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Technical Paper

Measuring Diesel Emissions with a Split Exhaust Configuration

2001-05-07
2001-01-1949
West Virginia University evaluated diesel oxidation catalysts (DOC) and lean-NOX catalysts as part of Diesel Emissions Control-Sulfur Effects (DECSE) project. In order to perform thermal aging of the DOC and lean-NOX catalysts simultaneously and economically, each catalyst was sized to accommodate half of the engine exhaust flow. Simultaneous catalyst aging was then achieved by splitting the engine exhaust into two streams such that approximately half of the total exhaust flowed through the DOC and half through the lean-NOX catalyst. This necessitated splitting the engine exhaust into two streams during emissions measurements. Throttling valves installed in each branch of the split exhaust were adjusted so that approximately half the engine exhaust passed though the active catalyst under evaluation and into a full flow dilution tunnel for emissions measurement.
Technical Paper

The Development of a Fourth Generation Hybrid Electric Vehicle at West Virginia University

2001-03-05
2001-01-0682
As a part of the FutureTruck 2000 advanced technology student vehicle competition sponsored by the US Department of Energy and General Motors, West Virginia University has converted a full-size sport utility vehicle into a high fuel efficiency, low emissions vehicle. The environmental impact of the Chevrolet Suburban SUV, in terms of both greenhouse gas emissions and exhaust emissions, was reduced through hybridization without losing any of the functionality and utility of the base vehicle. The approach taken was one of using a high efficiency, state-of-the-art direct injection, turbocharged diesel engine coupled to a high output electric traction motor for power assist and to recover regenerative braking energy. The vehicle employs a state-of-the-art combination lean NOx catalyst, oxidation catalyst and particulate filter to ensure low exhaust emissions.
Technical Paper

The Coaxial Cavity Resonator as a RF IC Engine Ignition Source

2001-03-05
2001-01-0987
The Quarter Wave Coaxial Cavity Resonator (QWCCR) plasma igniter is designed, from previous theoretical work, as an ignition source for an internal combustion engine. The present research has explored the implementation of the QWCCR into an internal combustion (IC) engine. The QWCCR design parameters of inner conductor length, loop geometry, and loop position were varied for two igniters of differing operating frequency. Variations of the QWCCR radio frequency (RF) parameters, as a function of engine geometry, were studied by placing the igniter in a combustion chamber and manually varying the crank position. Three identical igniters were fitted with dielectric inserts and the parameters were studied before and after ignition was sustained in a twin-cylinder engine. Optimal resonator geometries were determined. Radio frequency parameter invariance was found with respect to crank angle and piston distance. The first successful IC engine ignition using a QWCCR was achieved.
Technical Paper

Knock Prediction in Reciprocating Gas-Engines Using Detailed Chemical Kinetics

2001-03-05
2001-01-1012
Two and three-dimensional test cases were simulated using a detailed kinetic mechanism for di-methyl ether to represent methane combustion. A piston-bowl assembly for the compression and expansion strokes with combustion has been simulated at 1500 RPM. A fine grid was used for the 2-D simulations and a rather coarse grid was used for the 3-D calculations together with a k-ε subgrid-scale turbulence model and a partially stirred reactor model with three time scales. Ignition was simulated artificially by increasing the temperature at one point inside the cylinder. The results of these simulations were compared with experimental results. The simulation involved an engine with a homogeneous charge of methane as fuel. Results indicate that pressure fluctuations were captured some time after the ignition started, which indicates knock conditions.
Technical Paper

An Assessment of “Pyrolysis” as a Resource Recovery Option for Automobile Shredder Residue

1998-02-23
981163
Pyrolysis, the chemical cracking of organic materials such as polymeric materials represents an innovative technology to recover resources contained in automobile shredder residues (ASR). In this study the technical capabilities, economic viability and environmental impact of pyrolysis as applied to ASR has been investigated. Based upon data provided by pyrolysis equipment suppliers, the pyrolysis of ASR appears to be a viable option to deal with the growing quantities of this material currently being produced. However, the selection of the most appropriate pyrolysis technology is dependant upon local needs and requirements.
Technical Paper

Modularity in Spark Ignition Engines: A Review of its Benefits, Implementation and Limitations

1998-10-19
982688
A conceptual understanding of modularity in internal combustion engines (defined as design, operation, and sensing on an individual cylinder basis) is presented. Three fundamental modular concepts are identified. These are dissimilar component sizing and operation, component deactivation, and direct sensing. The implementation of these concepts in spark ignition internal combustion engines is presented. Several modular approaches are reviewed with respect to breathing, fueling, power generation, and sensing. These include dissimilar orientation, geometry, and activation of multiple induction runners, partial or total disablement of valves through direct or indirect means, dissimilar fueling of individual cylinders, skipping the combustion event of one or more cylinders, deactivation of dissimilar individual cylinders or a group of cylinders, and individual cylinder gas pressure and mixture strength sensing.
Technical Paper

Exhaust Gas Recirculation in a Lean-Burn Natural Gas Engine

1998-05-04
981395
Lean-burn natural gas engines offer attractively low particulate matter emissions and enjoy higher efficiencies than their stoichiometric counterparts. However, even though oxides of nitrogen emissions can be reduced through operation at lambda ratios of greater than 1.3, catalysts cannot reduce the oxides of nitrogen emissions in the oxidizing exhaust environment. Exhaust Gas Recirculation (EGR) offers the potential to reduce engine out oxides of nitrogen emissions by reducing the flame temperature and oxygen partial pressure that encourages their formation during the combustion process. A comparative study involving a change in the nature of primary diluent (air replaced by EGR) in the intake of a Hercules, 3.7 liter, lean-burn natural gas engine has been undertaken in this research. The Hercules engine was equipped with a General Motors electronically controlled EGR valve for low EGR rates, and a slide valve, constructed in house, for high EGR rates.
Technical Paper

