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Singh, Navtej
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Achieving Ultra-Low NOx Tailpipe Emissions with a High Efficiency Engine

Navistar Inc-Navtej Singh, Paul Charintranond, Josh Manis
Navistar Inc.-Brad Adelman
  • Technical Paper
  • 2020-01-1403
To be published on 2020-04-14 by SAE International in United States
Future regulatory targets for diesel engines pose unique challenges to achieve lower greenhouse gas (GHG) emissions concomitant with lower tailpipe (TP) NOx emissions. Generally, lower GHG emissions are achieved via combustion that generates higher engine out (EO) NOx and lower exhaust gas temperatures. To achieve the lower TP NOx targets with higher EO NOx and lower exhaust gas temperatures will require new aftertreatment architectures. North American on-highway heavy duty diesel (HDD) engines have traditionally used a DOC and DPF since the introduction of the US 2007 emission limits. For these systems, NOx control was achieved using engine calibration parameters. Starting in 2010, this system was augmented with a downstream SCR system. This allowed engine manufacturers to maintain the 2007 EO emission levels while relying on the SCR system to provide an additional 90% NOx reduction to meet the US 2010 limits of 0.2 g/hp.hr NOx. In subsequent years, emission regulations have introduced more stringent GHG limits which have been achieved by increasing EO NOx and relying on higher NOx conversion over the SCR. Unfortunately there…
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Ultra-Low NOx Emission Prediction for Heavy Duty Diesel Applications Using a Map-Based Approach

Navistar Inc.-Navtej Singh, Brad Adelman, Srinivasulu Malagari
Ohio State University-Kyle Hickey
Published 2019-04-02 by SAE International in United States
As vehicle emissions regulations become increasingly stringent, there is a growing need to accurately model aftertreatment systems to aid in the development of ultra-low NOx vehicles. Common solutions to this problem include the development of complex chemical models or expansive neural networks. This paper aims to present the development process of a simpler Selective Catalytic Reduction (SCR) conversion efficiency Simulink model for the purposes of modeling tail pipe NOx emission levels based on various inputs, temperature shifts and SCR locations, arrangements and/or sizes in the system. The main objective is to utilize this model to predict tail pipe NOx emissions of the EPA Federal Test Procedures for heavy-duty vehicles. The model presented within is focused exclusively on heavy-duty application compression ignition engines and their corresponding aftertreatment setups. The accuracy of the model depends heavily on the ability to gain precise and repeatable test cell data to calculate an expansive SCR conversion efficiency map for the given aftertreatment system. This conversion efficiency map is verifiable based on expected/known chemical and physical properties of SCR aftertreatment systems.…
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Direct Injection into the Exhaust Stream of Gaseous Ammonia: Design and Efficiency of Injection and Mixing Hardware

Navistar Inc-Brad Adelman, Navtej Singh, Paul Charintranond, Greg Griffin, Shyam Santhanam, Ed Derybowski, Adam Lack
Published 2015-04-14 by SAE International in United States
Current legislative trends regarding diesel emissions are striving to achieve two seemingly competing goals: simultaneously lowering NOx and greenhouse gas (GHG) emissions. These two goals are considered at odds since lower GHG emissions (e.g. CO2) is achieved via high combustion efficiency that result in higher engine out NOx emissions and lower exhaust gas temperatures [1, 2]. Conversely, NOx reduction technologies such as SCR require temperatures above 200°C for dosing the reductant (DEF) [3, 4, 5] as well as for high conversion efficiencies [1, 2, 6, 7, 8, 9]. Dosing DEF requires injection pressures around 5 bar to ensure proper penetration into the exhaust stream as well as generate the appropriate spray pattern and droplet sizes. Dosing DEF generally requires long mixing and/or high turbulence (high restriction) areas so that the aqueous urea solution can be converted into gaseous NH3 without deposit formation [8, 10, 11, 12, 13, 14, 15]. One alternative to dosing DEF, an aqueous solution of 32.5% wt. urea, is to inject gaseous NH3. Gaseous NH3 does not require evaporation of water nor…
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Development of the NOx Emission Model for the Heavy Duty Diesel Engine Application Using Combustion Characteristic Parameters

