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Reduction of NOx in Diesel Engine Emissions Using SNCR with In-Cylinder Injection of Aqueous Urea

Univ of North Florida-Anthony Timpanaro, John Nuszkowski
  • Technical Paper
  • 2019-24-0144
To be published on 2019-08-15 by SAE International in United States
The subject of this study was 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-CO-NH2) into the combustion chamber. A naturally aspirated single cylinder 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 to ensure precise delivery of the reducing agent without the risk of premature reactions. Aqueous urea also works as the primary 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 reduction agent, aqueous urea, was mixed with glycerol (C3H8O3) in an 80-20 ratio by weight with the desire to function as a lubricant for the secondary injector. The injection timing and duration of the aqueous urea is critical to the reduction of NOx emissions due to the dependence of SNCR NOx reduction on critical factors…

Experimental Analysis of SCR Spray Evolution and Sizing in High-Temperature and Flash Boiling Conditions

SAE International Journal of Fuels and Lubricants

Continental Automotive Systems US Inc., USA-Nic van
Universita degli Studi di Perugia, Italy-Gabriele Brizi, Lucio Postrioti
  • Journal Article
  • 04-12-02-0006
Published 2019-05-16 by SAE International in United States
In the last years, new stringent emission legislation in terms of nitrogen oxides (NOx) has been leading to a massive development of advanced after-treatment systems for diesel engines. Among them, selective catalytic reduction (SCR) technology has proved to be an effective approach for NOx reduction in a wide range of engine operating conditions. In SCR systems, the interaction between diesel exhaust fluid (DEF) and hot exhaust gas is crucial to promote the chemical reactions through which ammonia is produced. Hence, a proper matching between the exhaust pipe architecture and the DEF spray is mandatory for obtaining an adequate SCR efficiency, especially in close-coupled configurations and moderate exhaust gas temperature conditions. To this end, significant benefits could be derived via appropriate SCR injector thermal management, as the spray structure is significantly influenced by the DEF temperature upstream of the injector nozzle. In this article, the results of a spray analysis campaign carried out on a prototype DEF dosing system are presented. The goal of this research is to investigate the influence of both air and DEF…

Experimental and Computational Study of DOC on CSF for Heavy Duty Diesel Applications

Johnson Matthey Inc.-Sharan Sethuraman, Siddarth Sitamraju, Yaritza M Lopez-De Jesus, Penelope Markatou
Published 2019-04-02 by SAE International in United States
For diesel exhaust aftertreatment applications with space limitations, as well as to move the selective catalytic reduction system (SCR) to a warmer location closer to the engine, DOC on CSF technology can be used. This technology combines the diesel oxidation catalyst (DOC) and catalyzed soot filter (CSF) functionalities in one component, thereby enabling volume reduction. DOC on CSF maintains the abatement of hydrocarbon (HC), carbon monoxide (CO), and particulate matter (PM), and the oxidation of nitric oxide (NO) to nitrogen dioxide (NO2) for passive soot oxidation and fast SCR reaction of NOx on a downstream SCR catalyst. In this study, the performance of DOC on CSF was compared to a DOC + bare diesel particulate filter (DPF) and a DOC + CSF system, to understand the performance benefits and challenges.All the components were optimized individually for their respective functions. The DOC on CSF was optimized for NO oxidation and passive soot oxidation performance. Experimental data and simulations were used to understand the underlying mechanisms in the DOC on CSF technology. Steady state HC oxidation under…
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Super Ultra-Low NOX Emissions under Extended RDE Conditions - Evaluation of Light-Off Strategies of Advanced Diesel Exhaust Aftertreatment Systems

