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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

Fuel Sulfur Effects on a Medium-Duty Diesel Pick-Up with a NOX Adsorber, Diesel Particle Filter Emissions Control System: 2000-Hour Aging Results

2006-04-03
2006-01-0425
Increasing fuel costs and the desire for reduced dependence on foreign oil have brought the diesel engine to the forefront of future medium-duty vehicle applications in the United States due to its higher thermal efficiency and superior durability. One of the obstacles to the increased use of diesel engines in this platform is the Tier 2 emission standards. In order to succeed, diesel vehicles must comply with emissions standards while maintaining their excellent fuel economy. The availability of technologies-such as common rail fuel injection systems, low-sulfur diesel fuel, oxides of nitrogen (NOX) adsorber catalysts or NACs, and diesel particle filters (DPFs)-allows for the development of powertrain systems that have the potential to comply with these future requirements. In support of this, the U.S. Department of Energy (DOE) has engaged in several test projects under the Advanced Petroleum Based Fuels-Diesel Emission Control (APBF-DEC) activity [1, 2, 3, 4, 5].
Technical Paper

Performance of a NOx Adsorber Catalyst/Diesel Particle Filter System for a Heavy-Duty Engine During a 2000-Hour Endurance Test

2005-04-11
2005-01-1760
In this study, a 15-L heavy-duty diesel engine and an emission control system consisting of diesel oxidation catalysts, NOx adsorber catalysts, and diesel particle filters were evaluated over the course of a 2000 hour aging study. The work is a follow-on to a previously documented development effort to establish system regeneration and sulfur management strategies. The study is one of five projects being conducted as part of the U.S. Department of Energy's Advanced Petroleum Based Fuels - Diesel Emission Control (APBF-DEC) activity. The primary objective of the study was to determine if the significant NOx and PM reduction efficiency (>90%) demonstrated in the development work could be maintained over time with a 15-ppm sulfur diesel fuel. The study showed that high NOx reduction efficiency can be restored after 2000 hours of operation and 23 desulfation cycles.
Technical Paper

Achieving Tier 2 Bin 5 Emission Levels with a Medium Duty Diesel Pick-Up and a NOX Adsorber, Diesel Particulate Filter Emissions System-Exhaust Gas Temperature Management

2004-03-08
2004-01-0584
Increasing fuel costs and the desire for reduced dependence on foreign oil has brought the diesel engine to the forefront of future medium-duty vehicle applications in the United States due to its higher thermal efficiency and superior durability. The main obstacle to the increased use of diesel engines in this platform is the upcoming extremely stringent, Tier 2 emission standard. In order to succeed, diesel vehicles must comply with emissions standards while maintaining their excellent fuel economy. The availability of technologies such as common rail fuel injection systems, low sulfur diesel fuel, NOX adsorber catalysts (NAC), and diesel particle filters (DPFs) allow the development of powertrain systems that have the potential to comply with these future requirements. In meeting the Tier 2 emissions standards, the heavy light-duty trucks (HLDTs) and medium-duty passenger vehicles (MDPVs) will face the greatest technological challenges. In support of this, the U.S.
Technical Paper

Achieving Tier 2 Bin 5 Emission Levels with a Medium Duty Diesel Pick-Up and a NOX Adsorber, Diesel Particulate Filter Emissions System - NOX Adsorber Management

2004-03-08
2004-01-0585
Increasing fuel costs and the desire for reduced dependence on foreign oil has brought the diesel engine to the forefront of future medium-duty vehicle applications in the United States due to its higher thermal efficiency and superior durability. The main obstacle to the increased use of diesel engines in this platform is the upcoming extremely stringent, Tier 2 emission standard. In order to succeed, diesel vehicles must comply with emissions standards while maintaining their excellent fuel economy. The availability of technologies such as common rail fuel injection systems, low sulfur diesel fuel, NOX adsorber catalysts (NAC), and diesel particle filters (DPFs) allow the development of powertrain systems that have the potential to comply with these future requirements. In meeting the Tier 2 emissions standards, the heavy light-duty trucks (HLDTs) and medium-duty passenger vehicles (MDPVs) will face the greatest technological challenges. In support of this, the U.S.
Technical Paper