Navistar Inc.-Navtej Singh, Prasanna Nagabushan-Venkatesh, Eduardo Nigro, Adam Lack
Published 2013-04-08 by SAE International in United States
Tighter emission norms and fuel economy demands have prompted diesel engine manufacturers to implement Aftertreatment systems for both light-duty and heavy-duty diesel applications. After implementing Diesel Particulate Filter (DPF) technology to comply with 2007 Environmental Protection Agency (EPA) emissions regulations, OEMs have turned their attention towards NOx reductions with SCR technology. Current SCR technologies include liquid based Urea injection into the exhaust stream for NOx reductions and Solid Ammonia Storage and Delivery System (ASDS) which involves dosing gaseous Ammonia. Irrespective of the technology in use, the estimation of engine-out NOx emissions plays a vital role in reductant (Urea/Ammonia) dosing estimation via feed-back controls. The general method for determination of the engine-out NOx emissions is to use commonly available NOx emission sensors (NOx Sensors). However, NOx sensors have their own drawbacks. With On-Board Diagnostics (OBD) requirements in place for the 2013 model year, the use of additional sensors translates to additional implementation costs adding up to warranty and maintenance costs. Therefore, the necessity of the virtual engine out NOx emission estimation is very important. In this…
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Exhaust Volume Flow based Time Alignment in NOx Measurements in NOx Reduction Systems

Navistar Inc.-Vijayasarathy Subramanian, Navtej Singh, Adam Lack
Published 2012-09-24 by SAE International in United States
With the emission norms becoming more and more stringent along with the focus on reducing ownership and operating costs, the need to optimize the aftertreatment system becomes much more evident. Thus, the well monitored, optimized usage of urea or ammonia (NH₃) for the NOx reduction in an SCR system is critical to reduce the operating cost of the vehicles and to comply with emission regulations. In Ammonia Storage and Delivery System (ASDS), pure gaseous NH₃ from the NH₃ cartridges is being used for the reduction of the engine-out NOx in the exhaust stream over the NPF (NOx Particulate Filter). In almost all NOx reduction systems, NOx sensors play an important role in determining the amount of urea or NH₃ to be dosed for efficient NOx reduction with minimal NH₃ consumption and slippage for best possible fluid economy. In the NH₃ dosing strategy the NOx conversion efficiency plays a vital role as a feedback variable for calculating NH₃ dosing quantity and is based on the upstream and downstream NOx sensor measurements. Since the NOx sensors are…
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Investigation into Different DPF Regeneration Strategies Based on Fuel Economy Using Integrated System Simulation

Engine Research Center, Univ of Wisconsin-Navtej Singh, Christopher J. Rutland, David E. Foster
General Motor Research and Development-Kushal Narayanaswamy, Yongsheng He
Published 2009-04-20 by SAE International in United States
An integrated system model containing sub-models for a multi-cylinder diesel engine, NOx and soot(PM) emissions, diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) has been developed to simulate the engine and aftertreatment systems at transient engine operating conditions. The objective of this work is two-fold; ensure correct implementation of the integrated system level model and apply the integrated model to understand the fuel economy trade-off for various DPF regeneration strategies.The current study focuses on a 1.9L turbocharged diesel engine and its exhaust system. The engine model was built in GT-Power and validated against experimental data at full-load conditions. The DPF model is calibrated for the current engine application by matching the clean DPF pressure drop for different mass flow rates. Load, boost pressure, speed and EGR controllers are tuned and linked with the current engine model.DPF soot loading and the impact of backpressure on engine performance is captured. DPF regeneration studies are carried out by using fuel injection ahead of the DOC and various regeneration strategies are explored. Delaying regeneration and increased loading of…
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