Effect of post injections on mixture preparation and unburned hydrocarbon emissions in a heavy-duty diesel engine

详细信息    查看全文

• 作者：Jacqueline O'Connor^a ; ^{jxo22@engr.psu.edu" class="auth_mail" title="E-mail the corresponding author} ; ^{jxo22@psu.edu" class="auth_mail" title="E-mail the corresponding author} ; Mark P.B. Musculus^b ; Lyle M. Pickett^b
• 关键词：Low-temperature combustion ; Unburned hydrocarbon emissions ; Post injections ; Heavy-duty diesel
• 刊名：Combustion and Flame
• 出版年：2016
• 出版时间：August 2016
• 年：2016
• 卷：170
• 期：Complete
• 页码：111-123
• 全文大小：3438 K

文摘

This work explores the mechanisms by which a post injection can reduce unburned hydrocarbon (UHC) emissions in heavy-duty diesel engines operating at low-temperature combustion conditions. Post injections, small, close-coupled injections of fuel after the main injection, have been shown to reduce UHC in the authors’ previous work. In this work, we analyze optical data from laser-induced fluorescence of both CH₂O and OH and use chemical reactor modeling to better understand the mechanism by which post injections reduce UHC emissions. The results indicate that post-injection efficacy, or the extent to which a post injection reduces UHC emissions, is a strong function of the cylinder pressure variation during the post injection. However, the data and analysis indicate that the pressure and temperature rise from the post injection combustion cannot solely explain the UHC reduction measured by both engine-out and optical diagnostics. The fluid-mechanic, thermal, and chemical interaction of the post injection with the main-injection mixture is a key part of UHC reduction; the starting action of the post jet and the subsequent entrainment of surrounding gases are likely both important processes in reducing UHC with a post injection.