Experimental investigation on evaporation of urea‐water‐solution droplet for SCR applications

Wang, Tae Joong; Baek, Seung Wook; Lee, Seung Yeol; Kang, Dae Hwan; Yeo, Gwon Koo

doi:10.1002/aic.11939

Cited by 89 publications

(148 citation statements)

References 23 publications

(41 reference statements)

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“…The temporal size variation during the evaporation of a single droplet of urea-water solution is compared with the experimental data of Wang et al (2009). The squared diameter of droplet is normalized by the square of initial droplet diameter and the variation with respect to the normalized time is plotted in Fig.2.…”

Section: Resultsmentioning

confidence: 99%

“…Melting of urea occurs at around 406 K as reported by Sangster (1999). Schaber et al (2004) reports the vaporization of molten urea at 413 K and direct decomposition into ammonia and isocyanic acid at temperatures above 425 K. The experiments on a single droplet by Wang et al (2009) also show fast depletion of urea at temperatures above 423 K conforming to the observations of Schaber et al (2004). Whereas the experimental data of Emel 'Yanenko et al (2006) and Bernhard et al (2011) suggests urea phase change to gaseous state at temperatures around 406 K. Different numerical approaches have been used to solve this problem.…”

Section: Urea Depletion Thermolysis and Hydrolysismentioning

confidence: 99%

“…Experimental data on evaporation time and droplet size variation during evaporation of a single droplet of urea-water solution is given by Wang et al (2009). A solution of 32.5 % urea by weight is used in the study.…”

Section: Single Multi-component Dropletmentioning

confidence: 99%

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Urea-Water Droplet Phase Change and Reaction Modelling: Multi-Component Evaporation Approach

Shirodkar¹

2016

Frontiers in Heat and Mass Transfer

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Urea-water solution droplet evaporation is modelled using multi-component droplet evaporation approach. The heat and mass transfer process of a multi-component droplet is implemented in the Langrangian framework through a custom code in ANSYS-Fluent R15. The evaporation process is defined by a convection-diffusion controlled model which includes the effect of Stefan flow. A rapid mixing model assumption is used for the droplet internal physics. The code is tested on a single multi-component droplet and the predicted evaporation rates at different ambient temperatures are compared with the experimental data in the literature. The approach is used to model the injection of urea-water solution spray in a duct carrying hot air to predict the urea to ammonia conversion efficiency. Thermolysis reaction of the evaporated urea and the hydrolysis of the byproduct iso-cyanic acid are solved as volumetric reactions in the Eulerian framework using laminar finite rate approach. The spray simulation results are compared with the experimental data and the numerical results of surface reaction based direct thermolysis approach available in the literature.

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Section: Resultsmentioning

confidence: 99%

Section: Urea Depletion Thermolysis and Hydrolysismentioning

confidence: 99%

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Urea-Water Droplet Phase Change and Reaction Modelling: Multi-Component Evaporation Approach

Shirodkar¹

2016

Frontiers in Heat and Mass Transfer

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“…For a basic understanding of UWS spray evaporation, it is necessary to investigate the evaporation characteristics of a single UWS droplet. Wang et al (2009) experimented using a suspended droplet. The droplet evaporation rates were extracted for a variety of initial droplet diameters and ambient temperatures.…”

Section: Introductionmentioning

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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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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“…Despite numerous experimental studies (Kontin et al, 2010;Musa et al, 2006;Wang et al, 2009), theoretical understanding of evaporation and decomposition of UWS droplets is still far from satisfactory. Theoretical study conducted by Birkhold et al (2007) was implemented in FIRE and represents the trade-off between accuracy of results and computational demands.…”

Section: Evaporation and Thermolysis Of Uws Dropletsmentioning

confidence: 99%

Numerical modeling of urea water based selective catalytic reduction for mitigation of NOx from transport sector

Baleta

Vujanović

Pachler

et al. 2015

Journal of Cleaner Production

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a b s t r a c tVarious environmental regulations put ever stringent requirements on the automotive industry as a part of solution to the problem of global warming and climate change. In Europe, the upcoming Euro 6 standard that will come into force on September 1, 2014 demands reduction in NO x emissions from cars and vehicles intended for transport by more than 50% compared to the current standard. The urea-watersolution (UWS) based selective catalytic reduction (SCR) is currently the most promising method for fulfilling these requirements. In principle, the UWS spray is injected into a hot exhaust gas stream preceding the SCR catalyst and ammonia is generated through series of chemical reactions. Then, the generated ammonia acts in various deNO x reactions as a reductant.This paper investigates application of numerical modeling in the area of environmentally friendly technology of mobile SCR as a green engineering measure to reduce pollution in the road transport sector. Within this work the mathematical model of surface tension has been developed and compared to analytical expression for isothermal droplet spreading. Furthermore, this model was incorporated into the wall film module of the commercial computational fluid dynamics code FIRE for description of ureawater-solution injection into hot exhaust gases of diesel engine and compared to experimental data. Results of the conducted numerical study support the feasibility of commercial application of the presented model.

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Experimental investigation on evaporation of urea‐water‐solution droplet for SCR applications

Cited by 89 publications

References 23 publications

Urea-Water Droplet Phase Change and Reaction Modelling: Multi-Component Evaporation Approach

Urea-Water Droplet Phase Change and Reaction Modelling: Multi-Component Evaporation Approach

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

Numerical modeling of urea water based selective catalytic reduction for mitigation of NOx from transport sector

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