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A program has been completed to evaluate ultra-low sulfur diesel fuels and passive diesel particulate filters (DPFs) in truck and bus fleets operating in southern California. The fuels, ECD and ECD-1, are produced by ARCO (a BP Company) and have less than 15 ppm sulfur content. Vehicles were retrofitted with two types of catalyzed DPFs, and operated on ultra-low sulfur diesel fuel for over one year. Exhaust emissions, fuel economy and operating cost data were collected for the test vehicles, and compared with baseline control vehicles. Regulated emissions are presented from two rounds of tests. The first round emissions tests were conducted shortly after the vehicles were retrofitted with the DPFs. The second round emissions tests were conducted following approximately one year of operation. Several of the vehicles retrofitted with DPFs accumulated well over 100,000 miles of operation between test rounds.

Meeting the California Medium-Duty truck emissions standards presents a significant challenge to automotive engineers due to the combination of sustained high temperature exhaust conditions, high flow rates and relatively high engine out emissions. A successful catalyst for an exhaust treatment system must be resistant to high temperature deactivation, maintain cold start performance and display high three-way conversion efficiencies under most operating conditions. This paper describes a catalyst technology and precious metal loading study targeting a California Medium-Duty truck LEV (MDV2) application. At the same time a direction is presented for optimizing toward the Federal Tier 1 standard through reduction of precious metal use. The paper identifies catalytic formulations for a twin substrate, 1.23 L medium-coupled converter. Two are used per vehicle, mounted 45 cm downstream of each manifold on a 5.7 L V8 engine.

As connected and automated vehicle technologies emerge and proliferate, lower frequency vehicle trajectory data is becoming more widely available. In some cases, entire fleets are streaming position, speed, and telemetry at sample rates of less than 10 seconds. This presents opportunities to apply powertrain simulators such as the National Renewable Energy Laboratory’s Future Automotive Systems Technology Simulator to model how advanced powertrain technologies would perform in the real world. However, connected vehicle data tends to be available at lower temporal frequencies than the 1-10 Hz trajectories that have typically been used for powertrain simulation. Higher frequency data, typically used for simulation, is costly to collect and store and therefore is often limited in density and geography. This paper explores the suitability of lower frequency, high availability, connected vehicle data for detailed powertrain simulation.

Fuel economy estimates are provided for the CleanFleet vans operated for two years by FedEx in Southern California. Between one and three vehicle manufacturers (Chevrolet, Dodge, and Ford) supplied vans powered by compressed natural gas (CNG), propane gas, California Phase 2 reformulated gasoline (RFG), methanol (M-85), and unleaded gasoline as a control. Two electric G-Vans, manufactured by Conceptor Corporation, were supplied by Southern California Edison. Vehicle and engine technologies are representative of those available in early 1992. A total of 111 vans were assigned to FedEx delivery routes at five demonstration sites. The driver and route assignments were periodically rotated within each site to ensure that each vehicle would experience a range of driving conditions. Regression analysis was used to estimate the relationships between vehicle fuel economy and factors such as the number of miles driven and the number of delivery stops made each day.

Vehicle exhaust emissions measurements are reported for full-size panel vans operating on four alternative motor fuels and control gasoline. The emissions tests produced data on in-use vans. The vans were taken directly from commercial delivery service for testing as they accumulated mileage over a 24-month period. The alternative fuels tested were compressed natural gas, propane gas, California Phase 2 reformulated gasoline (RFG), and methanol (M-85 with 15 percent RFG). The control gasoline for the emissions tests was an industry average unleaded blend (RF-A). The vehicle technologies tested represent those options available in 1992 that were commercially available from Ford, Chrysler, and Chevrolet or which these manufacturers agreed to provide as test vans for daily use in commercial service by FedEx.

As the automobiles move closer to the ULEV, ULEV-2 and SULEV requirements, OBD (on board diagnostic) will become a design challenge. The present OBD II designs involve the use of dual oxygen sensors to monitor the hydrocarbon performance of the catalytic converter. The aim of this study was twofold: to determine the interaction of fuel sulfur and ceria in the catalyst formulation on the performance of a Pd/Rh TWC (three-way catalyst) to elucidate the sulfur and ceria interaction on the ability of the Pd/Rh catalyst to monitor the state of the catalyst relative to hydrocarbon activity and therefore it's utility in the OBD system. Catalyst samples were aged on a spark ignited engine using a “fuel cut” engine aging cycle operated for 50 hours. Maximum catalyst temperatures during this aging cycle were 850-870°C. The effect of sulfur was determined by measuring aged catalyst performance using both indolene (∼100 ppm sulfur) and premium unleaded gasoline (∼350 ppm sulfur).