FEV GmbH-Kai Deppenkemper, Markus Ehrly lng, Markus Schoenen, Matthias Koetter
Published 2019-04-02 by SAE International in United States
Super ultra-low NOX emission engine concepts are essential to comply with future emission legislations. To meet the future emission standards, application of advanced diesel exhaust aftertreatment systems (EATS), such as Diesel Oxidation Catalyst (DOC), Lean NOX Trap (LNT), Selective Catalytic Reduction coatings on Soot Filters (SCRF) and underfloor SCR, is required. Effective customized thermal management strategies are essential to ensure fast light-off of the EATS after engine cold start, and to avoid significant cooldown during part load operation.The authors describes the investigation of different exhaust gas heating measures, such as intake throttling, late fuel injection, exhaust throttling, advanced exhaust cam phasing, retarded intake cam phasing, cylinder deactivation, full turbine bypass, electric catalyst heating and electrically heated intake manifold strategies. For those investigations, a steady-state GT-Power simulation model of a state-of-the-art EU6c 2.0 L diesel engine, equipped with high and low pressure exhaust gas recirculation (EGR) and 2-stage boosting, was used. The results were then transferred to FEV´s complete powertrain simulation platform. As representative vehicles, a C segment car, a compact SUV and a light duty…
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Engine-Aftertreatment in Closed-Loop Modeling for Heavy Duty Truck Emissions Control

Oak Ridge National Laboratory-Zhiming Gao, Dean Deter, David Smith, Josh Pihl, C. Stuart Daw, James Parks
Published 2019-04-02 by SAE International in United States
An engine-aftertreatment computational model was developed to support in-loop performance simulations of tailpipe emissions and fuel consumption associated with a range of heavy-duty (HD) truck drive cycles. For purposes of this study, the engine-out exhaust dynamics were simulated with a combination of steady-state engine maps and dynamic correction factors that accounted for recent engine operating history. The engine correction factors were approximated as dynamic first-order lags associated with the thermal inertia of the major engine components and the rate at which engine-out exhaust temperature and composition vary as combustion heat is absorbed or lost to the surroundings. The aftertreatment model included catalytic monolith components for diesel exhaust oxidation, particulate filtration, and selective catalytic reduction of nitrogen oxides (NOx) with urea. Both the engine and aftertreatment models have been calibrated with dynamometer measurements from a commercial 2010-certificated 15-L Cummins diesel engine. The fuel consumption engine map with the reduced data is attached in the appendix. Simulations with the combined engine and aftertreatment models above appear to reveal important trends among the fuel efficiency, emissions control, power…
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A Real-Time Control Framework for Integrated Diesel Engine and Selective Catalytic Reduction System

Tennessee Technological University-Kuo Yang, Pingen Chen
Published 2019-04-02 by SAE International in United States
Diesel engines have been widely adopted in medium- to heavy-duty ground vehicles, due to high engine efficiency, high power output, and superior reliability. However, as Diesel engine emission regulation has been significantly tightened in the past decade, emission control has become a major barrier for Diesel engine efficiency improvement. Integrated Diesel engine and aftertreatment system controls are very important for modern Diesel engines to further improve fuel efficiency while facing increasingly stringent NOx and particulate matter (PM) emission regulations. In this paper, a real-time implementable, integrated engine-aftertreatment control framework was proposed to coordinate a modern Diesel engine with the coupled urea-based selective catalytic reduction (SCR) system for achieving close-to-optimal engine efficiency while meeting tight tailpipe NOx and NH3 slip requirements. With engine-out NOx emissions being considered as an additional active control input (other than urea solution injection rate) to the SCR system, both engine fuel efficiency and tailpipe emissions were incorporated in the new multi-input SCR control problem formulation. Nonlinear backstepping-based control allocation algorithms were designed to intentionally increase engine-out NOx emissions without sacrificing the…
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Thermally Durable Zeolite Based SCR Catalysts for Controlling NOx Emissions in Diesel Exhaust to Meet BS VI Norms

Ecocat India Pvt, Ltd.-Vishnuvarthan Muthusamy, Matti Harkonen, Arvind Kumar, Alok Trigunayat, Bosco Rajan
Published 2019-01-09 by SAE International in United States
From the recent past, automotive exhaust emission management strategies has been progressing towards an alternative for vanadia based selective catalytic reduction (V-SCR) of NOx in diesel powered vehicles. Some of the major inadequacies of existing V-SCR technology were as follows: poor thermal endurance (deteriorates at 550°-600°C), volatilization of harmful vanadium into environment and inadequate NO2 conversion.Metal incorporated zeolite systems, (the metals being preferably selected from transition metal elements), has gained momentum for commercial DeNOx applications. However, the major challenge with this zeolite SCR (Z-SCR) was its low thermal/hydrothermal stability. In the current study, it has been attempted to overcome this by various zeolites and metals combinations. Various combinations of metallic Z-SCR were extensively studied for their low and high temperature activities. The host zeolites were selected on the basis of various properties such as surface area, crystallinity, crystal size and pore opening etc. The active transition metals were also selected based on its affinity to react and attach with the zeolytic framework elements. It has been observed that when the selected transition metal is substituted…
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Medium/Heavy-Duty E/E Systems Diagnosis Nomenclature

