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A Holistic View on Urea Injection for NOx Emission Control: Impingement, Re-atomization, and Deposit Formation

Dörnhöfer, J.; Börnhorst, M.; Ates, C.; Samkhaniani, N.; Pfeil, J.; Wörner, M.; Koch, R.; Bauer, H.-J.; Deutschmann, O.; Frohnapfel, B.; Koch, T.

Abstract (englisch):
The injection of urea-water solution (UWS) sprays into engine-close selective catalytic reduction (SCR) systems faces developers with complex challenges regarding two-phase flow and deposit formation. Potential spray impact on the static mixing elements inside the exhaust duct can lead to accumulation of liquid film and solid deposits, which may result in detachment of large UWS droplets at the trailing edges of the mixer blades. Present work focuses on the mechanisms of film and deposit formation within the scope of a joint study on spray preparation in the mixing section of SCR systems. A production type SCR exhaust system is used for optical investigations on gas flow and UWS droplets at the mixing element using Laser Doppler Anemometry (LDA) and Long Distance Microscopy (LDM) with a high-speed camera. Measured shear flows inside the mixing element are up to three times higher than the flow velocity upstream the mixer. Here, a decrease of droplet diameters of detached droplets is revealed with increased shear flow velocity. Characteristic urea deposits are created in a laboratory test bench and their surface structure is measured by use of Confocal Microscopy. ... mehr

DOI: 10.1007/s40825-019-00151-0
Zitationen: 7
Zugehörige Institution(en) am KIT Institut für Katalyseforschung und -technologie (IKFT)
Institut für Kolbenmaschinen (IFKM)
Institut für Strömungsmechanik (ISTM)
Institut für Technische Chemie und Polymerchemie (ITCP)
Institut für Thermische Strömungsmaschinen (ITS)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2020
Sprache Englisch
Identifikator ISSN: 2199-3629, 2199-3637
KITopen-ID: 1000105871
HGF-Programm 37.03.01 (POF III, LK 01) Catalysts and Mechanisms
Erschienen in Emission control science and technology
Verlag Springer
Band 6
Seiten 228–243
Bemerkung zur Veröffentlichung SPECIAL ISSUE: 2019 MODEGAT September 8-10, Bad Herrenalb, Germany
Vorab online veröffentlicht am 15.02.2020
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