Achieving Near - Zero Emissions on Light - Duty Gasoline Vehicles

2003-01-18
2003-26-0001
The integration of advanced emission control technologies including advanced three-way catalysts and advanced, high cell density, ultra-thin wall substrates with advanced gasoline powertrains and advanced engine controls is necessary to achieve near-zero tailpipe emission requirements like California's SULEV or PZEV light-duty certification categories. The first gasoline vehicles meeting these near-zero regulations have been introduced in California in 2001. Advanced three-way catalysts targeted for these near-zero regulations feature layered architectures, thermally stable oxygen storage components and segregated precious metal impregnation strategies. Engine calibration strategies focused on tight stoichiometric air/fuel control and fast catalyst heat-up immediately after engine start are important enablers to achieve near-zero hydrocarbon and NOx emissions.
Technical Paper

Pushing the Envelope to Near-Zero Emissions on Light-duty Gasoline Vehicles

2001-03-05
2001-01-3840
The integration of advanced emission control technologies including advanced three-way catalysts and advanced, high cell density, ultra-thin wall substrates with advanced gasoline powertrains and advanced engine controls is necessary to achieve near-zero tailpipe emission requirements like California's SULEV or PZEV light-duty certification categories. The first gasoline vehicles meeting these near-zero regulations have been introduced in California in 2001. Advanced three-way catalysts targeted for these near-zero regulations feature layered architectures, thermally stable oxygen storage components, and segregated precious metal impregnation strategies. Engine calibration strategies focused on tight stoichiometric air/fuel control and fast catalyst heat-up immediately after engine start are important enablers to achieve near-zero hydrocarbon and NOx emissions.
Technical Paper

Phased Air/Fuel Ratio Perturbation - A Fuel Control Technique for Improved Catalyst Efficiency

2000-03-06
2000-01-0891
This paper describes the results of a study that examined the mechanism of phased perturbation as an emissions control technique. Phased perturbation involves independently controlling the fuel delivered to each bank of a dual bank engine (or each cylinder of a single manifold engine), which allows the two banks to have an adjustable, relative Air/Fuel (A/F) perturbation phase-shift from one another. The phase shifted exhaust is then recombined to achieve a near stoichiometric mixture prior to entering a single underbody catalyst. Phase shifting the exhaust Air/Fuel ratio creates a situation in which both rich exhaust constituents (unburnt hydrocarbons and carbon monoxide) and lean exhaust constituents (oxygen and oxides of nitrogen) arrive at the catalyst at the same time. The results of the study showed that phased perturbation produced a significant effect on A/F control and catalyst THC, CO, and NOx efficiency.
Technical Paper

A Comparison of Emissions and Flow Restriction of Thinwall Ceramic Substrates for Low Emission Vehicles

1999-03-01
1999-01-0271
The emission and flow restriction characteristics of three different ceramic substrates with varying wall thickness and cell density (400 cpsi/6.5 mil, 600/4.3, and 600/3.5) are compared. These 106mm diameter substrates were catalyzed with similar amounts of washcoat and fabricated into catalytic converters having a total volume of 2.0 liters. A Pd/Rh catalyst technology was applied at a concentration of 6.65 g/l and a ratio of 20/1. Three sets of converters (two of each type) were aged for 100 hours on an engine dynamometer stand. After aging, the FTP performance of these converters were evaluated on an auto-driver FTP stand using a 2.4L, four-cylinder prototype engine and on a 2.4L, four-cylinder prototype vehicle. A third set of unaged converters was used for cold flow restriction measurements and vehicle acceleration tests.
Technical Paper

Using Advanced Emission Control Systems to Demonstrate LEV II ULEV on Light-Duty Gasoline Vehicles

1999-03-01
1999-01-0774
A program to demonstrate the performance of advanced emission control systems in light of the California LEV II light-duty vehicle standards and the EPA's consideration of Tier II emission standards was conducted. Two passenger cars and one light-duty pick-up truck were selected for testing, modification, and emission system performance tuning. All vehicles were 1997 Federal Tier I compliant. The advanced emission control technologies evaluated in this program included advanced three-way catalysts, high cell density substrates, and advanced thermally insulated exhaust components. Using these engine-aged advanced emission control technologies and modified stock engine control strategies (control modifications were made using an ERIC computer intercept/control system), each of the three test vehicles demonstrated FTP emission levels below the proposed California LEV II 193,000 km (120,000 mile) ULEV levels.
Technical Paper