Truck Bus Control and Communications Network Committee
  • Ground Vehicle Standard
  • J2403_201812
  • Current
Published 2018-12-19 by SAE International in United States
This SAE Recommended Practice is applicable to all E/E systems on MD and HD vehicles. The terms defined are largely focused on compression-ignited and spark-ignited engines. Specific applications of this document include diagnostic, service and repair manuals, bulletins and updates, training manuals, repair data bases, under-hood emission labels, and emission certification applications. This document focuses on diagnostic terms, definitions, abbreviations, and acronyms applicable to E/E systems. It also covers mechanical systems which require definition. Nothing in this document should be construed as prohibiting the introduction of a term, abbreviation, or acronym not covered by this document. The use and appropriate updating of this document is strongly encouraged. Certain terms have already been in common use and are readily understood by manufacturers and technicians, but do not follow the methodology of this document. These terms fall into three categories: a Acronyms that do not logically fit the term. b Acronyms existing at the component level (i.e., their terms contain the base word or noun that describes the generic item that is being further defined). c Acronyms…
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Feasibility study of a near-infrared absorption sensor for detection of adulterated diesel exhaust fluid (Arla 32)

SENAI CIMATEC-Jorsiele Damasceno Cerqueira, Valéria Loureiro da Silva
UNIFACS-Paulo Alexandre Souza da Silva
Published 2018-09-03 by SAE International in United States
The Global trend to reduce toxic emissions associated with the expansion of Diesel engines usage led to the implementation of new regulations aimed at the reduction of diesel engine emissions. Since 2012, the PRONCONVE P7, which mandates a reduction in NOx emissions, has been in place in Brazil. Therefore, heavy duty vehicle manufacturers had to implement an after treatment system in new vehicles, where an aqueous urea solution (ARLA 32 in Brazil or AdBlue in some other countries) is injected into a Selective Catalytic Reduction (SCR) system to convert NOx gases into N2 and water. The Arla 32 is stored in a tank which needs to be periodically refilled at gas stations. As the ARLA 32 is an aqueous solution with no characteristic odor or color, it can be easily adulterated without any visible sign. A diluted or contaminated ARLA 32 will affect the system performance and cause significant problems for the truck owner, such as loss of engine power, greater maintenance cost and potentially damage the SCR system.In this work, we will describe the…
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CFD Modeling of Tailpipe NOx Sensor Accuracy

SAE International Journal of Engines

Cummins Emission Solutions-Apoorv Kalyankar, Achuth Munnannur, Z. Gerald Liu
  • Journal Article
  • 03-11-04-0029
Published 2018-08-08 by SAE International in United States
In a modern diesel aftertreatment system, a sensor for nitrogen oxides (NOx) placed downstream of the selective catalytic reduction (SCR) catalyst is necessary to determine if the tailpipe NOx concentration remains below the applicable On-board diagnostic (OBD) threshold. Typically the same NOx sensor also provides feedback to the dosing control module to adjust diesel exhaust fluid (DEF) dosing rate thereby controlling tailpipe NOx and ammonia emissions. However, feedback signal sent by the tailpipe NOx sensor may not always be accurate due to reasons including non-uniformity in NOx and ammonia distributions at SCR outlet. Flow based metrics from computational fluid dynamics (CFD) analyses, that are typically used to qualitatively assess NOx sensor accuracy in different designs are often inadequate. In this work, an improved CFD analysis procedure has been developed for assessing NOx sensor accuracy. This approach enables a direct comparison of NOx sensor accuracy between different sampling probe and sensor designs. This improved modeling approach was first validated against test data without spray effects by injecting gaseous NOx in a 5″ pipe. The impact of…
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