Dissertations / Theses on the topic 'Ignition engines'
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1
Calnan, Peter John Courtney Benedict. "Analysis of new engine cycles for spark ignition engines." Thesis, Brunel University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389985.
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Kaul, Brian Christopher. "Addressing nonlinear combustion instabilities in highly dilute spark ignition engine operation." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2008. http://scholarsmine.mst.edu/thesis/pdf/Kaul_09007dcc804ea67e.pdf.
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Thesis (Ph. D.)--Missouri University of Science and Technology, 2008.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 28, 2008) Includes bibliographical references (p. 170-176).
3
Hu, Zhengyun. "Turbulence enhancement in spark-ignition engines." Thesis, Imperial College London, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340890.
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Posylkin, Michael. "Mixture preparation in spark-ignition engines." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243438.
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Nates, Roy Jonathan. "Knock damage in spark-ignition engines." Doctoral thesis, University of Cape Town, 1995. http://hdl.handle.net/11427/11478.
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The objectives of this thesis were to identify, explain and quantify the damage caused by knocking combustion in spark-ignition engines. A literature review indicated that, in general, research into knock has focused on the causes and avoidance of knock, rather than on the damage resulting from knock. The few published works concerning the effects of knock were mainly interested in the prevention of one specific form of damage, namely piston erosion. The review highlighted the need to investigate the relationship between knock and the various forms of damage. Using the evidence from knock-damaged engines, the sequence of events leading to failure were reconstructed. The manner in which knock damage manifests itself as surface erosion, piston-ring failure, piston-land cracking, piston blow-by and seizure were examined. From these observations it was deduced that two independent damage paths result from knock. Consequently, the research diverged into two studies, namely: Local pressure-temperature transients in the end-gas zone which cause localised erosion damage; Excessive heat flux associated with knocking combustion which results in global piston and ring problems.
6
Mutzke, Johannes Gerhard. "Abnormal combustion in spark ignition engines." Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:0bba0e6c-a989-4791-a80a-8b39fe88f431.
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Emissions from internal combustion engines are a major contributor to anthropogenic climate change. In order to decrease the amount of emissions, car manufacturers are investing in increasing the efficiency of spark ignition engines. Means for this include downsizing and turbocharging which come with an exacerbated risk of abnormal and harmful combustion phenomena, notably autoignition, knock and pre-ignition and thus pose a limit to the efficiency of the engines. Abnormal combustion depends on the engine geometry, the operating conditions and the fuel. Industrial standard classification systems are outlined to be insufficient, misleading or non-existent for modern engines and fuels. This thesis aims to improve the understanding of the abnormal combustion phenomena through an experimental project which can be utilised for improved classification systems. The vast majority of the experiments were conducted on a variable compression ratio engine which was fitted with modern control, measurement and data acquisition equipment to resemble an industrially-used test engine. In a first study, methods of finding the ideal engine operating point were investigated. Knock was induced in the engine, and knock indicators and limitations of knock are discussed here. Enhanced humidity was passed into the heated air-inlet stream by means of a custom-built humidifying unit. Results showed that both the power output of the engine and the severity of knock were reduced with increased humidity. This was explained by the exclusion of combustible air. A fuel-vaporization unit allowed for experiments with fully vaporized fuel. It could be shown that this had an adverse effect on knock as the cooling effect of the enthalpy of vaporization was removed. A second study employed a temperature-controlled glow plug to induce surface pre-ignition. A range of analysis techniques were tested and discussed which ranged from flame ionization detection to several in-cylinder pressure based methods. A cycle-by-cycle analysis with a maximum pressure method revealed an unexpected trend of surface pre-ignition tendency in sweeps of stoichiometry and fuels, with slightly weak of stoichiometric mixtures being the most susceptible to pre-ignition. Enhanced humidity had a negligible effect on surface pre-ignition under real world conditions. A third study concerned itself with the analysis of knock-induced heat flux, which is both a major cause for damage to the engine and trigger for surface pre-ignition. A heat flux probe was fitted to the engine and results linking heat flux to knock could be obtained on cycle-by-cycle basis and cycleaveraged basis. A linear trend between heat flux and knock intensity was found.
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Lodi, Faisal Samad. "Reducing cold start fuel consumption through improved thermal management." Connect to thesis, 2008. http://repository.unimelb.edu.au/10187/3601.
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The thesis presents research in achieving faster warm-up of an SI engine, thereby affecting the fuel economy penalty. The faster warm-up relates to faster heating of the cylinder head and engine block, targeting reducing viscous friction in the cold oil as the most likely candidate to improve. The strategy applied was to reduce the coolant flow circulation rate to achieve a faster warm-up of the engine. A lumped parameter model for engine heat transfer, coolant flow and heat capacities, in a single cylinder, based on engine operating points like spark advance, engine speed and MAP was built in Modelica.The engine used for experimentation was a Ford in-line, 4 stroke, 6-cylinder engine, with a compression ratio of 10.3:1, in which 56 K-type thermocouples were installed at different locations to measure the temperature. The experiments were performed with varying coolant flow rate from normal down to zero, utilizing an electric water pump, over an approximation to the New European Drive Cycle (NEDC), at a speed of 1161 rev/min and load of 48 Nm. The selected speed and load were the average operating condition for 180 seconds of engine running over the urban part of a simulated NEDC. In addition, the coolant circuit was modified to a split cooling supply and the sets of results analyzed to find the reduction in engine warm-up time and fuel consumption.
