Selective Catalytic Reduction of NOx Gases in Diesel Exhaust Using Aqueous Urea PDF Download
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Author: Mohamed Ishtiaq Akbar
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Mohamed Ishtiaq Akbar
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Isabella Nova
Publisher: Springer Science & Business Media
ISBN: 1489980717
Category : Science
Languages : en
Pages : 715
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Urea-SCR Technology for deNOx After Treatment of Diesel Exhausts presents a complete overview of the selective catalytic reduction of NOx by ammonia/urea. The book starts with an illustration of the technology in the framework of the current context (legislation, market, system configurations), covers the fundamental aspects of the SCR process (catalysts, chemistry, mechanism, kinetics) and analyzes its application to useful topics such as modeling of full scale monolith catalysts, control aspects, ammonia injections systems and integration with other devices for combined removal of pollutants.
Author: Eric R. Snyder
Publisher:
ISBN:
Category : Automobiles
Languages : en
Pages : 654
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Abstract: Diesel engines offer significant advantages over spark-ignited engines in terms of peak torque production, carbon monoxide (CO) emissions, hydrocarbon (HC) emissions, and fuel consumption (and associated carbon dioxide (CO2) emissions known to cause the greenhouse effect). However, lean exhaust conditions render conventional three-way catalysts ineffective, making nitrogen oxide (NOx) reduction a considerable challenge. With increasing environmental concerns and stringent pending regulation of diesel exhaust emissions, urea-Selective Catalytic Reduction (urea-SCR) has emerged as a potential technology pathway to meet US 2007/2010 and Euro IV/V NOx emissions criterion. This technology uses ammonia (NH3) generated from aqueous urea as the NOx reducing agent. Water injection in the intake system has also demonstrated the potential for significant reductions in engine-out NOx emissions.
Author: Anthony Timpanaro
Publisher:
ISBN:
Category : Automobiles -- Motors (Diesel) -- Catalytic converters -- Industrial applications
Languages : en
Pages :
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The subject of this study is the effect of in-cylinder selective non-catalytic reduction (SNCR) of NOx emissions in diesel exhaust gas by means of direct injection of aqueous urea ((NH2)2CO) into the combustion chamber. A single cylinder diesel test engine was modified to accept an electronically controlled secondary common rail injection system to deliver the aqueous urea directly into the cylinder during engine operation. Direct in-cylinder injection was chosen in order to ensure precise delivery of the reducing agent without the risk of any premature reactions taking place. Unlike direct in-cylinder injection of neat water, aqueous urea also works as a reducing agent by breaking down into ammonia (NH3) and Cyanuric Acid ((HOCN)3). These compounds serve as the primary reducing agents in the NOx reduction mechanism explored here. The main reducing agent, aqueous urea, was admixed with glycerol (C3H8O3) in an 80-20 ratio, by weight, to function as a lubricant for the secondary injector. The aqueous urea injection timing and duration is critical to the reduction of NOx emissions due to the dependence of SNCR NOx reduction on critical factors such as temperature, pressure, reducing agent to NOx ratio, Oxygen and radical content, residence time and NH3 slip. From scoping engine tests at loads of 40 percent and 80 percent at 1500 rpm, an aqueous urea injection strategy was developed. The final injection strategy chosen was four molar ratios, 4.0, 2.0, 1.0 and 0.5 with five varying injection timings of 60, 20, 10, 0, and -30 degrees after top dead center (ATDC). In addition to the base line and aqueous urea tests, water injection and an 80-20 water-glycerol solution reduction agent tests were also conducted to compare the effects of said additives as well. The comparison of baseline and SNCR operation was expected to show that the urea acted as a reducing agent, lowering NOx emissions up to 100% (based on exhaust stream studies) in the diesel exhaust gas without the aid of a catalyst. The data collected from the engine tests showed that the aqueous urea-glycerol solution secondary had no effect on the reduction of NOx and even resulted in an increase of up to 5% in some tests. This was due to the low average in-cylinder temperature as well as a short residence time, prohibiting the reduction reaction from taking place. The neat water and water-glycerol solution secondary injection was found to have a reduction effect of up to 59% on NOx production in the emissions due to the evaporative cooling effect and increased heat capacity of the water.
