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Technical Paper

Performance of a NOX Adsorber and Catalyzed Particle Filter System on a Light-Duty Diesel Vehicle

2001-05-07
2001-01-1933
A prototype emissions control system consisting of a close-coupled lightoff catalyst, catalyzed diesel particle filter (CDPF), and a NOX adsorber was evaluated on a Mercedes A170 CDI. This laboratory experiment aimed to determine whether the benefits of these technologies could be utilized simultaneously to allow a light-duty diesel vehicle to achieve levels called out by U.S. Tier 2 emissions legislation. This research was carried out by driving the A170 through the U.S. Federal Test Procedure (FTP), US06, and highway fuel economy test (HFET) dynamometer driving schedules. The vehicle was fueled with a 3-ppm ultra-low sulfur fuel. Regeneration of the NOX adsorber/CDPF system was accomplished by using a laboratory in-pipe synthesis gas injection system to simulate the capabilities of advanced engine controls to produce suitable exhaust conditions. The results show that these technologies can be combined to provide high pollutant reduction efficiencies in excess of 90% for NOX and PM.
Technical Paper

Emissions Results for Dedicated Propane Chrysler Minivans: The 1996 Propane Vehicle Challenge

1997-02-24
970808
The U.S. Department of Energy, through Argonne National Laboratory, and in cooperation with Natural Resources-Canada and Chrysler Canada, sponsored and organized the 1996 Propane Vehicle Challenge (PVC). For this competition, 13 university teams from North America each received a stock Chrysler minivan to be converted to dedicated propane operation while maintaining maximum production feasibility. The converted vehicles were tested for performance (driveability, cold- and hot-start, acceleration, range, and fuel economy) and exhaust emissions. Of the 13 entries for the 1996 PVC, 10 completed all of the events scheduled, including the emissions test. The schools used a variety of fuel-management, fuel-phase and engine-control strategies, but their strategies can be summarized as three main types: liquid fuel-injection, gaseous fuel-injection, and gaseous carburetor. The converted vehicles performed similarly to the gasoline minivan.
Technical Paper

In-Cylinder Fuel Blending of Gasoline/Diesel for Improved Efficiency and Lowest Possible Emissions on a Multi-Cylinder Light-Duty Diesel Engine

2010-10-25
2010-01-2206
In-cylinder fuel blending of gasoline with diesel fuel is investigated on a multi-cylinder light-duty diesel engine as a strategy to control in-cylinder fuel reactivity for improved efficiency and lowest possible emissions. This approach was developed and demonstrated at the University of Wisconsin through modeling and single-cylinder engine experiments. The objective of this study is to better understand the potential and challenges of this method on a multi-cylinder engine. More specifically, the effect of cylinder-to-cylinder imbalances and in-cylinder charge motion as well as the potential limitations imposed by real-world turbo-machinery were investigated on a 1.9-liter four-cylinder engine. This investigation focused on one engine condition, 2300 rpm, 5.5 bar net mean effective pressure (NMEP). Gasoline was introduced with a port-fuel-injection system.
Technical Paper

Experimental Investigation of the Effects of Fuel Characteristics on High Efficiency Clean Combustion in a Light-Duty Diesel Engine

2009-11-02
2009-01-2669
An experimental study was performed to understand fuel property effects on low temperature combustion (LTC) processes in a light-duty diesel engine. These types of combustion modes are often collectively referred to as high efficiency clean combustion (HECC). A statistically designed set of research fuels, the Fuels for Advanced Combustion Engines (FACE), were used for this study. Engine conditions of 1500rpm, 2.6bar BMEP was chosen for investigating fuel property effects on HECC operation in a GM 1.9-L common rail diesel engine. The FACE fuel matrix includes nine combinations of fuel properties including cetane number (30 to 55), aromatic content (20 to 45%), and 90% distillation temperature (270 to 340°C). HECC operation was achieved with high levels of exhaust gas recirculation (EGR) and adjusting injection parameters, such as higher fuel rail pressure and single injection event, which is also known as premixed charge compression ignition (PCCI) combustion.
Technical Paper

Direct Measurement of EGR Cooler Deposit Thermal Properties for Improved Understanding of Cooler Fouling

2009-04-20
2009-01-1461
Exhaust gas recirculation (EGR) cooler fouling has become a significant issue for compliance with NOx emissions standards. This paper reports results of a study of fundamental aspects of EGR cooler fouling. An apparatus and procedure were developed to allow surrogate EGR cooler tubes to be exposed to diesel engine exhaust under controlled conditions. The resulting fouled tubes were removed and analyzed. Volatile and non-volatile deposit mass was measured for each tube. Thermal diffusivity of the deposited soot cake was measured by milling a window into the tube and using the Xenon flash lamp method. The heat capacity of the deposit was measured at temperatures up to 430°C and was slightly higher than graphite, presumably due to the presence of hydrocarbons. These measurements were combined to allow calculation of the deposit thermal conductivity, which was determined to be 0.041 W/mK, only ∼1.5 times that of air and much lower than the 304 stainless steel tube (14.7 W/mK).
Technical Paper

