Achievement of Diesel Low Temperature Combustion through Higher Boost and EGR Control Coupled with Miller Cycle
Diesel engines generally tend to produce a very low level of NOx and soot through the application of Miller Cycle, which is mainly due to the low temperature combustion (LTC) atmosphere resulting from the Miller Cycle utilization. A CFD model was established and calibrated against the experimental data for a part load operation at 3000 r/min. A designed set of Miller-LTC combustion modes were analyzed. It is found that a higher boost pressure coupled with EGR can further tap the potential of Miller-LTC cycle, improving and expanding the Miller-LTC operation condition. The simulated results indicated that the variation of Miller timings can decrease the regions of high temperatures and then improve the levels and trade-off relationship of NOx and soot. The in-cylinder peak pressure and NOx emissions were increased dramatically though the problem of insufficient intake charge was resolved by the enhanced intake pressure that is equivalent to dual-stage turbo-charging.