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Video

SCR Deactivation Kinetics for Model-Based Control and Accelerated Aging Applications

2012-06-18
Selective Catalytic Reduction (SCR) catalysts are used to reduce NOx emissions from internal combustion engines in a variety of applications [1,2,3,4]. Southwest Research Institute (SwRI) performed an Internal Research & Development project to study SCR catalyst thermal deactivation. The study included a V/W/TiO2 formulation, a Cu-zeolite formulation and a Fe-zeolite formulation. This work describes NH3 storage capacity measurement data as a function of aging time and temperature. Addressing one objective of the work, these data can be used in model-based control algorithms to calculate the current NH3 storage capacity of an SCR catalyst operating in the field, based on time and temperature history. The model-based control then uses the calculated value for effective DEF control and prevention of excessive NH3 slip. Addressing a second objective of the work, accelerated thermal aging of SCR catalysts may be achieved by elevating temperatures above normal operating temperatures.
Video

SCR Deactivation Study for OBD Applications

2012-06-18
Selective catalytic reduction (SCR) catalysts will be used to reduce oxides of nitrogen (NOx) emissions from internal combustion engines in a number of applications [1,2,3,4]. Southwest Research Institute® (SwRI)® performed an Internal Research & Development project to study SCR catalyst thermal deactivation. The study included a V/W/TiO2 formulation, a Cu-zeolite formulation and an Fe-zeolite formulation. This work describes NOx timed response to ammonia (NH3) transients as a function of thermal aging time and temperature. It has been proposed that the response time of NOx emissions to NH3 transients, effected by changes in diesel emissions fluid (DEF) injection rate, could be used as an on-board diagnostic (OBD) metric. The objective of this study was to evaluate the feasibility and practicality of this OBD approach.
Video

Brief Investigation of SCR High Temperature N2O Production

2012-06-18
Nitrous Oxide (N2O) is a greenhouse gas with a Global Warming Potential (GWP) of 298-310 [1,2] (298-310 times more potent than carbon dioxide (CO2)). As a result, any aftertreatment system that generates N2O must be well understood to be used effectively. Under low temperature conditions, N2O can be produced by Selective Catalytic Reduction (SCR) catalysts. The chemistry is reasonably well understood with N2O formed by the thermal decomposition of ammonium nitrate [3]. Ammonium nitrate and N2O form in oxides of nitrogen (NOx) gas mixtures that are high in nitrogen dioxide (NO2)[4]. This mechanism occurs at a relatively low temperature of about 200°C, and can be controlled by maintaining the nitric oxide (NO)/NO2 ratio above 1. However, N2O has also been observed at relatively high temperatures, in the region of 500°C.
Technical Paper

The Potential for Achieving Low Hydrocarbon and NOx Exhaust Emissions from Large Light-Duty Gasoline Vehicles

2007-04-16
2007-01-1261
Two large, heavy light-duty gasoline vehicles (2004 model year Ford F-150 with a 5.4 liter V8 and GMC Yukon Denali with a 6.0 liter V8) were baselined for emission performance over the FTP driving cycle in their stock configurations. Advanced emission systems were designed for both vehicles employing advanced three-way catalysts, high cell density ceramic substrates, and advanced exhaust system components. These advanced emission systems were integrated on the test vehicles and characterized for low mileage emission performance on the FTP cycle using the vehicle's stock engine calibration and, in the case of the Denali, after modifying the vehicle's stock engine calibration for improved cold-start and hot-start emission performance.
Technical Paper

Aging of Zeolite Based Automotive Hydrocarbon Traps

2007-04-16
2007-01-1058
This paper analyzes the aging of zeolite based hydrocarbon traps to guide development of diagnostic algorithms. Previous research has shown the water adsorption ability of zeolite ages along with the hydrocarbon adsorption ability, and this leads to a possible diagnostic algorithm: the water concentration in the exhaust can be measured and related to aging. In the present research, engine experiments demonstrate that temperature measurements are also related to aging. To examine the relationship between temperature-based and moisture-based diagnostic algorithms, a transient, nonlinear heat and mass transfer model of the exhaust during cold-start is developed. Despite some idealizations, the model replicates the qualitative behavior of the exhaust system. A series of parametric studies reveals the sensitivity of the system response to aging and various noise factors.
Technical Paper