Numerical Modeling and Experimental Investigations of EGR Cooler Fouling in a Diesel Engine

2009-04-20
2009-01-1506
EGR coolers are mainly used on diesel engines to reduce intake charge temperature and thus reduce emissions of NOx and PM. Soot and hydrocarbon deposition in the EGR cooler reduces heat transfer efficiency of the cooler and increases emissions and pressure drop across the cooler. They may also be acidic and corrosive. Fouling has been always treated as an approximate factor in heat exchanger designs and it has not been modeled in detail. The aim of this paper is to look into fouling formation in an EGR cooler of a diesel engine. A 1-D model is developed to predict and calculate EGR cooler fouling amount and distribution across a concentric tube heat exchanger with a constant wall temperature. The model is compared to an experiment that is designed for correlation of the model. Effectiveness, mass deposition, and pressure drop are the parameters that have been compared. The results of the model are in a good agreement with the experimental data.
Technical Paper

Lubricating Oil Consumption on the Standard Road Cycle

2013-04-08
2013-01-0884
Automobile manufacturers strive to minimize oil consumption from their engines due to the need to maintain emissions compliance over the vehicle life. Engine oil can contribute directly to organic gas and particle emissions as well as accelerate emissions degradation due to catalyst poisoning. During the Department of Energy Intermediate Ethanol Blends Catalyst Durability program, vehicles were aged using the Standard Road Cycle (SRC). In this program, matched sets of three or four vehicles were acquired; each vehicle of a set was aged on ethanol-free retail gasoline, or the same base gasoline blended with 10, 15, or 20% ethanol (E0, E10, E15, E20). The primary purpose of the program was to assess any changes in tailpipe emissions due to the use of increased levels of ethanol. Oil consumption was tracked during the program so that any measured emissions degradation could be appropriately attributed to fuel use or to excessive oil consumption.
Technical Paper

Soybean and Coconut Biodiesel Fuel Effects on Combustion Characteristics in a Light-Duty Diesel Engine

2008-10-06
2008-01-2501
This study investigated the effects of soybean- and coconut-derived biodiesel fuels on combustion characteristics in a 1.7-liter direct injection, common rail diesel engine. Five sets of fuels were studied: 2007 ultra low sulfur diesel (ULSD), 5% and 20% volumetric blends of soybean biodiesel with ULSD (soybean B5 and B20), and 5% and 20% volumetric blends of coconut biodiesel with ULSD (coconut B5 and B20). In conventional diesel combustion mode, particulate matter (PM) and nitrogen oxides (NOx) emissions were similar for all fuels studied except soybean B20. Soybean B20 produced the lowest PM but the highest NOx emissions. Compared with conventional diesel combustion mode, high efficiency clean combustion (HECC) mode, achieved by increased EGR and combustion phasing, significantly reduced both PM and NOx emissions for all fuels studied at the expense of higher hydrocarbon (HC) and carbon monoxide (CO) emissions and an increase in fuel consumption (less than 4%).
Technical Paper

Effectiveness Stabilization and Plugging in EGR Cooler Fouling

2014-04-01
2014-01-0640
Fouling in EGR coolers occurs because of the presence of soot and condensable species (such as hydrocarbons) in the gas stream. Fouling leads to one of two possible outcomes: stabilization of effectiveness and plugging of the gas passages within the cooler. Deposit formation in the cooler under high-temperature conditions results in a fractal deposit that has a characteristic thermal conductivity of ∼0.033 W/m*K and a density of 0.0224 g/cm3. Effectiveness becomes much less sensitive to changes in thermal resistance as fouling proceeds, creating the appearance of “stabilization” even in the presence of ongoing, albeit slow, deposit growth. Plugging occurs when the deposit thermal resistance is several times lower because of the presence of large amounts of condensed species. The deposition mechanism in this case appears to be soot deposition into a liquid film, which results in increased packing efficiency and decreased void space in the deposit relative to high-temperature deposits.
Technical Paper

