Improved urea-water solution spray model for simulations of selective catalytic reduction systems

Rogóż, Rafał; Kapusta, Łukasz Jan; Bachanek, Jakub; Vankan, Joseph; Teodorczyk, A.

doi:10.1016/j.rser.2019.109616

Cited by 15 publications

(3 citation statements)

References 45 publications

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“…6 However, the interactions between the UWS and the inner wall could cause damages to the SCR systems. 7 Ideally, the urea in the SCR system is decomposed into only NH 3 and CO 2 . Nevertheless, the impingement of UWS droplets on the wall of the SCR system is unavoidable.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation on the Urea Deposit Formation Process in a Selective Catalytic Reduction System of a Diesel Engine Based on a Fluid–Solid Coupling Method

Zhang

Liu

et al. 2021

ACS Omega

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Currently, selective catalytic reduction (SCR) systems have become an essential part in diesel engines, and urea crystallization is one of the most serious issues in SCR systems. In this paper, the urea deposit formation processes in the SCR system were investigated by numerical simulations based on a fluid−solid coupling method. The results show that the masses of the wall film and solid urea are larger at conditions with lower temperatures and higher injection rates. At higher temperatures, cyanate ions and ammonium ions are the most predominant compositions in the wall film, while at lower temperatures, solid urea is the main composition. It could also be deduced that the location of urea crystallization is more affected by the design of mixer at higher temperatures, whereas at lower temperatures, the location and installation angle of urea-water solution injector play a more important role.

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Section: Introductionmentioning

confidence: 99%

Numerical Investigation on the Urea Deposit Formation Process in a Selective Catalytic Reduction System of a Diesel Engine Based on a Fluid–Solid Coupling Method

Zhang

Liu

et al. 2021

ACS Omega

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“…In order to increase the accuracy of the spatial droplet dispersion, two separated conical zones with individual droplet size distributions were defined for each spray plume, as initially proposed in [44]. These individual droplet size distributions (for each spray zone) were also derived from the research [21,22] (Fig.…”

Section: Computational Meshmentioning

confidence: 99%

Numerical evaluation of urea-mixing devices for close-coupled selective catalytic reduction systems

Kaźmierski¹,

Kapusta²

2023

Combustion Engines

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The following research presents a numerical evaluation of existing and conceptual urea-mixing devices used in close-coupled (to the engine) selective catalytic reduction (SCR) systems. The analysis was aimed at the assessment of urea-mixing devices that could considerably enhance the reduction of nitrogen oxides from the diesel-engine combustion process under a wide range of operating conditions, including cold starts. The analysis showed that replacing blade-equipped static mixers with perforated stationary mixing devices may provide a more uniform spatial distribution of ammonia at the inlet to the SCR catalyst and reduce pressure drops generated by mixing devices. Moreover, the conceptual mixing devices, based on combinations of the blade and perforated mixers to develop intensive turbulence, enabled the increase of the mixing length leading to effective decomposition of the urea-water solution (UWS), and provided uniform spatial distribution of ammonia, even for the small-sized mixing systems. However, the intensive mixing was often associated with a significant rise in the pressure drop.

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“…Therefore, it is necessary to secure enough space for the initiation of the chemical reaction before NH 3 mixes with the SCR catalyst. Adequate mixing using the mixer should be applied to create a vortex so that the number of sprayed elements can be decomposed properly [28,29] and also the sufficient vaporization of urea solution must be improved [30,31]. For this reason, the SCR system is designed as shown in Figure 1, and each name of the design parameters is mentioned in Table 1.…”

Section: Scr System and Numerical Analysismentioning

confidence: 99%

Optimization of the Uniformity Index Performance in the Selective Catalytic Reduction System Using a Metamodel

Kim,

Park,

Yoo

et al. 2023

Sustainability

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The significance of the selective catalytic reduction system in vehicles increases in line with the high standards of emission control and enhanced selective catalytic reduction efficiency. This study aims to improve the performance of the selective catalytic reduction system through an optimization method using a metamodel. The objective function is defined as the ammonia uniformity index, and the design parameters are defined in relation to the pipe length and mixer related to the chemical reaction of the urea solution. The range of design parameters has been designated by a trial-and-error method in order to maintain the overall design drawings of the selective catalytic reduction system and prevent modeling errors. Three algorithms, namely, ensemble decision tree, Kriging, and radial basis function, are employed to develop the metamodel. The accuracy of the metamodel is verified based on three indicators: the normalized root mean square error, root mean square error, and maximum absolute error. The metamodel is generated using the Kriging model, which has the highest accuracy among the algorithms, and optimization is also performed. The predicted optimization results are confirmed by computational fluid dynamics numerical analysis with a 99.83% match. The ammonia uniformity index is improved by 1.38% compared to the base model, and it can be said that the NOx purification efficiency is improved by 30.95%. Consequently, optimizing the uniformity index performance through structural optimization is of utmost importance. Furthermore, this study reveals that the design variables related to the mixer play a crucial role in the performance. Therefore, using the metamodel to optimize the selectively catalytic reduction system’s structure should be considered significant. Finally, in the future, the analysis model can be validated using test equipment based on the findings of this study.

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Improved urea-water solution spray model for simulations of selective catalytic reduction systems

Cited by 15 publications

References 45 publications

Numerical Investigation on the Urea Deposit Formation Process in a Selective Catalytic Reduction System of a Diesel Engine Based on a Fluid–Solid Coupling Method

Numerical Investigation on the Urea Deposit Formation Process in a Selective Catalytic Reduction System of a Diesel Engine Based on a Fluid–Solid Coupling Method

Numerical evaluation of urea-mixing devices for close-coupled selective catalytic reduction systems

Optimization of the Uniformity Index Performance in the Selective Catalytic Reduction System Using a Metamodel

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