An experimental and numerical study on effects of exhaust gas temperature and flow rate on deposit formation in Urea-Selective Catalytic Reduction (SCR) system of modern automobiles

Prabhu, S. Sadashiva; Nayak, Nagaraj S.; Kapilan, N.; Hindasageri, Vijaykumar

doi:10.1016/j.applthermaleng.2016.09.134

Cited by 68 publications

(25 citation statements)

References 35 publications

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“…At transient operating conditions, the spray will inevitably impinge on the exhaust gas pipe. Liquid films will be formed on the wall leading to undesired formation of solid deposits [8][9][10][11][12][13][14]. As a result, NO x conversion decreases while backpressure increases, affecting both pollutant emissions and engine performance.…”

Section: Introductionmentioning

confidence: 99%

Maximum Spreading of Urea Water Solution during Drop Impingement

et al. 2019

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Droplet impingement of urea water solution (UWS) is a common source for liquid film and solid deposits formed in the tailpipe of diesel engines. In order to better understand and predict wetting phenomena on the tailpipe wall, this study focuses on droplet spreading dynamics of urea water solution. Impingement of single droplets is investigated under defined conditions by high‐speed imaging using shadowgraphy technique. The experimental studies are complemented by numerical simulations with a phase‐field method. Computational results are in good agreement with experimental data for the advancing phase of spreading and the maximum and terminal spreading radius, whereas for the receding phase notable differences occur. For the maximum spreading radius, an empirical correlation derived for glycerol‐water‐ethanol mixtures is found to be valid for millimeter‐sized UWS droplets as well. A numerical simulation for a much smaller droplet however indicates that this correlation is not valid for the tiny droplets of UWS sprays in technical applications.

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Section: Introductionmentioning

confidence: 99%

Maximum Spreading of Urea Water Solution during Drop Impingement

et al. 2019

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“…However, integration of the chemical reactions of urea decomposition to CFD models is Electronic supplementary material The online version of this article (https://doi.org/10.1007/s40825-020-00159-x ) contains supplementary material, which is available to authorized users. mostly limited to urea thermolysis and hydrolysis reactions in the gas phase directly relevant for ammonia production [1,4,15,19,25,26]. Liquid films resulting from spray/wall interaction consist of the two components-urea and water [4,19].…”

Section: Introductionmentioning

confidence: 99%

Deposit Formation from Urea Injection: a Comprehensive Modeling Approach

Budziankou

Börnhorst

Kuntz

et al. 2020

Emiss. Control Sci. Technol.

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Long-term reliability is one of the major requirements for automotive exhaust aftertreatment systems with selective catalytic reduction (SCR) using urea water solution (UWS) as NH 3 carrier fluid. A high injection rate of UWS or unfavorable operating conditions may lead to formation of solid deposits, which decrease system efficiency by increasing backpressure and impairing ammonia uniformity. A reliable numerical prediction of deposit formation in urea SCR systems is desired for optimization of system design. However, comprehensive modeling of physical and chemical processes in the tailpipe as well as different time scale phenomena represents a challenging task. This study presents a comprehensive approach for modeling UWS injection, droplet impingement, liquid film and deposit formation based on CFD-simulation. An existing kinetic model for urea decomposition is integrated into the CFD code to predict solid by-product formation from wall films. Physical simulation time is extensively increased by substituting the Lagrange-particles with source terms of mass, momentum and energy reducing simulation time by a factor of 20. The comparison of measured and simulated results shows the capability of the presented modeling approach to predict position and chemical composition of solid deposits.

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“…The reduction behaviour of NOx in SCR systems starts with UWS spray. following injection, evaporation of urea-water solution, thermolysis of urea, hydrolysis of Isocyanic acid (HNCO) and acid and reduction of NOx in the catalyst takes place [5]. Various studies have been done in the literature for evaporation and decomposition processes in SCRurea systems.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Exhaust Temperature on Urea-Water Decomposition in Marine SCR Systems

Bayramoğlu

Özmen²,

Cerit³

2019

International Journal of Computational and Experimental Science and Engineering

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Reduction of nitrogen oxide (NOx) emissions from ships due to environmental pollution and greenhouse gas impact has been made obligatory by regulations introduced by the International Maritime Organization (IMO). Basically, NOx emission control mechanisms are divided into primary methods and aftertreatment methods. After-treatment methods focus on reducing NOx emissions from the exhaust gas by various methods. In this study, the efficiency of the urea transformation for different exhaust temperature values for a modelled Selective Catalytic Reduction (SCR) system has been investigated numerically. As a result of numerical model, isocyanic acid, temperature, urea and ammonia values have been determined for Urea-Water Solutions (UWS) process values. The study has been calculated by the computational fluid dynamics (CFD). The numerical results obtained were confirmed by experimental studies from the literature.

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An experimental and numerical study on effects of exhaust gas temperature and flow rate on deposit formation in Urea-Selective Catalytic Reduction (SCR) system of modern automobiles

Cited by 68 publications

References 35 publications

Maximum Spreading of Urea Water Solution during Drop Impingement

Maximum Spreading of Urea Water Solution during Drop Impingement

Deposit Formation from Urea Injection: a Comprehensive Modeling Approach

The Effect of Exhaust Temperature on Urea-Water Decomposition in Marine SCR Systems

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