An Engine Start/Stop System for Improved Fuel Economy

2007-04-16
2007-01-1777
During city traffic or heavily congested roads, a vehicle can consume a substantial amount of fuel idling when the vehicle is stopped. Due to regulation enforcement, auto manufacturers are developing systems to increase the mileage and reduce emissions. Turning off the engine at traffic lights and regenerative braking systems are simple ways to reduce emissions and fuel consumption. In order to develop strong manufacturer and consumer interest, this type of operation needs to be automated such that the stop/start functionality requires no driver interaction and takes place without the intervention of the vehicle operator. Valeo Electrical Systems has developed such a system that replaces the OEM engine alternator with a starter/alternator driven by a standard multi-ribbed V belt. To avoid a break and dual voltage network, this system is based on a 12V electrical system using an Enhanced Power Supply.
Technical Paper

Locomotive Emissions Measurements for Various Blends of Biodiesel Fuel

2013-09-08
2013-24-0106
The objective of this project was to assess the effects of various blends of biodiesel on locomotive engine exhaust emissions. Systematic, credible, and carefully designed and executed locomotive fuel effect studies produce statistically significant conclusions are very scarce, and only cover a very limited number of locomotive models. Most locomotive biodiesel work has been limited to cursory demonstration programs. Of primary concern to railroads and regulators is understanding any exhaust emission associated with biodiesel use, especially NOX emissions. In this study, emissions tests were conducted on two locomotive models, a Tier 2 EMD SD70ACe and a Tier 1+ GE Dash9-44CW with two baseline fuels, conventional EPA ASTM No. 2-D S15 (commonly referred to as ultra-low sulfur diesel - ULSD) certification diesel fuel, and commercially available California Air Resource Board (CARB) ULSD fuel.
Technical Paper

Fuel Efficiency Effects of Lubricants in Military Vehicles

2010-10-25
2010-01-2180
The US Army is currently seeking to reduce fuel consumption by utilizing fuel efficient lubricants in its ground vehicle fleet. An additional desire is for a lubricant which would consist of an all-season (arctic to desert), fuel efficient, multifunctional Single Common Powertrain Lubricant (SCPL) with extended drain capabilities. To quantify the fuel efficiency impact of a SCPL type fluid in the engine and transmission, current MIL-PRF-46167D arctic engine oil was used in place of MIL-PRF-2104G 15W-40 oil and SAE J1321 Fuel Consumption In-Service testing was conducted. Additionally, synthetic SAE 75W-140 gear oil was evaluated in the axles of the vehicles in place of an SAE J2360 80W-90 oil. The test vehicles used for the study were three M1083A1 5-Ton Cargo vehicles from the Family of Medium Tactical Vehicles (FMTV).
Journal Article

Performance and Emissions of Diesel and Alternative Diesel Fuels in a Heavy-duty Industry-Standard Older Engine

2010-10-25
2010-01-2281
Conventional diesel fuel has been in the market for decades and used successfully to run diesel engines of all sizes in many applications. In order to reduce emissions and to foster energy source diversity, new fuels such as alternative and renewable, as well as new fuel formulations have entered the market. These include biodiesel, gas-to-liquid, and alternative formulations by states such as California. Performance variations in fuel economy, emissions, and compatibility for these fuels have been evaluated and debated. In some cases contradictory views have surfaced. “Sustainable”, “Renewable”, and “Clean” designations have been interchanged. Adding to the confusion, results from one fuel in one type of engine such as an older heavy-duty engine, is at times compared to that of another type such as a modern light-duty. This study was an attempt to compare the performance of several fuels in an identical environment, using the same engine, for direct comparison.
Technical Paper

Performance and Emissions of Diesel and Alternative Diesel Fuels in Modern Light-Duty Diesel Vehicles

2011-09-11
2011-24-0198
Conventional diesel fuel has been in the market for decades and used successfully to run diesel engines of all sizes in many applications. In order to reduce emissions and to foster energy source diversity, new fuels such as alternative and renewable, as well as new fuel formulations have entered the market. These include biodiesel, gas-to-liquid, and alternative formulations by states such as California. Performance variations in fuel economy, emissions, and compatibility for these fuels have been evaluated and debated. In some cases contradictory views have surfaced. “Sustainable”, “Renewable”, and “Clean” designations have been interchanged. Adding to the confusion, results from one fuel in one type of engine such as an older heavy-duty engine, is at times compared to that of another fuel in another type such as a modern light-duty engine. This study was an attempt to compare the performance of several fuels in identical environments, using the same engine, for direct comparison.
Technical Paper

