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Exhaust emissions from off-highway diesel engines are a significant contributor of both oxides of nitrogen (NOx) and particulate matter (PM) to air inventories. Yet, emissions research activities aimed solely at the off-highway arena have been minimal - largely overshadowed by the extensive efforts directed toward the on-highway sector. However, with current trends indicating that the performance of these off-highway vehicles will become increasingly more scrutinized by federal regulatory agencies, augmentation of current research efforts will be necessary. The global objective for this study was to collect vehicle activity information for diesel-powered off-highway vehicles while they were operated in the field. Engine speed and raw exhaust CO2 concentrations were recorded and then used to create engine dynamometer test cycles. The engine was exercised according to these cycles in the laboratory so that the mass emissions rates of exhaust gas pollutants could be measured.

The historical lack of continuous data for PM emissions from heavy-duty diesel engines hampers advanced inventory approaches and hampers second-by-second engine control optimization. Continuos PM data can be obtained using a Tapered Element Oscillating Microbalance (TEOM), but moisture correction of data is needed to remove unwanted transient components of the mass. Reasonable correlation can be found between TEOM data integrated over the cycle and conventional PM filter data. Considerable scatter was evident when continuous TEOM data were plotted against instantaneous power, but by dispersing the power in time a clearer relationship was evident. Continuous TEOM data showed the same gross trends as PM filter mass distributed over a cycle in proportion to instantaneous CO, but it was evident that this CO proportioning technique is at best approximate. Binning of PM mass rate as a function of vehicle speed and acceleration were also evaluated for inventory purposes.

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.

Emissions tests for heavy-duty diesel-fueled vehicles are normally performed using an engine dynamometer or a chassis dynamometer. Both of these methods generally entail the use of laboratory-grade emissions measurement instrumentation, a CVS system, an environment control system, a dynamometer, and associated data acquisition and control systems. The results obtained from such tests provide a means by which engines may be compared to the emissions standards, but may not be truly indicative of an engine's in-vehicle performance while operating on the road. An alternative to such a testing methodology would be to actively record the emissions from a vehicle while it was operating on-road. A considerable amount of discussion has been focused on the development of on-road emissions measurement systems (OREMS) that would provide for such in-use emissions data collection.

Cummins Westport Inc. (CWI) released for production the latest version of its C8.3G natural gas engine, the C Gas Plus, in July 2001. This engine has increased ratings for horsepower and torque, a full-authority engine controller, wide tolerance to natural gas fuel (the minimum methane number is 65), and improved diagnostics capability. The C Gas Plus also meets the California Air Resources Board optional low-NOx (2.0 g/bhp-h) emission standard for automotive and urban buses. Two pre-production C Gas Plus engines were operated in a Viking Freight fleet for 12 months as part of the U.S. Department of Energy's Fuels Utilization Program. In-use exhaust emissions, fuel economy, and fuel cost were collected and compared with similar 1997 Cummins C8.3 diesel tractors. CWI and the West Virginia University developed an ad-hoc test cycle to simulate the Viking Freight fleet duty cycle from in-service data collected with data loggers.

The use of Artificial Neural Networks (ANNs) as a predictive tool has been shown to have a broad range of applications. Earlier work by the authors using ANN models to predict carbon dioxide (CO2), carbon monoxide (CO), oxides of nitrogen (NOx), and particulate matter (PM) from heavy-duty diesel engines and vehicles yielded marginal to excellent results. These ANN models can be a useful tool in inventory prediction, hybrid vehicle design optimization, and incorporated into a feedback loop of an on-board, active fuel injection management system. In this research, the ANN models were trained on continuous engine and emissions data. The engine data were used as inputs to the ANN models and consisted of engine speed, torque, and their respective first and second derivatives over a one, five, and ten second time range. The continuous emissions data were the desired output that the ANN models learned to predict through an iterative training process.