It is shown from the results that the warm-up time of the engine and the fuel consumption were notably reduced, as the flow was reduced from maximum to minimum in steps. On average over an interval of engine running for 300 seconds from cold start, the cylinder head temperature was increased by about 2°C , the average engine block temperature was increased by about 6.5°C and the average cylinder head coolant temperature was increased by about 4°C . However, the bulk temperature of the oil in the oil sump showed marginal improvement and remained consistent, even at the lowest coolant flow rate. Nonetheless, the improvements in block temperature had significant effects on reducing the friction between the piston and cylinder walls.
Analysis of the results show that the coolant flow pattern changed with the use of an electric water pump. The flow is less evenly distributed around the cylinders with the use of an electric water pump, whilst retaining the mechanical water pump body, compared to the mechanical water pump operation.
The model was applied to simulate for two engine operating points, i.e., 1161 rev/min, 48 Nm load and 700 rev/min and 0 Nm load. The model was calibrated at 1161 rev/min, 48 Nm load and validated at 700 rev/min, 0 Nm load. The modeling results were in fair agreement with the experimental results. The model can be employed to investigate electric water pump control.
The important finding is that around 3% fuel consumption savings are possible over the NEDC by management strategies that lead to faster cylinder block warm up, even though this may result in little or no change in oil temperature as measured in the sump.
8
Wiseman, Marc William. "Spark ignition engine combustion process analysis." Thesis, University of Nottingham, 1990. http://eprints.nottingham.ac.uk/11131/.
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Cylinder pressure analysis is widely used in the experimental investigation of combustion processes within gasoline engines. A pressure record can be processed to reveal detail of charge burning, which is a good indicator of combustion quality. The thesis describes the evaluation of an approximate technique for calculating the mass fraction of the charge that has burnt; a novel approach for determining heat loss to the block; the development of a powerful system for combustion analysis; and the investigation of the correlation between the crank angle location of the 50% mass burnt and minimum timing advance necessary to obtain the maximum engine torque. A detailed examination has been carried out into the uncertainties in the determination of the mass fraction burnt as suggested by Rassweiler and Withrow. A revised procedure has been developed which does not require a priori identification of the combustion end point, and a new approach is suggested to calculate the polytropic indices necessary for the pressure processing. This particular implementation of the analysis is able to identify late burning and misfiring cycles, and then take appropriate steps to ensure their proper analysis. The problems associated with the assumption of uniform pressure; alignment of the pressure changes to the volume changes; pressure sampling rate; clearance volume estimation; and calibrating the acquired pressure to absolute are also evaluated. A novel method is developed to ascertain, directly from the pressure history, the heat loss to the cylinder block. Both experimental and simulated data are used to support the accuracy of the suggested heat loss evaluation, and the sensitivity of the method to its inputs is examined. The conversion of procedures for combustion analysis into a format suitable for undertaking high speed analysis is described. The analysis techniques were implemented so that the engine can be considered to be on-line to the analysis system. The system was entitled Quikburn. This system can process an unlimited number of cycles at a particular running condition, updating the screen every 1.5 seconds. The analysis system has been used to study the potentially beneficial correlation between the location of the 50% mass burnt and MBT. The correlation is examined in detail, and found to be valid except under lean fueling conditions, which is seen to be caused by slow flame initiation. It is suggested that the optimum location of the 50% mass burnt can be used as a reference setting for the ignition timing, and as an indicator of combustion chamber performance. An engine simulation was employed to verify that changes in bum shape account for the small variation seen in the optimum 50% bum locations at different operating conditions of the engine. The bum shape changes also account for the range of optimum locations of the 50% mass burnt encountered in different engines.
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Kapil, Anil. "Cycle-to-cycle variations in spark-ignition engines." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28392.
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Pressure data measurements have been made in a single-cylinder, spark-ignition engine over 100 consecutive cycles. The engine was operated on natural gas at a wide range of engine speed and equivalence ratios. The effects of spark electrode geometry, combustion chamber geometry, spark gap and throttling have also been examined. From these pressure measurements standard deviations in burning times in mass-fraction-burned values were determined. Because of the existing evidence that the origin of cyclic variations is in the early combustion period, the standard deviations of cyclic variation in time required for a small (almost zero) mass-fraction-burned is estimated by extrapolation. These extrapolated values of standard deviation are compared with the implication of a hypothesis that cyclic variations in combustion in spark-ignition engines originate in the small-scale structure of turbulence (after ignition).
The nature of turbulence structure during combustion is deduced
from existing knowledge of mixture motion within the combustion chamber
of the engine. This research determines the turbulent parameters, such
as turbulence intensity, turbulent length scales and laminar burning
velocity. The standard deviation in burning times in the early stages
of combustion is estimated, within experimental uncertainty, by the
parameter ⋋/4uℓ where ⋋ is the Taylor microscale and uℓ is the laminar
burning velocity of the unburned mixture. This parameter is the
consequence of the Tennekes model of small-scale structure of
turbulence and Chomiak's explanation of the high flame propagation
rate in regions of concentrated vorticity and the assumption that theignition behaves as though it were from a point source.
The general conclusion reached is that the standard deviation in the burning time for small mass-fraction-burned is associated with the early stages of burning-predictable from the knowledge of the Taylor microscale and the laminar burning velocity.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
10
Hong, C. W. "Computer simulation of turbocharged spark ignition engines." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/47281.
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Pashley, Nicholas C. "Ignition systems for lean burn gas engines." Thesis, University of Oxford, 1997. http://ora.ox.ac.uk/objects/uuid:b5fcf2d4-b27b-4b3b-a593-ee307ec80f3a.
