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When the compression ratio of the spark ignition engine is set high as a method of improving the fuel efficiency of passenger cars, it is often combined with the direct fuel injection system for knock mitigation. In port injection, there are also situations where the fuel is guided into the cylinder while the vaporization is insufficient, especially at the cold start. If the fuel is introduced into the cylinder in a liquid state, the temperature in the cylinder will change due to sensible heat and latent heat of the fuel during vaporization. Further, if the fuel is unevenly distributed in the cylinder, the effect of the specific heat is added, and the local temperature difference is expanded through the compression process. In this research, an experiment was conducted using a rapid compression machine for the purpose of discussing the effect of the temperature-pressure time history of fuel on ignition delay time.

In PCCI combustion with multiple injections, the mechanism having two heat release peaks which has a favorable characteristic of reducing noise is studied using numerical tool of single- and also multi-zone model of CHEMKIN PRO. In the present investigation, the physical issues, such as variations in the equivalent ratio and temperature caused by the fuel injection are simplified first so that the key issues of chemical reaction occurred in the combustion chamber can be extracted and are discussed in detail. The results show that the interval of two heat-release peaks can be controlled and as the number of zones of the calculation increases, the change in the timing of a heat release peak is increased but over three-zones, it is not affected any more. This indicates that to study about complex diesel combustion phenomena, three-to four-zone model shall give sufficiently accurate results.

A combustion method called Noise Canceling Spike (NC-Spike) Combustion [1, 2] has been reported in the co-author's previous paper, which reduces combustion noise in PCCI with split injection. This NC-Spike Combustion uses interference of the following “spike” of pressure rise on the preceding peak of pressure rise. The overall combustion noise is reduced by lowering the maximum frequency component of the noise spectrum. The period of this frequency is two times of the time interval between the two peaks of the pressure rise rate. This maximum load range of conventional PCCI combustion is limited by the combustion noise, since the maximum pressure rise rate increases as the amount of injected fuel increases. The NC-Spike Combustion has a potential to extend of the operating range of PCCI combustion.

For the reduction of greenhouse gas emission in the transportation sector, various countermeasures against CO₂ emission have been taken. The eco-driving has been paid attention because of its immediate effect on the CO₂ reduction. Eco-driving is defined as a driving method with various driving techniques to save fuel economy. The eco-driving method has been promoted to the common drivers as well as the drivers of carriers. Additionally, there are many researches about improvement of fuel efficiency and CO₂ reduction. However, the eco-driving will have the reduction effect of CO₂ emission, the influence of the eco-driving on air pollutant emission such as NOx is not yet clear. In this study, the effect of the eco-driving on real-world emission has been analyzed using the diesel freight vehicle with the on-board measurement system.