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

Dörnhöfer, Johannes; Börnhorst, Marion; Ates, Cihan; Samkhaniani, Nima; Pfeil, Jürgen; Wörner, Martin; Koch, Rainer; Bauer, Hans‐Jörg; Deutschmann, Olaf; Koch, Thomas

doi:10.1007/s40825-019-00151-0

Cited by 15 publications

(5 citation statements)

References 40 publications

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“…Our previous measurements uncovered a unique scaling behavior for surface morphology under practically relevant conditions [1], a finding later confirmed in controlled single droplet experiments [43]. Additionally, we demonstrated that changes in deposit morphology significantly affect the re-atomization performance over static mixers, a crucial step in managing NO x emissions in SCR systems [44]. Therefore, the representation of surface morphology for modeling other physical phenomena holds significant practical value.…”

Section: Proof-of-concept: Urea Deposit Formationsupporting

confidence: 67%

A Versatile Deposition Model for Natural and Processed Surfaces

Ates,

Koch,

Bauer

2024

Dynamics

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This paper introduces a robust deposition model designed for exploring the growth dynamics of deposits on surfaces under practical conditions. The study addresses the challenge of characterizing the intricate morphology of deposits, exhibiting significant visual variations. A generative approach is deployed to create diverse natural and engineered surface textures, governed by probabilistic principles. The model’s formulation addresses key questions related to deposition initiation, nucleation point behaviour, spatial scaling, deposit growth rates, spread dynamics, and surface mobility. A versatile algorithm, relying on six parameters and employing nested loops and Gaussian sampling, is developed. The algorithm’s efficacy is examined through extensive simulations, involving variations in nucleation scaling densities, aggregate scaling scenarios, spread factors, and diffusion rates. Surface statistics are computed for simulated deposits and analyzed using Fast Fourier Transform (FFT). The resulting database enables quantitative comparisons of surfaces generated with different parameters, where the database-derived parallel coordinates offer guidance for selecting optimal model parameters to achieve desired surface morphologies. The proposed approach is validated against urea-derived deposits, exhibiting statistical consistency and agreement with experimental observations. Overall, the model’s adaptable framework holds promise for understanding and predicting deposit growth on surfaces in diverse practical scenarios.

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Section: Proof-of-concept: Urea Deposit Formationsupporting

confidence: 67%

A Versatile Deposition Model for Natural and Processed Surfaces

Ates,

Koch,

Bauer

2024

Dynamics

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“…Droplets larger than 90 µm have an increased probability to impinge on walls of the SCR system [42]. From the trailing edges of the mixer blades, however, drops up to millimetre size may be shed [88]. Thus, in the following simulations, the investigation range of the initial droplet diameter is 25800 µm and that of the impact velocity is 0.01 − 10 m s −1 .…”

Section: Impingement Of Uws Dropletsmentioning

confidence: 98%

Spreading and rebound dynamics of sub-millimetre urea-water-solution droplets impinging on substrates of varying wettability

Wörner

Samkhaniani

Cai

et al. 2021

Applied Mathematical Modelling

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“…However, the urea deposits in the exhaust after-treatment system (ATS) have always been a challenging problem. Severe deposits can lead to ammonia leakage and exhaust pipe blockage, and they will add back pressure, reducing nitrogen oxide conversion efficiency [4,5]. Therefore, the actual operation process of a commercial vehicle equipped with an SCR system (hereinafter referred to as "vehicle real road test") was tracked and monitored, and it was found that there was a large amount of deposits formation on the wall surface of the exhaust pipe.…”

Section: Introductionmentioning

confidence: 99%

Influence of Exhaust Pipe Structure on Urea-Related Deposits in Diesel Engine SCR System

et al. 2023

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To solve the problem of deposits formation in the exhaust pipe of a diesel engine SCR (selective catalytic reduction) system, the CFD (computational fluid dynamics) model of the exhaust pipe was established to research the influence of structural parameters on the wall film from the perspective of optimizing the flow field. The solid structure was simplified in the modeling without considering the flow fields inside the catalytic converter. The simulation conditions were obtained through bench tests and vehicle real road tests. The spray and temperature simulation results were verified via high-speed photographic and bench tests under three typical operating conditions. The conclusions are as follows: compared to the case with a step surface, wall film mass was reduced by 48.27~55.4% when the exhaust pipe had no step surface; compared to the case where the nozzle orifices were located 10 mm off center axis, wall film mass reduced by 2.83~6.38% when the nozzle orifices located in the center axis of exhaust pipe; compared to the case of 110 mm, wall film mass reduced by 21.3~24.72% when the exhaust pipe diameter was 100 mm. To eliminate the potential problem of deposit formation inside the catalytic converter, the nozzle should be arranged close to the engine turbine, and there should be no abrupt cross-section downstream of the exhaust pipe.

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

Cited by 15 publications

References 40 publications

A Versatile Deposition Model for Natural and Processed Surfaces

A Versatile Deposition Model for Natural and Processed Surfaces

Spreading and rebound dynamics of sub-millimetre urea-water-solution droplets impinging on substrates of varying wettability

Influence of Exhaust Pipe Structure on Urea-Related Deposits in Diesel Engine SCR System

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