The goal of this project was to demonstrate a low emissions, high efficiency heavy-duty on-highway natural gas engine. The emissions targets for this project are to demonstrate US 2010 emissions standards on the 13-mode steady state test. To meet this goal, a chemically correct combustion (stoichiometric) natural gas engine with exhaust gas recirculation (EGR) and a three way catalyst (TWC) was developed. In addition, a Sturman Industries, Inc. camless Hydraulic Valve Actuation (HVA) system was used to improve efficiency. A Volvo 11 liter diesel engine was converted to operate as a stoichiometric natural gas engine. Operating a natural gas engine with stoichiometric combustion allows for the effective use of a TWC, which can simultaneously oxidize hydrocarbons and carbon monoxide and reduce NOx. High conversion efficiencies are possible through proper control of air-fuel ratio.

European car manufacturers have traditionally used Pt/Rh or Pd/Rh TWCs with PM loadings of 40-60 g/ft3. New regulations, however have stimulated interest in high Pd loadings (100 g/ft3 or more) in order to drastically reduce HC emissions. Pd is known to have good HC oxidation activity, high thermal stability and is relatively inexpensive. However, it suffers from excessive sensitivity to poisons and is usually associated with poor NOx conversion. A research program was initiated with the goal of capturing the benefits of high Pd concentrations while minimizing its disadvantages. It was found that trimetal formulations (Pt/Pd/Rh) could achieve high NOx conversions provided the loadings of the PMs were optimized based on a Box-Behnken design. Data showing the high thermal stability and low H2S emissions of these new “TriMax” catalysts will be presented. Their high performance has led to commercial acceptance by several European car manufacturers.

The key hurdles to achieving wide consumer acceptance of battery electric vehicles (BEVs) are weather-dependent drive range, higher cost, and limited battery life. These translate into a strong need to reduce a significant energy drain and resulting drive range loss due to auxiliary electrical loads the predominant of which is the cabin thermal management load. Studies have shown that thermal sub-system loads can reduce the drive range by as much as 45% under ambient temperatures below −10 °C. Often, cabin heating relies purely on positive temperature coefficient (PTC) resistive heating, contributing to a significant range loss. Reducing this range loss may improve consumer acceptance of BEVs. The authors present a unified thermal management system (UTEMPRA) that satisfies diverse thermal and design needs of the auxiliary loads in BEVs.

Due to its high efficiency and superior durability the diesel engine is again becoming a prime candidate for future light-duty vehicle applications within the United States. While in Europe the overall diesel share exceeds 40%, the current diesel share in the U.S. is 1%. Despite the current situation and the very stringent Tier 2 emission standards, efforts are being made to introduce the diesel engine back into the U.S. market. In order to succeed, these vehicles have to comply with emissions standards over a 120,000 miles distance while maintaining their excellent fuel economy. The availability of technologies such as high-pressure common-rail fuel 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 the light-duty Tier 2 emission requirements. In support of this, the U.S.

Urea based mobile Selective Catalytic Reduction (SCR) systems typically use a pulse width modulated injector to control the amount of reductant added to the exhaust stream. Additionally, an air assist system is provided to ensure uniform distribution of the reductant in the exhaust and to prevent injector clogging. We report on the adaptation of a commercially available pulse width modulated injector for use with a urea solution and an air assist. Flow rates and flow rate reproducibility were determined at combinations of pulse width, frequency and injector pressure drop selected to span the injector operating range. After correcting for density, deviations in flowrates were determined from the published injector calibration data when using n-heptane. These deviations were not uniform across the injector map. At the combination of low pulse width and high frequency, the deviation from the published n-heptane calibration data was the greatest.

In this work, the influences of ethanol and iso-butanol blended with gasoline on engine-out and post three-way catalyst (TWC) particle size distribution and number concentration were studied using a General Motors (GM) 2.0L turbocharged spark ignition direct injection (SIDI) engine. The engine was operated using the production engine control unit (ECU) with a dynamometer controlling the engine speed and the accelerator pedal position controlling the engine load. A TSI Fast Mobility Particle Sizer (FMPS) spectrometer was used to measure the particle size distribution in the range from 5.6 to 560 nm with a sampling rate of 1 Hz. U.S. federal certification gasoline (E0), two ethanol-blended fuels (E10 and E20), and 11.7% iso-butanol blended fuel (BU12) were tested. Measurements were conducted at 10 selected steady-state engine operation conditions. Bi-modal particle size distributions were observed for all operating conditions with peak values at particle sizes of 10 nm and 70 nm.

In this paper, researchers at the National Renewable Energy Laboratory present the results of simulation studies to evaluate potential fuel savings as a result of improvements to vehicle rolling resistance, coefficient of drag, and vehicle weight as well as hybridization for four powertrains for medium-duty parcel delivery vehicles. The vehicles will be modeled and simulated over 1,290 real-world driving trips to determine the fuel savings potential based on improvements to each technology and to identify best use cases for each platform. The results of impacts of new technologies on fuel saving will be presented, and the most favorable driving routes on which to adopt them will be explored.

