emissions and lower BSFC.
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MacMillan, David James. "Influences on the cold start behaviour of a diesel engine at reduced compression ratio." Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/10759/.
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The design trend for light duty diesel engines is towards lower compression ratio and higher turbocharger boost. This can enable higher specific power and lower pollutant emissions to be achieved, but raises concerns that cold start operation might be adversely affected. This is investigated and quantified through the study of a modern light duty diesel engine at two compression ratios and temperatures down to -20ºC. Key indicators of cold start performance are the magnitude and cycle-to-cycle variation of indicated mean effective pressure. Initial studies were carried out at 300 rpm, a speed representative of post-first-fire conditions. Studies were then conducted at higher engine speeds representative of cold idle. The utility of different injection strategies, timings and quantities is investigated when varying test temperature and engine speed through a range of values encountered during the cold start phase of engine operation. The importance of the glow plug as a cold start aid is also investigated by varying its operating temperature and protrusion into the combustion chamber. The indicated mean effective pressure was used to assess the effects of varying input parameters, and gross heat release rate information is used to identify the phenomena responsible for desirable or undesirable characteristics. Reduction in compression ratio led to no deterioration of initial start performance from speeds just above cranking, provided an appropriate injection strategy was chosen. Higher indicated mean effective pressure was possible at low speeds using low compression ratio due to reduced losses and more complete combustion. Cycle-to-cycle variability in indicated mean effective pressure increased markedly for both compression ratios at engine speeds representative of cold idle, especially when test temperature was reduced. Stability reduction was more severe at low compression ratio. Multiple pilot injections at high compression ratio cold idle resulted in better cycle-to-cycle stability. Analysis of heat release profiles suggested that additional pilots assisted fuel mixing, a conclusion supported by a computational fluid dynamics model. Multiple pilots created a more homogeneous fuel distribution through the bowl at time of main injection. Multiple pilots could not stabilise operation at low compression ratio. Improvement in cold idle at low compression ratio was achieved by increasing glow plug temperature, which significantly increased the rate of fuel preparation. This increased the initial rate of heat release and resulted in significantly less variation in the heat release rate profiles. Small changes in glow plug protrusion rapidly degraded cold idle performance, indicating the importance of correct design.
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Stewart, Marcus Clayton. "Design and analysis of a variable-compression, ratio internal-combustion engine : the Alvar engine concept." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43419.
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Williams, Benjamin Ashley Oliver. "Quantitative laser diagnostics for combustion." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:37ea0034-03ac-4021-80e3-5d72200fbd0e.
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Quantitative Planar Laser Induced Fluorescence (QPLIF) is developed as a diagnostic technique and then applied to a prototype Jaguar optical internal combustion engine. QPLIF derives quantitative, two-dimensional, spatially-resolved measurements of fuel concentration. This work reports the first demonstration of a fully-fractionated surrogate fuel which exhibits all the characteristics of a typical gasoline. This 'pseudo' fuel, developed in association with Shell UK, is blended to accept a fluorescent tracer which may track one of the light, middle or heavy fractions of the fuel, each of different volatility. The traditional weaknesses of PLIF for quantitative measurements are addressed by use of a fired in-situ calibration method, which maps the quantum efficiency of the tracer and concurrently corrects for window fouling and exhaust gas residuals (EGR). Fuel distributions are presented with an estimated super-pixel accuracy of 10% at different operating conditions, and then compared to the computational fluid dynamics (CFD) predictions of an in-house Jaguar model. Fuel/Air Ratios by Laser Induced thermal Gratings (FARLIG) is developed theoretically, and results of validation experiments conducted in a laboratory setting are reported. FARLIG conceptually enables the measurement of fuel concentration, oxygen concentration and temperature within a spatially-localised probe volume. Uniquely, the technique exploits the dominant influence of molecular oxygen on non-radiative quenching processes in an aromatic tracer molecule. The changing character of a model quenching mechanism potentially allows the oxygen concentration in the measurement volume to be derived. Absolute signal strength is used to determine fuel concentration, while the oscillation period of the signal provides a precise measurement of temperature (~0.3% uncertainty), with accuracy limited by knowledge of the gas composition.
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Wirth, Douglas A. "An experimental investigation of the effect of temporal equivalence ratio fluctuations on NOx emissions in premixed flames." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/37948.
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Harris, Charles G. "Development of air/fuel ratio control and secondary combustion for a commercial-scale biomass-fueled boiler." Thesis, Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/76044.
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The development, testing, and modeling of a multi-fuel biomass combustion system is described. The system is developed by adding air/fuel ratio control and catalytic secondary combustion to a commercially available 150 kW biomass-fueled boiler. The basis of the air/fuel ratio control system is an inexpensive electrochemical oxygen sensor. A catalytic secondary combustion system is developed from monolithic noble metal catalytic combustor segments commonly used on domestic wood burning equipment. The development and understanding of the combustion system is supported by both experimental measurements and theoretical modeling of the combustion process. Experimentally measured variables include gas temperatures, combustion air and exhaust gas flow rates, exhaust gas CO and CO₂ concentrations, and useful heat output. Both equilibrium and chemical kinetic models of the gas-phase combustion process are developed. In the kinetic model, mixing is modeled by assuming the combustion passages behave as a series of perfectly mixed reactors.
