Flex Fuel Gasoline-Alcohol Engines For Near Zero Emissions Plug-In Hybrid Long Haul Trucks 2019-01-0565
Internal combustion engines for plug-in hybrid heavy duty trucks, especially long haul trucks, can 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 fall short in meeting these objectives, especially because of high NOx emissions. In this paper we describe features of flex fuel alcohol enhanced gasoline engines in series hybrid powertrains where the engines have the same or greater efficiency of diesel engines while also having 90% lower NOx emissions. Ethanol or methanol is employed to increase knock resistance and provide improved combustion. The engines use special features, including high efficiency high rpm operation, to enable fueling with mainly gasoline when desired. If needed, high rpm operation can be facilitated by a prechamber enhanced by alcohol use. These engines can also employ alcohol-enhanced exhaust heat recovery to increase efficiency by up to 25% when the engine is fueled with 100% alcohol or a high alcohol concentration alcohol-gasoline mixture. Alcohol use further reduces greenhouse gas emissions when the alcohol is made from a source that reduces lifecycle greenhouse gas.
Daniel Cohn, Leslie Bromberg
MIT, Massachusetts Institute of Technology