Effects of Cetane Number, Aromatics, and Oxygenates on Emissions From a 1994 Heavy-Duty Diesel Engine With Exhaust Catalyst

1995-02-01
950250
A Coordinating Research Council sponsored test program was conducted to determine the effects of diesel fuel properties on emissions from two heavy-duty diesel engines designed to meet EPA emission requirements for 1994. Results for a prototype 1994 DDC Series 60 were reported in SAE Paper 941020. This paper reports the results from a prototype 1994 Navistar DTA-466 engine equipped with an exhaust catalyst. A set of ten fuels having specific variations in cetane number, aromatics, and oxygen were used to study effects of these fuel properties on emissions. Using glycol diether compounds as an oxygenated additive, selected diesel fuels were treated to obtain 2 and 4 mass percent oxygen. Cetane number was increased for selected fuels using a cetane improver. Emissions were measured during transient FTP operation of the Navistar engine tuned for a nominal 5 g/hp-hr NOx, then repeated using a 4 g/hp-hr NOx calibration.
Technical Paper

Observations from Cylinder Liner Wear Studies in Heavy Duty Diesel Engines and the Evolution towards Lower Viscosity Heavy Duty Engine Lubricants

2011-04-12
2011-01-1207
Since the invention of the internal combustion engine, the contact between piston ring and cylinder liner has been a major concern for engine builders. The quality and durability of this contact has been linked to the life of the engine, its maintenance, and its exhaust gas and blowby emissions, but also to its factional properties and therefore fuel economy. While the basic design has not changed, many factors that affect the performance of the ring/liner contact have evolved and are still evolving. This paper provides an overview of observations related to the lubrication of the ring/liner contact.
Technical Paper

Dependence of Fuel Consumption on Engine Backpressure Generated by a DPF

2010-04-12
2010-01-0535
In recent years, Diesel Particulate Filter (DPF) systems have become the state-of-the-art technology to realize low particulate emission for light, medium or heavy-duty diesel vehicles. In addition to good filtration efficiency and thermo-mechanical robustness, the engine backpressure resulted from the DPF installation is an important parameter which directly impacts the fuel economy of the engine. The goal of this experimental test series was to determine the dependence of fuel consumption on engine backpressure resulted from a DPF installed on a heavy-duty application. The testing was executed on a MY2003 Volvo D12 heavy-duty diesel engine in an engine test cell at Southwest Research Institute (SwRI). Empty DPF cans were used with an exhaust valve to mimic the post turbo pressure levels for two different types of DPF materials at nine selected engine operating points of the European Stationary Cycle (ESC).
Technical Paper

Evaluation of Cold Start Technologies on a 3L Diesel Engine

2016-04-05
2016-01-0823
Increasingly stringent emissions regulations require that modern diesel aftertreatment systems must warm up and begin controlling emissions shortly after startup. While several new aftertreatment technologies have been introduced that focus on lowering the aftertreatment activation temperature, the engine system still needs to provide thermal energy to the exhaust for cold start. A study was conducted to evaluate several engine technologies that focus on improving the thermal energy that the engine system provides to the aftertreatment system while minimizing the impact on fuel economy and emissions. Studies were conducted on a modern common rail 3L diesel engine with a custom dual loop EGR system. The engine was calibrated for low engine-out NOx using various combustion strategies depending on the speed/load operating condition.
Technical Paper

Technical Approach to Increasing Fuel Economy Test Precision with Light Duty Vehicles on a Chassis Dynamometer

2016-04-05
2016-01-0907
In 2012, NHTSA and EPA extended Corporate Average Fuel Economy (CAFE) standards for light duty vehicles through the 2025 model year. The new standards require passenger cars to achieve an average of five percent annual improvement in fuel economy and light trucks to achieve three percent annual improvement. This regulatory requirement to improve fuel economy is driving research and development into fuel-saving technologies. A large portion of the current research is focused on incremental improvements in fuel economy through technologies such as new lubricant formulations. While these technologies typically yield less than two percent improvement, the gains are extremely significant and will play an increasing role in the overall effort to improve fuel economy. The ability to measure small, but statistically significant, changes in vehicle fuel economy is vital to the development of new technologies.
Technical Paper

Investigation of Urea Derived Deposits Composition in SCR Systems and Their Potential Effect on Overall PM Emissions

