Analysis of the Injection of Urea-Water-Solution for Automotive SCR DeNOx-Systems: Modeling of Two-Phase Flow and Spray/Wall-Interaction
Date Published: 2006-04-03
Paper Number:2006-01-0643
DOI: 10.4271/2006-01-0643
Citation:
Birkhold, F., Meingast, U., Wassermann, P., and Deutschmann, O., "Analysis of the Injection of Urea-Water-Solution for Automotive SCR DeNOx-Systems: Modeling of Two-Phase Flow and Spray/Wall-Interaction," SAE Technical Paper 2006-01-0643, 2006, doi:10.4271/2006-01-0643.
The selective catalytic reduction (SCR) based on urea-water-solution is an effective technique to reduce nitrogen oxides (NO
x
) emitted from diesel engines. A 3D numerical computer model of the injection of urea-water-solution and their interaction with the exhaust gas flow and exhaust tubing is developed to evaluate different configurations during the development process of such a DeNOx-system. The model accounts for all relevant processes appearing from the injection point to the entrance of the SCR-catalyst:
momentum interaction between gas phase and droplets
evaporation and thermolysis of droplets
hydrolysis of isocyanic acid in gas phase
heat transfer between wall and droplets
spray/wall-interaction
two-component wall film including interaction with gas phase and exhaust tube
The single modeling steps are verified with visualizations, patternator measurements, phase-doppler-anemometer results and temperature measurements. CFD simulations of a SCR DeNOx-system are compared to experimental data to determine the decomposition parameters for urea-water-solution droplets. Numerical results for an injection including all processes addressed above are discussed.
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