Investigation of Urea Deposits in Urea SCR Systems for Medium and Heavy Duty Trucks

Zheng, Guanyu; Fila, A.; Kotrba, Adam; Floyd, Ryan

doi:10.4271/2010-01-1941

Cited by 73 publications

(42 citation statements)

References 6 publications

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“…As for the inner wall temperature, note that it is an average value in the computational grid because of the 1D assumption. Therefore, the simulated temperature reduction of the wall is different from those of other studies (Birkhold et al, 2006;Zheng et al, 2010). This may lead to a slight overestimation of the film temperature.…”

Section: Effect Of Uws Injection Rate On Urea Depositscontrasting

confidence: 39%

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Quasi 1D modeling of two-phase flow and deposit formation for urea-selective catalytic reduction systems

Gan

Yao

et al. 2016

J. Zhejiang Univ. Sci. A

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A quasi 1D model of two-phase flow for a urea-selective catalytic reduction (SCR) system is developed which can calculate not only the generation of reducing agent but also the formation of deposits in the exhaust pipe. The gas phase flow is solved through Euler method, variables are stored on staggered grids, and the semi-implicit method for pressure-linked equation (SIMPLE) algorithm is applied to decouple the pressure and velocity. The liquid phase is treated in a Lagrangian way, which solves the equations of droplet motion, evaporation, thermolysis, and spray wall interaction. A combination of a direct decomposition model and a kinetic model is implemented to describe the different decomposition behaviors of urea in the droplet phase and wall film, respectively. A new 1D wall film model is proposed, and the equations of wall film motion, evaporation, thermolysis, and species transport are solved. The position, weight, and components of deposits can be simulated following implementation of the semi-detailed kinetic model. The simulation results show that a decrease in the exhaust temperature will increase the wall film region and the weight of deposits. Deposit components are highly dependent on temperature. The urea-water-solution (UWS) injection rate can affect the total mass of wall film and expand the film region, but it has little influence on deposit components. An increase in exhaust mass flow can decrease the total weight of deposits on the pipe wall because of the promotion of the mass and heat transfer process both in the droplets and wall film.

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Section: Effect Of Uws Injection Rate On Urea Depositscontrasting

confidence: 39%

“…Analyzing the previous studies (Strots et al, 2009;Zheng et al, 2010), wall film formation is a key cause of deposits. To predict deposit formation, a semi-detailed kinetic model of urea thermolysis is implemented into the wall film.…”

Section: Wall Film Modelmentioning

confidence: 99%

Quasi 1D modeling of two-phase flow and deposit formation for urea-selective catalytic reduction systems

Gan

Yao

et al. 2016

J. Zhejiang Univ. Sci. A

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“…In SCR a reducing agent is injected into the exhaust pipe 3 for removal of harmful NOx emissions through several steps. Normally H2, CO [4][5][6] , hydrocarbons [7][8][9] and urea-water solution (UWS) 10,11 are the preferred reducing agents. As soon as the urea-water solution is injected into the exhaust tailpipe, water will evaporate to leave a trail of solid molten urea, which will convert into gaseous ammonia.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Urea Decomposition and Uniform Concentration of Urea Water Solution in SCR System for Diesel Engine Exhaust Using CFD

2017

Rasayan J Chem

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Urea-SCR has received worldwide attention for reducing the harmful NOx emission from present diesel engines. But this faces lot of challenges such as complete decomposition of reducing agent urea and its deposition at the bottom of exhaust tail pipe, lack of uniform distribution of the urea-decomposed ammonia during the continuous running of the engine. This study is involved with CFD evaluation of urea decomposition rate by adopting different urea injection angles and nozzle positions. Also, urea atomization and evaporation/decomposition to ammonia and ammonia distribution on tail pipe cross-sectional area are investigated. Exhaust tail pipe is fitted with guided pipe at different angles. Also, urea and air are injected at different pressures respectively, in the twin-flow nozzle. The CFD analysis indicated that, the ammonia conversion rate is well improved using guided pipe fitted at 30 o inclination with exhaust tail pipe. The CFD analysis is validated by engine experiments. It was proven that, the conversion increased for the 5bar urea and 1bar air.

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“…(Fang and DaCosta, 2003;Koebel et al, 2003;Koebel et al, 2002). (Zheng et al, 2010;Koebel et al, 2002). 플라즈마의 특징을 활용한 다양한 반응기에 대한 연구 가 지속적으로 연구되어 왔다 (Kim et al, 2013;.…”

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Performance Evaluation for Fast Conversion from Urea to an Ammonia Conversion Technology with a Plasma Burner

Jo¹,

Kim²,

Lee³

et al. 2016

Journal of Korean Society for Atmospheric Environment

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Investigation of Urea Deposits in Urea SCR Systems for Medium and Heavy Duty Trucks

Cited by 73 publications

References 6 publications

Quasi 1D modeling of two-phase flow and deposit formation for urea-selective catalytic reduction systems

Quasi 1D modeling of two-phase flow and deposit formation for urea-selective catalytic reduction systems

Investigation of Urea Decomposition and Uniform Concentration of Urea Water Solution in SCR System for Diesel Engine Exhaust Using CFD

Performance Evaluation for Fast Conversion from Urea to an Ammonia Conversion Technology with a Plasma Burner

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