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This thesis describes an experimental investigation into ignition systems, their effects on the combustion process, and how the discharge is affected by the prevailing pressure, temperature and flow. The work is divided into four main areas, a comprehensive literature review, engine testing for ignition system suitability, non-flow rig testing (including erosion) and flow rig testing. The literature review concluded that the most practical ignition system for lean burn gas engines will continue to be based on the spark plug, but in the medium to long term, laser ignition may become viable. The measurement of the HT voltage and current is not straightforward, and appropriate methods have been identified. Capacitive and inductive ignition system types were compared in lean and diluted conditions on a single cylinder research engine of modern design at different engine loads and speeds. It was found that the most beneficial ignition system was an inductive ignition system, although that for some conditions, capacitive systems induced better engine performance with a fraction of the stored energy of the inductive alternative. Non flow tests showed that the early part of the spark discharge is sensitive to pressure and temperature effects, and as a consequence, the latter stages of the discharge are also affected. A correlation has been developed, for use with conventional nickel electrode spark plugs, to predict breakdown voltage as a function of pressure, temperature and gap. Experiments were carried out at elevated pressures in a stream of flowing air with capacitive and inductive ignition systems. Different electrode designs and orientations were also compared. It was shown that when exposed to a flow field, the discharge can be stretched which results in a shortened spark duration; in some cases the electrode can shield the discharge from flow field effects. This work showed that flow through the spark gap is a hindrance to the spark process, especially for longer duration systems. However for flame kernel growth, the literature review identified that flow is beneficial, serving to convect the kernel away from the electrodes, reducing the heat transfer from the flame. Analysis of the glow voltage history in the pressurised flow rig has been used to develop a correlation relating the voltage, current, flow velocity, pressure and time. This correlation was used to analyse the velocity records from the spark plug in a firing engine. The predicted velocities and turbulence intensity were in agreement with independent measurements.
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Bleimschein, G. E. "The octane requirement of spark ignition engines." Master's thesis, University of Cape Town, 1991. http://hdl.handle.net/11427/8286.
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Bibliography: leaves 81-85.The thesis covers the fundamentals of refining and fuel technology, engine technology as regards parameters which influence knock and the results of engine tests. Definitions of octane number and the interpretation of the system developed to establish these numbers using the CFR engine are given. The literature survey covers the fundamental refining processes which are used to upgrade gasoline components in order to raise their octane quality or to achieve a more suitable distillation range. Some of the reactions which take place are described and operating conditions for the reactions to occur are given. The chemistry of fuels which affects their octane quality is given and discussed. Generally, aromatics have very good octane values but straight chain paraffins are poor in this regard.
13
Kayes, David J. (David Jonathan) 1972. "Particulate matter formation in spark-ignition engines." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9417.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1999.Includes bibliographical references (leaves 180-184).
Recent health concerns over airborne particulate matter (PM) have prompted examination of the mechanisms by which PM is formed in spark ignition (SI) internal combustion engines. A study was undertaken in order to understand the effects of dilution on measured PM, to examine and model the effect of steady state engine operating conditions on engine-out PM, and to characterize the effect of transient engine conditions on particle growth and dynamics. Particle dynamics in diluted SI and compression ignition (Cl) engine exhaust are examined and discussed in the context of SI exhaust dilution. Temperature measurements in the exhaust pipe and dilution tunnel reveal the degree of mixing between exhaust and dilution air, the effect of flowrate on heat transfer from undiluted and diluted exhaust to the environment, and the minimum permissible dilution ratio for a maximum sample temperature of 52°C. Measurements of PM concentrations as a function of dilution ratio, using a Scanning Mobility Particle Sizer (SMPS), show the competing effects of temperature and particle/vapor concentrations on particle growth dynamics, which result in a range of dilution ratios - from 13 to 18 - where the effect of dilution ratio, independent of flowrate, is kept to a minimum and is therefore optimal in order to achieve repeatable PM concentration measurements. Particle dynamics in transit through the dilution tunnel are measured and compared to previous research. PM emissions are strongly affected by steady state engine parameters that affect global and local air/fuel ratios, the concentration of liquid fuel in the cylinder, and the availability of soot precursors. PM emissions vary by up to six orders of magnitude between the fuels tested, when at the same fuel/air equivalence ratio. Minimum PM concentrations are emitted at a global fuel/air ratio within 10% of stoichiometric, with the exact value depending on the particular fuel, and concentrations can increase by more than three orders of magnitude when the fuel/air ratio is either increased or decreased 30% from stoichiometric. Burning liquid fuel is a significant source of PM, as evidenced by the fact that open valve fuel injection increases PM emissions by up to three orders of magnitude relative to closed valve injection. Coolant and oil temperatures, spark timing, and Exhaust Gas Recirculation (EGR) affect PM through their effect on intake port and cylinder temperatures, as well as through the effect on the availability of liquid fuel in the cylinder. Particles derived from oil consumption were found to be between zero and 40% of the total PM concentration for the oils used in the present experiments. Differences in PM emissions with and without the catalytic converter are not statistically significant. Particulate number and mass concentrations plus particle sizes are addressed in the present paper, as is the correlation between PM and emissions of gaseous pollutants - hydrocarbons (HCs), oxides of nitrogen (NOx), oxides of carbon (CO and CO2) - as well as oxygen and characteristic temperatures and pressures during the engine cycle. A model of PM formation via homogeneous- and heterogeneous-phase reactions, growth via condensation and adsorption/absorption of vapors, and diminution via oxidation explains the observed behavior of PM emissions with respect to each of the engine, fuel, and dilution parameters above. PM emissions during transient engine operation are generally a first-order time response with characteristic times similar to those involved in the fuel evaporation process, suggesting that PM emissions respond to instantaneous engine conditions and may be modeled using a quasi-steady state application of the model.
by David Kayes.
