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Particulate emission control from diesel engines is one of the major concerns in the urban areas in California. Recently, regulations have been proposed for stringent PM emission requirements from both existing and new diesel engines. As a result, particulate emission control from urban diesel engines using advanced particulate filter technology is being evaluated at several locations in California. Although ceramic based particle filters are well known for high PM reductions, the lack of effective and durable regeneration system has limited their applications. The continuously regenerated diesel particulate filter (CRDPF) technology discussed in this presentation, solves this problem by catalytically oxidizing NO present in the diesel exhaust to NO2 which is utilized to continuously combust the engine soot under the typical diesel engine operating condition.

Recent chassis testing of hybrid buses demonstrated the potential of hybrid technology to reduce emissions and raise fuel economy relative to conventional buses. However, hybrid buses represent a certification quandary because the engines must be certified using the accepted Federal Test Procedure (FTP), without regard for benefits that may arise from less transient engine operation. Actual engine operating data from series configuration hybrid buses were analyzed to determine the envelopes of torque and speeds covered by the engine. Transient engine operation was also considered in terms of rates of change of torque, power and speed. These measures did not compare closely with similar measures computed from the FTP because the series hybrid engines explored a more structured zone of operation than the FTP implied and because the FTP represented more transient operation.

Selective Catalytic Reduction (SCR), using urea injection, is being examined as a method for substantial reduction of oxides of nitrogen (NOx) for diesel engines, but the urea injection rates must be controlled to match the NOx production which may need to be predicted during open loop control. Unfortunately NOx is usually measured in the laboratory using a full-scale dilution tunnel and chemiluminescent analyzer, which cause delay and diffusion (in time) of the true manifold NOx concentration. Similarly, delay and diffusion of measurements of all emissions cause the task of creating instantaneous emissions models for vehicle simulations more difficult. Data were obtained to relate injections of carbon dioxide (CO2) into a tunnel with analyzer measurements. The analyzer response was found to match a gamma distribution of the input pulse, so that the analyzer output could be modeled from the tunnel CO2 input.

The recent oil crisis has once again emphasized the need to develop both fuel efficient engines and alternately fueled engines, particularly for automotive applications. Engines which burn coal or coal pyrolysis products are attractive, but ignition delay and metal erosion problems continue to limit high speed operation of such engines. Further, the throttled spark ignition engine often used with methanol and natural gas does not prove an efficient or tolerant device for the combustion of a wide range of fuel. Therefore, an novel approach must be taken in order to achieve the efficient and flexible operation of such an engine. A novel design of a fuel tolerant engine suitable for burning coal fuels separates the combustion from the piston in order to have more careful flame control and to exclude the particulate matter from the engine's piston rings.

In order to obtain meaningful analyses of exhaust gas emissions and fuel economy for a heavy duty vehicle from a chassis dynamometer, the accurate simulation of road load characteristics is crucial. The adjusted amount of power to be absorbed by the chassis dynamometer during road driving of the tested vehicle needs to be calculated. In this paper, the performance of the chassis dynamometer under transient load cycle operations is discussed and the transient response of the power absorption system is presented. In addition, the design criteria of the chassis dynamometer used to test heavy duty vehicles under steady and transient load is described.

A research program at West Virginia University sought to identify and quantify the individual hydrocarbon species present in alternative fuel exhaust. Compressed natural gas (CNG) has been one of the most widely researched fuels proposed to replace liquid petroleum fuels. Regulated CNG non-methane hydrocarbon emissions are often lower than hydrocarbon emissions from conventional liquid fuels because of the absence of heavier hydrocarbons in the fuel. Reducing NOx and non-methane organic gas (NMOG) emission levels reduces the ozone forming potential (OFP) of the exhaust gases. A Hercules GTA 3.7 liter medium duty CNG engine was operated at seven load and speed set points using local supply CNG gas. The engine was operated at several rated, intermediate and idle speed set points. The engine was operated while the air/fuel ratio value was varied.

The Rand Cam engine is a novel design which avoids the use of pistons in favor of a cavity of varying size and shape. A set of vanes protrudes from a rotor into a circular trough in a stator. The vanes seal to the walls and base of the trough, which is of varying depth, and progress around the trough with rotation of the rotor. These vanes therefore pass through the rotor and are constrained to move parallel to the rotational axis. Intake and exhaust processes occur through ports in the stator wall which are revealed by the passing vanes. Advantages of the basic design include an absence of valves, reduction in reciprocating masses, presence of an integral flywheel in the rotor and strong fluid movement akin a swirl induced by the relative velocity between the rotor and stator.

