This content is not included in your SAE MOBILUS subscription, or you are not logged in.
In-Situ Exhaust Visualization of Near-Nozzle Urea-Based Deposits Formation in an Underfloor SCR Injection Location
ISSN: 0148-7191, e-ISSN: 2688-3627
Published October 08, 2017 by SAE International in United States
This content contains downloadable datasetsAnnotation ability available
Selective Catalytic Reduction (SCR) diesel exhaust aftertreatment systems are virtually indispensable to meet NOx emissions limits worldwide. These systems generate the NH3 reductant by injecting aqueous urea solution (AUS-32/AdBlue®/DEF) into the exhaust for the SCR NOx reduction reactions.
Understanding the AUS-32 injector spray performance is critical to proper optimization of the SCR system. Specifically, better knowledge is required of the formation of near-nozzle deposits that have been observed on existing underfloor SCR systems.
The current work presents in-situ time lapse imaging of an underfloor mounted AUS-32 exhaust-mounted urea dosing unit. The operating conditions under examination are representative of low-load low speed urban driving interspersed with high temperature exposures typical of periodic DPF regeneration.
Analysis is provided of various phenomena leading to the creation of urea-based thermal decomposition products and their deposition on the near-nozzle injector surfaces. Further imaging during the high temperature exposure reveals the subsequent polymerization of liquid films generated during the lower temperature operation. Burnoff of solid urea buildup is also observed during the high temperature events.
The present test campaign provides new insights on the various mechanisms leading to the near-nozzle deposits, including indications of urea vapor transport back to the dosing unit injection point.
CitationVan Vuuren, N. and Armitage, P., "In-Situ Exhaust Visualization of Near-Nozzle Urea-Based Deposits Formation in an Underfloor SCR Injection Location," SAE Technical Paper 2017-01-2376, 2017, https://doi.org/10.4271/2017-01-2376.
Data Sets - Support Documents
|[Unnamed Dataset 1]|
- Koebel, M., Elsener, M., and Kleemann, M., “Urea-SCR: A promising technique to reduce NOx emissions from automotive diesel engines.” Catalysis Today, 335-345, 2000.
- Schaber, P., Colson, J., Higgins, S., Dietz, E., Thielen, D., Anspach, B., and Brauer, J., “Study of the urea thermal decomposition (pyrolysis) reaction and importance to cyanuric acid production.” American Laboratory, August 1999, pp. 13-21.
- 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, doi:10.4271/2009-01-0633.
- Dong, H., Shuai, S., and Wang, J., "Effect of Urea Thermal Decomposition on Diesel NOx-SCR Aftertreatment Systems," SAE Technical Paper 2008-01-1544, 2008, doi:10.4271/2008-01-1544.
- 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, doi:10.4271/2010-01-1941.
- Weeks, C., Ibeling, D., Han, S., Ludwig, L. et al., "Analytical Investigation of Urea Deposits in SCR System," SAE Int. J. Engines 8(3):1219-1239, 2015, doi:10.4271/2015-01-1037.
- van Vuuren, N. and Qin, J., "High Speed Video Measurements with Water of a Planar Laser Illuminated Heated Tip Urea Injector Spray," SAE Technical Paper 2013-01-1073, 2013, doi:10.4271/2013-01-1073.