This paper summarizes the Next Generation Natural Gas Vehicle (NG-NGV) Program that is led by the U.S. Department Of Energy's (DOE's) Office of Heavy Vehicle Technologies (OHVT) through the National Renewable Energy Laboratory (NREL). The goal of this program is to develop and implement one Class 3-6 compressed natural gas (CNG) prototype vehicle and one Class 7-8 liquefied natural gas (LNG) prototype vehicle in the 2004 to 2007 timeframe. OHVT intends for these vehicles to have 0.5 g/bhp-hr or lower emissions of oxides of nitrogen (NOx) by 2004 and 0.2 g/bhp-hr or lower NOx by 2007. These vehicles will also have particulate matter (PM) emissions of 0.01 g/bhp-hr or lower by 2004. In addition to ambitious emissions goals, these vehicles will target life-cycle economics that are compatible with their conventionally fueled counterparts.

This paper summarizes the several of the studies in the Environmental Science Program being sponsored by DOE's Office of Heavy Vehicle Technologies (OHVT) through the National Renewable Energy Laboratory (NREL). The goal of the Environmental Science Program is to understand atmospheric impacts and potential health effects that may be caused by the use of petroleum-based fuels and alternative transportation fuels from mobile sources. The Program is regulatory-driven, and focuses on ozone, airborne particles, visibility and regional haze, air toxics, and health effects of air pollutants. Each project in the Program is designed to address policy-relevant objectives. Current projects in the Environmental Science Program have four areas of focus: improving technology for emissions measurements; vehicle emissions measurements; emission inventory development/improvement; ambient impacts, including health effects.

This paper summarizes current work in the Environmental Science & Health Effects (ES&HE) Program being sponsored by DOE's Office of Heavy Vehicle Technologies (OHVT) through the National Renewable Energy Laboratory (NREL). The program is regulatory-driven, and focuses on ozone, airborne particles, visibility and regional haze, air toxics, and health effects of air pollutants. The goal of the ES&HE Program is to understand atmospheric impacts and potential health effects that may be caused by the use of petroleum-based and alternative transportation fuels. Each project in the program is designed to address policy-relevant objectives. Studies in the ES&HE Program have four areas of focus: improving technology for emissions measurements; vehicle emissions measurements, emission inventory development/improvement; and ambient impacts, including health effects.

A NOx trap catalyst was evaluated in a light-duty diesel engine bench under steady-state speed/load conditions with alternating lean and rich exhaust streams. The NOx conversion was correlated with several engine operating and control parameters, such as speed, lean / rich timing and catalyst temperature. The NOx conversion is a result of balance between stored NOx in a lean stream and the quantity of reductant applied in a rich transient pulse. The conversion is inversely proportional to the lean / rich ratio, R, (at R< 17) and engine speed. At a given speed and lean/rich ratio, the conversion is proportional to the catalyst inlet temperature. If the temperature is too high, thermal NOx release may decrease the overall NOx conversion. With a fully regenerated NOx trap catalyst, its cumulative NOx storage, at a given trapping period (or an instantaneous NOx trapping efficiency), is proportional to engine speed.

The Diesel Emission Control - Sulfur Effects (DECSE) program is a joint U.S. government/industry program that studies the impact of diesel sulfur levels on four types of emission control systems. One type of system, Diesel Particulate Filters (DPF), removes particulate matter (PM) from the exhaust stream by collection on a filter. The critical operating issue for DPF technology is the cleaning or regeneration of the control device (by oxidation of the collected PM) to prevent plugging. However, oxidation of sulfur in the exhaust forms sulfates, which are measured as PM. Two types of tests are conducted to evaluate the impacts of fuel sulfur on DPF performance: (1) emissions tests for PM components and gases, and (2) experiments to measure the effect of fuel sulfur on the regeneration temperature required by the filter devices.

A study was performed in the spring of 2001 to chemically characterize exhaust emissions from trucks and buses fueled by various test fuels and operated with and without diesel particle filters. This study was part of a multi-year technology validation program designed to evaluate the emissions impact of ultra-low sulfur diesel fuels and passive diesel particle filters (DPF) in several different heavy-duty vehicle fleets operating in Southern California. The overall study of exhaust chemical composition included organic compounds, inorganic ions, individual elements, and particulate matter in various size-cuts. Detailed descriptions of the overall technology validation program and chemical speciation methodology have been provided in previous SAE publications (2002-01-0432 and 2002-01-0433).

Annual fuel use for long-haul truck rest period idling is estimated at 667 million gallons in the United States. The U.S. Department of Energy's National Renewable Energy Laboratory's CoolCab project aims to reduce heating, ventilating, and air conditioning (HVAC) loads and resulting fuel use from rest period idling by working closely with industry to design efficient long-haul truck climate control systems while maintaining occupant comfort. Enhancing the thermal performance of cab/sleepers will enable smaller, lighter, and more cost-effective idle reduction solutions. In order for candidate idle reduction technologies to be implemented at the original equipment manufacturer and fleet level, their effectiveness must be quantified. To address this need, a number of promising candidate technologies were evaluated through experimentation and modeling to determine their effectiveness in reducing rest period HVAC loads.