New experimental insights in AdBlue-spray/ wall interaction and its impacts on EGT system design

Autoren

David Schweigert, Björn Damson, Hartmut Lüders, Carsten Becker, Robert Bosch GmbH, Powertrain Solutions, Advanced Engineering Exhaust Systems;
Olaf Deutschmann, Karlsruher Institut für Technologie (KIT), Institut für Technische Chemie und Polymerchemie

Jahr

2019

Zusammenfassung

With the introduction of new emission legislation (e.g. EU6-RDE, LEVIII/SULEV) and related nitrogen oxides (NOx) emission limitations, the automotive industry is facing new challenges concerning efficient and robust exhaust gas treatment (EGT). For conversion of NOx, selective catalytic reduction (SCR) via AdBlue has prevailed in Diesel exhaust gas treatment. The preferably complete reduction of NOx in EGT systems still remains one of the most important and challenging tasks of today’s powertrain development.
For fast warm-up and early catalyst light-off, for quite some time now SCR systems are positioned close to the engine, leading to a very compact EGT design with strongly confined space. Simultaneously, fuel-efficient engine calibration (with respect to a CO₂ optimization) results in higher AdBlue dosing amounts and demands for new innovative approaches to prevent excessive wall wetting and, thus, formation of undesired solid AdBlue by-products. While the optimization of injector and compact exhaust/mixing geometries is commonly considered, the role of the AdBlue-impinged wall has not been investigated sufficiently. The wall material-relevant requirements and impacts on EGT system design are not fully understood and deserve further studies.
Through the build-up of a basic laboratory test bench and advanced experimental approaches, the impact of surface and material properties on spray/wall interaction phenomena is comprehensively investigated. Remarkable interdependencies were found and described quantitatively for the very first time. These new spray/wall interaction findings reveal high potential regarding the optimization of SCR system robustness and efficiency.

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