CHARACTERISTICS OF REAL TIME NANOPARTICLE SIZE DISTRIBUTION INSIDE EXHAUST GAS OF LIGHT-DUTY DIESEL ENGINE

摘要

Due to the stronger emission regulations and the introduction of advanced technology in diesel engine, the specific particulate emissions in term of g/km and g/kWh have decreased by about one order of magnitude since the 1980's. However the number concentration of fine particles, that are suspected of being hazardous to human health, emitted by diesel combustion engine might increase considerably and recently attracted attention. So, this research has been performed for the better understanding about the measurement principle and characteristics of diesel nano-particle and as a part of the establishment of KPMP(Korea Particle Measurement Program). Firstly, the light-duty driving cycles used in this study are the new European driving cycle(NEDC) and US FTP 75 cycle, which has been in use in Korea. A significant difference between these driving test modes is that the NEDC cycle has no weight factors, whereas the FTP cycle has weighting factors for each phase. However the start of the engine and the start of emission sampling are simultaneous. So the cold start phase has more influence on the cycle averaged emissions in NEDC cycle than FTP cycle. And we investigated the effects of these driving cycles on the diesel nano-particle measurement. An Electrical Low Pressure Impactor(ELPI) was mainly used as the measuring tool for diesel nano-particle distribution and concentration during the transient cycles. As some experiment results on different driving cycles, the range of particle diameter and difference in size distribution due to the transient operating effects were examined. Also the influence of the dilution ratio and exhaust temperature, which is corresponding to the engine load, on the diesel nano-particle measurement was investigated in this study.