Increased concerns about the emissions produced from mobile sources have placed an emphasis on the in-use monitoring of on- and off-road vehicles. Measuring the emissions emitted from an in-use vehicle during its operation provides for a rich dataset that is generally too expensive and too time consuming to reproduce in a laboratory setting. Many portable systems have been developed and implemented in the past to acquire in-use emissions data for spark ignited and compression ignited engines. However, the majority of these systems only measured the concentration levels of the exhaust constituents and or reported the results in time-specific (g/s) and or distance-specific (g/km) mass units through knowledge of the exhaust flow. For heavy-duty engines, it is desirable to report the in-use emission levels in brake-specific mass units (g/kW-hr) since that is how the emission levels are reported from engine dynamometer certification testing.

West Virginia University redesigned a 2002 Ford Explorer and created a diesel electric hybrid vehicle to satisfy the goals of the 2002 FutureTruck competition. These goals were to demonstrate a 25% improvement in fuel economy, to reduce greenhouse gas emissions, to achieve California ULEV emissions, to demonstrate 1/8-mile acceleration of 11.5 seconds or less, and to maintain vehicular comforts and performance. West Virginia University's 2002 hybrid sport utility vehicle (SUV), the Exclaim!, meets or exceeds these goals. Using a post-transmission parallel configuration, WVU integrated a 2.5L Detroit Diesel Corporation engine along with a Unique Mobility 75kW electric motor to replace the stock drivetrain. With an emphasis on maintaining performance, WVU strived to improve areas where SUVs have traditionally performed poorly: fuel economy and emissions. Using regenerative braking, fuel economy has been significantly improved.

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.

The 1998 Consent Decrees between the United States Government and the settling heavy-duty diesel engine manufacturers require in-use emissions testing from post 2000 model year engines. The emissions gathered from these engines must be reported on a brake-specific mass basis. To report brake-specific mass emissions, three primary parameters must be measured. These are the concentration of each emission constituent, the exhaust mass flow rate, and the engine power output. The measurement of the concentration level and exhaust mass flow rate can be (and are generally) measured directly with instrumentation installed in the exhaust transfer tube. However, engine power cannot be measured directly for in-use emissions testing due to the direct coupling of the engine output shaft to the vehicle's transmission. Engine power can be inferred from the electronic control unit (ECU) broadcast of engine speed and engine torque.

The 1998 Consent Decrees between the settling heavy-duty diesel engine manufacturers and the United States Government require the engine manufacturer to perform in-use emissions testing to evaluate their engine designs and emissions when the vehicle is placed into service. This additional requirement will oblige the manufacturer to account for real-world conditions when designing engines and engine control algorithms and include driving conditions, ambient conditions, and fuel properties in addition to the engine certification test procedures. Engine operation and ambient conditions can be designed into the engine control algorithm. However, there will most likely be no on-board determination of fuel properties or composition in the near future. Therefore, the engine manufacturer will need to account for varying fuel properties when developing the engine control algorithm for when in-use testing is performed.

Reactivity controlled compression ignition (RCCI) is a form of dual-fuel combustion that exploits the reactivity difference between two fuels to control combustion phasing. This combustion approach limits the formation of oxides of nitrogen (NOX) and soot while retaining high thermal efficiency. The research presented herein was performed to determine the influences that high reactivity (diesel) fuel properties have on RCCI combustion characteristics, exhaust emissions, fuel efficiency, and the operable load range. A 4-cylinder, 1.9 liter, light-duty compression-ignition (CI) engine was converted to run on diesel fuel (high reactivity fuel) and compressed natural gas (CNG) (low reactivity fuel). The engine was operated at 2100 revolutions per minute (RPM), and at two different loads, 3.6 bar brake mean effective pressure (BMEP) and 6 bar BMEP.

