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Transit buses contribute a meager amount to the U.S. criteria pollutant and greenhouse gas (GHG) inventory, but they attract a lot of attention from the public and from local government, due to their nature of operation. Transit bus fleets are often employed for the introduction of advanced heavy-duty vehicle technology and the formulation of new performance models. Emissions and fuel consumption data, gained using a chassis dynamometer, are often used to evaluate performance of these buses. However, the effect of road grade on fuel consumption and emissions most often is not accounted for in chassis dynamometer characterization. Grade effect on transit buses' fuel consumption was investigated using the road-load equation. It was observed that two parameters, including the type of terrain that buses traverse and the percentage of grade for that terrain, needed to be determined for this investigation.

Cooperative collision warning (CCW) systems use communication networks as a main component for creating situational awareness and eventually hazard detection. Simulation and analysis of such systems are generally more complicated due to the system being composed of components from very different domains of communication and vehicle safety. These components are inherently developed and modeled in different domains, as their basic operations are usually defined and engineered by researchers from different disciplines. Creating a simulation tool for CCW systems requires combining simulation models that are developed using different methodologies. As a result, a unified tool for study of such systems is not readily available. In this paper, we describe a co-simulation tool that models both components of communication and hazard prediction in one framework. The tool uses several different levels of abstraction for the communication model, while modeling the application in a precise manner.

This research numerically investigated the combustion process and exhaust emissions from a light-duty Gasoline Compression Ignition (GCI) engine operating at low load as well as medium load conditions using a commercial computational fluid dynamic (CFD) software Converge. The fuel injection strategies and thermal boundary conditions effects were examined to produce locally stratified and globally lean partially premixed compression ignition (PPCI) combustion. The effects of fuel injection pressure, number of injections, and the quantity of fuel injected in each pulse were examined and optimized for emissions and fuel consumption (FC) under the design constraints of 180 bar peak cylinder pressure (PCP) and 10 bar/° CA maximum pressure rise rate (MPRR).

Heavy-duty trucks are an important sector to evaluate when seeking fuel consumption savings and emissions reductions. With fuel costs on the rise and emissions regulations becoming stringent, vehicle manufacturers find themselves spending large amounts of capital improving their products in order to be compliant with regulations. The Powertrain System Analysis Toolkits (PSAT), developed by the Argonne National Laboratory (ANL), is a simulation tool that helps mitigate costs associated with research and automotive system design. While PSAT has been widely used to predict the fuel consumption and exhaust emissions of conventional and hybrid light-duty vehicles, it also may be employed to test heavy-duty vehicles. The intent of this study was to develop an accurate model that predicts emissions and fuel economy for heavy-duty vehicles for use within PSAT.

The objective of this study was to quantify engine-out emissions of potentially toxic compounds from a modern diesel engine operated with different fuels including 15% v/v dimethoxy methane in a low sulfur diesel fuel. Five diesel fuels were examined: a low-sulfur, low-aromatic hydrocracked (∼1 ppm) fuel, the same low sulfur fuel containing 15% v/v dimethoxy methane, a Fischer-Tropsch fuel, a CARB fuel, and an EPA number 2 certification fuel. A DaimlerChrysler OM611 CIDI engine was controlled with a SwRI Rapid Prototyping Electronic Control system. The engine was operated over 4 speed-load modes. Each operating mode and fuel combination was run in triplicate. Thirty three potentially toxic compounds were measured for each fuel and mode.

The objective of this study was to quantify the effect of pilot fuel injection on engine-out emissions of potentially toxic compounds from a modern diesel engine operated with different fuels including 15% v/v dimethoxy methane in a low-sulfur diesel fuel. Five diesel fuels were examined: a low-sulfur (∼1 ppm), low aromatic, hydrocracked fuel, the same low-sulfur fuel containing 15% v/v dimethoxy methane, a Fischer-Tropsch fuel, a California reformulated fuel, and a EPA number 2 certification fuel. A DaimlerChrysler OM611 CIDI engine was controlled with a SwRI Rapid Prototyping Electronic Control system. The pilot fuel injection was either turned off or turned on with engine control by either Location of Peak Pressure (LPP) of combustion or the original equipment manufacturer (OEM) calibration strategy. These three control strategies were compared over 2 speed-load modes run in triplicate. Thirty-three potentially toxic compounds were measured.

Adding oxygenates to diesel fuel has shown the potential for reducing particulate (PM) emissions in the exhaust. The objective of this study was to select the most promising oxygenate compounds as blending components in diesel fuel for advanced engine testing. A fuel matrix was designed to consider the effect of molecular structure and boiling point on the ability of oxygenates to reduce engine-out exhaust emissions from a modern diesel engine. Nine test fuels including a low-sulfur (∼1 ppm), low-aromatic hydrocracked base fuel and 8 oxygenate-base fuel blends were utilized. All oxygenated fuels were formulated to contain 7% wt. of oxygen. A DaimlerChrysler OM611 CIDI engine for light-duty vehicles was controlled with a SwRI Rapid Prototyping Electronic Control System. The base fuel was evaluated in four speed-load modes and oxygenated blends only in one mode. Each operating mode and fuel combination was run in triplicate.

