Thermal Efficiency Comparison of Different Injector Constellations in a CI Engine

Gustav Nyrenstedt, Kazumasa Watanabe, Kenji Enya, Hao Shi, Noboru Uchida, Bengt Johansson

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

7 Scopus citations


More stringent emission regulations call for high-efficiency engines in the heavy-duty vehicle sector. Towards this goal, reduced heat losses, as well as increased work output, are needed. In this study, a multiple injector concept to control the combustion as well as reduce the hot boundary zones is proposed. Earlier studies have proven that multiple injectors experience lower heat losses and higher efficiency. However, a comprehensive investigation of the causes for experimental heat loss was not performed in depth. Experiments in a heavy-duty CI engine equipped with three injectors were thus performed. Engine configurations of single, dual and triple injectors were compared for a single-injection case as well as a multi-injection (Sabathe-cycle) case. Heat losses, efficiency and the emission levels were quantified and investigated. Optical experiments were performed to investigate the temperature field as well as flame behavior. This led to further understanding of the heat loss drivers. Experimental data was coupled with the double compression expansion engine concept for waste heat recovery, utilizing the energy from reduced heat losses. Notable findings included an efficiency increase of 1.9 %-points when using all three injectors for a single injection. Three injectors improved the efficiency an additional 1.2 %-points in a Sabathe-cycle case as compared to a single injector case. These gains mainly followed by reduced heat losses caused by hot zones being kept away from the boundaries. Thus, the benefits of multiple injectors were proven.
Original languageEnglish (US)
Title of host publicationSAE Technical Paper Series
PublisherSAE International
StatePublished - Sep 9 2019

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The authors would like to thank the N.A.C.E. consortium in Tsukuba, Japan for funding and support in terms of experimental setup. The authors would further like to thank the Clean Combustion Research Center at KAUST for support and funding.


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