自動車用エンジンの高効率化の可能性

抄録

Significant reductions in NOx and particulate emissions are required in diesel engines keeping their inherent high efficiency whereas spark-ignition or gasoline engines have achieved sufficiently low emission characteristics by using precise fueling control and three way catalysts. Toward 2020 and beyond, more emphasis will be placed on improvements in fuel economy in both engines to reduce oil dependence in the transportation sector, thereby mitigating global warming. It is essential to optimize combinations of technologies related to combustion, aftertreatment and fuel properties to achieve higher efficiency. Combustion technologies include downsizing the engine with turbocharging, multiple direct injection, exhaust gas recirculation and so forth. Homogeneous charge compression ignition will also be employed at part load for both engine types. For these purposes, detailed numerical combustion and chemical kinetics modeling should be developed and utilized not only to understand fuel-air mixture formation and combustion phenomena but also to devise, design and control advanced combustion systems. Such models must carefully be validated by comparing numerical results with detailed measurements associated with these phenomena.