The modified boiler reduces CO output to about 10 to 15 percent of the CO produced by the baseline unit in steady operation. Results of the combustion modeling indicate that the combustion proceeds nearly to equilibrium except when operating with fuel/air equivalence ratios less than about 0.7 and immediately after addition of a batch of fuel. Under these conditions the gas temperatures are usually low enough to impose a kinetic limit on the combustion process. Equilibrium calculations reveal that more than one-half of the total heat transfer from the combustion products occurs in the combustion zone, indicating that there may be opportunity to reduce kinetic limitations by restricting heat losses from the combustion zone.<br>Master of Science
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Woodbury, Simon Edward. "Application of gas chromatography combustion-isotope ratio mass spectrometry to the detection of adulteration of vegetable oils." Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246268.
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Mathias, Spencer D. "Investigation of Thermoplastic Polymers and Their Blends for Use in Hybrid Rocket Combustion." DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7416.
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This thesis set out to find a blend of thermoplastics that had better combustion properties than the current ABS (acrylonitrile butadiene styrene) plastic or “Lego TM plastic” used by Utah State University. The current work is in an effort to eliminate toxic propellants from small space applications. High and low density polyethylene plastics were used because they are common plastic waste items. In this way rocket fuel can be made from these items to reduce the waste found in landfills. Three plastics were considered for replacement and as mixture components with the ABS plastic, namely low and high density polyethylene, and high impact polystyrene. These plastics failed to have superior combustion properties when used in rockets designed to achieve 12 pounds or less of thrust compared to the current ABS plastic.
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Ahuja, Vivek Hartfield Roy J. "Optimization of fuel-air mixing for a scramjet combustor geometry using CFD and a genetic algorithm." Auburn, Ala, 2008. http://hdl.handle.net/10415/1406.
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Shakya, Rikesh. "Mass Airflow Sensor and Flame Temperature Sensor for Efficiency Control of Combustion Systems." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1447679976.
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Tunestål, Per. "Estimation of the in-cylinder air/fuel ratio of an internal combustion engine by the use of pressure sensors /." Lund, 2001. http://www.lub.lu.se/luft/diss/tec432_transit.html.
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Ghomashi, Hossein. "Modelling the combustion in a dual fuel HCCI engine : investigation of knock, compression ratio, equivalence ratio and timing in a Homogeneous Charge Compression Ignition (HCCI) engine with natural gas and diesel fuels using modelling and simulation." Thesis, University of Bradford, 2013. http://hdl.handle.net/10454/7344.
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This thesis is about modelling of the combustion and emissions of dual fuel HCCI engines for design of “engine combustion system”. For modelling the combustion first the laminar flamelet model and a hybrid Lagrangian / Eulerian method are developed and implemented to provide a framework for incorporating detailed chemical kinetics. This model can be applied to an engine for the validation of the chemical kinetic mechanism. The chemical kinetics, reaction rates and their equations lead to a certain formula for which the coefficients can be obtained from different sources, such as NASA polynomials [1]. This is followed by study of the simulation results and significant findings. Finally, for investigation of the knock phenomenon some characteristics such as compression ratio, fuel equivalence ratio, spark timing and their effects on the performance of an engine are examined and discussed. The OH radical concentration (which is the main factor for production of knock) is evaluated with regard to adjustment of the above mentioned characteristic parameters. In the second part of this work the specification of the sample engine is given and the results obtained from simulation are compared with experimental results for this sample engine, in order to validate the method applied in AVL Fire software. This method is used to investigate and optimize the effects of parameters such as inlet temperature, fuels ratio, diesel fuel injection timing, engine RPM and EGR on combustion in a dual fuel HCCI engine. For modelling the dual fuel HCCI engine AVL FIRE software is applied to simulate the combustion and study the optimization of a combustion chamber design. The findings for the dual fuel HCCI engine show that the mixture of methane and diesel fuel has a great influence on an engine's power and emissions. Inlet air temperature has also a significant role in the start of combustion so that inlet temperature is a factor in auto-ignition. With an increase of methane fuel, the burning process will be more rapid and oxidation becomes more complete. As a result, the amounts of CO and HC emissions decrease remarkably. With an increase of premixed ratio beyond a certain amount, NOX emissions decrease. With pressure increases markedly and at high RPM, knock phenomenon is observed in HCCI combustion.
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Rundin, Patrick. "Evaluation of a statistical method to use prior information in the estimation of combustion parameters." Thesis, Linköping University, Department of Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6255.
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<p>Ion current sensing, where information about the combustion process in an SI-engine is gained by applying a voltage over the spark gap, is currently used to detect and avoid knock and misfire. Several researchers have pointed out that information on peak pressure location and air/fuel ratio can be gained from the ion current and have suggested several ways to estimate these parameters.</p><p>Here a simplified Bayesian approach was taken to construct a lowpass-like filter or estimator that makes use of prior information to improve estimates in crucial areas. The algorithm is computationally light and could, if successful, improve estimates enough for production use.</p><p>The filter was implemented in several variants and evaluated in a number of simulated cases. It was found that the proposed filter requires a number of trade-offs between variance, bias, tracking speed and accuracy that are difficult to balance. For satisfactory estimates and trade-off balance the prior information must be more accurate than was available.</p><p>It was also found that similar a task, constructing a general Bayesian estimator, has already been tackled in the area of particle filtering and that there are promising and unexplored possibilities there. However, particle filters require computational power that will not be available to production engines for some years. </p><br><p>Vid jonströmsmätning utvinns information om förbränningsprocessen i en bensinmotor genom att en spänning läggs över gnistgapet och den resulterande strömmen mäts. Jonströmsmätning används idag för knack- och feltändningsdetektion. Flera forskare har påpekat att det finns än mer information i jonströmmen, bl.a. om bränsleblandningen och cylindertrycket och har även föreslagit metoder för att utvinna och använda den informationen för skattning av dessa parametrar.</p><p>Här presenteras en förenklad Bayesisk metod i form av en lågpassfilter-liknande skattare som använder förkunskap till att förbättra estimat på relevanta områden. Algoritmen är beräkningsmässigt lätt och kan, om den är framgångsrik, leverera skattningar av förbränningsparametrar som är tillräckligt bra för att användas för sluten styrning av en bensinmotor.</p><p>Skattaren, eller filtret, implementerades i flera varianter och utvärderades i ett antal simulerade fall. Resultaten visade på att flera svåra avvägningar måste göras mellan förbättring i varians, avvikelse och följning eftersom förbättring i den ena ledde till försämring i de andra. För att göra dessa avvägningar och få goda skattningar krävs bättre förhandskunskap och mätdata än vad som var tillgängligt.</p><p>Bayesisk skattning är ett stort befintligt område inom statistik och signalbehandling och den mest generella skattaren är partikelfiltret som har många intressanta tillämpningar och möjligheter. De har hittills inte använts inom skattning av förbränningsparametrar och har således go potential för framtida utveckling. De är dock beräkningsmässigt tunga och kräver beräkningsresurser utöver vad som är tillgängliga i ett motorstyrsystem idag.</p>
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Meyer, Jason Andrew. "Innovations in Representation and Calibration of Residual Gas Fraction and Volumetric Efficiency in a Spark Ignited, Internal Combustion Engine." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1211990310.
