Experimental Analysis of the Urea-Water Solution Temperature Effect on the Spray Characteristics in SCR Systems

Vuuren, Nic van; Brizi, Gabriele; Buitoni, Giacomo; Postrioti, Lucio; Ungaro, Carmine

doi:10.4271/2015-24-2500

Cited by 14 publications

(6 citation statements)

References 6 publications

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“…Studies by Oh and Lee [7] and Varna et al [8] showed the importance of spray distribution, droplet diameter and wall impingement on the deposit formation and the NO x conversion efficiency. From the global perspective, spray imaging measurements were carried out by Van Vuuren et al [9,10] using an aqueous urea solution (AUS-32) in a hot air test bench, reaching both fluid and air temperatures of 130 °C and 490 °C respectively. They concluded that the temperature of the fluid had a strong influence on the global spray parameters, due to the atmospheric boiling point of the fluid.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the urea-water solution atomization process in engine exhaust-like conditions

Payri

Bracho

Gimeno

et al. 2019

Experimental Thermal and Fluid Science

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Section: Introductionmentioning

confidence: 99%

Investigation of the urea-water solution atomization process in engine exhaust-like conditions

Payri

Bracho

Gimeno

et al. 2019

Experimental Thermal and Fluid Science

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“…Some other investigations indicated that the physical state of UWS (mainly temperature) can affect the behavior of the spray and the evolution of the spray structure when injected into a hot environment (Vuuren et al, 2015). However, this is beyond the scope of this paper and the temperature effect on the spray characteristics was neglected in this study.…”

Section: Liquid Phase Modelmentioning

confidence: 95%

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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“…Postrioti et al have used PDA along with backlight imaging to determine a methodology for global spray characterization in heated crossflow conditions [15]. Flash boiling effect was studied under stationary and heated crossflow conditions by N. Van et al [16,17]. At the same time investigations on UWS interaction with the walls of the exhaust system have also been densely conducted.…”

Section: Eq (3)mentioning

confidence: 99%

Experimental Characterization and Numerical Modelling of Urea Water Solution Spray in High-Temperature Crossflow for Selective Catalytic Reduction Applications

Khan¹,

Bjernemose²,

Lund³

2022

SAE J. STEEP

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Engines have improved a lot and reached a new state of the art in terms of combustion technology, but they alone still fall short in achieving emission limitations without any trade-off on performance. Selective Catalytic Reduction (SCR) is the key technology used to meet the increasingly strict Nitrogen Oxides (NOx) emission regulations. The injection of Urea Water Solution (UWS-32.5% urea solution) upstream the catalyst is currently the leading technique for reducing the emission of NOx from the exhaust (DeNOx). A uniform distribution of the spray droplets is very crucial to achieve a good conversion efficiency. Therefore, the size and velocity distribution of the droplets are of high importance in deciding the fate of the DeNOx process. This article describes an approach of modelling the UWS spray and its validation against experimental data collected under realistic exhaust-like conditions. Droplet size distributions and velocities were recorded using Phase Doppler Anemometry (PDA) in a high-temperature wind tunnel. Simulations of the spray were performed using a commercial Computational Fluid Dynamics (CFD) code, ANSYS Fluent, in Lagrangian solver framework under the same flow conditions.The results show that initializing the droplets with the correct diameter and velocity distributions is a vital element in determining the fate of droplets and their impingement location. Using the proposed methodology, validation of diameter and velocity distributions were performed and the average deviations in Sauter Mean Diameter (SMD) were found to be less than 8%. Deviations in velocity distributions were recorded with larger differences appearing in planes closer to the nozzle. It was seen that the simulation initiated with the correct momentum had an average difference of around 8% whereas the simulation initiated with a single velocity value had an average difference of around 32%, when compared with the actual measurement data.

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Experimental Analysis of the Urea-Water Solution Temperature Effect on the Spray Characteristics in SCR Systems

Cited by 14 publications

References 6 publications

Investigation of the urea-water solution atomization process in engine exhaust-like conditions

Investigation of the urea-water solution atomization process in engine exhaust-like conditions

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

Experimental Characterization and Numerical Modelling of Urea Water Solution Spray in High-Temperature Crossflow for Selective Catalytic Reduction Applications

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