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论文类型：期刊论文
发表时间：2009-03-01
发表刊物：PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART D-JOURNAL OF AUTOMOBILE ENGINEERING
收录刊物：SCIE、EI、Scopus
卷号：223
期号：D3
页面范围：395-412
ISSN号：0954-4070
关键字：homogeneous charge compression ignition; diesel engine; multi-dimensional model; soot model
摘要：An improved phenomenological soot model coupled with a reduced n-heptane chemical mechanism was implemented into KIVA-3V code to describe soot formation and oxidation processes in diesel homogeneous charge compression ignition (HCCI) combustion. This model was first validated by the shock tube experiments with a rich n-heptane mixture over wide temperature and pressure ranges. The computational results demonstrate that the phenomenological soot model is capable of predicting the soot yield, particle diameter, and number density with satisfactory accuracy. Then the model was applied to investigate the influence of the orifice diameter and injection pressure on soot emissions in a constant-volume combustion vessel under typical diesel combustion conditions. The predictions showed qualitative agreement with the measurements on the soot volume fraction distribution. The results also indicate that the soot formation can almost be suppressed as the local equivalence ratio is kept lower than 2.0. Finally, the model was used to explore the potentials of soot reduction with HCCI combustion for diesel engines. The overall trend of soot with the variations in the start of injection timing was well reproduced by the model. With the help of an equivalence ratio-temperature map, it was found that nitrogen oxide emissions Could be markedly reduced by applying a high exhaust gas recirculation rate and relative low compression ratio for diesel HCCI engines. However, the mixture preparation by using a multi-hole injector with early injection strategy remains a limitation for further reduction in soot emissions.