Study of Higher Alcohol Potential as a Drop-In Fuel for a High Thermal Efficiency Heavy-Duty Diesel Engine 2023-24-0049

To reduce carbon dioxide (CO₂) emissions from heavy-duty diesel engines down to zero until 2050, alternative powertrain strategies have been proposed in lieu of the improvements in internal combustion engines (ICEs). However, total amount of renewable electricity could be limited for the constructing infrastructure, the production of new battery and/or fuel cell vehicles and the operation of them compared with the growing demand of transportation in the future. Therefore, drastic improvement in transport efficiency with suppressing the increase of total CO₂ emissions is essential. From these points of view, extremely high efficiency ICEs, combined or at least compatible with carbon neutral or renewable fuels having the capability of drop-in into the conventional fuels, should be attracted attention. Nevertheless, there have been few studies on the effects of fuel properties for further improving fuel consumption of diesel ICEs. This study focused on the prerequisite fuel properties for the high efficiency diesel engines which we have been developing. Since the compression ratio of the engine is much higher than that of conventional engines, in-cylinder temperature and density are quite high and cavity volume is very small. In such severe conditions, engine performance and exhaust emissions by fueling conventional diesel fuel were deteriorated by the poor mixture formation, whereas 1-octanol of 50vol% mixing diesel fuel achieved significant improvements in both NOx-soot trade-offs and thermal efficiency and much lower cooling loss under higher compression ratio without any engine optimizations dedicated to the fuel.