Concern over dwindling oil supplies has led to the adoption of alternate fuels to power fleet vehicles. However, during the interim period when alternate fuel supply stations are few and far between, dual fuel engines prove a necessity. In the light duty arena, these engines are typically gasoline engines modified to accommodate compressed natural gas (CNG) as an alternate fuel, but they are seldom optimized with both fuels in mind. A Saturn 1.9 liter 4 cylinder dual overhead cam engine was selected as a base for developing an optimized gasoline/CNG powerplant. Baseline data on power and steady state emissions (CO2, CO, NOx, HC) were found using the standard Saturn controller. In addition to monitoring standard sensor measurements, real-time pressure traces were taken for up to 256 cycles using a modified head with embedded PCB piezoelectric pressure transducers.

The Rand-Cam engine is a positive displacement machine, operating on a four stroke cycle, which consists of a rotor with multiple axial vanes forming combustion chambers as the rotor and vanes rotate in a cam shaped housing. The cam housing, consisting of two “half-housings” or stators, contains a toroidal trough of varying depth machined into each stator. The two stators are phased so that the shallowest point on one trough corresponds to the deepest on the other. A set of six vanes, able to move axially through machined holes in the rotor, traverses the troughs creating six captured zones per side. These zones vary in volume with rotor rotation. Since each trough has two deep sections and two shallow sections with ramps in between, full four stroke operation is obtained between each pair of vanes in each trough, corresponding to twelve power “strokes” per revolution.

A bi-fuel engine capable of operating either on compressed natural gas (CNG) or gasoline is being developed for the transition to alternative fuel usage. A Saturn 1.9 liter 4-cylinder engine was selected as a base powerplant. A control system that allows closed-loop optimization of both fuel delivery and spark timing was developed. Stock performance and emissions of the engine, as well as performance and emissions with the new controller on gasoline and CNG, have been documented. CNG operation in an engine designed for gasoline results in power loss because of the lower volumetric efficiency with gaseous fuel use, yet such an engine does not take advantage of the higher knock resistance of CNG. It is the goal of this research to use the knock resistance of CNG to recover the associated power loss. The two methods considered for this include turbocharging with a variable boost wastegate and raising the compression ratio while employing variable valve timing.

A bi-fuel engine with the ability to run optimally on both compressed natural gas (CNG) and gasoline is being developed. Such bi-fuel automotive engines are necessary to bridge the gap between gasoline and natural gas as an alternative fuel while natural gas fueling stations are not yet common enough to make a dedicated natural gas vehicle practical. As an example of modern progressive engine design, a Saturn 1.9 liter 4-cylinder dual overhead cam (DOHC) engine has been selected as a base powerplant for this development. Many previous natural gas conversions have made compromises in engine control strategies, including mapped open-loop methods, or resorting to translating the signals to or from the original controller. The engine control system described here, however, employs adaptive closed-loop control, optimizing fuel delivery and spark timing for both fuels.

Concern over atmospheric pollution has led to the development of testing procedures to evaluate the hydrocarbon, carbon dioxide, carbon monoxide and oxides of nitrogen emissions from internal combustion engines. In order to perform emissions testing on vehicles, a chassis dynamometer capable of simulating expected driving conditions must be employed. West Virginia University has developed a Heavy Duty Transportable Emissions Testing Laboratory to perform chassis testing on trucks and buses. Emissions from the vehicle are monitored and recorded over the duration of a testing schedule. Usually the vehicle emissions from the whole test are reported as mass of emissions per unit distance driven. However, there is interest in relating the instantaneous emissions to the immediate conditions at specific points in the test, and in determining the emissions for discrete segments of the test (modal analysis).

Emissions from light duty vehicles have traditionally been measured using a chassis dynamometer, while heavy duty testing has been based on engine dynamometers. However, the need for in-use vehicle emissions data has led to the development of two transportable heavy duty chassis dynamometers capable of testing buses and heavy trucks. A test cycle has been developed for Class 8 trucks, which typically have unsyncronized transmissions. This test cycle has five peaks, each consisting of an acceleration, cruise period, and deceleration, with speeds and acceleration requirements that can be met by virtually all vehicles in common service. Termed the “WVU 5 peak truck test”, this 8 km (5 mile) cycle has been used to evaluate the emissions from diesel and ethanol powered over-the-road tractors and from diesel and ethanol powered snow plows, all with Detroit Diesel 6V92 engines.

An alternative fuel that has demonstrated considerable potential in reducing emissions and crude oil dependence is compressed natural gas (CNG). A dedicated CNG vehicle suffers from the lack of an adequate number of fueling stations and the poor range limited by CNG storage technology. A vehicle capable of operating on either gasoline or natural gas allows alternative fuel usage without sacrificing vehicle range and mobility. Although many such bi-fuel vehicles are in existence, historically they have employed older engine designs and made compromises in engine control parameters that can degrade performance relative to gasoline and increase emissions. A modern production engine, a 1992 Saturn 1.9 liter 16 valve powerplant, is being optimized for operation on each fuel to realize the full potential of CNG in a bi-fuel system. CNG operation in an engine designed for gasoline typically suffers from reduced power, due in part to displacement of air by gaseous fuel.

