An Experimental Investigation into DEF Dosing Strategies for Heavy Duty Vehicle Applications

Gaynor, Paul D.; Reid, Benjamin; Hargrave, Graham K.; Lockyer, Thomas O.; Wilson, Jonathan

doi:10.4271/2015-01-1028

Cited by 11 publications

(10 citation statements)

References 19 publications

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“…Exhaust pipe vibration due to the random fluctuation of pressure may also cause distortion in the spray structure while capturing. Researchers have introduced optically-accessible visualization chambers to capture the urea-SCR spray images [27,48]. An optical chamber was designed and constructed to visualize the UWS spray-wall impingement phenomena in the current investigation.…”

Section: Optical Chamber and Heating Arrangementmentioning

confidence: 99%

“…The injection quantity of the experimental injector was measured in our previous study for different rpm to determine the injector mass flow rate, and the value was found as 4.824 kg/h [27]. [27,48]. An optical chamber was designed and constructed to visualize the UWS spray-wall impingement phenomena in the current investigation.…”

Section: Optical Chamber and Heating Arrangementmentioning

confidence: 99%

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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: Optical Chamber and Heating Arrangementmentioning

confidence: 99%

Section: Optical Chamber and Heating Arrangementmentioning

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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“…The 2 mm droplet used for the experimental work above is atypical of a urea SCR spray with an example SMD ~20 -90 µm [25]. Where mass and momentum are sufficient for the droplet to impact on a surface and form a film the experimental results above are directly relevant and would demonstrate the rate of boiling at different conditions.…”

Section: Impact Of Droplet Sizementioning

confidence: 99%

“…Schematic of the hot flow facility for diesel engine exhaust simulation.Idealised square test section with optical access for SCR injection [25]. …”

mentioning

confidence: 99%

Analysis of a Novel Method for Low-Temperature Ammonia Production Using DEF for Mobile Selective Catalytic Reduction Systems

Wilson¹,

Hargrave²

2018

SAE Technical Paper Series

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The worldwide introduction of new emission standards and new, more encompassing, legislating cycles have led to a need to increase both a selective catalytic reduction (SCR) system's capacity and conversion efficiency. To this end, it is important for an SCR system to operate to the extremes of its temperature range which in many systems is currently limited by the temperature at which diesel exhaust fluid (DEF) can easily decompose without the formation of deposits. This paper analyses a new system for low-temperature ammonia provision to the SCR reaction. Ammonia Creation and Conversion Technology (ACCT) uses pressure controlled thermal decomposition of DEF followed by reformation to form a fluid with greater volatility and the same ammonia density as DEF. A dosing strategy can be employed with any combination of DEF and ACCT solution to provide ammonia as a reductant over the entire temperature range of the catalyst. High-speed shadowgraphy data identifies ammonia production below 100°C with rapid decomposition and full water vaporisation above 100 °C. This study has also equipped an optically accessible hot flow, diesel exhaust simulation rig with a prototype ACCT device. The optical components allow rapid visual verification of deposit growth for bench-marking urea-based system. At a variety of exhaust temperature and mass flow conditions, the study identified a minimum deposit limited working temperature for DEF of approximately 200 °C whereas ACCT solution was shown not to form any deposits and readily generate ammonia as low as 100 °C. Further to this, gaseous species quantification using FTIR techniques has shown ammonia release in an 800 mm flow path for ACCT solution to be in excess of 80 %. The study has demonstrated the effectiveness of ACCT at extending low temperature operating limits of DEF based SCR systems thereby increasing the total possible NOx conversion.

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“…Apesar de existirem vários trabalhos publicados sobre o sistema SCR e a solução de ureia [3,4,5], não foram encontradas muitas publicações relacionando as emissões de NOx com a qualidade da solução de ureia usada [6,7].…”

Section: /19unclassified

EFEITO DA QUALIDADE DA SOLUÇÃO DE ARLA 32 NA EFICIÊNCIA DO SCR, NAS EMISSÕES DE NOx E NO SISTEMA DE INJEÇÃO DE ARLA

Melo¹,

Giongo²,

Brito³

et al. 2015

Anais Do XXIII Simpósio Internacional De Engenharia Automotiva

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A solução ARLA 32 contém 32,5% de ureia de elevada pureza e 67,5% de água desmineralizada e fornece amônia ao sistema SCR para a redução das emissões de NOx. Com o crescimento desse mercado no país surgiram alterações na sua qualidade que podem comprometer as emissões de NOx e a durabilidade do SCR. Entre exemplos de alterações de qualidade foram relatados produtos com excesso de água, uso de água potável e também o uso de ureia fertilizante ou industrial. Estas formulações, de forma geral, não atendem a especificação do ARLA 32, IN-nº 23 de 11 de julho de 2009 do IBAMA. As formulações preparadas para esse trabalho incluem o uso de água potável comum, ureia fertilizante e ureia industrial, que simulam algumas das alterações de qualidade do mercado. Esse artigo apresenta resultados das emissões de NOx em um motor CONAMA P7 com SCR em banco de provas de motor e o impacto no sistema de injeção de ARLA 32do uso dessas formulações. No artigo também são apresentados resultados de emissões de NOx, com o uso de um sistema de medição embarcado, em um caminhão CONAMA P7 equipado com SCR na configuração original e com o uso de dispositivo emulador ("chip"), que inibe a injeção de ARLA 32. INTRODUÇÃOCom a entrada em vigor da fase CONAMA P7 do PROCONVE, em 2012, exigindo novos limites de emissões para veículos pesados, em especial NOx e material particulado (MP), se tornou necessário um grande avanço na tecnologia de motores a diesel [1]. Foram definidas então duas rotas tecnológicas principais: o EGR (Exhaust Gas Recirculation) e o SCR (Selective Catalyst Reduction -catalisador redutor de NOx).No caso da tecnologia EGR, uma parte dos gases de escapamento é redirecionada para a admissão, passando por uma válvula de controle e por um resfriador. Com isso, o gás de escape é reintroduzido na câmara de combustão de forma controlada para reduzir a quantidade de oxigênio e a temperatura da combustão, reduzindo as emissões de NOx.

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An Experimental Investigation into DEF Dosing Strategies for Heavy Duty Vehicle Applications

Cited by 11 publications

References 19 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

Analysis of a Novel Method for Low-Temperature Ammonia Production Using DEF for Mobile Selective Catalytic Reduction Systems

EFEITO DA QUALIDADE DA SOLUÇÃO DE ARLA 32 NA EFICIÊNCIA DO SCR, NAS EMISSÕES DE NOx E NO SISTEMA DE INJEÇÃO DE ARLA

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