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Kim, Chung-Gong. "A crank angle resolved CIDI engine combustion model with arbitrary fuel injection for control purpose." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5num=osu1086154960.
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Thesis (Ph. D.)--Ohio State University, 2004.<br>Title from first page of PDF file. Document formatted into pages; contains xxiv, 266 p. : ill. (some col.). Advisor: Yann G. Guezennec, Dept. of Mechanical Engineering. Includes bibliographical references (p. 259-266).
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Cambridge, Shevonn Nathaniel. "The effect of compression ratio on emissions from an alcohol-fueled engine." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09122009-040220/.
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Nori, Venkata Narasimham. "Modeling and analysis of chemiluminescence sensing for syngas, methane and jet-A combustion." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24681.
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Thesis (Ph.D.)--Aerospace Engineering, Georgia Institute of Technology, 2008.<br>Committee Chair: Seitzman, Jerry; Committee Member: Jagoda, Jechiel; Committee Member: Lieuwen, Tim; Committee Member: Menon, Suresh; Committee Member: Docquier, Nicolas; Committee Member: Huey, Gregory.
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Vittori, Ruggero Maria. "Experimental study on the effect of stoichiometric air/fuel ratio of three binary oxygenated fuel blends on combustion and emissions of a heavy duty Diesel engine." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18203/.
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Low Temperature Combustion (LTC) is believed to be the best solution to the Diesel NOx and soot emissions trade-off: the latest development in LTC methods is PPC (Partially Premixed Combustion) which can be considered as a combination of Homogeneous Charge Compression Ignition (HCCI) and conventional Diesel combustion.
The increasing interest in high-octane alternative fuels, such as alcohols and aromatic compounds, leads to investigate their combustion behaviour, in order to develop cleaner fuels, making another small step towards new cleaner engines.
In this thesis, three binary oxygenated fuel blends are selected, with the aim of studying how their molecular structures and stoichiometric air-fuel ratio influenced the combustion performances and emissions of a truck heavy-duty Diesel engine.
The first part describes the fundamental elements of LTC and gives a background on the typical Diesel combustion emissions, with the description of the alternative test fuels of this research.
The second part is about the engine setup, with particular attention towards the emission measurement and data acquisition systems.
The third part gives a background on the important parameters of this research, mostly combustion control parameters: it is fundamental to understand the test results, which are presented in the final part of the thesis.
This master thesis project has been developed in collaboration with the “Multiphase and reactive flows” research group at TU/e, Eindhoven University of Technology, in the Netherlands.
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Albayrak, Alp [Verfasser], Wolfgang [Akademischer Betreuer] Polifke, Wolfgang [Gutachter] Polifke, and Aimee S. [Gutachter] Morgans. "Time Scales of Equivalence Ratio and Inertial Waves in Unsteady Combustion Dynamics / Alp Albayrak ; Gutachter: Wolfgang Polifke, Aimee S. Morgans ; Betreuer: Wolfgang Polifke." München : Universitätsbibliothek der TU München, 2019. http://d-nb.info/1184476918/34.
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Clapperton, Allan Thomas. "Development of new techniques to measure insulin sensitivity using ¹³c-glucose, gas chromatography/combustion/isotope ratio mass spectrometry and the minimal model of glucose kinetics." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616085.
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Malfatti, Laércio. "Análise qualitativa do ciclo real e tempo de combustão em um motor padrão ASTM-CFR operando com mistura de gasolina e etanol hidratado." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/19041.