Ph.D.
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Kenny, Wilhelm Jordaan. "Development of an engine testing facility for spark ignition engine fuels." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80043.
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Thesis (MScEng)--Stellenbosch University, 2013.ENGLISH ABSTRACT: This thesis comprises of the development of a facility were spark ignition engine fuels can be tested. Development of the facility included the installation of a standard spark ignition engine, an engine dynamometer, control and monitoring equipment, control and monitoring software, and an in-cylinder pressure measurement setup. The system was tested using petrol as well as a petrol-ethanol blend. The results indicated good accuracy and repeatability of the system. Analysis of the performance and combustion of the petrol-ethanol blend showed no significant difference in comparison to the petrol fuel. The petrol-ethanol blend showed a slight increase in oxygen content and fuel consumption as well as an increase in CO2 emissions and a decrease in CO emissions. During the project, a comparison was also made between the performance of fibre optic transducers and a piezoelectric transducer. It was found that the fibre optic transducers performed similarly to the piezoelectric transducer during low engine load conditions. At high load conditions however, the fibre optic transducers were not able to produce the same accuracy as the piezoelectric transducer.
AFRIKAANSE OPSOMMING: Hierdie tesis bestaan uit die ontwikkeling van 'n fasiliteit waar brandstowwe vir 'n vonkontsteking binnebrandenjin getoets kan word. Ontwikkeling van die fasiliteit sluit in die installering van 'n standaard vonkontsteking binnebrandenjin, 'n enjin rem, beheer en monitering toerusting, beheer en monitering sagteware, en 'n insilinder drukmeting opstelling. Die fasiliteit is getoets met suiwer petrol sowel as 'n petrol-etanol mengsel. Die resultate het hoë vlakke van akkuraatheid en herhaalbaarheid getoon. Ontleding van die werksverrigting en verbranding van die petrol-etanol mengsel het geen beduidende verskil getoon in vergelyking met die suiwer petrol brandstof nie. Die petrol-etanol mengsel het 'n effense toename in suurstofinhoud, brandstofverbruik, sowel as CO2 vrylating en 'n afname in CO vrylating getoon. Tydens die projek is 'n vergelyking getref tussen die akkuraatheid van optiese vesel drukmeters en 'n piësoëlektriese drukmeter. Daar is bevind dat die akkuraatheid van die optiese vesel drukmeters soortgelyk is aan die piësoëlektriese drukmeter gedurende lae enjin lastoestande. By hoë las omstandighede was die optiese vesel drukmeters egter nie in staat om dieselfde akkuraatheid as die piësoëlektriese drukmeter te handhaaf nie.
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Duszynski, Marek. "Measurement of lubricant film thickness in reciprocating engines." Thesis, Imperial College London, 1999. http://hdl.handle.net/10044/1/8268.
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Roberts, Philip John. "Fuel and residual effects in spark ignition and homogeneous charge compression ignition engines." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.530821.
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Weinrotter, Martin [Verfasser]. "Laser Ignition of Internal Combustion Engines : Basic Laser and Ignition Optics Developments, Engine Application and Optical Diagnostics / Martin Weinrotter." München : GRIN Verlag, 2011. http://d-nb.info/1182238203/34.
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Andersson, Per. "Air charge estimation in turbocharged spark ignition engines /." Linköping : Dept. of Electrical Engineering, Linköping University, 2005. http://www.bibl.liu.se/liupubl/disp/disp2005/tek989s.pdf.
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Xiaofeng, Gao. "Real time knock detection for spark ignition engines." Thesis, Brunel University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241624.
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Baker, Philip. "Investigation of barrel swirl in spark ignition engines." Thesis, Coventry University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364160.
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Mullett, Jack Daniel. "Laser-Induced Ignition Systems for Gasoline Automotive Engines." Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507466.
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Daham, Basil. "Measuring real-world emissions from spark ignition engines." Thesis, University of Leeds, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426900.
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Williams, Paul Andrew. "Characterization of fuel sprays in spark ignition engines." Thesis, University College London (University of London), 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282716.
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Sandoval, Daniel 1980. "An improved friction model for spark ignition engines." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/80657.
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Hasson, Dhari A. "Mixture preparation and combustion in spark ignition engines." Thesis, Aston University, 1986. http://publications.aston.ac.uk/11867/.
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Hynes, John. "Turbulence effects on combustion in spark ignition engines." Thesis, University of Leeds, 1986. http://etheses.whiterose.ac.uk/3712/.
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Described in this thesis are the results of an experimental and theoretical study of the effects of turbulence on combustion in single and dual chamber spark ignition engines. The techniques adopted in the experimental study included the use of high speed cine photography, and the collection of simultaneous cylinder pressure records using an on-line computer. The experimental results confirmed the potential of the dual chamber design for increasing burning rate, and for controlling the level of turbulence within an engine cylinder. High speed photographs were filmed through a perspex window in the engine cylinder head. These showed that flame propagation was much faster when the engine was fitted with a divided chamber cylinder head than when equipped with a disc shaped single chamber head. The acceleration of combustion rate has been shown to be a function of flow velocity through the interconnecting orifice during the compression stroke. At very high flow velocities the nozzle became choked, and engine performance was impaired. In the theoretical work, a computer model for the thermodynamic cycle of an engine was developed. The use in this model of empirical laws to describe combustion rate was shown to be inadequate; this was primarily because of uncertainty in the length of the combustion period, which one needs to specify when using this method. When burning velocity data (derived from work by colleagues using a turbulent combustion bomb) were incorporated into the model, good qualitative results were possible. The use of an empirical law to describe the effect of turbulence on the burning velocity of a developing flame was, however, shown to be inaccurate. The turbulent flame front in an engine is a thick reaction zone containing pockets of unbumt charge. Analysis o f data for flame projected area (derived from high speed photographs) and simultaneous cylinder pressure data, revealed that a considerable quantity of unburnt charge was present behind the visible flame front. There was some evidence that a greater proportion of unburnt charge was present behind the flame when the mixture was lean than when it was stoichiometric. Modelling of this effect by assuming that mass, once entrained, would burn at an exponential rate, was shown to produce reasonable results.