Metal Converter Technology Using Precoated Metal Foil

1996-10-01
962080
A novel process for coating and assembling metal converters utilizing precoated foil as building blocks has been developed which yields a converter capable of withstanding typical industry specified hot vibration protocols. The precoating process used here results in uniform catalyst coating distributions with coating adhesion to the foil on a par with the coatings' adhesion to ceramic substrates. FTP and MVEG vehicle emission performance of this unique precoated metal converter design versus a more conventional dip-coated metal monolith (parts with the same volume, cell density, and tri-metal catalyst coating), exhibited improved catalyst emission breakthrough efficiencies with respect to HC, CO, and NOx after two different engine-aging protocols. These advantages were observed on three different test vehicles across most phases of these driving cycles.
Technical Paper

EHC Design Options and Performance

1996-02-01
960341
Engine-aged EHC integrated cascades with equivalent overall volumes and several different design features were evaluated for FTP emission performance on a late-model V6 test vehicle. Design options evaluated included low and high cell densities (160 cpsi vs. 400 cpsi, a non-straight flow channel geometry (160 cpsi), and several low-power, zoned heating strategies (all with 160 cpsi). Cold-start hydrocarbon emission performance for the aged low cell density, high cell density, and non-straight channel designs (all with full face heating strategies) were found to be equivalent in the under-floor location used on the test vehicle in this program.
Technical Paper

EHC Impact on Extended Hot Soak Periods

1995-10-01
952418
Emission performance of a late model vehicle equipped with an electrically-heated catalytic converter (EHC) system was evaluated after extended vehicle soak periods that ranged from 30 to 180 minutes. As soak periods lengthened, NMHC and CO emissions measured in hot transient driving cycles increased by 125 percent and 345 percent, respectively. These tests were baseline operations which had no resistance heating or secondary air injection to the converter system. Sources of increased NMHC and CO emissions as a function of vehicle soak time were both the converter system cool-down characteristics and engine restart calibration strategy. For soak periods of 30 and 60 minutes, EHC resistance heating without secondary air injection resulted in large improvements in NMHC and CO emission performance (i.e., 74 percent and 54 percent lower NMHC emissions versus no heat, no air operation after a 30- and 60-minute period, respectively).
Technical Paper

Emissions Performance of Extruded Electrically Heated Catalysts in Several Vehicle Applications

1995-02-01
950405
Low mass, extruded electrically heated catalysts (EHC) followed directly by a light-off and main converter reduced cold start non-methane hydrocarbons (NMHC) by greater than 80 percent. These reductions were demonstrated on several vehicle applications operating over the Light Duty Federal Test Procedure (FTP). To achieve this level of reduction, the design of the EHC cascade system, power level and heating time must be appropriately established. This paper discusses the impact of these design parameters on cold-start emissions reduction. From the test results, a generic empirical model was developed to predict EHC system conversion efficiency as a function of EHC power, heating time, and inlet exhaust temperature to the EHC.
Technical Paper

Alternative EHC Heating Patterns and Their Impact on Cold-Start Emissions Performance

1994-10-01
941996
EHC heating patterns which utilize zones covering less than the available inlet face cross-sectional area have been evaluated for cold-start FTP performance. Both NMHC and CO cold-start emission performance were found to be significantly reduced relative to an EHC-inactive basecase for heating patterns that covered as little as 44% of the cross-section. In low-mileage tests, NMHC and CO cold-start emission dependencies on heating patterns were found to be relatively constant for patterns with heating coverages of 44% or more of the inlet face cross-sectional area. In these low mileage tests, reductions in Bag 1 FTP NMHC and CO emissions averaged about 30% lower with the preferred zoned heating patterns relative to the EHC-inactive basecase. FTP tests run on a similar engine-aged EHC showed less asymptotic dependence on EHC zoned heating strategies.
Technical Paper