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A duração da combustão tem implicação direta na determinação do trabalho negativo no ciclo motor. A duração da combustão tem relação inversa com a velocidade de propagação da chama. Assim, quanto maior a velocidade de propagação da chama, menor a duração da combustão. Além disto, a duração da combustão está relacionada com a relação volumétrica de compressão, com a razão de mistura e com o tipo de combustível, entre outros fatores. Neste sentido, quanto maior a velocidade de queima da mistura ar-combustível, menor o trabalho negativo no ciclo. Neste contexto, foram ensaiadas 3 relações de compressão e 3 razões de mistura, para 6 combustíveis de composição conhecida: gasolina comum tipo C, álcool etílico hidratado combustível (AEHC) e AEHC adicionado à gasolina comum tipo C nas proporções de 20%, 40%, 60% e 80%. A variação da pressão no interior da câmara de combustão, para todos os combustíveis, e a posição da centelha de ignição foram determinadas com a utilização da base angular e com variação da relação volumétrica de compressão e da razão de mistura. O diagrama , para fins de cálculo de área, foi traçado por pós-processamento. Os resultados obtidos indicam que a duração da combustão aumenta com o aumento da razão de mistura e diminui com o aumento da relação volumétrica de compressão, para todos os combustíveis ensaiados. Verificou-se que a amplitude da pressão, no interior da câmara de combustão, se comporta inversamente à duração da combustão. Mostrou-se que o aumento da razão de mistura implica na redução do trabalho líquido entregue ao êmbolo ao longo de todo o ciclo do motor. Opostamente ocorre com o aumento da relação volumétrica de compressão, que implica no aumento do trabalho líquido por ciclo. Concluiu-se que o máximo valor para o trabalho líquido ao longo de todo o ciclo foi obtido para a maior relação volumétrica de compressão (8:1) e a menor razão de mistura (λ = 0,9). O combustível que representou este resultado foi o álcool etílico hidratado combustível adicionado à gasolina comum tipo C em 80% (AEHC80). O mínimo valor para o trabalho líquido, ao longo de todo o ciclo foi obtido, para a menor relação volumétrica de compressão (6:1) e a maior razão de mistura dos ensaios (λ = 1,1). O combustível que representou este resultado foi o álcool etílico hidratado combustível (AEHC).<br>The duration of the combustion is directly implicative on determining the negative work of the motor cycle. The duration of the combustion has an inverse relation with the flame propagation speed. Thus, the higher propagation of the flame, the shorter duration of the combustion. Besides that, the duration of the combustion is related to the relation of compression, to the air/fuel relation and to the type of fuel, among other factors. In this way, the higher burning speed of the air/fuel mixture, the smallest negative work in the cycle. In such a context, there were tried three compression relations and three mixture ratios for six fuels of know compositions: ordinary gasoline C type, combustible hydrated ethyl alcohol and combustible hydrated ethyl alcohol added to ordinary gasoline C type in the proportions of 20%, 40%, 60% and 80%. The pressure variation inside the combustion chamber, for all fuels, and the position of the ignition spark were determined using the angular base and with variation of the compression relation and the mixture ratio. The diagram, for area calculation, was traced by post processing. The obtained results indicate that the combustion duration increases with the rising of the mixture ratio and decreases with the rising of the compression relation, for all the tried combustibles. It was found that the pressure amplitude inside the combustion chamber behaves inversely to the combustion duration behavior. It was shown that the rising of the mixture ratio implies on the reduction of the net work delivered by the piston all through the cycle of the motor. The opposite occurs with the rising of the compression relation, that implies on the increase of the net work by cycle. It was concluded that the maximum value for the net work all through the cycle was obtained for the higher compression relation (8:1) and the least mixture ratio of the tests (λ = 0,9). The combustible that achieved such a result was the combustible hydrated ethyl alcohol added to ordinary gasoline C type in 80%. The least value for the net work all through the cycle was obtained by the least compression relation (6:1) and the highest mixture ratio of the tests (λ = 1,1). The fuel that achieved that result was the combustible hydrated ethyl alcohol.
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Jääskö, Pontus, and Petter Morén. "Internal combustion engine durability monitor : Identifying and analysing engine parameters affecting knock and lambda." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-25498.
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This study has been performed at Powertrain Engineering Sweden AB (PES), a fully owned subsidiary of Volvo Cars Group, which is constantly working to develop and improve internal combustion engines. As part of this work, durability tests are performed to analyse the impact of wear on the engines. At present, there is a strong focus on visual inspections after the engines have undergone durability tests. PES wants to develop a method where collected data from these tests can be used to explain how the phenomenon of knocking and the control of lambda changes over time. The study analyses one specific durability test and investigates the methodology of data analysis by using the open-source software platform Sympathy for Data, with an add-on developed by Volvo Cars Group, for data management, visualisation and analysis. To execute the analysis, engine parameters that affect these systems as well as parameters suitable to use as response variables are identified through literature studies of internal combustion engine fundamentalsas well as internal material, and knowledge acquired at the company. The result is presented in the form of an analysis generated by the node for partial least squares regression (PLSR) which is pre-programmed in Sympathy for Data as well as the images and graphs obtained as output. For knock, the signal for the final ignition angle was found to be suitable to use as the response variable in the PLSR. A suitable response variable for lambda was more difficult to identify, this is why both signals for the measured lambda and lambda adaptation are analysed. Studies of the internal material and knowledge highlighted the fact that several engine subsystems are highly dependent on each other and that even deeper research would be necessary to fully understand the process and identify the primary cause for the variations observed in the generated models. However, partial least squares regression was performed using parameters derived from literature reviews as input (predictors) in order produce regression models to explain the variance in sought response. Well-fitting models could be created with a varying number of latent variables needed for the different responses. The output obtained from the PLSR enables further studies of the specific cases as well as the methodology itself, hence, increase the use of data analysis with the help of the software used in the department for durability testing at PES.