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 66 for “"engine efficiency"”.
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Enhanced engine efficiency through subsystem lubricant viscosity investigations
… to investigate the potential benefits in fuel efficiency, engine emissions, lubricant longevity, and engine durability. Two experimental testing platforms were designed and implemented to empirically study the effects of lubricant formulations on the internal combustion engine's frictional …
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Crevice volume effect on spark ignition engine efficiency
… to quantify the effect of the piston crevice on engine efficiency. The simulation study breaks down the loss mechanisms on brake efficiency at different displacement volumes (300 - 500 cc) and compression ratios (8-20). Experiments focus on indicated efficiencies for a narrow range of compression …
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Turbocharged engine operations using knock resistant fuel blends for engine efficiency improvements
Engine downsizing with a turbocharger has become popular these days in automotive industries. Downsizing the engine lets the engine operate in a more efficient region, and the engine boosting compensates for the power loss accompanied by downsizing. However, the use of high boost in a downsized …
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Optimizing diesel engine efficiency using the controllability of a variable ratio hydrostatic transmission
"A linear mathematical model of a diesel engine, hydrostatic transmission, and electric dynamometer system was developed. This model was used as an aid in designing a single input controller which regulates engine speed to optimize efficiency while maintaining constant transmission output speed …
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Ignition study in rapid compression machine
… traditional gasoline and diesel fuels so that engine efficiency and other engine behaviors may be affected To improve engine efficiency and to identify which alternative fuel is the cleanest fuel solution, it is necessary to compile information about the ignition delay, which governs …
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Combustion lean limits fundamentals and their application to a SI hydrogen-enhanced engine concept
Operating an engine with excess air, under lean conditions, has significant benefits in terms of increased engine efficiency and reduced emissions. However, under high dilution levels, a lean limit is reached where combustion becomes unstable, significantly deteriorating drivability and engine …
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Internal Combustion Engine Performance using Aluminum as Fuel
… This paper explores internal combustion engines as an alternative energy conversion method to hydrogen fuel cells for aluminum-fuel applications. Specifically, this paper characterizes the impact of steam on engine performance. The aluminum-water reaction is highly exothermic, resulting …
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Heat Transfer to Arrays of Oscillating Impingement Jets
<p>In gas turbine engines, the desire to increase turbine entry temperatures has become more relevant in order to increase engine efficiency. However, materials used in these engines can only withstand temperatures that are so high. Because of this, the ability to cool hot section components will …
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A Thermal Switch from Thermoresponsive Polymer Aqueous Solutions
… of applications including heat dissipation and engine efficiency improving. The commercial thermal switch based on mechanical design is very slow and the structure is too complicated to make them smaller. To enable fast thermal switch as well as to make thermal switch more compact, I try to use …
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Modeling the evolution of composition of the fuel and lubricant mixture on the cylinder wall in internal combustion engines
Improvements in engine efficiency are necessary for the advancement of modem engine technology. Fuels and lubricants used in internal combustion (IC) engines play an important role in governing the engine efficiency. In IC engines some amount of fuel spray can eventually end up on the cylinder …
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Addressing nonlinear combustion instabilities in highly dilute spark ignition engine operation
… promising approach for increasing spark-ignition engine efficiency, in the form of either lean burn (air dilution) or EGR (inert dilution). High levels of charge dilution, however, lead to cyclic variability that is largely deterministic in nature. The determinism and nonlinear nature of the …
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Effects of lubricant viscosity and surface texturing on ring-pack performance in internal combustion engines
… the mechanical losses in an internal combustion engine. Both lubricant viscosity and surface texturing were investigated in an effort to reduce this ring-pack friction and increase engine efficiency. While both optimizing viscosity and surface texturing are predicted to cause a reduction in …
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Modeling Truck Motion along Grade Sections
… will be of considerable assistance to traffic engineers in the design of roadways. The Global Positioning System (GPS) was originally built by the U.S. Department of Defense to provide the military with a super-precise form of worldwide positioning. With time, GPS units were introduced into the …
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Effects of piston design and lubricant selection on reciprocating engine friction
… the piston and the liner in a reciprocating engine is of much interest because it affects reliability, noise, and efficiency. This study evaluated various changes to the piston skirt with the specific goal of minimizing friction. An analytical model of the piston, previously developed at MIT, …
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Characterization of lubricant-derived ash deposition within pores of Diesel Particulate Filters through non-destructive advanced imaging techniques
… the past thirty years to trap and oxidize diesel engine exhaust gas particulate matter in order to meet increasingly stringent emission regulations. Due to engine lubrication oil inorganic additives and internal engine wear, ash particles tend to accumulate within the DPF, contributing to a sharp …
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Hybrid Electric Vehicle Control Strategy Based on Power Loss Calculations
… For a HEV, simply operating the vehicle's engine in its regions of high efficiency does not guarantee the most efficient vehicle operation. The results presented are meant only to define a literal strategy; that is, an understanding as to why the vehicle should operate in a certain way …
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Conceptual Design for a Laminar-Flying-Wing Aircraft
… on the basis of this, an assessment of the fuel efficiency through a detailed conceptual design study. It is shown that there is a minimum power requirement independent of the suction system design, associated with the stagnation pressure loss in the boundary layer. This requirement increases …
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Performance limits of axial turbomachine stages
This thesis assesses the limits of stage efficiency for axial compressor and turbine stages. A stage model is developed, consisting of a specified geometry and a surface velocity distribution with turbulent boundary layers. The assumptions and parameterization of the stage geometry allow for …
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Predicting the behavior of a lean-burn hydrogen-enhanced engine concept
… of a spark ignition (SI) internal combustion engine (ICE) offers attractive performance incentives. Lowered combustion temperatures inhibit formation of nitrogen oxides (NOx), while reduced intake manifold throttling minimizes pumping losses leading to higher efficiency. These benefits are …
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Silicon carbide process development for microengine applications : residual stress control and microfabrication
… high power densities expected for the MIT microengine (silicon MEMS-based micro-gas turbine generator) require the turbine and compressor spool to rotate at a very high speed at elevated temperatures (1300 to 1700 K). However, the thermal softening of silicon (Si) at temperatures above 900 K …
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