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We have developed a novel engine cycle simulation program (UniDES: universal diesel engine simulator) to reproduce the diesel combustion process over a wide range of engine operating parameters, such as the amount of injected fuel, the injection timing, and the EGR ratio. The approach described in this paper employs a zoning model, where the in-cylinder region is divided into up to five zones. We also applied a probability density function (PDF) concept to each zone to consider the effect of spatial non-homogeneities, such as local equivalence ratios and temperature, on the combustion characteristics. We linked this program to the commonly used commercial GT-Power® software (UniDES+GT). As a result, we were able to reproduce transient engine behavior very accurately.

Through the basic research of the plasma assisted catalyst system using DeNOx catalysts and the gas analysis of the system, its conceptual use for automobile diesel engine applications has been studied. This study has shown that the length between the plasma reactor and the catalyst reactor does not affect the NOx conversion. To obtain an efficient NOx conversion, the plasma should affect both the HC as the reductant and NOx at the same time. In the case of γ-Al2O3 and C3H6, the main component for NOx reduction was CH3CHO generated by the plasma. Under 250 deg. C, the temperature was too low for the γ-Al2O3 to become effective. Therefore, the NOx conversion became low. At 400 deg. C, the NOx conversion became high. However, at 600 deg. C, the CH3CHO for reducing NOx was not generated, and the NOx conversion decreased.

A concept of dual-fuel, Premixed Compression Ignition (PCI) combustion controlled by two fuels with different ignitability has been developed to achieve drastically low NOx and smoke emissions. In this system, isooctane, which was used to represent high-octane gasoline, was supplied from an intake port and diesel fuel was injected directly into an engine cylinder at early timing as ignition trigger. It was found that the ignition timing of this PCI combustion can be controlled by changing the ratio of amounts of injected two fuels and combustion proceeds very mildly by making spatial stratifications of ignitability in the cylinder even without EGR, as preventing the whole mixture from igniting simultaneously. The operable range of load, where NOx and smoke were less than 10ppm and 0.1 FSN, respectively, was extended up to 1.2MPa of IMEP using an intake air boosting system together with dual fueling.