<br>Denna studie är utförd hos Powertrain Engineering Sweden AB (PES), vilka är ett helägt dotterbolag till Volvo Cars Group, som arbetar med att ta fram och förbättra förbränningsmotorer. En del i detta arbete är att genomföra långtidstest för att analysera hur motorernas egenskaper ändras vid förslitning över tid. I nuläget ligger stort fokus på visuella inspektioner efter att motorerna genomgått långtidstester. PES önskar utveckla en metod där redan insamlad data som registrerats i dessa tester kan förklara hur fenomenet knack och regleringen för lambda förändras över tid. Studien är genomförd i form av en fallstudie av ett specifikt långtidstest där den öppna programvaran Sympathy for Data, tillsammans med det av Volvo Cars Group utvecklade tillägget, används för datahantering, visualisering och analys. Studien undersöker också metodiken för dataanalys med nämnd programvara. För att genomföra detta identifieras motorparametrar som påverkar de undersökta systemen samt parametrar som lämpar sig att användas som responsvariabler i en regressionsmodell. Dessa parametrar togs fram genom litteraturstudier om de fundamentala delarna i en förbränningsmotor samt från företaget förvärvad intern kunskap kring systemen. Resultatet presenteras i form av en analys genomförd med den, i Sympathy for Data, förprogrammerade noden för partial least squares regression(PLSR) samt de bilder och grafer som erhålls. För knack visade det sig att den slutliga tändningsvinkeln var lämplig att använda som respons i PLSR-modellen. En lämplig responsvariabel för lambda var mer svåridentifierad, detta förklarar varför signalerna för uppmätt lambda och lambda adaption analyseras. Inläsning av internt material och grundläggande information om förbränningsmotorer visade att delsystem i ottomotorn är beroende och påverkas av varandra vilket innebär att mer ingående studier i dessa delsystem är nödvändigt för att förstå hela processen och hitta grundorsakerna till variationerna som påvisas för responssignalerna. Vidare utfördes PLSR med de parametrar som härletts från litteraturstudier som indatasignaler (prediktorer) för att skapa en regressionsmodell som förklarar variansen i sökta responssignaler. Beroende av responssignal krävdes varierande antal latenta variabler för att uppnå en tillräckligt precis modell. Resultatet från PLSR möjliggör vidare forskning inom området och metoden som använts och har på så sätt möjliggjort för fortsatt utveckling. Detta i sin tur kan öka användandet av dataanalys med hjälp av den programvara som används vid avdelningen för långtidstest hos PES.
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Reboux, Josué. "Une nouvelle approche de la fluorescence induite par laser pour la détermination de la richesse à haute pression. Application à l'étude de la combustion dans un moteur à allumage commandé." Rouen, 1995. http://www.theses.fr/1995ROUES026.
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L'objectif de cette étude est de fournir un nouvel outil pour la mesure du rapport carburant-air (richesse) dans la chambre de combustion d'un moteur à allumage commandé. Cette méthode de diagnostic optique, basée sur une nouvelle approche de la fluorescence induite par laser, profite de l'effet des désexcitations collisionnelles non radiatives (quenching). Le toluène présent dans une faible proportion (5% dans l'iso-octane) est utilisé comme traceur pour visualiser la distribution du carburant. Un laser à excimère KRF (248 nm) bande large est utilisé pour induire la fluorescence du toluène. Dans la première partie de cette étude, nous effectuons une étude spectroscopique du mélange iso-octane -toluène dans une cellule de réference. Lorsque la pression d'air est supérieure à 3 bars, nous montrons que la fluorescence du toluène est alors directement proportionnelle à la richesse du mélange. Dans la seconde partie, des cartographies de la richesse dans la chambre de combustion du moteur sont réalisées durant la phase de compression. Nous étudions l'effet de différentes configurations d'injection sur l'homogénéité spatiale de la richesse et sur les variations cycle-à-cycle de la richesse moyenne. Lorsque l'injecteur est éloigné de la soupape d'admission, ou lorsque la pipe d'admission est refroidie, l'inhomogénéité du mélange et les fluctuations cycle-à-cycle de la richesse moyenne augmentent. L'étude de la corrélation entre la distribution de la richesse et la fraction de masse brûlée 10 après le point mort haut montre l'effet bénéfique des inhomogénéités de charge éloignées de la bougie sur la vitesse de combustion
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Ding, Yi. "Application de la chimiluminescence de flamme et du courant d’ionisation à la surveillance de l’état de combustion pour une chaudière à gaz domestique." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLC039/document.
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Les variations de la composition des gaz naturels nécessitent un system de réglage automatique de la richesse de flamme pour des chaudières domestiques à gaz. Dans ce travail,deux solutions potentielles sont étudiées, à savoir la chimiluminescence de flamme et le courant d’ionisation. Des indicateurs de richesse sont déduits des signaux de chimiluminescence obtenus expérimentalement. L’impact de l’échange de chaleur entre la flamme et le brûleur sur des signaux de chimiluminescence est ensuite étudié. Une analyse est également faite des principaux facteurs pouvant perturber la caractérisation du signal de chimiluminescence. Le courant d’ionisation est ensuite étudié sur une flamme conique pour comprendre l’évolution de son intensité avec la position de sonde et avec les conditions de flamme. Il est montré ensuite que ces évolutions sont corrélées avec le changement de la distance entre la flamme et le brûleur. Enfin, une boucle de contrôle est développée pour démontrer la faisabilité d’un réglage automatique de richesse en exploitant le signal de chimiluminescence<br>The variations of natural gas composition call for an automatic equivalence ratio regulation system for domestic gas boilers. Two potential techniques for this purpose are investigated, i.e. the flame chemiluminescence and ionization current. Equivalence ratio indicators are inferred from the chemiluminescence signal based on the experiments. The investigation proceeds by examining effects of the flameburner heat exchange on the chemiluminescence signal. The interference of several disturbing factors for the chemiluminescence signal characterization is also analyzed. The flame ionization current is investigated on a conical flame to understand the evolution of its intensity with the probe position and flame conditions. These changes are then attributed to modifications of the distance between the flame base and the burner rim. Finally a control loop is developed to demonstrate the feasibility of equivalence ratio self-regulation with the chemiluminescence signal
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Lezzar, Balahouane. "Contribution à l'étude de la combustion et des limites de fonctionnement dans un monocylindre à taux de compression variable alimenté au méthane, au gaz de groningue et avec un mélange méthane-éthane." Valenciennes, 1987. https://ged.uphf.fr/nuxeo/site/esupversions/0d1a9c0a-0df4-4fab-8206-316c90031798.