Analysis of Lacquer Deposits and Plugging Found in Field-Tested EGR Coolers

2014-04-01
2014-01-0629
All high-pressure exhaust gas recirculation (EGR) coolers become fouled during operation due to thermophoresis of particulate matter and condensation of hydrocarbons present in diesel exhaust. In some EGR coolers, fouling is so severe that deposits form plugs strong enough to occlude the gas passages thereby causing a complete failure of the EGR system. In order to better understand plugging and means of reducing its undesirable performance degradation, EGR coolers exhibiting plugging were requested from and provided by industry EGR engineers. Two of these coolers contained glassy, brittle, lacquer-like deposits which were analyzed using gas chromatography-mass spectrometry (GC-MS) which identified large amounts of oxygenated polycyclic aromatic hydrocarbons (PAHs). Another cooler exhibited similar species to the lacquer but at a lower concentration with more soot.
Technical Paper

Neutron Tomography of Exhaust Gas Recirculation Cooler Deposits

2014-04-01
2014-01-0628
Exhaust gas recirculation (EGR) cooler fouling has become a significant issue for compliance with NOx emissions standards. Exhaust gas laden with particulate matter flows through the EGR cooler which causes deposits to form through thermophoresis and condensation. The low thermal conductivity of the resulting deposit reduces the effectiveness of the EGR system. In order to better understand this phenomenon, industry-provided coolers were characterized using neutron tomography. Neutrons are strongly attenuated by hydrogen but only weakly by metals which allows for non-destructive imaging of the deposit through the metal heat exchanger. Multiple 2-D projections of cooler sections were acquired by rotating the sample around the axis of symmetry with the spatial resolution of each image equal to ∼70 μm. A 3-D tomographic set was then reconstructed, from which slices through the cooler sections were extracted across different planes.
Technical Paper

An Estimate of Diesel High-Efficiency Clean Combustion Impacts on FTP-75 Aftertreatment Requirements

2006-10-16
2006-01-3311
A modified Mercedes 1.7-liter, direct-injection diesel engine was operated in both normal and high-efficiency clean combustion (HECC) combustion modes. Four steady-state engine operating points that were previously identified by the Ad-hoc fuels working group were used as test points to allow estimation of the hot-start FTP-75 emissions levels in both normal and HECC combustion modes. The results indicate that operation in HECC modes generally produce reductions in NOX and PM emissions at the expense of CO, NMHC, and H2CO emissions. The FTP emissions estimates indicate that aftertreatment requirements for NOX are reduced, while those for PM may not be impacted. Cycle-average aftertreatment requirements for CO, NMHC, and H2CO may be challenging, especially at the lowest temperature conditions.
Technical Paper

Catalyzed Diesel Particulate Filter Performance in A Light-Duty Vehicle

2000-10-16
2000-01-2848
Light-duty chassis dynamometer driving cycle tests were conducted on a Mercedes A170 diesel vehicle with various sulfur-level fuels and exhaust emission control systems. Triplicate runs of a modified light-duty federal test procedure (FTP), US06 cycle, and SCO3 cycle were conducted with each exhaust configuration and fuel. Ultra-low sulfur (3-ppm) diesel fuel was doped to 30- and 150-ppm sulfur so ppm sulfur so that all other fuel properties remained the same. The fuels used in these experiments met the specifications of the fuels from the DECSE (Diesel Emission Control Sulfur Effects) program. Although the Mercedes A170 vehicle is not available in the United States, its emissions in the as tested condition fell within the U.S. Tier 1 full useful life standards with the OEM catalysts installed. Tests with the OEM catalysts removed showed that the OEM catalysts reduced PM emissions from the engine-out condition by 30-40% but had negligible effects on NOx emissions.
Technical Paper

Particulate Emissions from a Pre-Emissions Control Era Spark-Ignition Vehicle: A Historical Benchmark

2000-06-19
2000-01-2213
This study examined the particulate emissions from a pre-emissions control era vehicle operated on both leaded and unleaded fuels for the purpose of establishing a historical benchmark. A pre-control vehicle was located that had been rebuilt with factory original parts to approximate an as-new vehicle prior to 1968. The vehicle had less than 20,000 miles on the rebuilt engine and exhaust. The vehicle underwent repeated FTP-75 tests to determine its regulated emissions, including particulate mass. Additionally, measurements of the particulate size distribution were made, as well as particulate lead concentration. These tests were conducted first with UTG96 certification fuel, followed by UTG96 doped with tetraethyl lead to approximate 1968 levels. Results of these tests, including transmission electron micrographs of individual particles from both the leaded and unleaded case are presented. The FTP composite PM emissions from this vehicle averaged 40.5 mg/mile using unleaded fuel.
Technical Paper

Implications of Particulate and Precursor Compounds Formed During High-Efficiency Clean Combustion in a Diesel Engine

