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Diesel particles are formed and also reduced during diffusion-controlled spray combustion in the chamber of a Diesel engine. In earlier investigations it was found that the particles directly sampled near the exhaust valve were irregularly shaped, having a median diameter of 50 to 100 nm. The engine combustion process is cyclic and nonuniform and is imbedded in a highly nonstationary flow. The soot particles formed during the combustion process were emitted during the opening period of the exhaust valve together with the burned gas. This results in strong time-dependent fluctuations of the particle mass density in the exhaust pipe. It is the aim of this study to measure the dynamic particle behaviour during the exhaust gas flow. Laser light scattered by the diesel particles was measured very close to the exhaust valve. The light flux signals obtained under several fixed angles showed a periodic structure and were interpreted in terms of size parameters by applying the Mie theory.

Growing concern about energy conservation and exhaust gas emissions from heavy duty engines of trucks and buses has increased the demand for the use of alternate fuels. A unique transportable testing laboratory designed to measure specific constituents of exhaust gas emissions from the engines of heavy duty vehicles operating on conventional or alternate fuels has been constructed by a team from West Virginia University. In this transportable facility, a special flat-bed trailer has been constructed to accommodate drive train units, free-rotating rollers, power-absorbing units to simulate road load, and flywheels to simulate vehicle inertia. Four hydraulic jacks are used to lower it to the ground at the fleet site. This allows the tested vehicle to be driven onto rollers embedded in the flat-bed. Hub adapters are connected at the outboard wheel locations at each side of the drive shaft of the vehicle.

A woven fiber Diesel particulate filter has been developed which demonstrates good low-mileage soot-trapping and regeneration efficiencies. The fiber filters are wound around electric heating elements, which provide uniform energy in close proximity to the soot-laden fiber during regeneration. The filters are loaded with particulate to a target backpressure and energized one at a time with intermittent particulate loading to the target backpressure between successive filter regenerations. These design features were utilized to help minimize regeneration power requirements, and maximize mileage accumulation between regenerations. Regenerations are performed with unbypassed exhaust flow and can be accomplished under high vehicle speed operation as well as under idle conditions. The passenger car system contains four filters which are approximately 20 inches long and 3.0 inches in diameter.

This paper reviews the history of heavy truck noise legislation in the U.S. Both legislative activity and the response of vehicle and engine manufacturers are described. The cost cycle experienced by manufacturers is also described. Over a period of time, the costs involved in meeting noise regulations are reduced without increasing truck noise levels. Data is presented which shows that public complaints about truck noise are often related to modified vehicle exhaust systems. The data shows that modified exhaust systems have an especially severe effect on compression brake noise. Additional results suggest that some trucks with extensively modified exhaust systems may be able to pass the in-use noise standard.

Natural Gas engines are viewed as an alternative to diesel power in the quest to reduce heavy duty vehicle emissions in polluted urban areas. In particular, it is acknowledged that natural gas has the potential to reduce the inventory of particulate matter, and this has encouraged the use of natural gas engines in transit bus applications. Extensive data on natural gas and diesel bus emissions have been gathered using two Transportable Heavy Duty Vehicle Emissions Testing Laboratories, that employ chassis dynamometers to simulate bus inertia and road load. Most of the natural gas buses tested prior to 1997 were powered by Cummins L-10 engines, which were lean-burn and employed a mechanical mixer for fuel introduction. The Central Business District (CBD) cycle was used as the test schedule.

In July 1989, Hino Motors, Ltd. launched a new medium-duty truck series called the Cruising Ranger (Fig. 1), replacing its nine-year-old conventional model. The Cruising Ranger series has been developed under the concept of a “Stylish, Driver-Friendly, Profitable Truck” with an emphasis on harmonization with the social environment. It features major changes in exterior style and interior design, and improvements in basic performance such as comfort, drivability, safety, and fuel efficiency with careful consideration given to market requirements. The series also meets the 1989 Japanese exhaust emission standards. To accomplish these design enhancements, a number of new technologies have been introduced in the Cruising Ranger.

Protection of the Earth's environment by means of energy saving and cleaning up of air pollution on a global scale is one of the most important subjects in the world today. Because of this, the requirements for better fuel economy and cleaner exhaust emissions of internal combustion engines have been getting stronger, and, in particular, simultaneous reduction in nitrogen oxides (NOx) and particulate matter (PM) from heavy-duty diesel engines (HDDEs) without degrading fuel economy has become a major subject. Mitsubishi Motors Corporation (MM) has been selling diesel-powered heavy-duty trucks in the U.S. market since 1985 and has agressively carried out development work for meeting the 1991 model year exhaust emission standards.

