Advanced combustion for low emissions and high efficiency Part 1: Impact of engine hardware on HCCI combustion
Two single-cylinder diesel engines were optimised for advanced combustion performance by means of practical and cumulative hardware enhancements that are likely to be used to meet Euro 6 emissions limits and beyond. These enhancements included high fuel injection pressures, high exhaust gas recirculation levels and charge cooling, increased in-cylinder swirl, and a fixed combustion phasing. These enhancements achieved low engine-out emissions of NOx and particulate matter emissions with engine efficiencies equivalent to today.s diesel engines. These combustion conditions approach those of Homogeneous Charge Compression Ignition, especially at the lower part-load operating points. Four fuels exhibiting a range of ignition quality, volatility, and aromatics contents were used to evaluate the performance of these hardware enhancements on engine-out emissions, performance, and noise levels.