Diesel engines are highly reliable, durable and are used for a wide range of applications with low fuel usage owing to its higher thermal efficiency compared to other mobile power sources. Heavy-duty diesel engines are used for both on-road and off-road applications and dominate the heavy-duty engine segment of the United States transportation market. Due to their high reliability, there are considerable numbers of on-road legacy heavy-duty diesel engine fleets still in use in the United States. These engines are relatively higher oxides of nitrogen (NOx) and particulate matter (PM) producers than post 2007 model year diesel engines. There have been various emission certification or verification programs which are carried out in states like California and Texas for different aftermarket retrofit devices, fuels and additive technologies for reducing NOx and PM emissions from these legacy diesel engines.

With continuously increasing concern for the emissions from two-stroke engines including regulated hydrocarbon (HC) and oxides of nitrogen (NOx) emissions, non-road engines are implementing proven technologies from the on-road market. For example, four stroke diesel generators now include additional internal exhaust gas recirculation (EGR) via an intake/exhaust valve passage. EGR can offer benefits of reduced HC, NOx, and may even improve combustion stability and fuel efficiency. In addition, there is particular interest in use of natural gas as fuel for home power generation. This paper examines exhaust throttling applied to the Helmholtz resonator of a two-stroke, port injected, natural gas engine. The 34 cc engine was air cooled and operated at wide-open throttle (WOT) conditions at an engine speed of 5400 RPM with fueling adjusted to achieve maximum brake torque. Exhaust throttling served as a method to decrease the effective diameter of the outlet of the convergent cone.

Both field research and certification data show that the lean burn natural gas powered spark ignition engines offer particulate matter (PM) reduction with respect to equivalent diesel power plants. Concerns over PM inventory make these engines attractive despite the loss of fuel economy associated with throttled operation. Early versions of the Cummins L-10 natural gas engines employed a mixer to establish air/fuel ratio. Emissions measurements by the West Virginia University Transportable Heavy Duty Emissions Testing Laboratories on Cummins L-10 powered transit buses revealed the potential to offer low emissions of PM and oxides of nitrogen, (NOx) but variations in the mixture could cause emissions of NOx, carbon monoxide and hydrocarbons to rise. This was readily corrected through mixer repair or readjustment. Newer versions of the L-10 engine employ a more sophisticated fueling scheme with feedback control from a wide range oxygen sensor.

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.

Results of a research effort directed towards identifying and measuring the genotoxic properties of respirable particulate matter involved in mining exposures, especially those which may synergistically affect genotoxic hazard, are presented. Particulate matter emissions from a direct injection diesel engine have been sampled and assayed to determine the genotoxic potential as a function of engine operating conditions. Diesel exhaust from a Caterpillar 3304 diesel engine, representative of the ones found in underground mines, rated 100 hp at 2200 rpm is diluted in a multi-tube mini-dilution tunnel and the particulate matter is collected on 70 mm fluorocarbon coated glass fiber filters as well as on 8″ x 10″ hi-volume filters. A six mode steady state duty cycle was used to relate engine operating conditions to the genotoxic potential.

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 zero dimensional combustion model of an axial vane rotary engine has been developed. The engine is a positive displacement mechanism that permits the four “stroke” action to occur in one revolution of the shaft with a minimum number of moving components. Current modeling efforts for this engine require improved estimations of engine parameters such as chamber pressure, chamber wall temperature, gas temperature, and heat loss. The purpose of this investigation was to develop a zero dimensional combustion model that predicts the above-mentioned parameters in a quick and accurate manner for a spark ignition or compression ignition version of the engine. For this effort, NASA's ZMOTTO code was modified. Piston engine data and the results from the modified ZMOTTO code are in good agreement.

This paper outlines the development process of a radio frequency (RF) plasma ignitor and its application to internal combustion engines. The system features a high Q quarter-wave coaxial cavity resonator that serves as an electric field magnifier and as a discharge device. The preliminary characteristics of the cavity have been studied by the construction and operation of larger scaled devices. Testing has been performed using these devices in a testing apparatus operating under ambient conditions. Once an analysis of the large-scale device is complete, a smaller device, more inclined to interfacing with a standard engine, will be constructed and tested on a full scale engine. The final device is intended to operate in the 800-1500 MHz range.