Effects of Post-Injections Strategies on UHC and CO at Gasoline PPC Conditions in a Heavy-Duty Optical Engine

2017-01-0753

03/28/2017

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Event
WCX™ 17: SAE World Congress Experience
Authors Abstract
Content
Gasoline partially premixed combustion (PPC) has shown potential in terms of high efficiency with low emissions of oxides of nitrogen (NOx) and soot. Despite these benefits, emissions of unburned hydrocarbons (UHC) and carbon monoxide (CO) are the main shortcomings of the concept. These are caused, among other things, by overlean zones near the injector tip and injector dribble. Previous diesel low temperature combustion (LTC) research has demonstrated post injections to be an effective strategy to mitigate these emissions. The main objective of this work is to investigate the impact of post injections on CO and UHC emissions in a quiescent (non-swirling) combustion system. A blend of primary reference fuels, PRF87, having properties similar to US pump gasoline was used at PPC conditions in a heavy duty optical engine. The start of the main injection was maintained constant. Dwell and mass repartition between the main and post injections were varied to evaluate their effect. All points were run at 7 bar IMEPg. High-speed imaging of the natural combustion luminescence was performed together with measurements of performance and engine out emissions. Results show reduction in both CO and UHC with close coupled injections. A large close coupled post injection show the largest reduction in UHC. Analysis show that a post injection prior to combustion reduces the dribble and increases the recirculation in the downstream region of the fuel jet, hence reaching more of the UHC in the area near the injector. General observations show that the partition of fuel between the injections have the largest impact on the CO while the dwell time affects UHC emissions. Injector dribble seems to be a significant contributor to the UHC emissions.
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DOI
https://doi.org/10.4271/2017-01-0753
Pages
15
Citation
Lundgren, M., Wang, Z., Matamis, A., Andersson, O. et al., "Effects of Post-Injections Strategies on UHC and CO at Gasoline PPC Conditions in a Heavy-Duty Optical Engine," SAE Technical Paper 2017-01-0753, 2017, https://doi.org/10.4271/2017-01-0753.
Additional Details
Publisher
Published
Mar 28, 2017
Product Code
2017-01-0753
Content Type
Technical Paper
Language
English