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Srivastava, Shalabh. "Numerical simulation of a direct injection spark ignition engine using ethanol as fuel." Diss., Connect to online resource - MSU authorized users, 2008.
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Thesis (M.S.)--Michigan State University. Dept. of Mechanical Engineering, 2008.Title from PDF t.p. (viewed on July 27, 2009) Includes bibliographical references (p. 119-122). Also issued in print.
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Sleightholme-Albanis, G. R. "Measurements of spark-ignition engine fuelling variations." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241120.
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Hamori, Ferenc. "Exploring the limits of hydrogen assisted jet ignition /." Connect to thesis, 2006. http://eprints.unimelb.edu.au/archive/00001606.
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Dymala-Dolesky, Robert. "The effects of turbulence enhancement on the performance of a spark-ignition engine." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26696.
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An attempt has been undertaken to enhance turbulence in an S.I. engine at the final stage of the compression stroke, without affecting the intake process. The method employed to control the turbulence level made use of an original design called the squish-jet combustion chamber. The design had potential to generate jets in the chamber before CTDC and thus create dramatically different turbulent flow patterns. Natural gas, a slow burning fuel, was used for performance tests, and different levels of turbulence were expected to markedly affect the combustion process.
A flow visualization experiment was performed under conditions similar to a motored engine. As a result, the jet development in the squish-jet type combustion chamber was documented.
A new type of a flat cylinder head, and a set of squish-jet pistons were designed and manufactured. Experiments conducted on the redesigned Ricardo Hydra, single cylinder research engine, evaluated the influence of the squish-jet chamber on the mixture motion and the engine performance
over a wide range of operating conditions. The jet velocities were measured with a hot wire probe located in the piston bowl, and turbulence parameters with a probe inserted through a cylinder head. The squish-jet design was evaluated for 6 different configurations.
As a result it has been established that the squish-jet design does not create jets strong enough to dramatically enhance the turbulent flow field. The design, however, diminished the squish effect which is shown to be very important for the middle part of flame development. The simple squish design produces faster burning rate in the first half of the combustion process and develops the highest peak pressures. Variabilities of both cyclic IMEP and peak pressure are found to be unaffected by the presence or absence of strong squish motion. This suggests that the most important phase of combustion for the cyclic variation is the initial stage of the flame development. A comparison of ensembled pressure signals between combustion chamber designs, conducted at RAFR=1.00 and at RAFR=1.25 shows less dispersion in the latter case. It appears that at lean operation mixture motion influences combustion process to a lesser degree than at stochiometric conditions.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Norouzi, Shahrouz. "Interaction of diesel type fuels and engine fuel system components in compression ignition engines." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/5369/.
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Contact of fuels with engine components at low and elevated temperatures for various amounts of time is found to be challenging as this contact has several effects on engine fuel system components and fuels. Also, storage of fuels for a long period of time is found to have almost the same effect on both engine components and fuels upon engine use. In this thesis fuel and engine components’ contact have been studied for four typical metals used in the construction of many engine fuel systems; in form of pure or alloys (copper, aluminium, mild carbon steel and stainless steel), studied after contact with three of the currently available fuels for use in compression ignition engines. Ultra-low sulphur diesel fuel (ULSD) was used as the fossil fuel, rapeseed methyl ester (RME) as the first generation biofuel and finally gas-to-liquid (GTL) as the second generation of biofuel, obtained via the Fischer-Tropsch process. The investigation was performed in different sections: fuels and metals have been studied for any degradation after contact at low and high temperatures for short and long exposure times, and an understanding of the corrosion process and any degradation on both metals and fuels has been achieved; due to the high hygroscopic character of these fuels and the presence of possible impurities in the fuel, the investigation was extended for analysis of the effect of the presence or absence of absorbed water and dissolved air (in the form of Oxygen) in fuels on degradation and corrosion characteristics of these fuels.
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Min, Kyoungdoug. "The effects of crevices on the engine-out hydrocarbon emissions in spark ignition engines." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12221.
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Lim, Emmanuel G. (Emmanuel Gocheco). "The engine reformer : syngas production in engines using spark-ignition and metallic foam catalysts." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100109.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 133-135).