The Detroit Diesel 6V-92TA engine has been redesigned to run on alcohol fuels to meet 1991 urban bus emission standards. A prototype engine was tested over the EPA transient procedure, using mixtures of methanol, ethanol (with and without water), gasoline, and ignition enhancer. Regulated and selected unregulated emissions were measured. Organic material hydrocarbon equivalent (OMHCE) emissions were significantly above the hydrocarbon emission standard; however, emissions of CO and NO, were below the 1991 emission standards for the fuel combinations used. Particulate emissions were close to the 1991 urban bus emission standard for some configurations. The method used for calculating OMHCE emissions when ethanol was used is also given.

A new, enclosed brushless alternator is developed for use in either hazardous or contaminated environments which can produce 50 Amps at 28 Volts DC. The fully enclosed design of this alternator allows it to work in environments which contain corrosive agents, metallic particulates, or volatile media. The brushless design of this unit in conjunction with the enclosure makes this alternator virtually maintenance free.

Past work suggests that finer filtration of engine lubricating oil reduces wear caused by abrasive particles. However, field data confirming this is limited. Filters were tested in the laboratory to establish micron ratings and in the field to relate filtration and wear. Field tests were conducted on city buses powered by Detroit Diesel 6V92 engines. Oil analysis was used as an indicator of engine wear and as the basis for comparing different filtration systems. Used oil was analyzed for particle size distribution, wear metal concentration and oxidation. Lower particle concentrations resulted when finer full-flow oil filters were used. Further reductions in particle concentrations resulted from the addition of bypass filters to the filtration systems. Corresponding decreases in engine wear metals accompanied reductions in particle concentrations.

A dual-voltage alternator is a single alternator which produces two simultaneous and independently regulated electrical outputs, as shown in Fig. 1. This means that a vehicle with a single dual voltage alternator will be capable of powering, simultaneously, both the standard vehicle 12 volt electrical system (which powers lights, horn, instruments) and also to power another electrical system at a different voltage. The other, or secondary electrical system, is typically a higher voltage system. It may be a 24 volt electrical system to power military communications equipment, or it may be a 48 volt electrical system to provide power for other vehicle electrical power needs, such as electrical heaters for engine emission control. This paper describes a dual-voltage alternator design for automotive applications.

Exhaust gas composition and particulate matter emission levels were obtained from in-use heavy duty transit buses powered by 6V-92TA engines with different fuels. Vehicles discussed in this study were pulled out of revenue service for a day, in Phoenix, AZ, Pittsburgh, PA and New York, NY and tested on the Transportable Heavy Duty Vehicle Emissions Testing Laboratory employing a transient chassis dynamometer. All the vehicles, with engine model years ranging from 1982 to 1992, were operated on the Federal Transit Administration Central Business District Cycle. Significant reductions in particulate matter emissions were observed in the 1990-1992 model year vehicles equipped with the trap oxidizer systems. Testing vehicles under conditions that represent “real world” situations confirmed the fact brought to light that emission levels are highly dependent upon the maintenance and operating conditions of the engines.

The federal emission standards for heavy duty vehicle engines require the exhaust emissions to be measured and calculated in unit form as grams per break horse-power-hour (g/bhp-hr). Correct emission results not only depend on the precise emission measurement but also rely on the correct determination of vehicle energy consumption. A Transportable Heavy-Duty Vehicle Emission Testing Laboratory (THDVETL) designed and constructed at West Virginia University provides accurate vehicle emissions measurements in grams over a test cycle. This paper contributes a method for measuring the energy consumption (bhp-hr) over the test cycle by a chassis dynamometer. Comparisons of analytical and experimental results show that an acceptable agreement is reached and that the THDVETL provides accurate responses as the vehicle is operated under transient loads and speeds. This testing laboratory will have particular value in comparing the behavior of vehicles operating on alternative fuels.