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Benzler, Thorsten [Verfasser], and Christof [Akademischer Betreuer] Schulz. "Photo-physical characterization of aromatic compounds for laser-induced fluorescence based diagnostics of fuel concentration, temperature, and equivalence ratio in practical combustion processes / Thorsten Benzler ; Betreuer: Christof Schulz." Duisburg, 2019. http://d-nb.info/1191691314/34.
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Tea, Gabrielle [Verfasser], and Christof [Akademischer Betreuer] Schulz. "Development and exploitation of optical diagnostic techniques for simultaneous 2D temperature and equivalence ratio measurements for the understanding of combustion phenomena in reciprocating engine / Gabrielle Tea. Betreuer: Christof Schulz." Duisburg, 2015. http://d-nb.info/1066206333/34.
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Cho, Ju Hyeong. "Analysis of the Wave Scattering From Turbulent Premixed Flame." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/11494.
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A theoretical investigation of acoustic wave interactions with turbulent premixed flames was performed. Such interactions affect the characteristic unsteadiness of combustion processes, e.g., combustion instabilities. The small perturbation method (SPM) was utilized to evaluate the scattered fields as a result of the flame-wave interaction at the instantaneous wrinkling surface of a randomly moving turbulent flame. Stochastic analysis of ensemble-averaged net acoustic energy was conducted to examine coherent and incoherent acoustic energy amplification /damping by the interaction. Net acoustic energy flux out of the flame is due to two factors: the acoustic velocity jump due to unsteady heat release from flame. The other is the flames unsteady motion. Five(5) dimensionless parameters that govern this net acoustic energy were determined: rms height and correlation length of flame front, incident wave frequency, the ratio of flames diffusion time to flame fronts correlation time, and incidence angle. The dependence of net acoustic energy upon these dimensionless parameters was illustrated and discussed by numerical simulations in case of Gaussian statistics of flame front.
The laminar flame response to equivalence ratio perturbations was also examined, showing that the overall heat release response is controlled by the superposition of three disturbances: heat of reaction, flame speed, and flame area. Heat of reaction disturbances dominate the flame response at low Strouhal numbers, roughly defined as (frequency x flame length)/(axial flow velocity). All three disturbances play equal roles at Strouhal numbers of O(1). In addition, the mean equivalence ratio exerts little effect upon this transfer function at low Strouhal numbers. At O(1) Strouhal numbers, the flame response increases with decreasing values of the mean equivalence ratio.
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Faust, Stephan [Verfasser], Christof [Akademischer Betreuer] Schulz, and Volker [Akademischer Betreuer] Sick. "Characterisation of organic fuel tracers for laser-based quantitative diagnostics of fuel concentration, temperature, and equivalence ratio in practical combustion processes / Stephan Martin Faust. Gutachter: Volker Sick. Betreuer: Christof Schulz." Duisburg, 2013. http://d-nb.info/1035599686/34.
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Morin, Julien. "Etudes expérimentales des réactions des radicaux OH et des atomes d’oxygène d’intérêt pour l’atmosphère et la combustion." Thesis, Orléans, 2016. http://www.theses.fr/2016ORLE2034/document.
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L’objectif de ce travail consiste à étudier, d’une part, les réactions des nitrates d’alkyles avec OH qui ont un intérêt atmosphérique, et d’autre part, les réactions des radicaux OH avec les alcanes et des atomes d’oxygène avec les oléfines qui ont un intérêt pour la combustion. Toutes les réactions ont été étudiées dans des réacteurs à écoulement à basse pression, y compris le réacteur à écoulement à haute température mis en place dans le cadre de la thèse, couplés à un spectromètre de masse quadripolaire à ionisation par impact électronique. Pour les réactions OH + nitrate d’alkyle, la dépendance en température de la constante de vitesse a été mesurée pour dix nitrates d'alkyles, dont pour huit nitrates pour la première fois, sur une large plage de température. Pour six nitrates, les produits de la voie réactionnelle menant au recyclage direct de NO₂, arrachement d’atome H de carbone α, ont été observés et leur rendements mesurés. La grande quantité de données obtenues dans ce travail a été utilisée pour une mise à jour de la relation structure-activité (SAR) pour les réactions d'alkyles nitrates avec OH et a permis d'améliorer les modèles atmosphériques actuels. Les études de réactions de radicaux OH avec les trois alcanes et de l'atome O avec l’éthylène et le propène ont permis de déterminer les constantes de vitesse respectives sur une large gamme de température allant de 220 à 900 K. De plus, la distribution des produits de réactions multivoies O + oléfine en fonction de la température a été déterminée pour la première fois. Ces résultats permettront d’améliorer les modèles de combustion actuellement utilisés<br>The objective of this work was to study the reactions of alkyl nitrates with OH radicals relevant to atmosphere and reactions of OH radical with alkanes and oxygen atoms with olefins of interest for combustion chemistry. All reactions were studied in low pressure flow reactors (including high temperature flow reactor developed during the thesis) coupled to a quadrupole mass spectrometer with electron impact ionization. For OH reaction with nitrates, the temperature dependence of the rate constant was measured in an extended temperature range for ten alkyl nitrates, for eight of them for the first time. For six nitrates, the products of reaction pathway leading to direct recycling of NO₂ (H atom abstraction from α carbon) were observed and their yields were measured. The large amount of data obtained in this work has been used for an update of the structure-activity relation (SAR) for the reactions of alkyl nitrates with OH and will improve existing atmospheric models. For the reactions of OH radicals with three alkanes and O atoms with ethene and propene the rate constants were measured over a wide temperature range, 220-900 K. Moreover, the distribution of the products of the multichannel reactions O + olefin was determined as a function of temperature for the first time. These results are expected to improve current combustion models
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Bábíček, Ondřej. "Návrh řízení spalovací komory." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-444302.
