This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Development of Compact SCR Systems with Closely Coupled Injector Configurations
Technical Paper
2014-01-1546
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
In order to satisfy China IV (equivalent to EU IV) emission regulations, an unconventional design concept was proposed with injector closely coupled with SCR can body. The benefit of this design is that the urea decomposition pipe was removed or drastically shortened, resulting in much smaller packaging space and lower cost of the whole system. However, the resulting short urea mixing distance generates concerns on low urea mixing efficiency and risks of urea deposits.
In particular, airless urea injectors tend to generate incomplete evaporation of urea water solution, resulting in high risks of urea deposits. New aftertreatment mixing structures need to be developed to resolve these technical challenges. To this end, stepwise and systematic enhancements of the design have been employed, resulting in multiple designs to eventually meet a set of performance targets, including emission reduction efficiency, reagent mixing, urea evaporation, ammonia and velocity distribution, back pressure, and urea deposits.
Two types of injectors are studied: (1) Bosch 2.2 airless injector; (2) Albonair air-assisted injector. With respect to droplet sizes, the former has Saunter Mean Diameter (SMD) of 70 μm vs. the latter's 30 μm. Evidently, compared with air-assisted injectors, airless injector has higher risks of urea deposits and less mixing efficiency with exhaust stream. To overcome these challenges from airless injector, significant development work has been performed. The optimized mixing structure is able to improve NOx reduction uniformity, eliminate urea deposits, and improve NOx conversion efficiency while satisfy existing installation packing space. This development demonstrates that good system performance can be achieved despite the challenges of meeting strict and often-conflicting performance targets. System perspectives combined with assessment and understanding of major components / mechanisms are critical to achieving aggressive performance targets while reducing development time for urea SCR systems.
Recommended Content
Authors
- Guanyu Zheng - Weichai Power Emission Solutions Technology, Inc.
- Fengshuang Wang - Weichai Power Emission Solutions Technology, Inc.
- Suying Zhang - Weichai Power Emission Solutions Technology, Inc.
- Jianhua Zhang - Weichai Power Emission Solutions Technology, Inc.
- Jianzhong Tao - Weichai Power Emission Solutions Technology, Inc.
- Zhiguo Zhao - Tenneco, Inc.
- Jianqing Fan - Tenneco, Inc.
Topic
Citation
Zheng, G., Wang, F., Zhang, S., Zhang, J. et al., "Development of Compact SCR Systems with Closely Coupled Injector Configurations," SAE Technical Paper 2014-01-1546, 2014, https://doi.org/10.4271/2014-01-1546.Also In
References
- EPA Regulatory Standards http://epa.gov/diesel
- Oesterle , J. , Calvo , S. , Damson , B. , Neumann , F. et al. SCR Technology with Focus to Stringent Emissions Legislation SAE Technical Paper 2008-01-2640 2008 10.4271/2008-01-2640
- Way , P. , Viswanathan , K. , Preethi , P. , Gilb , A. et al. SCR Performance Optimization Through Advancements in Aftertreatment Packaging SAE Technical Paper 2009-01-0633 2009 10.4271/2009-01-0633
- Scott Sluder , C. , Storey , J. , Lewis , S. , and Lewis , L. Low Temperature Urea Decomposition and SCR Performance SAE Technical Paper 2005-01-1858 2005 10.4271/2005-01-1858
- Xu , L. , Watkins , W. , Snow , R. , Graham , G. et al. Laboratory and Engine Study of Urea-Related Deposits in Diesel Urea-SCR After-Treatment Systems SAE Technical Paper 2007-01-1582 2007 10.4271/2007-01-1582
- Zheng , G. , Fila , A. , Kotrba , A. , and Floyd , R. Investigation of Urea Deposits in Urea SCR Systems for Medium and Heavy Duty Trucks SAE Technical Paper 2010-01-1941 2010 10.4271/2010-01-1941
- Zheng , G. , Palmer , G. , Salanta , G. , and Kotrba , A. Mixer Development for Urea SCR Applications SAE Technical Paper 2009-01-2879 2009 10.4271/2009-01-2879
- Fluent methodology manual 2007
- Stiesch , G. Modeling Engine Spray and Combustion Processes Springer-Verlag Berlin 2003