Choice of urea-spray models in CFD simulations of urea-SCR systems

Ström, Henrik; Lundström, Andreas; Andersson, Bengt

doi:10.1016/j.cej.2008.12.003

Cited by 105 publications

(77 citation statements)

References 30 publications

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“…The dispersed phase governing equations are discretized using a second-order implicit trapezoidal scheme. This setup has been validated for urea-SCR in our previous work [8,9] and recently also against experiments for urea-SNCR.…”

Section: Methodsmentioning

confidence: 99%

“…The injection of the urea-water solution will result in two processes -evaporation of water and thermolysis of urea [8] that can both be modeled as evaporation processes [9]. The non-isothermal, chemically reactive turbulent gas flow is modeled using the Standard k- turbulence model and an Eulerian-Lagrangian approach is used to predict the droplet flow.…”

Section: Methodsmentioning

confidence: 99%

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The effect of turbulent velocity fluctuations on the convective heat transfer to droplets subjected to evaporation and thermolysis

Guo¹,

Finnerman²,

Ström³

2016

AIP Conference Proceedings

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Abstract. The effect of turbulent velocity fluctuations on the convective heat transfer to single droplets in a turbulent channel flow are investigated numerically. It is found that for properties relevant to typical liquid spray applications, the convective heat transfer is enhanced with increasing droplet size and bulk Reynolds number. The combined effect of convective heat transfer enhancement and increased driving forces for heat and mass transfer due to droplet dispersion is thereafter investigated for a commercial spray application. The probability distribution functions of droplet properties in the spray are found to be significantly affected by the presence of turbulent velocity fluctuations in the carrier phase.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

The effect of turbulent velocity fluctuations on the convective heat transfer to droplets subjected to evaporation and thermolysis

Guo¹,

Finnerman²,

Ström³

2016

AIP Conference Proceedings

Self Cite

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“…20 Generation and distribution of the urea reducing agent are developed and implemented in the three-dimensional numerical model in the commercial CFD code. 21 NOx of the exhaust gas must react with the ammonia obtained from the injected urea and get reduced to nitrogen and oxygen. This reaction is made easier in the presence of catalysts like MoO3-CeO2 Nano Particles 22 , Zn-Mg-Al 23 , Ni-Mg-Al 23 and Cu-Mg-Al 23 , to name a few.…”

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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“…The exact state of aggregation of urea during decomposition is still uncertain [15,16]. Two recent theoretical studies [17,18] …”

Section: Steady-state Engine Operationmentioning

confidence: 99%

Concept of Vaporized Urea Dosing in Selective Catalytic Reduction

2017

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This work tried to identify the influence of dosing vaporized urea solution in a selective catalytic reduction (SCR) system. In the SCR method, optimising the urea evaporation and mixing properties can significantly improve the NO x conversion efficiency in the catalyst. It can also exert a positive effect on the uniformity of NH 3 concentration distribution across the catalyst face. The concept of an electrically evaporated urea-dosing system was investigated and it was found that urea pre-heating prior to introduction into the exhaust gas is favourable for enhancing NO x removal under steady-state and transient engine operation. In the urea evaporating system the heating chamber was of a cylindrical tube shape and the urea vapour was introduced into the exhaust by means of a Venturi orifice. The concept urea dosing was only a custom-made solution, but proved to be superior to the regular dosing system operating in the liquid phase.

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Choice of urea-spray models in CFD simulations of urea-SCR systems

Cited by 105 publications

References 30 publications

The effect of turbulent velocity fluctuations on the convective heat transfer to droplets subjected to evaporation and thermolysis

The effect of turbulent velocity fluctuations on the convective heat transfer to droplets subjected to evaporation and thermolysis

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

Concept of Vaporized Urea Dosing in Selective Catalytic Reduction

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