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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.

China VI standards for heavy duty vehicles require that the mileage of CNG catalysts for vehicles with a maximum design total mass of more than 18 tons should reach 700000 km. In order to quickly evaluate the durability of CNG catalyst, muffle furnace aging and natural gas engine bench aging were usually adopted. The advantages of muffle furnace aging were simple operation, short time and low cost, but the aging atmosphere is quite different from the exhaust atmosphere of natural gas engine, which is difficult to reflect the actual durability of the catalyst. The aging of natural gas engine can reflect the durability of the catalyst, but it usually takes about 1000 hours. Due to long time, and high cost, it is difficult to be widely applied in the early stage of catalyst development. Therefore, it is a very interesting research direction to develop new methods with the advantages of muffle furnace aging and natural gas bench aging.

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.

Natural gas (NG) engines have attracted increasing attention in the heavy duty (HD) vehicle market as an alternative to conventional diesel fuel often due to the abundance and low price of NG. However, it is challenging to meet the increasingly stringent China VI legislation, particularly for hydrocarbons (mainly CH4), carbon monoxide (CO), nitrogen oxides (NOx) and ammonia (NH3). In this work, approaches were explored in which a gasoline three-way catalyst (TWC) was modified through optimization of promoters, OSC materials, and catalyst structure. The optimized TWC was evaluated in a laboratory reactor and with a HD stoichiometric NG engine. Lab reactor results showed that promoters can improve CH4 light off performance with T50 decreases of 20 oC and 13 oC for the fresh and aged catalyst respectively.

Lubricating oil consumption (LOC) is a direct source of hydrocarbon and particulate emissions from internal combustion engines. LOC also inhibits the lifetime of exhaust aftertreatment system components, preventing their ability to effectively filter out other harmful emissions. Due to its influence on piston ring- bore conformability, bore distortion is arguably the most critical parameter for engine designers to consider in prevention of LOC. Bore distortion also has a significant influence on the contact forces between the piston ring and cylinder wall, which determine the wear rate of the ring and cylinder wall and can cause durability issues. Two drivers of bore distortion: thermal expansion and head bolt stresses, are routinely considered in conformability and contact analyses. Separately, bore distortion/vibration due to piston impact and combustion/cylinder pressures has been previously analyzed in wet liner engines for coolant cavitation and noise considerations.

Internal combustion (IC) engines still power most of the vehicles on road and will likely to remain so in the near future, especially for heavy duty applications in which electrification is typically more challenging. Therefore, continued improvements on IC engines in terms of efficiency and longevity are necessary for a more sustainable transportation sector. Two important design objectives for heavy duty engines with wet liners are to reduce friction loss and to lower the risks of cavitation damages, both of which can be greatly influenced by the piston-liner clearance and the design of the piston skirt. However, engine design optimization is difficult due to the nonlinear interactions between the key design variables and the design objectives, as well as the multi-physics and multi-scale nature of the mechanisms that are relevant to the design objectives.