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The subject of the diploma thesis is research of the testing process exhaust clamps. There is a description of a testing device designed to provide simulations of the real operating conditions on an exhaust assembly. The testing device is named the Hot Gas Test Bench. The thesis solves the optimization process of the test setup by determining the optimal fuel ratio, which is given by air flow as oxidizer and flow of natural gas as fuel. The input parameters which provide flow of mentioned fluids are speeds of blowers. In diploma thesis is created a design of initialization and control process to ensure the optional combustion ratio during the entire length of the test.
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Messedi, Nouri. "Contribution à l'étude du comportement d'un moteur à taux de compression variable alimenté au méthane." Valenciennes, 1986. https://ged.uphf.fr/nuxeo/site/esupversions/0f357994-0e2f-428c-be57-1551bb305d52.
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Une partie expérimentale étudie l'influence de la richesse du mélange carburant et des paramètres de fonctionnement d'un moteur monocylindre, quatre temps sur la combustion et les conditions d'apparition du cliquetis en faisant une comparaison méthane/super carburant. Cette étude est complétée par le développement d'un programme de calcul du cycle théorique qui permet de déterminer les pressions et températures ainsi que l'évolution des produits de combustion au cours du cycle.
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Costa, Fabiano Tadeu Mathias. "Estimação da relação ar-combustível utilizando o sinal de pressão no cilindro em um motor ciclo Otto a etanol." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-12022016-115907/.
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A crescente demanda de diminuição das emissões e redução do consumo dos motores de combustão interna exige a melhoria dos métodos para diagnose, em tempo real, e para melhor controle do processo de combustão. Portanto, é desejável determinar a relação ar-combustível sobre uma extensa faixa de condições de operação para obter um melhor controle do motor. Este trabalho apresenta a aplicação do Método dos Momentos para obtenção de um modelo de estimação da relação ar-combustível, através do sinal de pressão no cilindro, em um motor ciclo Otto a etanol. O modelo obtido permitirá o desenvolvimento de novos sistemas de controle utilizando como estratégia a pressão no cilindro.<br>The increasing demands for low emission and low fuel consumption in internal combustion engines require improved methods for diagnosis, in real-time and best possible control of the combustion process. Therefore, determining air-fuel ratio over a wide range of engine operating conditions is desirable for better engine control. This work presents the Moment Method application for obtaining air-fuel ratio estimation model, by cylinder pressure sign, in Otto cycle engine powered by ethanol. The obtained model will allow the development of new control systems, for engine powered alcohol, using as strategy the cylinder pressure.
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Plaks, Dmitriy Vital. "Dynamics of longitudinally forced bluff body flames with varying dilatation ratios." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31767.
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Thesis (M. S.)--Aerospace Engineering, Georgia Institute of Technology, 2010.<br>Committee Chair: Tim Lieuwen; Committee Member: Jeff Jagoda; Committee Member: Suresh Menon. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Egbert, Scott Cutler. "Pressurized Combustion Product Temperature Measurement Using Integrated Spectral Band Ratios." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7535.
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With increasing global power demands, there is a growing need for the clean and efficient use of fossil fuel resources. Gas turbine engines are a commonly used means for generating power; from the propulsion of aircraft to electricity on municipal grids. Measuring the temperature within a turbine combustor or at a turbine inlet could provide numerous advantages related to engine control, durability, efficiency, and emissions and yet this relatively straightforward task has eluded turbine engine manufacturers, primarily because of the high temperatures and pressures, harsh environment, and limited access. Optical emissions measurements are of particular interest for this task as they only require one optical access point and can be accomplished using thin optical fibers that can be fit within existing turbine geometries.This work extends an optical emission method known as the integrated spectral band ratio (ISBR) method beyond previously obtained temperature measurements on atmospheric combustion products to temperature measurements in a pressurized turbine combustor. The ISBR correlates modeled integrated spectral band ratios of spectral water emission to gas temperature, comparable to two-color pyrometry. When the integrated spectral bands are measured, the temperature can be inferred from this correlation. This technique has previously been successfully applied at atmospheric conditions over pathlengths as short at 25 cm but in this case has been applied at pressures of 0.7 and 1.2 MPa and a pathlength of 15 cm.Optical measurements were taken in a pressurized combustion test rig at Solar Turbines Inc. in San Diego California. Two temperature sweeps at high load and low load (pressures of 1.2 and 0.7 MPa, respectively) were measured. The average ISBR optical temperature measurements were approximately 200 K higher than the downstream thermocouple measurements. Thermocouple radiative losses were predicted to yield a bias of -175 K. The slope of a change in optical temperature to change in thermocouple temperature was 1.03 over the 87 K variation seen. Repeatability of the optical measurement at a given operating condition was on the order of ± 15 K and the absolute uncertainty of a single measurement was estimated to be ± 70 K over a temperature range of 1350 to 1500 K. The spectra, measured with a Fourier Transform Infrared Spectrometer (FTIR), was in very good agreement with spectral emission models produced using a derivative of the HITEMP database. All of the measured peak locations matched the model, and the measured data matched changes in spectral wings with changing pressure. A linear correlation was also found between raw optical signal and thermocouple measurements.