Within Europe, agreed EEC Directives now exist to control exhaust emissions from heavy duty truck engines. An agreed EEC directive requires that emissions are reduced in two stages, Euro I and Euro II in accordance with current state-of-the-art developments in technology. Euro I standards were implemented in 1992/93 and Euro II standards will be in place for 1995/96. A third step, Euro III is now envisaged for introduction around the 1999 model year. In this paper, results from research work are presented showing how, with an advanced, heavy duty diesel engine, featuring 4 valves per cylinder and a very high pressure, electronic unit injector, effective control of NOx is possible using exhaust gas recirculation (EGR). After optimising the combustion system and air-fuel ratio with EGR, the test data obtained allow the limits for achievable emissions to be explored.

The authors used a mass spectrometer to determine an SOF reduction mechanism of a diesel oxidation catalyst. The results indicate that SOF reduction lies in the catalytic conversion of high molecular organic matter to low molecular organic matter. And unregulated emissions are also reduced through this conversion. It is also found that the SOF reduction performance is highly dependent up on the condition of the wash coat. There is some limitation to improving diesel oxidation catalyst performance because of the sulfur content found in diesel fuel. Finally, the authors have determined what we think are the specifications of the presently best catalytic converter.

Diesel particulate emissions continue to challenge researchers and scientists in the industrialized world. ( 1 ) * In spite of many design improvements in recent years, diesel engines are still emitting particulate emissions which are uncomfortably close to the mandated levels.(2) Engineers have been working on solutions involving exhaust aftertreatment.(3) Two solutions were subjects of intense research since the mid-seventies, and appear to be ready for serial production at this time. One of these two solutions is the diesel particulate trap, while the other is the catalytic converter.(4) Traps are usually more effective with insoluble particulate, while catalysts reduce organic particulate. Detailed analysis of exhaust particulate for a given engine should assist in selecting the most effective method of aftertreatment for that application.

Gaseous and particulate emissions from heavy-duty vehicles are affected by fuel types, vehicle/engine parameters, driving characteristics, and environmental conditions. Transient chassis tests were conducted on twenty-six heavy-duty vehicles fueled with methanol, compressed natural gas (CNG), #1 diesel, and #2 diesel, using West Virginia University (WVU) Transportable Heavy-Duty Vehicle Emissions Testing Laboratory. The vehicles were operated on the central business district (CBD) testing cycle, and regulated emissions of carbon monoxide (CO), total hydrocarbon (HC), nitrogen oxides (NOx), and particulate matter (PM) were measured. Comparisons of regulated emissions results revealed that the vehicles powered on methanol and CNG produced much lower particulate emissions than the conventionally fueled vehicles.

Natural gas appears to be the alternative fuel of choice for both light-duty and heavy-duty applications. Conversion kits are typically retrofitted to existing gasoline or diesel fueled engines. One problem area is the very limited amount of meaningful exhaust emissions test data on vehicles converted to natural gas, especially for heavy-duty vehicles. In an attempt to characterize the air quality implications of a large-scale natural gas conversion of the City of Houston's fleet of over 9,000 vehicles. a demonstration program was initiated Nine of the City's heavy-duty trucks were converted by the City to operate on compressed natural gas (CNG) fuel.

Bench reactor experiments were carried out to investigate the effects of operating temperature, precious metal loading, space velocity, and air-fuel (A/F) ratio on the performance of palladium (Pd) catalysts under simulated natural gas vehicle (NGV) exhaust conditions. The performance of these catalysts under simulated gasoline vehicle (GV) conditions was also investigated. In the case of simulated NGV exhaust, where methane was used as the prototypical hydrocarbon (HC) species, peak three-way conversion was obtained under richer conditions than required with simulated GV exhaust (propane and propene HC species). Moreover, the hydrocarbon efficiency of the catalyst under simulated NGV exhaust conditions was more sensitive to both A/F ratio and perturbations in A/F ratio than the HC efficiency under GV exhaust conditions.

The recent tightening of emission standards for new heavy duty engines has lead to the development and implementation of alternative fuel engines, particularly for urban transit bus applications. Alternative fuels are intended to offer a potential emissions benefit with regards to the regulated emissions, and especially the particulate matter, which has received the greatest degree of regulatory action. However, the entire composition of the engine emissions should be considered when evaluating the environmental benefits of these new fuels, and also the continued performance of these engines in actual fleet service. In this study the exhaust emissions from methanol, ethanol, and diesel - powered buses were determined during transient operation of the vehicles on a heavy duty chassis dynamometer. The tests of the alcohol fuelled buses, and a control diesel bus were conducted as the buses accumulated mileage in revenue generating service.