Author: Hoin Kang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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A NOx emission is one of the problems of diesel engines. SCR is well known to be effective for the reduction of NOx emission. Among many types of SCR, Urea-SCR is known as the most stable. Therefore, this research focuses to evaluate a performance of urea-SCR system in a heavy-duty diesel engine. At first, urea injection system is developed and optimum injection condition is observed. Numerical model of above condition applies to simulation calculation using FLUENT, CFD code. The simulation results determine experimental method on the engine test. Therefore, the aqueous urea solution is injected to reversing direction of exhaust gas into elbow exhaust pipe. Optimal quantity of a reducing agent is estimated by using accurate programming technique under different engine loads and speeds. Furthermore, emission variation between with SCR and without SCR is compared and performance of urea-SCR system is evaluated. This research may provide the fundamental data for the practical use of urea-SCR in future.
Author: Ming-Feng Hsieh
Publisher:
ISBN:
Category :
Languages : en
Pages : 181
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Abstract: A systematic nonlinear control methodology for urea-SCR systems applicable for light-to-heavy-duty Diesel engine platforms in a variety of on-road, off-road, and marine applications is developed and experimentally validated in this dissertation. Urea selective catalytic reduction (urea-SCR) systems have been proved of being able to reduce more than 90% of Diesel engine-out NOx emissions and have been favored by the automotive industry in recent years. Urea-SCR systems utilize ammonia, converted from 32.5% aqueous urea solution (AdBlue) injected at upstream of the SCR catalyst, as the reductant for NOx reductions. Because ammonia is considered a hazardous material, urea injection should be systematically controlled to avoid undesired tailpipe ammonia slip while achieving a sufficient level of SCR NOx reduction. The novelty of the control methodology is to regulate the ammonia storage distribution along the axial direction of a SCR catalyst to a staircase profile and thus to simultaneously realize high NOx reduction efficiency and low ammonia emissions. To achieve this control objective, several relevant subjects are studied, including: 1) aftertreatment system control-oriented modeling, 2) online NOx sensor ammonia cross-sensitivity correction, 3) SCR catalyst ammonia coverage ratio estimation, as well as 4) adaptive urea dosing controller design. A unique SCR system which consists of a urea injector and two SCR catalysts connected in-series with several NOx and NH3 sensors is used for the study of the proposed urea-SCR control methodology. Such a SCR system is integrated with a state-of-the-art Diesel engine and aftertreatment system (DOC-DPF). The US06 test cycle experimental results show the proposed control methodology, in comparison to a conventional control strategy, is capable of improving the SCR NOx reduction by 63% and reducing the tailpipe ammonia slip amount by 74%. The contributions of this research to the art include: 1) A novel, efficient, and generalizable urea-SCR dosing control methodology; 2) Diesel engine-DOC-DPF NO/NO2 ratio control-oriented models and observer-based estimations; 3) SCR catalyst ammonia coverage ratio estimation methods; 4) An online correction approach for NOx sensor ammonia cross-sensitivity elimination; and 5) An improved SCR control-oriented model.
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Author: Ronald Johannes Hultermans
Publisher:
ISBN: 9789056510169
Category :
Languages : en
Pages : 181
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Author: Oliver Kröcher
Publisher: MDPI
ISBN: 3038973645
Category : Science
Languages : en
Pages : 281
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This book is a printed edition of the Special Issue "Selective Catalytic Reduction of NO
x" that was published in Catalysts
Author: David Morales-Morales
Publisher: Elsevier
ISBN: 0080545157
Category : Science
Languages : en
Pages : 467
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Book Description
Pincer complexes are formed by the binding of a chemical structure to a metal atom with at least one carbon-metal bond. Usually the metal atom has three bonds to a chemical backbone, enclosing the atom like a pincer. The resulting structure protects the metal atom and gives it unique properties.The last decade has witnessed the continuous growth in the development of pincer complexes. These species have passed from being curiosity compounds to chemical chameleons able to perform a wide variety of applications. Their unique metal bound structures provide some of the most active catalysts yet known for organic transformations involving the activation of bonds. The Chemistry of Pincer Compounds details use of pincer compounds including homogeneous catalysis, enantioselective organic transformations, the activation of strong bonds, the biological importance of pincer compounds as potential therapeutic or pharmaceutical agents, dendrimeric and supported materials.* Describes the chemistry and applications of this important class of organometallic and coordination compounds* Covers the areas in which pincer complexes have had an impact* Includes information on more recent and interesting pincer compounds not just those that are well-known
Author:
Publisher: DIANE Publishing
ISBN: 1428902805
Category :
Languages : en
Pages : 57
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