With the implementation of a closed loop fuel control system, operation of lean-burn natural gas engines can be optimized in terms of reducing emissions while maximizing efficiency. Such a system would compensate for variations in fuel composition, but also would correct for variations in volumetric efficiency due to immediate engine history and long-term engine component wear. Present day engine controllers perform well when they are operated with the same gas composition for which they were calibrated, but because fuel composition varies geographically as well as seasonally, some method of compensation is required. A closed loop control system on a medium-duty lean-burn engine will enhance performance by maintaining the desired air-fuel ratio to eliminate any unwanted rich or lean excursions (relative to the desired air-fuel ratio) that produce excess engine-out emissions. Such a system can also guard against internal engine damage due to overheating and/or engine knock.

A novel engine concept, currently under study, addresses many of the problems commonly associated with conventional internal combustion engines. In its simplest form the novel engine consists of a single crankshaft operating both a piston compressor and a piston expander which are connected by a continuous flame combustion chamber. One might regard this as a Brayton piston engine which is similar to a previous engine investigated by Warren. Also, due to the use of piston cylinders as the compression and expansion devices, this engine varies little mechanically from current engine technology thus allowing for easy implementation. The main improvement from conventional engine design is that the expansion cylinder can have a larger displacement than that of the compression cylinder. This allows more power to be extracted by lowering the loss due to blowdown and this will increase the thermal efficiency.

Growing concern over ground-level ozone and its role in smog formation has resulted in extensive investigation into identifying ozone sources. Motor vehicle exhaust, specifically oxides of nitrogen and hydrocarbons, have been identified as major ozone precursors in urban areas. Past research has concentrated on assessing the impact of emissions from gasoline fueled light duty vehicles. However, little work has been done on identifying ozone precursors from medium and heavy duty diesel fueled vehicles. This paper presents the results of testing performed on a Navistar T 444E 190 horsepower diesel engine which is certified as a light/heavy-duty emissions classification and is used in medium duty trucks up to 11,800 kg (26,000 lb) GVW. Regulated emissions and speciated hydrocarbon emissions were collected using a filter, bag and Tenax adsorption cartridges for both steady state and transient engine operation.

The Stiller-Smith mechanism is a new mechanism for the translation of linear motion into rotary motion, and has been considered as an alternative to the conventional slider-crank mechanism in the design of internal combustion engines and piston compressors. Piston motion differs between the two mechanisms, being perfectly sinusoidal for the Stiller-Smith case. Plots of dimensionless volume and volume rate-change are presented for one engine cycle. It is argued that the different motion is important when considering rate-based processes such as heat transfer to a cylinder wall and chemical kinetics during combustion. This paper also addresses the fact that a Stiller-Smith engine will be easier to configure for adiabatic operation, with many attendant benefits.

The objective of this project, which is supported by the U.S. Department of Energy (DOE) through the National Renewable Energy Laboratory (NREL), is to provide a comprehensive comparison of heavy-duty trucks operating on alternative fuels and diesel fuel. Data collection from up to eight sites is planned. Currently, the project has four sites: Raley's in Sacramento, CA (Kenworth, Cummins L10-300G, liquefied natural gas - LNG); Pima Gro Systems, Inc. in Fontana, CA (White/GMC, Caterpillar 3176B Dual-Fuel, compressed natural gas - CNG); Waste Management in Washington, PA (Mack, Mack E7G, LNG); and United Parcel Service in Hartford, CT (Freightliner Custom Chassis, Cummins B5.9G, CNG). This paper summarizes current data collection and evaluation results from this project.

Synthetic diesel fuel can be made from a variety of feedstocks, including coal, natural gas and biomass. Synthetic diesel fuels can have very low sulfur and aromatic content, and excellent autoignition characteristics. Moreover, synthetic diesel fuels may also be economically competitive with California diesel fuel if produced in large volumes. Previous engine laboratory and field tests using a heavy-duty chassis dynamometer indicate that synthetic diesel fuel made using the Fischer-Tropsch (F-T) catalytic conversion process is a promising alternative fuel because it can be used in unmodified diesel engines, and can reduce exhaust emissions substantially. The objective of this study was a preliminary assessment of the emissions from older model transit operated on Mossgas synthetic diesel fuel. The study compared emissions from transit buses operating on Federal no. 2 Diesel fuel, Mossgas synthetic diesel (MGSD), and a 50/50 blend of the two fuels.