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Parkes, Anthony Richard. "The impact of size and location of pool fires on compartment fire behaviour." Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2009. http://hdl.handle.net/10092/3444.
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An understanding of compartment fire behaviour is important for fire protection
engineers. For design purposes, whether to use a prescriptive code or performance
based design, life safety and property protection issues are required to be assessed. The
use of design fires in computer modelling is the general method to determine fire safety.
However these computer models are generally limited to the input of one design fire,
with consideration of the complex interaction between fuel packages and the
compartment environment being simplified. Of particular interest is the Heat Release
Rate, HRR, as this is the commonly prescribed design parameter for fire modelling. If
the HRR is not accurate then it can be subsequently argued that the design scenario may
be flawed. Therefore the selection of the most appropriate fire design scenario is
critical, and an increased level of understanding of compartment behaviour is an
invaluable aid to fire engineering assumptions.
This thesis details an experimental study to enhance the understanding of the impact and
interaction that the size and location of pool fires within an enclosure have upon the
compartment fire behaviour. Thirty four experiments were conducted in a reduced scale
compartment (½ height) with dimensions of 3.6m long by 2.4m wide by 1.2m high
using five typical ventilation geometries (fully open, soffit, door, window and small
window). Heptane pool fires were used, located in permutations of three evenly
distributed locations within the compartment (rear, centre and front) as well as larger
equivalent area pans located only in the centre. This thesis describes the experimental
development, setup and results of the experimental study. To assist in the classification
of compartment fire behaviour during the experiments, a ‘phi’ meter was developed to
measure the time dependent equivalence ratio. The phi meter was developed and
configured to measure O₂, CO₂ and CO. The background development, calibration, and
experimental results are reported. A review of compartment fire modelling using Fire
Dynamics Simulator, has also been completed and the results discussed.
The results of this experimental study were found to have significant implications for
Fire Safety Engineering in that the size of the fire is not as significant as the location of
the fire. The effect of a fire near the vent opening was found to have a significant impact
on compartment fire behaviour with the vent located fuel source increasing the total
compartment heat release rate by a factor of 1.7 to that of a centrally placed pool fire of
the same total fuel area. The assumption that a fire located in the centre of the room
provides for the highest heat release rate is not valid for post-flashover compartment
fires. The phi meter was found to provide good agreement with the equivalence ratio
calculated from total compartment mass loss rates, and the results of FDS modelling
indicate that the use of the model in its current form can not be applied to complex pool
fire geometries.
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Kapadia, Bhavin Kanaiyalal. "Development Of A Single Cylinder SI Engine For 100% Biogas Operation." Thesis, Indian Institute of Science, 2006. http://hdl.handle.net/2005/283.
Full textAbstract:
This work concerns a systematic study of IC engine operation with 100% biogas as fuel (as opposed to the dual-fuel mode) with particular emphasis on operational issues and the quest for high efficiency strategies. As a first step, a commercially available 1.2 kW genset engine is modified for biogas operation. The conventional premixing of air and biogas is compared with a new manifold injection strategy. The effect of biogas composition on engine performance is also studied.
Results from the genset engine study indicate a very low overall efficiency of the system. This is mainly due to the very low compression ratio (4.5) of the engine. To gain further insight into factors that contribute to this low efficiency, thermodynamic engine simulations are conducted. Reasonable agreement with experiments is obtained after incorporating estimated combustion durations. Subsequently, the model is used as a tool to predict effect of different parameters such as compression ratio, spark timing and combustion durations on engine performance and efficiency. Simulations show that significant improvement in performance can be obtained at high compression ratios.
As a step towards developing a more efficient system and based on insight obtained from simulations, a high compression ratio (9.2) engine is selected. This engine is coupled to a 3 kW alternator and operated on 100% biogas. Both strategies, i.e., premixing and manifold injection are implemented. The results show very high overall (chemical to electrical) efficiencies with a maximum value of 22% at 1.4 kW with the manifold injection strategy. The new manifold injection strategy proposed here is found to be clearly superior to the conventional premixing method. The main reasons are the higher volumetric efficiency (25% higher than that for the premixing mode of supply) and overall lean operation of the engine across the entire load range. Predictions show excellent agreement with measurements, enabling the model to be used as a tool for further study. Simulations suggest that a higher compression ratio (up to 13) and appropriate spark advance can lead to higher engine power output and efficiency.
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Huška, Lukáš. "Software pro řízení zapalování a vstřikování spalovacích motorů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218797.
Full textAbstract:
This master thesis deals with ignition systems which are used in cars vehicles with gas engines and also with setting of the best moment of ignition of gasoline-air mixture in cylinders of engine. Ways of gas injection at diesel engines and their control systems are also described in this thesis. Next chapter deals with control unit and describes main actions which are necessary for today’s motor vehicles. As illustration is used example of succession of actions which are necessary for calculation and setting regular value of pre-ignition. At the end is shown animation, which can be used for practice lessons in a subject Automobile Electric and Electronic Systems as a example. It will simplify understanding of described activities which are all accomplished by central control unit. For purposes of laboratory lessons is in this thesis also discussed measuring of engine performance with changes of parameter of central control unit.