An experimental study was performed to assess the feasibility of performing methane (CH4) partial oxidation (POX) in two internal combustion engines: one equipped to perform spark-ignition (the "spark-ignited engine"), and the other containing a catalyst in the engine cylinder (the "catalytic engine"). The exhaust gases were rich in hydrogen- (H 2) and carbon monoxide- (CO), and could be used as synthesis gas ("syngas") for the synthesis of liquid fuels such as methanol. Conventional syngas production techniques are only economical on a large scale and cannot be transported to hard-to-reach gas sources, where gas-to-liquids (GTL) would have the biggest impact on the transportability of that gas. Engines could be deployed at these locations to produce syngas on a small scale and at low cost, as they benefit from the economies of mass production that have been achieved through advanced manufacturing techniques. We call this type of engine an "engine reformer". This thesis contrasts the results of performing methane POX in two different engine reformers, using atmospheric air as the oxidizer. One of four cylinders in a Yanmar 4TNV84T marine diesel generator was converted to ignite methane POX mixtures using a spark plug. Intake temperatures > 350 °C were required to minimize misfire. Exhaust H2 to CO ratios of 1.4 were achieved with methane-air equivalence ratios (0m) up to 2.0, while ratios of > 2.0 were achieved with hydrocarbon-air equivalence ratios (PHc) up to 2.8 with the assistance of hydrogen (H 2) and ethane (C 2H6). High equivalence ratios °PHC > 2.2 showed reduced CH4 conversion efficiency, therefore PHC = 2.2 (with H2 produced a good tradeoff between syngas quality and CH4 conversion. A single-cylinder Lister-Petter TRl diesel generator was used to perform methane POX using a palladium (Pd) washcoat catalyst deposited on a Fecralloy® disk. With > 150 °C intake temperatures, exhaust H2 to CO ratios of 1.0 were achieved with methane-air equivalence ratios (PM = 4.0 with varying amounts of CO2 to simultaneously perform methane dry reforming. Spark-ignition appeared to provide higher reliability, though tests will continue to be performed on the catalytic engine to optimize performance. A larger engine of a similar design to the spark-ignited Yanmar will be deployed at a demonstration plant in North Carolina to produce syngas at higher flow rates, and will be integrated with a liquids synthesis reactor to produce methanol.
by Emmanuel G. Lim.
S.M.
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Ahmed, Irufan. "Simulation of turbulent flames relevant to spark-ignition engines." Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/245288.
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Combustion research currently aims to reduce emissions, whilst improving the fuel economy. Burning fuel in excess of air, or lean-burn combustion, is a promising alternative to conventional combustion, and can achieve these requirements simultaneously. However, lean-burn combustion poses new challenges, especially for internal combustion (IC) engines. Therefore, models used to predict such combustion have to be reliable, accurate and robust. In this work, the flamelet approach in the Reynolds-Averaged Navier- Stokes framework, is used to simulate flames relevant to spark-ignition IC engines. A central quantity in the current modelling approach is the scalar dissipation rate, which represents coupling between reaction and diffusion, as well as the flame front dynamics. In the first part of this thesis, the predictive ability of two reaction rate closures, viz. strained and unstrained flamelet models, are assessed through a series of experimental test cases. These cases are: spherically propagating methane- and hydrogen-air flames and combustion in a closed vessel. In addition to these models, simpler algebraic closures are also used for comparison. It is shown that the strained flamelet model can predict unconfined, spherically propagating methane-air flames reasonably well. By comparing spherical flame results with planar flames, under identical thermochemical and turbulence conditions, it is shown that the turbulent flame speed of spherical flames are 10 to 20% higher than that of planar flames, whilst the mean reaction rates are less influenced by the flame geometry. Growth of the flame brush thickness in unsteady spherical flames have been attributed to turbulent diffusion in past studies. However, the present analyses revealed that the dominant cause for this increase is the heat-release induced convective effects, which is a novel observation. Unlike methane-air flames, hydrogen-air flames have non-unity Lewis numbers. Hence, a novel two degrees of freedom approach, using two progress variables, is used to describe the thermochemistry of hydrogen-air flames. Again, it is shown that the strained flamelet model is able to predict the experimental flame growth for stoichiometric hydrogen-air flames. However, none of the models used in this work were able to predict lean hydrogen-air flames. This is because these flames are thermo-diffusively unstable and the current approach is inadequate to represent them. When combustion takes place inside a closed vessel, the compression of the end gases by the propagating flame causes the pressure to rise. This is more representative of real IC engines, where intermittent combustion takes place. The combustion models are implemented in a commercial computational fluid dynamics (CFD) code, STAR-CD, and it is shown that both strained and unstrained flamelet models are able to predict the experimental pressure rise in a closed vessel. In the final part of this work, a spark-ignition engine is simulated in STAR-CD using the flamelet model verified for simpler geometries. It is shown that this model, together with a skeletal mechanism for iso-octane, compares reasonably well with experimental cylinder pressure rise. Results obtained from this model are compared with two models available in STAR- CD. These models require some level of tuning to match the experiments, whereas the modelling approach used in this work does not involve any tunable parameters.
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Bennett, Guy Malcolm. "CFD modelling of ignition and combustion in diesel engines." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408413.
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Hull, David Richard. "Combustion technology in the lean-burn spark-ignition engines." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244514.
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Ball, Jeffrey K. "Cycle-by-cycle variation in spark ignition combustion engines." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390474.
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Yuen, Hong Chuen Raymond. "An investigation of thermal conditions in spark ignition engines." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366457.
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Landsberg, Gary B. (Gary Bryan) 1975. "Liquid fuel hydrocarbon emissions mechanisms in spark-ignition engines." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/89274.
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Angelos, John P. (John Phillip). "Fuel effects in homogeneous charge compression ignition (HCCI) engines." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/50615.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2009.Includes bibliographical references (p. 209-217).