The overall program objectives were three fold: assess the benefits and limitations of oxygenated diesel fuels on engine performance and emissions identify oxygenates most suitable for potential use in future diesel formulations based on physico-chemical properties (e.g. flash point), toxicity, biodegradability and estimated cost of production perform limited emissions and performance testing of the oxygenated diesel blends select at least two oxygenated compounds for advanced engine testing In Part 1 of this program which is described in this paper, an extensive literature review was conducted to identify potential oxygenates for blending into diesel fuels. As many as 71 oxygenates were identified for the initial screening process. Based on a set of physical and chemical properties, a screening methodology was developed to select the 8 oxygenates that will be eligible for engine testing.

A weighted composite of four engine-operating modes, representative of typical operating modes found in the US FTP driving schedule, were used to compare engine-out emissions of toxic compounds using five diesel fuels. The fuels examined were: a low-sulfur low-aromatic hydrocracked diesel fuel, the same low-sulfur fuel containing 15% v/v dimethoxy methane, a Fischer-Tropsch fuel, a CARB fuel, and a EPA number 2 diesel certification fuel. A DaimlerChrysler OM611 CIDI engine was operated over 4 speed-load modes: mode 5, 2600 RPM, 8.8 BMEP; mode 6, 2300 RPM, 4.2 BMEP; mode 10, 2000 RPM, 2.0 BMEP; mode 11, 1500 RPM, 2.6 BMEP. The four engine operating modes were weighted as follows: mode 5, 25/1200; mode 6, 200/1200; mode 10, 375/1200; and mode 11, 600/1200. Each operating mode and fuel combination was run in triplicate.

The control of NOx emissions is the greatest technical challenge in meeting future emission regulations for diesel engines. In this work, a modal analysis was performed for developing an engine control strategy to take advantage of fuel properties to minimize engine-out NOx emissions. This work focused on the use of EGR to reduce NOx while counteracting anticipated PM increases by using oxygenated fuels. A DaimlerChrysler OM611 CIDI engine for light-duty vehicles was controlled with a SwRI Rapid Prototyping Electronic Control System. Engine mapping consisted of sweeping parameters of greatest NOx impact, starting with OEM injection timing (including pilot injection) and EGR. The engine control strategy consisted of increased EGR and simultaneous modulation of both main and pilot injection timing to minimize NOx and PM emission indexes with constraints based on the impact of the modulation on BSFC, Smoke, Boost and BSHC.

The nitrogen dioxide (NO₂) emissions of compression ignition diesel engines are usually relatively small, especially when operated at medium and high loads. Recent experimental investigations have suggested that adding hydrogen (H₂) into the intake air of a diesel engine leads to a substantial increase in NO₂ emissions. The increase in NO₂ fraction in the total NOx is more pronounced at lower engine load than at medium- and high-load operation, especially when a small amount of H₂ is added. However, the chemistry causing the increased NO₂ formation in H₂-diesel dual-fuel engines has not been fully explored. In the present work, kinetics of NO and NO₂ formation in a H₂-diesel dual-fuel engine are investigated using a CFD model integrated with a reduced hydrocarbon oxidation chemistry and an oxides of nitrogen (NOx) formation mechanism. A low-load and a medium-load operating condition are selected for numerical simulations.

The objective of this paper is to present the results of diesel exhaust aftertreatment testing and analysis done under the FreedomCAR program. Nitrogen Oxides (NOx) adsorber technology was selected based on a previous investigation of various NOx aftertreatment technologies including non-thermal plasma, NOx adsorber and active lean NOx. Particulate Matter (PM) emissions were addressed by developing a catalyzed particulate filter. After various iterations of the catalyst formulation, the aftertreatment components were integrated and optimized for a light duty vehicle application. This compact exhaust aftertreatment system is dual leg and consists of a sulfur trap, NOx adsorbers, and catalyzed particulate filters (CPF). During regeneration, supplementary ARCO ECD low-sulfur diesel fuel is injected upstream of the adsorber and CPF in the exhaust. Steady state and transient emission test results with and without the exhaust aftertreatment system (EAS) are presented.

The U.S. Environmental Protection Agency (EPA) established an automobile fuel economy information program shortly after the oil embargo, effective for the 1974 model year. The U.S. Department of Energy (formerly the Federal Energy Administration) joined EPA soon afterward in sponsoring the information program. The program is aimed at furnishing consumers with information on estimated miles per gallon of new cars and light duty trucks. The mechanisms for distributing such information include mandatory display of fuel economy ratings on new vehicles, and copies of a printed Gas Mileage Guide for New Car Buyers required to be made available in car dealer showrooms. The program has gone through a number of changes over the years. Consumer interest in fuel economy has also increased in the past few years. Along with this increasing interest has come increased criticism of the EPA/EOE information program.