2016-04-05
2016-01-0989
Ideally, complete thermal decomposition of urea should produce only two products in active Selective Catalytic Reduction (SCR) systems: ammonia and carbon dioxide. In reality, urea thermal decomposition reaction includes the formation of isocyanic acid as an intermediate product. Being highly reactive, isocyanic acid can initiate the formation of larger molecular weight compounds such as cyanuric acid, biuret, melamine, ammeline, ammelide, and dicyandimide [1,2,3,4]. These compounds can be responsible for the formation of deposits on the walls of the decomposition reactor in urea SCR systems. Composition of these deposits varies with temperature exposure, and under certain conditions, can create oligomers such as melam, melem, and melon [5, 6] that are difficult to remove from exhaust systems. Deposits can affect the efficiency of the urea decomposition, and if large enough, can inhibit the exhaust flow.
Technical Paper

Evaluation of Emerging Technologies on a 1.6 L Turbocharged GDI Engine

2018-04-03
2018-01-1423
Low-pressure loop exhaust gas recirculation (LP- EGR) combined with higher compression ratio, is a technology package that has been a focus of research to increase engine thermal efficiency of downsized, turbocharged gasoline direct injection (GDI) engines. Research shows that the addition of LP-EGR reduces the propensity to knock that is experienced at higher compression ratios [1]. To investigate the interaction and compatibility between increased compression ratio and LP-EGR, a 1.6 L Turbocharged GDI engine was modified to run with LP-EGR at a higher compression ratio (12:1 versus 10.5:1) via a piston change. This paper presents the results of the baseline testing on an engine run with a prototype controller and initially tuned to mimic an original equipment manufacturer (OEM) baseline control strategy running on premium fuel (92.8 anti-knock index).
Technical Paper

Achieving Fast Catalyst Light-Off from a Heavy-Duty Stoichiometric Natural Gas Engine Capable of 0.02 g/bhp-hr NOX Emissions

2018-04-03
2018-01-1136
Recently conducted work has been funded by the California Air Resources Board (CARB) to explore the feasibility of achieving 0.02 g/bhp-hr NOX emissions for heavy-duty on-road engines. In addition to NOX emissions, greenhouse gas (GHG), CO2 and methane emissions regulations from heavy-duty engines are also becoming more stringent. To achieve low cold-start NOX and methane emissions, the exhaust aftertreatment must be brought up to temperature quickly while keeping proper air-fuel ratio control; however, a balance between catalyst light-off and fuel penalty must be addressed to meet future CO2 emissions regulations. This paper details the work executed to improve catalyst light-off for a natural gas engine with a close-coupled and an underfloor three-way-catalyst while meeting an FTP NOX emission target of 0.02 g/bhp-hr and minimizing any fuel penalty.
Technical Paper

Optimization of Heavy Duty Diesel Engine Lubricant and Coolant Pumps for Parasitic Loss Reduction

2018-04-03
2018-01-0980
As fuel economy becomes increasingly important in all markets, complete engine system optimization is required to meet future standards. In many applications, it is difficult to realize the optimum coolant or lubricant pump without first evaluating different sets of engine hardware and iterating on the flow and pressure requirements. For this study, a Heavy Duty Diesel (HDD) engine was run in a dynamometer test cell with full variability of the production coolant and lubricant pumps. Two test stands were developed to allow the engine coolant and lubricant pumps to be fully mapped during engine operation. The pumps were removed from the engine and powered by electric motors with inline torque meters. Each fluid circuit was instrumented with volume flow meters and pressure measurements at multiple locations. After development of the pump stands, research efforts were focused on hardware changes to reduce coolant and lubricant flow requirements of the HDD engine.
Technical Paper

Demonstration of a Novel, Off Road, Diesel Combustion Concept

2016-04-05
2016-01-0728
There are numerous off-road diesel engine applications. In some applications there is more focus on metrics such as initial cost, packaging and transient response and less emphasis on fuel economy. In this paper a combustion concept is presented that may be well suited to these applications. The novel combustion concept operates in two distinct operation modes: lean operation at light engine loads and stoichiometric operation at intermediate and high engine loads. One advantage to the two mode approach is the ability to simplify the aftertreatment and reduce cost. The simplified aftertreatment system utilizes a non-catalyzed diesel particulate filter (DPF) and a relatively small lean NOx trap (LNT). Under stoichiometric operation the LNT has the ability to act as a three way catalyst (TWC) for excellent control of hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx).
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