Homogenous-charge, compression-ignition (HCCI) combustion is a new method of burning fuel in internal combustion (IC) engines. In an HCCI engine, the fuel and air are premixed prior to combustion, like in a spark-ignition (SI) engine. However, rather than using a spark to initiate combustion, the mixture is ignited through compression only, as in a compression-ignition (CI) engine; this makes combustion in HCCI engines much more sensitive to fuel chemistry than in traditional IC engines. The union of SI- and CI-technologies gives HCCI engines substantial efficiency and emissions advantages. However, one major challenge preventing significant commercialization of HCCI technology is its small operating range compared to traditional IC engines. This project examined the effects of fuel chemistry on the size of the HCCI operating region, with an emphasis on the low-load limit (LLL) of HCCI operability. If commercialized, HCCI engines will have to operate using standard commercial fuels. Therefore investigating the impact of fuel chemistry variations in commercial gasolines on the HCCI operability limits is critical to determining the fate of HCCI commercialization. To examine these effects, the operating ranges of 12 gasolines were mapped in a naturally-aspirated, single-cylinder HCCI engine, which used negative valve overlap to induce HCCI combustion. The fuels were blended from commercial refinery streams to span the range of market-typical variability in aromatic, ethanol, and olefin concentrations, RON, and volatility. The results indicated that all fuels achieved nearly equal operating ranges. The LLL of HCCI operability was completely insensitive to fuel chemistry, within experimental measurement error. The high-load limit showed minor fuel effects, but the trends in fuel performance were not consistent across all the speeds studied. These results suggest that fuel sensitivity is not an obstacle to auto-makers and/or fuel companies to introducing HCCI technology.
(cont.) Developing an understanding of what causes an HCCI engine to misfire allows for estimation of how fuel chemistry and engine operating conditions affect the LLL. The underlying physics of a misfire were studied with an HCCI simulation tool (MITES), which used detailed chemical kinetics to model the combustion process. MITES was used to establish the minimum ignition temperature (Tmisfire) and full-cycle, steady-state temperature (Tss) for a fuel as a function of residual fraction. Comparison of Tmisfire and Tss near the misfire limit showed that Tss approaches Tmisfire quite closely (to within ~ 14 K), suggesting that the primary cause of a misfire is insufficient thermal energy needed to sustain combustion for multiple cycles. With this relationship, the effects of engine speed and fuel chemistry on the LLL were examined. Reducing the engine speed caused a reduction in T, which allowed fuel chemistry effects to be more apparent. This effect was also observed experimentally with 2 primary reference fuels (PRFs): PRF60 and PRF90. At 1000 RPM, PRF60 obtained a substantially lower (~30%) LLL than PRF90, but at speeds >/= 1500 RPM, fuel ignitability had no effect on the LLL. Fuel chemistry was shown to influence the LLL by increasing both Tmisfire and Tss for more auto-ignition resistant fuels. However, the extent to which fuel chemistry affects these temperatures may not be equivalent. Therefore, the relative movement of each temperature determines the extent to which fuel chemistry impacts the LLL.
by John P. Angelos.
Ph.D.
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Bhave, Amit. "Stochastic reactor models for homogeneous charge compression ignition engines." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616153.
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Thoo, Wei Jet. "A study of the ignition delay characteristics of combustion in a compression ignition engine operating on blended mixtures of diesel and gasoline." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/32843/.
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The interest to study diesel-gasoline fuel mix for CI engine combustion had been motivated by the higher thermal efficiency of CI engine compared to SI engine which gasoline normally runs in and the report of having lower NOx and PM emissions for gasoline combustion in CI engine. The experimental CI engine was unable to run on 100% gasoline but able to run on gasoline blend as high as G80 with default SOI timing setting. 100% gasoline would not run despite it contains only 20% more gasoline than G80 due to its extremely longer ignition delay caused by the exponential increase of gasoline blend’s ID. Engine brake thermal efficiencies of all gasoline blends tested up to G80 were comparable and averaged at 24.2%, 33.8% and 39.8% for engine speed-load conditions of 2000rev/min 2.5bar BMEP, 2000rev/min 5bar BMEP and 2000rev/min 8.5bar BMEP, accordingly. This finding confirmed that gasoline blend could be a new alternative fuel that offers comparable performance to the liquid fuel market for CI engine. In Europe, diesel blended with a small percentage of biodiesel or ethanol has been common to liquid fuel market. The study focused on ID that was closely correlated to NOx and soot formations in engine cylinder instead of NOx and PM emissions at tailpipe. The longer ID of 100% gasoline in relative to diesel could go up to 14CAD resulted in increased proportion of premixed combustion to mixing-controlled combustion at the rate of 40 Joule per CAD increase in ID. This incremental premixed combustion proportion was ideal for low NOx and soot formations in CI engine. ID was able to be discriminated into physical delay, a period dictated by engine speed-load conditions and controlled fuel breakup, fuel vaporisation and fuel-air mixing; and chemical delay, a period dictated by fuel chemical kinetic mechanism and controlled the amount of heat released. This finding gave valuable insight to the fact that proportion of premixed combustion and mixing-controlled combustion were controlled by chemical delay. Zero-dimensional theoretical combustion study with chemical kinetic mechanism confirmed that the exponential increased ID trend of gasoline blends was attributed to chemical delay. Hence a gasoline blend close to 100% gasoline would have very lean premixed combustion and small mixing-combustion which correlated to very low NOx and soot formations in cylinder. In order to understand the NOx and soot formations in cylinder in detail, a 73species reduced chemical kinetic mechanism that could represent gasoline blend combustion in CFD was developed. This reduced chemical kinetic mechanism could be used for future CFD work to understand effect of interactions between physical processes (fuel breakup, fuel vaporisation and fuel-air mixing) and chemical processes (activation of fuel combustion chemistry) on NOx and soot formations in cylinder. This work founded an effective semi-automatic reduction methodology with MATLAB algorithms for developing the 73species CFD-compatible reduced chemical kinetic mechanism of gasoline blends. This platform made building a surrogate fuel’s reduced chemical kinetic mechanism from multiple detailed chemical kinetic mechanisms of single component fuels fast, accessible and friendly to users of all background. DRG reduction technique had been enhanced by the multiple-stage ROP and multiple-step DRG approaches. The multiple-stage ROP and multiple-step approaches increased the species size reduction of chemical kinetic mechanisms by additional 8% and 13.5%, accordingly. The additional species size reduction capability of both approaches would be beneficial for the reduction of chemical kinetic mechanism for CFD use which is practically limited to size of 100species for feasible computational errors and speed. Apart from the limitation for the percentage of gasoline blend that could be used in the experimental CI engine, the lower compressibility of gasoline blends in relative to diesel had caused the SOI timing to be retarded up to 3CAD in this pump-triggered type of injection system. This shift of combustion phase had no significant effect on the ID and heat-release characteristics. The combustion phase shift can be easily compensated by advancing the SOI accordingly.
