| Autor: |
Kim, Dongchan, Kook, Sanghoon, Kusakari, Ryosuke, Shinohara, Koya, Iijima, Katsuki, Aizawa, Tetsuya |
| Zdroj: |
Proceedings of the Combustion Institute; 2020, Vol. 38 Issue 4, p5761-5768, 8p |
| Abstrakt: |
This study shows the structure of soot particles sampled directly from wall wetting-induced pool fires formed on the piston top in a spark-ignition direct-injection (SIDI) engine. Of particular interest is its variation with injection pressure considering the current trend of high-pressure DI system development to reduce engine-out particulate emissions. Thermophoretic particle sampling was performed for transmission electron microscope (TEM) imaging, which was post-processed for statistical analysis of key morphology and internal structure parameters. These include the size distribution of soot aggregates and primary particles as well as carbon-layer fringe-to-fringe gap and concentricity. With the fixed engine speed and load conditions, in-flame soot particles are compared to the exhaust particles sampled simultaneously at selected 5 and 15 MPa injection pressures corresponding to low-speed/low-load and high-speed/high-load in practical engine operation. From the TEM images and statistical analysis, it was found that more concentrated and taller pool fire developed for 5-MPa injection leads to smaller soot aggregates composed of smaller soot primary particles due to suppressed soot growth in fuel-rich flames. However, the soot particles formed in 15-MPa injection-induced pool fires are at a more reactive status evidenced by less defined core-shell boundaries and higher fringe separation. The higher soot reactivity results in enhanced soot oxidation, which explains smaller soot aggregates and primary particles found for the 15-MPa injection in the exhaust sample. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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