Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 26 for “"combustion phasing"”.
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Effect of ambient conditions and fuel properties on homogeneous charge compression ignition engine operation
… Homogeneous Charge Compression Ignition (HCCI) combustion must demonstrate robust responses to variations in environmental conditions. This work examines the impact of ambient conditions and fuel changes on HCCI engine operation, and evaluates cam phasing as a mechanism to compensate for these …
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Knock mitigation on boosted Controlled Auto-Ignition engines with fuel stratification and Exhaust Gas Recycling
… This indicates strong effect of EGR for CAI combustion knock mitigation. Engine tests demonstrates that fuel stratification has high potential for CAI knock mitigation, but its effect heavily depends on the extent of fuel stratification, engine configuration, and in-cylinder conditions. While …
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Two contrasting approaches to auto-ignition modelling for HCCI engines
… models formulated for the emulation of combustion dynamics in Homogeneous Charge Compression Ignition (HCCI) engines. The first (empirical) auto-ignition model was adapted from its previously published form, for HCCI engine model implementation. This model was then combined with an …
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Predictive Control of HCCI Engines Using Physical Models
… Ignition (HCCI) is a promising internal combustion engine concept. It holds promise of combining low emission levels with high efficiency. However, as ignition timing in HCCI operation lacks direct actuation and is highly sensitive to operating conditions and disturbances, robust …
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Research on late-robust combustion
… was found between exhaust temperature and combustion phasing. The turbulence test data showed a correlation between exhaust temperature and COV as well as between COV and combustion phasing. However, the change in laminar flame speed data showed a weaker correlation in both.
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Closed-Loop Control of HCCI Engine Dynamics
… actuators for closed-loop control of the HCCI combustion. Closed-loop control of the HCCI combustion using ion current is demonstrated. Models of the HCCI dynamics suitable for purposes of control design are presented. It is shown that low-order models are sufficient to describe the HCCI …
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Model-Based Control of Gasoline Partially Premixed Combustion
Partially Premixed Combustion (PPC) is an internal combustion engine concept that aims to yield low NOx and soot emission levels together with high engine efficiency. PPC belongs to the class of low temperature combustion concepts where the ignition delay is prolonged in order to promote the …
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Understanding HCCI characteristics in mini-HCCI engines
… Homogeneous-Charge, Compression-Ignition (HCCI) combustion in a standard issue model-aero “diesel” engine. This two-stroke engine, unlike the more common glow-plug versions, operates without any form of combustion initiator. The fuel and air are premixed using a simple carburettor and ignited by …
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Investigation to direct ethanol injection in spark ignition gasoline engines
… EDI+GPI showed a positive impact in relation to combustion with reduced combustion duration and advanced central combustion phasing. However, with further increase of EER, the combustion duration prolonged and central combustion phasing retarded. This may be caused by over cooling due to …
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Modelling and simulation of combustion of dilute syngas fuels in a CFR engine
… as sources of energy, many conventional internal combustion engines are being modified to operate on these new fuels. Optimization of engine specifications including compression ratio, intake/piston geometry, valve timing, and combustion phasing, can greatly improve performance when an engine is …
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Impact of retarded spark timing on engine combustion, hydrocarbon emissions, and fast catalyst light-off
… effects of substantial spark retard on engine combustion, hydrocarbon (HC) emissions, feed gas enthalpy, and catalyst light-off. Engine experiments were conducted at cold engine conditions for various ignition timings and air/ fuel ratios. Chemical and thermal energy of the exhaust gas was …
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Effects of operating conditions, compression ratio, and gasoline reformate on SI engine knock limits
… fuels (TRFs), and test gasolines. A new combustion phasing parameter based on the timing of 50% mass fraction burned, ternled "combustion retard", was found to correlate well to engine performance. Increasing air- fuel ratio increases the combustion retard required to just avoid knock for …
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Closed-Loop Combustion Control of a Multi Cylinder HCCI Engine using Variable Compression Ratio and Fast Thermal Management
… efficiency of the SI engine. A third internal combustion engine type, which combines the principles of the SI and CI engines, has the potential to meet demands from society in terms of current and foreseeable future emissions regulations. This engine type is called Homogeneous Charge …
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Spray and combustion characteristics of acetone-butanol-ethanol and diesel in a constant volume chamber and a diesel engine
… done in the past five years concerning spray and combustion processes of both neat ABE and ABE-diesel mixtures. Additionally, different compositions of ABE mixtures had been characterized with a similar experimental approach. This thesis reviews the production of ABE and characterization of its …
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Effects of oxygenated fuels on DI diesel combustion and emissions
… Mechanisms responsible for changes in the combustion process and emissions were investigated with a matrix containing 14 fuels, addressing oxygenate proportionality, structure, volatility, equivalent structure without oxygen, and changes in the base diesel fuel. A scanning mobility particle …
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Investigations on the pollutant emissions of gasoline direct injection engines during cold-start
… on the temperature and pressure history of the combustion process. The results show that unconventional valve timing strategies with large, symmetric, negative valve overlap and delayed combustion phasing are the most effective ways to reduce engine-out emissions during both crank-start and …
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Physical Modeling and Control of Low Temperature Combustion in Engines
… of this thesis is model-based control of two combustion engine concepts, Homogeneous Charge Compression Ignition (HCCI) and Partially Premixed Combustion (PPC), using physics-based models. The studied combustion concepts hold promise of reducing the emission levels and fuel consumption of …
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Characterization of the exhaust gas condensate pH values of gasoline engines
… condensate pH for different air-fuel ratios and combustion phasing, for each gas separately and then together, assuming equilibrium between exhaust gas and condensate. Condensate pH was also measured experimentally for these running conditions to attempt to verify the calculations. Calculations …
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In-Cylinder Soot Oxidation in an Optically Accessible Automotive Diesel Engine
… formation of soot particles because of higher combustion temperature caused by enhanced premixed combustion or advanced combustion phasing. However, the increased high-temperature reaction also leads to enhanced soot oxidation, which outperforms the increased soot formation and thereby …
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