A New Energy-based Model for the Prediction of Primary Atomization of Urea-Water Sprays

Risi, Arturo de; Donateo, Teresa; Sciolti, Aldebara; Calò, Michele; Gaballo, Maria Rosaria

doi:10.4271/2009-01-0902

Cited by 3 publications

(1 citation statement)

References 6 publications

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“…Infrared thermography was implemented to assess the spray cooling of the impingement wall surface at an improved temporal and spatial resolution along the impingent area. Solid deposits formed because of wall impingement and imperfect urea decomposition were characterized by FTIR Several numerical simulation studies regarding urea-SCR sprays have been conducted [7,15,25,26]. On the other hand, recently, a limited amount of SCR experimental spray investigation data has been made available to disclose the droplet breakup, distribution, and associated phenomena [4,14,[27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

A Study on Urea-Water Solution Spray-Wall Impingement Process and Solid Deposit Formation in Urea-SCR de-NOx System

Shahariar

2018

Energies

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Selective catalytic reduction (SCR) has been exhibited as a promising method of NOx abatement from diesel engine emissions. Long-term durability is one of the key requirements for the automotive SCR system. A high NOx conversion, droplet distribution and mixing, and fluid film and solid deposit formation are the major challenges to the successful implementation of the SCR system. The current study is therefore three-fold. Firstly, high-speed images disclose detailed information of the spray impingement on the heated impingement surface. The spray impingement investigation took place in a specially-designed optically-accessible visualization chamber where the Z-type shadowgraph technique was used to capture the high-speed images. Wall temperature has a great influence on the film formation and wall wetting. A higher wall temperature can significantly increase the droplet evaporation, and consequently, wall wetting decreases. The numerical analysis was performed based on the Eulerian-Lagrangian approach using STAR CCM+ CFD code. Secondly, the resultant phenomena due to spray-wall impingement such as fluid film generation and transport, solid deposit formation, and thermal decomposition were recorded using a high-speed camera operating at a low frame rate. Infrared thermal imaging was used to observe the spray cooling effect after impingement. Spray impingement caused local cooling, which led to wall film formation, which introduced urea crystallization. Finally, solid deposits were analyzed and characterized using Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). FTIR analysis revealed that urea decomposition products vary based on the temperature, and undecomposed urea, biuret, cyanuric acid, ammeline, and melamine can be formed at different temperatures. TGA analysis showed that accumulated deposits were hard to remove. Moreover, complete thermal decomposition of deposits is not possible at the regular exhaust temperature, as it requires a comparatively long time span.

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Section: Introductionmentioning

confidence: 99%

A Study on Urea-Water Solution Spray-Wall Impingement Process and Solid Deposit Formation in Urea-SCR de-NOx System

Shahariar

2018

Energies

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Characterization of the urea-water spray impingement in diesel selective catalytic reduction systems

et al. 2017

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Exhaust after-treatment selective catalytic reduction (SCR) systems based on urea-water solution are state-of-the-art technologies mitigating NOx emissions for diesel and lean combustion systems. Major challenges for implementing the systems are high NOx reduction performance, uniform mixture formation and solid deposits formation. This study presents a detailed analysis of the urea-water spray wall impingement and influences on reducing agent distribution and deposit formation, thus system performance. High speed images provide detailed information of the impingement process. Moreover, impinging spray mass flux distribution and droplet size distribution have been quantified under typical diesel exhaust flow conditions. The work has been performed with a commercial 3-Hole pressure-driven injector dosing into a flow channel. Under all tested conditions, the impingement is significant. At gas flow conditions of 300°C, 200kg/h, 35.6% of the injected fluid impinges on the opposed wall due to entrainment and evaporation. The entrainment level has been found to scale logarithmically with the gas flow momentum, related correlations are provided. Having an integrated analysis of a mechanical patternator and non-intrusive Phase Doppler Anemometry (PDA) results, it is concluded that droplets below 20μm are completely entrained or evaporated. The impingement rate is gradually increasing with increasing droplet diameter up

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Application of a Modular Simulation Approach: Optimizations from Combustion to Vehicle Management

Gaballo¹,

Giodice²,

Diano³

et al. 2015

SAE Technical Paper Series

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A New Energy-based Model for the Prediction of Primary Atomization of Urea-Water Sprays

Cited by 3 publications

References 6 publications

A Study on Urea-Water Solution Spray-Wall Impingement Process and Solid Deposit Formation in Urea-SCR de-NOx System

A Study on Urea-Water Solution Spray-Wall Impingement Process and Solid Deposit Formation in Urea-SCR de-NOx System

Characterization of the urea-water spray impingement in diesel selective catalytic reduction systems

Application of a Modular Simulation Approach: Optimizations from Combustion to Vehicle Management

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