The effect of after injection on in-cylinder soot particulates in a small bore diesel engine

L. Rao, Y. Zhang, D. Kim, S. Kook, K. S. Kim, C. B. Kweon

Research output: Chapter in Book/Report/Conference proceedingConference PaperOther


After injection, which introduces a short injection following the main injection, is proven to be effective in reducing diesel engine soot emissions. The present study aims to investigate the in-cylinder soot reduction mechanism triggered by after injection in a small-bore optical diesel engine with a particular emphasis on the morphology of soot particles. Accordingly, in-bowl soot sampling based on the thermophoresis principle was performed for the direct collection of soot from the reacting diesel flame. The subsequent transmission electron microscope imaging enabled the structural analysis of soot particles, which provides fundamental insight regarding the formation and oxidation processes of in-bowl soot particles. The results show that, with the introduction of after injection, a downsizing trend of soot particles is found regardless of the sampling locations, which was explained by the increased in-cylinder bulk gas temperature and thus higher oxidation rate. A significant after-injection-induced decrease in soot aggregate size also suggests an accelerated oxidation of in-bowl soot particles through the fragmentation of large soot aggregates.

Original languageEnglish
Title of host publication11th Asia-Pacific Conference on Combustion, ASPACC 2017
Publication statusPublished - 2017
Externally publishedYes
EventAsia Pacific Conference on Combustion 2017 - Sydney, Australia
Duration: 10 Dec 201714 Dec 2017
Conference number: 11th


ConferenceAsia Pacific Conference on Combustion 2017
Abbreviated titleASPACC 2017
Internet address

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