2005-10-24
2005-01-3844
Advanced diesel combustion modes offer the promise of reduced engine-out particulate and nitrogen oxide emissions, thereby reducing the demand on post-combustion emission control devices. In this activity, a light-duty diesel engine was operated in conventional and advanced combustion modes. The advanced combustion modes investigated correspond to both clean (i.e., low PM and low NOX) and clean efficient combustion. The low-NOX, low-PM mode is considered an intermediate condition and the low-NOX, low-PM efficient mode is referred to as high efficiency clean combustion (HECC). Particulate and gaseous emissions were analyzed during all of these experiments. The detailed exhaust chemistry analysis provided significant new information to improving our understanding of these modes as well as identifying potentially important unregulated emissions.
Technical Paper

Fuel Property Effects on Emissions from High Efficiency Clean Combustion in a Diesel Engine

2006-04-03
2006-01-0080
High-efficiency clean combustion (HECC) modes provide simultaneous reductions in diesel particulate matter and nitrogen-oxides emissions while retaining efficiencies characteristic of normal diesel engines. Fuel parameters may have significant impacts on the ability to operate in HECC modes and on the emissions produced in HECC modes. In this study, 3 diesel-range fuels and 2 oxygenated blends are burned in both normal and HECC modes at 3 different engine conditions. The results show that fuel effects play an important role in the emissions of hydrocarbons, particulate matter, and carbon monoxide but do not significantly impact NOx emissions in HECC modes. HECC modes are achievable with 5% biodiesel blends in addition to petroleum-based and oil-sands derived fuels. Soot precursor and oxygenated compound concentrations in the exhaust were observed to generally increase with the sooting tendency of the fuel in HECC modes.
Technical Paper

NOx Adsorber Performance In A Light-Duty Diesel Vehicle

2000-10-16
2000-01-2912
Light-duty chassis dynamometer driving cycle tests were conducted on a Mercedes A170 diesel vehicle with various sulfur-level fuels and exhaust emission control systems. Triplicate runs of a modified light-duty federal test procedure (FTP), US06 cycle, and SCO3 cycle were conducted with each exhaust configuration and fuel. The fuels used in these experiments met the specifications of the fuels from the DECSE (Diesel Emission Control Sulfur Effects) program (1, 2, 3 and 4)1. Ultra-low sulfur (3 ppm) diesel fuel was doped to 30 and 150 ppm sulfur so that all fuel properties except sulfur content would be the same. Although the Mercedes A170 vehicle is not certified for sale in the United States, its particulate matter (PM) and nitrogen oxide (NOx) emissions in the as-tested condition were within the Environmental Protection Agency's Tier 1 full useful life standards with its OEM oxidation catalysts installed. Engine-out tests showed that the OEM catalysts reduce PM by 30-40%.
Technical Paper

Exhaust Chemistry of Low-NOX, Low-PM Diesel Combustion

2004-03-08
2004-01-0114
The exhaust chemistry of combustion regimes characterized by simultaneous low-NOX and low-PM emissions were investigated on a Mercedes 1.7-L diesel engine. Two approaches for entering low-NOX low-PM regimes were explored using a California specification low aromatic certification diesel fuel. Detailed characterizations of gas-phase hydrocarbons, particulate soluble organics, and aldehydes are presented for both approaches. Results indicate significant formation of partially oxygenated hydrocarbons and fuel reformation products during periods of low-NOX, low-PM combustion.
Technical Paper

Effects of Regeneration Conditions on NOX Adsorber Performance

2002-10-21
2002-01-2876
A 1999 Mercedes A170 CDI has been equipped with prototype NOX adsorber devices in order to study the impacts of regeneration conditions on the emissions reduction performance of the devices. This study consisted of a number of laboratory experiments utilizing a bottled-gas injection system to periodically provide fuel-rich exhaust conditions for device regeneration. The NOX adsorbers were evaluated on the LA4 driving cycle using a fixed regeneration schedule. The rich-pulse duration and minimum air/fuel ratio during the rich pulse were varied and the impacts upon pollutant emission rates measured. Results are presented for 5 prototype NOX adsorbers.
Technical Paper

A Thermal Conductivity Approach for Measuring Hydrogen in Engine Exhaust

2004-10-25
2004-01-2908
Thermal conductivity detection has long been used in gas chromatography to detect hydrogen and other diatomic gases in a gas sample. Thermal conductivity instruments that are not coupled to gas chromatographs are useful for detecting hydrogen in binary gas mixtures, but suffer from significant cross-interference from other gas species that are separated when the detector is used with a gas chromatograph. This study reports a method for using a commercially-available thermal conductivity instrument to detect and quantify hydrogen in a diesel exhaust stream. The instrument time response of approximately 40 seconds is sufficient for steady-state applications. Cross-interference from relevant gas species are quantified and discussed. Measurement uncertainty associated with the corrections for the various species is estimated and practical implications for use of the instrument and method are discussed.
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