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Flex Fuel Gasoline-Alcohol Engine for Near Zero Emissions Plug-In Hybrid Long-Haul Trucks

Massachusetts Institute of Technology-Daniel Cohn, Leslie Bromberg
Published 2019-04-02 by SAE International in United States
Internal combustion engines for plug-in hybrid heavy duty trucks, especially long haul trucks, could play an important role in facilitating use of battery power. Power from a low carbon electricity source could thereby be employed without an unattractive vehicle cost increase or range limitation. The ideal engine should be powered by a widely available affordable liquid fuel, should minimize air pollutant emissions, and should provide lower greenhouse gas emissions. Diesel engines could fall short in meeting these objectives, especially because of high emissions. In this paper we analyze the potential for a flex fuel gasoline-alcohol engine approach for a series hybrid powertrain. In this approach the engine would provide comparable (or possibly greater) efficiency than a diesel engine while also providing 90 around lower NOx emissions than present cleanest diesel engine vehicles. Ethanol or methanol would be employed to increase knock resistance. Engines that could be deployed in the relatively near term could also use high rpm operation and /or water injection, to allow operation with a very small amount of alcohol in addition to…
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Dual-Fuel Gasoline-Alcohol Engines for Heavy Duty Trucks: Lower Emissions, Flexible-Fuel Alternative to Diesel Engines

Massachusetts Institute of Technology-Daniel Cohn, Leslie Bromberg
Published 2018-04-03 by SAE International in United States
Long-haul and other heavy-duty trucks, presently almost entirely powered by diesel fuel, face challenges meeting worldwide needs for greatly reducing nitrogen oxide (NOx) emissions. Dual-fuel gasoline-alcohol engines could potentially provide a means to cost-effectively meet this need at large scale in the relatively near term. They could also provide reductions in greenhouse gas emissions. These spark ignition (SI) flexible fuel engines can provide operation over a wide fuel range from mainly gasoline use to 100% alcohol use. The alcohol can be ethanol or methanol. Use of stoichiometric operation and a three-way catalytic converter can reduce NOx by around 90% relative to emissions from diesel engines with state of the art exhaust treatment.Alcohol from a second tank is used to provide increased knock resistance at higher values of torque, enabling high compression ratio, turbocharged operation that provides comparable efficiency and torque to a diesel engine in a smaller size engine. The alcohol can be neat or a high concentration blend. It can also be a hydrous alcohol (alcohol and water). Hydrous alcohol use can reduce the…
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Optimized PFI+DI Operation For Minimizing DI Gasoline Engine Particulates

Ethanol Boosting Systems LLC-Leslie Bromberg, Daniel Cohn
Published 2018-04-03 by SAE International in United States
Direct Injection (DI) fueled gasoline engines provide higher efficiency than port fueled injected (PFI) engines. However, emission of small particulates is greatly increased when DI is used. Particulate mass emission is increased by more than a factor of 10 and particulate number is increased by a factor of 10-100 relative to PFI engines leading to health concerns and to implementation and consideration of new regulations.Optimized combinations of PFI and DI can greatly reduce DI-generated particulate emissions without compromising efficiency and performance. A DI enhanced PFI mode of engine operation is employed where PFI is the dominant means in dual-injection fueling over a drive cycle, and the fuel fraction that is directly injected is reduced/minimized while still preventing knock at high loads. Further reduction can be obtained by optimal use of spark retard. The already low particulate emissions are further reduced by decreasing the percentage of DI fuel that results in particulate generation from wall wetting; this is accomplished by adjustment of injection timing, injection rate and pulse length.We have developed a computational model of DI-generated…
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Alcohol Fueled Heavy Duty Vehicles Using Clean, High Efficiency Engines

Massachusetts Institute of Technology-Leslie Bromberg, Daniel Cohn
Published 2010-10-25 by SAE International in United States
Non-petroleum based liquid fuels are essential for reducing oil dependence and greenhouse gas generation. Increased substitution of alcohol fuel for petroleum based fuels could be achieved by 1) use in high efficiency spark ignition engines that are employed for heavy duty as well as light duty operation and 2) use of methanol as well as ethanol. Methanol is the liquid fuel that is most efficiently produced from thermo-chemical gasification of coal, natural gas, waste or biomass. Ethanol can also be produced by this process but at lower efficiency and higher cost. Coal derived methanol is in limited initial use as a transportation fuel in China. Methanol could potentially be produced from natural gas at an economically competitive fuel costs, and with essentially the same greenhouse gas impact as gasoline. Waste derived methanol could also be an affordable low carbon fuel. In this paper we describe modeling studies of alcohol fuel operation in highly turbocharged direct injection spark ignition engines operated at high compression ratio. The studies suggest that these engines could be as or more…
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