Optimization of Extruded Electrically Heated Catalysts

1994-03-01
940468
Low mass extruded electrically heated catalysts (EHC) followed directly by light-off and main converters resulted in non-methane hydrocarbon emissions (NMHC) between .020 and .023 g/mi at power levels as low as 1 kw and energy levels as low as 4 whr. These results were achieved on a 1993, 2.2 liter vehicle. The success of this system is due to rapid heat up of the catalyzed surface areas of both the heater and light-off converter. The energy added to the exhaust from both the heater and the light-off is then efficiently transferred to the main converter. In addition, the impact of power and energy on NMHC levels was determined. The Ultra-Low Emissions Vehicle (ULEV) standard was also achieved with uncatalyzed heaters and on a 1990, 3.8 L vehicle. The new California Low Emission Vehicle (LEV) and Ultra Low Emission Vehicle (ULEV) standards require a significant reduction in tail pipe emissions compared to current standards.
Technical Paper

Fuel Effects on Emissions from an Advanced Technology Vehicle, Part II

1994-03-01
940783
A 1991 Toyota Camry equipped with an electrically-heated catalyst/light-off converter system was evaluated for emissions in duplicate over the light-duty Federal Test Procedure (FTP) with three different fuels. Evaluations were conducted with the electrically heated catalyst (EHC) in place, both without any external heating and with the EHC operated using a post-crank heating strategy The EHC system was placed immediately upstream of an original production catalyst which was located 40.6 cm from the exhaust manifold. The three test fuels were: 1) a fuel meeting California's Phase II gasoline specifications; 2) a low-sulfur (48 ppm) version of the Auto/Oil industry average gasoline; and 3) the Auto/Oil industry average gasoline, RF-A. On average, NMOG emissions and the ozone forming potential of the exhaust hydrocarbons exhibited the following trend for tests run in unheated and EHC-active modes: Phase II < low-sulfur RF-A < RF-A.
Technical Paper

Electrically Heated Catalysts and Reformulated Gasolines

1993-03-01
930385
A 1991 Volvo model 960 equipped with an electrically heated catalytic converter system (EHC) was evaluated in multiple FTP tests with three different gasolines: current certification fuel, the Auto/Oil industry average fuel (RF-A), and a fuel that meets the 1996 California Phase II reformulated gasoline standards. Tests of each fuel were run with a low-mileage EHC located upstream of either a low-mileage stock main converter or a stock converter that had been road aged for 100,000 miles under European driving conditions. Test results with EHC operation showed significant variations in NMHC, CO, and NOX emissions with the three test fuels. NMHC emissions were 2-2.5 times lower for the Phase II fuel versus RF-A, with the certification fuel intermediate in NMHC emissions. Tests with the EHC/high-mileage converter system exhibited higher overall FTP emissions compared to the EHC/low-mileage main converter system, as expected.
Technical Paper

Fuel Effects on Emissions from an Advanced Technology Vehicle

1992-10-01
922245
A 1991 Toyota Camry equipped with an electrically-heated catalyst (EHC) system was evaluated in duplicate over the Federal Test Procedure (FTP) with three different fuels. Evaluations were conducted with the EHC in place but without any external heating, and with the EHC operated with a post-crank heating strategy. The EHC system was placed immediately upstream of an original production catalyst, which was then moved to a location 40.6 cm from the exhaust manifold. The three test fuels were: 1) the Auto/Oil industry average gasoline, RF-A; 2) a fuel meeting California's Phase II gasoline specifications; and 3) a paraffinic test fuel. Non-methane organic gas (NMOG) emission rates with the EHC active were similiar with all three fuels, with absolute levels less than or equal to California's 50,000 mile Ultra-Low Emission Vehicle (ULEV) standard. Substantial differences, however were observed in the ozone forming potential of these fuels with the EHC active.
Technical Paper

DATA ANALYSIS OF INDEPENDENTLY RUN EHC PROGRAMS

1992-02-01
920850
In the last several years, there have been a number of independently run research programs evaluating the effects of electrically-heated catalysts (EHCs) on exhaust emissions from gasoline-fueled light-duty passenger vehicles. This paper “pools” data from several of these programs to determine the fleet effect by statistical methods. Evaluation of the overall data set from the eight car fleet indicates a very large reduction in total hydrocarbon (THC) and carbon monoxide (CO) but an accompanying increase (appreciably smaller in magnitude) in oxides of nitrogen (NOx). A follow-up program is under way to examine fuel sensitivity issues.
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