Search Results

A series of paired fuel tests were conducted comparing certification-grade highway diesel fuel with 5 to 50 vol% soy-methyl-ester biodiesel blends. Each fuel pair was tested for up to seven transient cycles representing various load conditions, using a 2006 model year Cummins ISB compression ignition engine equipped with exhaust gas recirculation. Except for the most lightly-loaded cycle, the results show statistically significant differences in NOx emission for all fuel pairs. The average NOx emissions due to biodiesel increased over each cycle, ranging from 0.9 to 6.6% and from 2.2 to 17.2% for the B20/B0 and B50/B0 fuel pairs, respectively. Significant reductions in CO and PM were observed over a majority of the cycles tested. The data also reveal that the change in NOx emissions increases linearly with the average cycle load. To complement the transient results, a single modal point was monitored daily to investigate biodiesel effects on engine operating parameters.

The U.S. Environmental Protection Agency has completed a program to demonstrate the feasibility of using low-cost engine management systems and modern, high-efficiency exhaust catalysts for nonroad spark ignition gasoline Class II engines (sub-19 kW, greater than 225 cc). Low-cost electronic engine management and fuel injection systems originally developed for motor-scooter and small motorcycle applications were installed on two 500cc single-cylinder spark-ignition lawn-and-garden engines. Integrated catalyst-muffler systems were developed for both engines and fuel control was calibrated to achieve emission control goals while maintaining or improving fuel consumption, engine durability and performance. NOx+HC emissions were reduced approximately 75% and brake-specific fuel-consumption improved by 6 to 12%. .

A 5.9 liter medium-heavy-duty diesel engine, meeting the emissions performance of a MY 2000 US heavy-duty on-highway engine, was tested with and without a diesel exhaust emission control system consisting of catalyzed diesel particulate filters and adsorber catalysts NOx arranged in a four-flow path configuration. This four-flow path system represents a significant reduction in catalyst volume when compared to previous systems tested by EPA. The goal of this project was to achieve high NOx reduction over the Heavy-Duty Diesel Engine Federal Test Procedure (HDDE-FTP) and Supplemental Emission Test (SET), consistent with the 2007 U.S. heavy-duty engine emissions standards, using this reduced volume system. Supply of hydrocarbon reductant for NOx adsorber regeneration was accomplished via a secondary exhaust fuel injection system.

A diesel exhaust emission control system consisting of catalyzed diesel particulate filters and NOx adsorber catalysts arranged in a dual-path configuration was developed and evaluated using a 1999-specification 5.9 liter medium-heavy-duty diesel engine. NOx adsorber regeneration was accomplished via a secondary exhaust fuel injection system. An alternating restriction of the exhaust flow between the two flow paths allowed injection and adsorber regeneration to occur under very low space velocity conditions. NOx and PM reductions in excess of 90% were observed over a broad range of steady-state operating conditions and over the hot-start HDDE-FTP transient cycle.

The U.S. Environmental Protection Agency (U.S. EPA) has been conducting a test program to evaluate efforts to bring light-duty diesel vehicles into compliance with U.S. Federal Tier 2 Light-duty Emission Standards. Between April 2002 and October 2003, five advanced prototype light-duty diesel vehicles equipped with NOx adsorption catalysts, PM-traps, and diesel oxidation catalysts were tested at the U.S. EPA's National Vehicle and Fuel Emission Laboratory (NVFEL). The vehicle testing was conducted using low sulfur (<15 ppm) diesel fuel. All of the tested vehicles demonstrated the considerable progress recently made by vehicle manufacturers and systems integrators in applying advanced NOx and PM emission control technology to light duty diesel vehicles in anticipation of the U.S. Light-duty Tier 2 emission standards. PM emissions for all of the vehicles were well below the Tier 2 Bin-5 emission levels.

A 5.9 liter medium-heavy-duty diesel engine was modified to approximate the emissions performance of a MY 2004 US heavy-duty on-highway engine. The engine was tested with and without a diesel exhaust emission control system consisting of catalyzed diesel particulate filters and NOx adsorber catalysts arranged in a dual-path configuration. The goal of this project was to achieve hot-start HDDE-FTP emissions consistent with the recently announced 2007 U.S. heavy-duty engine emissions standards. Supply of hydrocarbon reductant for NOx adsorber regeneration was accomplished via a secondary exhaust fuel injection system. An alternating restriction of the exhaust flow between the two flow paths allowed injection and adsorber regeneration to occur under very low space velocity conditions. NOx and PM emissions over the hot-start portion of the HDDE-FTP transient cycle were 0.13 g/bhp-hr and less than 0.002 g/bhp-hr, respectively.

An advanced prototype of the Toyota Avensis light-duty diesel vehicle equipped with a version of Toyota's DPNR exhaust emission control system was tested at the U.S. EPA - NVFEL facility. The vehicle is under development by Toyota Motor Corporation for introduction in Europe. While this particular model is not anticipated to be offered for sale in the U.S., EPA evaluated the vehicle to gauge the current state of light-duty diesel vehicle technology. The vehicle was tested using a low sulfur (6 ppm) diesel fuel with a cetane number that was improved to near typical European levels (∼50 cetane). Emission levels over the FTP75 consistent with U.S. Federal Light-Duty Tier 2 emission standards were achieved at levels of fuel economy that are competitive with current light-duty diesel passenger vehicles offered for sale in the U.S. The vehicle was tested with relatively low accumulated mileage.

A 5.9 liter medium-heavy-duty diesel engine, equipped with a diesel exhaust emission control system consisting of catalyzed diesel particulate filters (CDPF) and NOx adsorber catalysts arranged in a dual-path configuration, was evaluated with the goal of developing desulfation strategies for in-use NOx adsorber desulfation. NOx adsorber desulfation was accomplished by providing reductant via a secondary exhaust fuel injection system and exhaust flow via an exhaust bypass valve. An alternating restriction of the exhaust flow between the two flow paths allowed reductant injection and adsorber desulfation to occur under very low space velocity conditions. An exhaust bypass valve connecting the dual path configuration upstream of the catalyzed diesel particulate filters allowed controlled addition of exhaust into the desulfating pathway for desulfation method development.

A 5.9-liter medium-heavy-duty diesel engine, equipped with a diesel exhaust emission control system consisting of catalyzed diesel particulate filters and NOx adsorber catalysts arranged in a dual flow path configuration was evaluated with the goal of studying the thermal aging characteristics of a number of NOx adsorber formulations. These adsorbers were tested with near zero sulfur fuel and low sulfur engine oil to minimize the impact of sulfur poisoning on the test results. Testing was performed at a high temperature engine operating mode to provide accelerated but not abusive aging. The test duration ranged from 100 to 250 hours depending on the severity of the aging at the 100 hour mark. The initial “zero” sulfur testing screened the NOx adsorber formulations for future testing and established a thermal aging baseline.

The U.S. Environmental Protection Agency initiated a program to demonstrate feasibility of the Tier 2 emissions standards for the largest vehicles regulated under the new standards. Advanced emission control systems were developed and evaluated using a large 1999 sport utility vehicle and a large 1999 light-duty pickup truck. The trucks were originally certified to California LEV-I or Federal Tier 1 emission standards. Advanced, high-cell density, ceramic and metallic substrate three-way catalysts were thermally aged to the equivalent of 80,000 km (50,000 miles) and integrated into the exhaust systems for evaluation. Low mass, thermally insulated exhaust system components were fabricated and evaluated. Engine control strategies were modified via ROM-emulation and powertrain control module (PCM) flash reprogramming. Both of the tested trucks demonstrated FTP emissions at levels below 2004 U.S Federal Tier 2 emissions standards.