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

Payri, Raúl; Bracho, Gabriela; Gimeno, J.; Moreno, Armando

doi:10.1016/j.expthermflusci.2019.05.019

Cited by 25 publications

(28 citation statements)

References 30 publications

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“…The graph presented in Figure 5 shows the average (for frames between 10 and 12 ms after start of injection, and for five injections) spray visualisation angle measured for both UWS and water at all considered injection pressures. It may be observed that for both liquids the spray angle increases with injection pressure, which is consistent with results shown by other researchers for similar injection parameters [24,26]. When considering differences between the studied fluids it can be seen that the visualization angle determined for UWS was higher than for water for all considered injection pressures.…”

Section: Spray Visualization Anglesupporting

confidence: 90%

“…Different optical properties could be compensated (e.g., by using stronger light to illuminate the spray or by using a different intensity threshold value to separate the spray cloud from the background), but as stated earlier, the idea behind this work was to compare the sprays using the same set-up and the same conditions, which includes the data processing as well. Especially as setting the intensity threshold value for It may be observed that for both liquids the spray angle increases with injection pressure, which is consistent with results shown by other researchers for similar injection parameters [24,26]. When considering differences between the studied fluids it can be seen that the visualization angle determined for UWS was higher than for water for all considered injection pressures.…”

Section: Spray Visualization Anglesupporting

confidence: 88%

“…They made 5 additional measurements in order to compare the results with backlight imaging. Payri et al [24] studied the atomization of UWS sprays in hot co-flow to simulate exhaust system conditions. They used a diffused back illumination technique at high imaging speed.…”

Section: Parameter Unit Water Uwsmentioning

confidence: 99%

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Characteristics of Water and Urea–Water Solution Sprays

et al. 2019

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In spray studies related to selective catalytic reduction (SCR) systems a common approach is to replace the urea–water solution (UWS) with pure water, even though there is very limited detailed information on the spray properties for these two liquids obtained under the same conditions using the same experimental equipment. Neither is it known how the possible differences in spray properties influence computational fluid dynamics (CFD) simulations. In this study, besides the flow characteristics, we compare both global and local spray parameters measured for UWS and pure water in the same conditions. To our knowledge, this is the first study which examines the influence on the injection process of replacing UWS with water over such a wide range. Moreover, the influence of different spray properties on CFD simulations is also examined. The experimental studies showed differences in almost all considered spray parameters. Moreover, different spray behaviour was noticed in terms of primary break-up. One important finding is that water and UWS sprays do have a similar Sauter mean diameter, but at the same time the droplet size distribution is considerably different. The simulation results indicated noticeable differences in terms of wall film formation; nevertheless, the overall mixing performance was not significantly affected.

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Section: Spray Visualization Anglesupporting

confidence: 90%

Section: Spray Visualization Anglesupporting

confidence: 88%

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Characteristics of Water and Urea–Water Solution Sprays

et al. 2019

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“…14 Increasing the injection pressure affects the atomization process and produces smaller particles at higher speeds, promoting wider overall spray angles, and that when combined with a high-temperature mass flow can improve the evaporation and mixing process in the SCR system. 15…”

Section: Introductionmentioning

confidence: 99%

Ammonia injection optimization for selective catalytic reduction aftertreatment systems

Plá

Bares

Sanchis

et al. 2020

International Journal of Engine Research

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This work presents an optimized ammonia injection strategy for the Worldwide Harmonized Light Vehicles Test Cycle and its potential benefits in terms of NO x emissions and ammonia consumption in selective catalytic reduction. An optimization tool based on optimal control was used to improve the ammonia injection in the selective catalytic reduction with different NO x emission limits. This optimal control can be used in two ways: one to minimize NO x emission and another to reduce the ammonia consumption in the selective catalytic reduction. The optimized strategy and the standard ammonia injection strategy were tested and compared on a fully instrumented engine test bench when applied in a Worldwide Harmonized Light Vehicles Test Cycle. The results showed a considerable improvement in the use of the optimization tool. When compared to the standard calibration, the new injection strategy for the same amount of ammonia injection reduced NO x emissions by 13.7%, and for the same NO x concentration emissions 33.5% of ammonia consumption was saved.

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“…Also the velocity is calculated with a frame to frame droplet search algorithm to calculate the speed of the droplets. 21 The data has been obtained at three different windows of interest, P1, P2 and P3, as…”

Section: Experimental Datasetmentioning

confidence: 99%

Computational Study of Urea–Water Solution Sprays for the Analysis of the Injection Process in SCR-like Conditions

Payri

Bracho

Martí-Aldaraví

et al. 2020

Ind. Eng. Chem. Res.

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Exhaust after-treatment devices for NOx reduction have become mandatory for achieving the strict diesel emission standards. The Selective Catalytic Reduction (SCR) method has proven to be efficient in this task. Nonetheless, in order to improve the efficiency of the system, the Urea-Water Solution (UWS) injection process needs to be properly characterized due to the limited geometry of the exhaust line and its flow conditions. In combination with the experimental analysis into the system in a dedicated test rig, Computational Fluid Dynamics (CFD) studies provide better insight of the physical phenomena. Therefore, the main objective of this investigation is to achieve validated droplet size and velocity distributions in the simulation similar when compared to experiments. Three different positions along the spray are evaluated for that. The methodology adopted includes an Eulerian-Lagrangian approach to study the UWS spray. The results obtained with it show a proper experimental validation as well as the Sauter Mean Diameter distribution for the conditions tested. The proposed model accurately reproduces the main spray characteristics for different injection pressures and ambient conditions. Thus, the main conclusions obtained sum up in a good methodology for predicting UWS sprays in SCR-like conditions.

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

Cited by 25 publications

References 30 publications

Characteristics of Water and Urea–Water Solution Sprays

Characteristics of Water and Urea–Water Solution Sprays

Ammonia injection optimization for selective catalytic reduction aftertreatment systems

Computational Study of Urea–Water Solution Sprays for the Analysis of the Injection Process in SCR-like Conditions

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