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Johns, R. A. "The analysis of the combustion of methanol in lean-burning, high-compression engines using an engine combustion model." Thesis, University of Surrey, 1985. http://epubs.surrey.ac.uk/847267/.
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Alcohol fuels are expected to become an economic/strategic alternative to oil over the next decade as oil reserves are depleted and countries seek to become more energy self-sufficient. Methanol, produced from natural gas deposits, and ethanol, produced locally by distillation of biomass, offer easily transportable alternatives. The use of a wider range of fuels in spark-ignition engines and the quest for fuel economy whilst meeting exhaust emissions legislation are important issues in engine design. The performance of current and proposed combustion chamber designs needs to be assessed with lean mixtures of both conventional and alternative fuels. The parameters defining combustion chamber performance, initial flame development and cycle-to-cycle variations in combustion may be readily determined using computer in-cylinder combustion models in a diagnostic manner to reduce experimentally acquired cylinder pressure data. This thesis develops and applies two analysis techniques to the study of the combustion of methanol in the lean burning regime with experimental results from three engines. The pressure increment technique, in which the pressure rise owing to combustion at constant volume is computed, is suitable for use directly on microcomputer systems. The two-zone equilibrium theory model, in which the mass burnt to give the measured pressure rise is evaluated, provides a more comprehensive analysis but is demanding in computer power. Higher burning rates were achieved using highly turbulent combustion chambers with methanol and equivalence ratios could be leaned to about 0.8 before cycle-to-cycle variations in combustion limited stable operation. The results obtained indicated the significant phases of initial flame development, the influence of early flame development on subsequent burning rates, and the influence of differing chamber geometries on performance. The combustion process was modelled for use in parametric studies of engine performance based on empirical data.
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Schäfer, Lukas [Verfasser]. "Modeling and Simulation of Spark Ignition in Turbocharged Direct Injection Spark Ignition Engines / Lukas Schäfer." München : Verlag Dr. Hut, 2016. http://d-nb.info/1106593502/34.
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Alqahtani, Ali Mubark. "Computational studies of homogeneous charge compression ignition, spark ignition and opposed piston single cylinder engines." Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7899/.
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In this research, possible improvements in engine specifications using the simulations developed on the AVL BOOST™ and Ricardo WAVE™ platforms were investigated. These modelling simulations help the author to predict the effect of any improvements in engine specifications without practical experimental challenges and difficulties. Firstly, HCCI and SI engines were modelled with the intention of maximizing the engine’s efficiency and minimizing the emissions. Changes of valve timing and throttle angle influence emissions’ reduction and the efficiency of the engine. In SI engines, the emissions of NOx can be reduced by using EGR, while only having a little effect on performance. The emissions from the HCCI, due to their intrinsically low emission output, were not improved. The effect of increasing the bore to stroke ratio in an opposed piston engine whilst maintaining a constant swept volume, port geometry and combustion timing, shows an increase of heat losses due to the lower ratio of exposed surface area to volume; an increase in thermal and mechanical efficiency; and most importantly, an improvement in fuel consumption. Also, in this research study, different strategies for opposed piston engines were investigated to increase the engine’s efficiency. The effect of a variable compression ratio on an opposed piston engine’s performance indicates different behaviour at various engine speeds and under different running conditions.
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Toulson, Elisa. "Applying alternative fuels in place of hydrogen to the jet ignition process /." Connect to thesis, 2008. http://repository.unimelb.edu.au/10187/3532.
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Hong, Guang. "Feedback control of transient smoke emissions from compression ignition engines." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304278.
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Kontarakis, George A. "Homogeneous charge compression ignition in four-stroke internal combustion engines." Thesis, University of Cambridge, 2001. https://www.repository.cam.ac.uk/handle/1810/272293.
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Vezzosi, Riccardo. "State of the art and critical review of pre-chamber ignition systems for passenger car spark ignition engines." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22702/.
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Pre-chamber ignition systems are currently one of the most
attractive developments for SI engines. The objective of this thesis is to present the technology at it's current state, focusing on passenger vehicles application, to analyse what issues need to be addressed for it to widely come to the market and what the potential of this techology is for the SI engine future.
Replacing the spark plug with a new system capable of igniting a much leaner mixture, to reduce the likelyhood of knock, was the initial goal of the pre-chamber ignition system. What the system achieves is also a much faster combustion speed, which can deliver greater effciency, power, and reduce knock occurrence even with stoichiometric AFR.
The implementation of the system presents signifcant challenges, which led many researchers to propose and patent a multitude of solutions which spawned from the original idea. Although for long time the diffculties with respect to a common spark plug ignition system have far outweighted the pros of the pre-chamber ignition, with time and the advancements in electronic controls, injectors and other systems, the research on this system gains a renewed interest.
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He, Yuesheng. "Effect of intake primary runner blockages on combustion characteristics and emissions in spark ignition engines." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1190053207.
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