A number of different and perhaps conflicting claims have been made about the fuel-economy benefits of Diesel-fueled automobiles versus their gasoline-fueled counterparts. While a “traditional” figure of a 25 percent fuel-economy gain with Diesels is often used, this figure has varied due to differences in vehicle performance, driving conditions, fuel Btu content, and advances In engine design (particularly in spark-ignition engines). This paper looks at fuel economy, in the broad sense of the term, from the consumer's perspective. The analysis is based on EPA-measured fuel economy in model year 1980, actual on-road fuel economy for 1975-1980 automobiles, and recent fuel price data for gasoline and Diesel fuel. Comparisons of gasoline and Diesel fuel economy that account for these three variables are presented. Also considered is the way that gasoline and Diesel fuel economy comparisons may change in the future with changes in fuel prices, emission standards, and engine design.

Over the last century, petroleum has become the major source of energy for transportation and the raw material for petrochemical products. As a result, there are tens of thousands of experts who support the technology and contribute to the economy of this country. For people who were born, brought up, educated, and matured in a climate of using and depending on petroleum, it is most logical to think in terms of the resources, processes and products that are used to produce petroleum. If the resulting experience, knowledge and expertise is put to use, this “petroleum mentality” can be a tremendous asset in our search for and the development of new energy sources. However, only a small fraction of this pool of know-how is now being applied to new energy. Obstacles result from assuming too much and from being too comfortable and/or myoptic about the status, the potential, and the needs regarding petroleum substitutes.

Given that a transportation fuel transition away from oil will occur, this paper explores fuel selection and government involvement. Arguments are made for choosing a petroleum replacement now, establishing methanol as the fuel of choice, planning for the transition and involving government in market readiness. Mandatory introduction of methanol compatible fuel vehicles and a national fuel distribution system, so that the marketplace can accommodate methanol when it is economically viable, is proposed. The cost of this approach is comparable to that of other energy activities designed to deal with transportation's oil dependence. This approach is consistent with a free market based energy policy and offers the opportunity to limit petroleum price increases.

Automobile fuel economy standards have been controversial since they were first considered over a decade ago. The controversy has increased recently as some auto manufacturers have struggled to meet the standards. This paper addresses the question of whether a change in the form of the standard is needed to reduce the perceived problems and make the program more effective. The paper argues that the main purpose of the standards is to increase the technical level of fuel economy in all vehicles while leaving the mix of vehicle sizes largely to be determined by the market. Alternative groupings of vehicles and fuel economy measures are considered. Three alternative measures are presented in detail. Their impacts on different types of manufacturers are presented through sample calculations. The paper concludes that alternatives are needed and possible.

Alternative compression ignition engine fuels are of interest both to reduce emissions and to reduce U.S. petroleum fuel demand. A Malaysian Fischer-Tropsch gas-to-liquid fuel was compared with California #2 diesel by characterizing emissions from over the road Class 8 tractors with Caterpillar 3176 engines, using a chassis dynamometer and full scale dilution tunnel. The 5-Mile route was employed as the test schedule, with a test weight of 42,000 lb. Levels of oxides of nitrogen (NOx) were reduced by an average of 12% and particulate matter (PM) by 25% for the Fischer-Tropsch fuel over the California diesel fuel. Another distillate fuel produced catalytically from Fischer-Tropsch products originally derived from natural gas by Mossgas was also compared with 49-state #2 diesel by characterizing emissions from Detroit Diesel 6V-92 powered transit buses, three of them equipped with catalytic converters and rebuilt engines, and three without.

Natural gas is a promising alternative gaseous fuel due to its availability, economic, and environmental benefits. A solution to increase its use in the heavy-duty transportation sector is to convert existing heavy-duty compression ignition engines to spark-ignition operation by replacing the fuel injector with a spark plug and injecting the natural gas inside the intake manifold. The use of numerical simulations to design and optimize the natural gas combustion in such retrofitted engines can benefit both engine efficiency and emission. However, experimental data of natural gas combustion inside a bowl-in-piston chamber is limited. Consequently, the goal of this study was to provide high-quality experimental data from such a converted engine fueled with methane and operated at steady-state conditions, exploring variations in spark timing, engine speed and equivalence ratio.

Fuel economy and regulated emissions were measured from eight forty-foot transit buses operated on petroleum diesel and a “B20” blend of 80% diesel fuel and 20% biodiesel by volume. Use of biodiesel is attractive to displace petroleum fuel and reduce an operation's carbon footprint. Usually it is assumed that biodiesel will also reduce particulate matter (PM) emissions relative to those of petroleum diesel. Model years of the vehicles evaluated were newer 2007-08 Gillig low-floor buses, 2005 Gillig Phantom buses, and a 2002 Gillig Phantom bus. Engine technology represented three different emissions standards, and included buses with OEM diesel particulate filters. Each bus was evaluated using two transient speed-time schedules, the Orange County Transit Authority (OCTA) driving schedule which represents moderate speed urban/suburban operation and the Urban Dynamometer Driving Schedule (UDDS) which represents a mix of suburban and higher speed on-highway operation.