研究発表

It is investigated of the DME spray characteristics about varied ambient pressure and fuel injection pressure using the common rail fuel injection system when the nozzle holes diameter is varied. The common rail fuel injection system and fuel cooling system is used since DME has compressibility and vaporization in atmospheric temperature. The fuel injection quantity and spray characteristics were measured. The spray was analyzed of spray shape, penetration length, and spray angle at the six nozzle holes. The 2 type injectors were used, the one was 0.166mm diameter the other one was 0.250mm diameter. The ambient pressure which is based on gage pressure was 0MPa, 2.5MPa, and 5MPa. The fuel injection pressure was varied by 5MPa from 35MPa to 70MPa. When using the converted injector, compared to using the common injector, the DME injection quantity was increased 127% but it didn’t have the same heat release. Both of the common and converted injectors had symmetric spray shapes. In case of converted injector, there were asymmetrical spray shapes until 1.2ms, but after 1.2ms the spray shape was symmetrical. Compared with the common and converted injector, the converted injector had shorter penetration length and wider spray angle than the common injector.

エコドライブによるCO2削減効果とリアルワールドでのNOx排出特性への影響を明らかにするために，車載型排出ガス計測システムを搭載したディーゼル貨物車による実路走行試験を実施した。エコドライブの運転技術を実施した際の，CO2排出量の削減効果とNOx排出量の変化を積載条件別に解析したので報告する。

The present study focuses on clarifying the auto-ignition and combustion mechanism in HCCI engine, and acquiring the comparable results in numerical calculations with elementary reactions. Chemical luminescences from radicals were measured in single cylinder 4-stroke optical access engine with DME fuel. DME shows multistage heat release with low temperature reaction (LTR) and high temperature reaction (HTR) at compressed rapidly. DME is expected to be alternative fuel, because of low flame temperature and no soot in a reciprocating engine. Before experimental research, predictions of chemical luminescence intensity were tried by calculated with elementary reactions added chemical luminescence model. After that, in experiment, two dimensional chemical luminescence images under auto-ignition and combustion were obtained by framing camera, and influences of homogeneity of fuel concentration in combustion chamber on auto-ignition and combustion was clarified. Next the luminescence spectrums were measured by spectroscope and luminescence intensity profiles were measured by photo multipliers with band pass filters.

Homogeneous charge compression ignition (HCCI) engine is expected as next generation engine. However, it is difficult to control auto-ignition timing and combustion duration. In this study numerical calculations with elementary reactions were carried out in order to investigate auto-ignition and combustion completion of DME/Air Mixtures in HCCI engine. As a result, it was clarified relation of maximum temperature and combustion efficiency, and emissions And it was also clarified that in case of same combustion efficiency, increase of EGR rate was effective method to keep slow combustion speed.