TY - JOUR
T1 - Effect of post injections on mixture preparation and unburned hydrocarbon emissions in a heavy-duty diesel engine
AU - O'Connor, Jacqueline
AU - Musculus, Mark P.B.
AU - Pickett, Lyle M.
N1 - Funding Information:
The optical engine experiments were performed at the Combustion Research Facility, Sandia National Laboratories, Livermore, CA. Support for this research was provided by the U.S. Department of Energy, Office of Vehicle Technologies . Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company for the United State Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. The injector was provided by Delphi Diesel Systems, and the authors would like to thank Delphi and Philip Dingle for their support of this system. The authors gratefully acknowledge the contributions of Keith Penney and Dave Cicone for their assistance in maintaining the lasers and research engine used in this study, and Dipankar Sahoo for assistance with the UHC analyzer.
Publisher Copyright:
© 2016.
PY - 2016/8/1
Y1 - 2016/8/1
N2 - 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.
AB - 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.
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U2 - 10.1016/j.combustflame.2016.03.031
DO - 10.1016/j.combustflame.2016.03.031
M3 - Article
AN - SCOPUS:84971351743
VL - 170
SP - 111
EP - 123
JO - Combustion and Flame
JF - Combustion and Flame
SN - 0010-2180
ER -