Emissions from Trucks and Buses Powered by Cummins L-10 Natural Gas Engines

1998-05-04
981393
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.
Technical Paper

Alternative Fuel Truck Evaluation Project - Design and Preliminary Results

1998-05-04
981392
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. This paper summarizes the design of the project and early results from the first two sites. Data collection is planned for operations, maintenance, truck system descriptions, emissions, duty cycle, safety incidents, and capital costs and operating costs associated with the use of alternative fuels in trucking.
Technical Paper

Numerical Prediction of Knock in a Bi-Fuel Engine

1998-10-19
982533
Dedicated natural gas engines suffer the disadvantages of limited vehicle range and relatively few refueling stations. A vehicle capable of operating on either gasoline or natural gas allows alternative fuel usage without sacrificing vehicle range and mobility. However, the bi-fuel engine must be made to provide equal performance on both fuels. Although bi-fuel conversions have existed for a number of years, historically natural gas performance is degraded relative to gasoline due to reduced volumetric efficiency and lower power density of CNG. Much of the performance losses associated with CNG can be overcome by increasing the compression ratio. However, in a bi-fuel application, high compression ratios can result in severe engine knock during gasoline operation. Variable intake valve timing, increased exhaust gas recirculation and retarded ignition timing were explored as a means of controlling knock during gasoline operation of a bi-fuel engine.
Technical Paper

Comparison of the Exhaust Emissions of Diesel Fuels Derived from Oil Sands and Conventional Crude Oil

1998-10-19
982487
The effects of fuel properties of both oil-sands-derived and conventional-crude-oil-derived diesel fuels were investigated on a single-cylinder DI research engine. The engine used in this study incorporated features of contemporary medium- to heavy-duty diesel engines and was tuned to the U.S. EPA 1994 emission standards. The engine experiments were run using the AVL 8-mode steady-state simulation of the U.S. EPA heavy-duty transient test procedure. The experimental fuels included 12 fuels blended using refinery streams to have controlled total aromatic levels and 7 other diesel fuels obtained from different sources. The results showed that at a constant cetane number (44) and sulfur content (150 ppm), oil-sands-derived fuels produced similar NOx emissions as their conventional-crude-oil-derived counterparts and total aromatic content and fuel density could be used in a regression model to predict NOx emissions.
Technical Paper

A Long Term Field Emissions Study of Natural Gas Fueled Refuse Haulers in New York City

1998-10-19
982456
New York City Department of Sanitation has operated natural gas fueled refuse haulers in a pilot study: a major goal of this study was to compare the emissions from these natural gas vehicles with their diesel counterparts. The vehicles were tandem axle trucks with GVW (gross vehicle weight) rating of 69,897 pounds. The primary use of these vehicles was for street collection and transporting the collected refuse to a landfill. West Virginia University Transportable Heavy Duty Emissions Testing Laboratories have been engaged in monitoring the tailpipe emissions from these trucks for seven-years. In the later years of testing the hydrocarbons were speciated for non-methane and methane components. Six of these vehicles employed the older technology (mechanical mixer) Cummins L-10 lean burn natural gas engines.
Technical Paper

A Phenomenological Model for Soot Formation and Oxidation in Direct-Injection Diesel Engines

1995-10-01
952428
The concentration of carbonaceous particulate matter in the exhaust of diesel engines depends on the rates of formation and oxidation of soot in the combustion chamber. Soot forms early in the combustion process when local fuel-rich areas exist, whereas soot oxidation occurs later when more air is entrained into the fuel spray. Based on this understanding, a phenomenological combustion model is established. In the model, the cylinder volume is divided into four zones: a rich fuel spray core, a premixed-burning/burned gas zone, a mixing controlled burning zone and a lean air zone. Soot formation takes place in the mixing controlled burning zone where the local C/O ratio is above the critical value. Soot oxidation occurs in the premixed-burning/burned gas zone as air is entrained. By using a quasi-global chemical reaction scheme, the oxidation of soot particles by different species can be investigated.
Technical Paper

Pyrolysis: A “Recycling” Option for Automobile Shredder Residue

1995-10-01
951863
The recyclability of old automobiles is of major interest to auto manufacturers, original equipment manufacturers and regulatory bodies concerned about sustainable development. While the majority of the ferrous and non-ferrous metals are currently recycled, the non-metallic waste fraction generated by automobile shredding operations is currently disposed of in landfills. In view of the relatively large concentration of plastics and rubber in this material, pyrolysis, the thermal degradation of polymeric materials to predominantly hydrocarbon products, appears an ideal resource recovery option for this waste stream. In this study, the results of pyrolysis experiments performed in our laboratory will be examined and compared with pyrolysis data reported in the literature. The importance of pyrolysis temperature, pyrolysis reaction time and pyrolysis process design on product formation (liquids, solids and gases) as well as chemical composition are compared.
Technical Paper

Effects of Fuel Properties on Exhaust Emissions of a Single Cylinder DI Diesel Engine

1996-10-01
962116
In this study, the AVL 8-mode steady-state simulations of the EPA transient test were conducted on a two litre single cylinder Ricardo Proteus research engine using two fuel matrices, one consisting fuels having different cetane numbers and the other consisting fuels of different aromatic contents. Engine exhaust emissions of NOx, HC, CO, CO2 and particulates were measured at two different injection timings. The results show that the single cylinder engine behaves similarly as a number of multi-cylinder production engines. The 8-mode simulation was also shown to produce exhaust emissions close to those obtained from the EPA transient test procedure. The cetane number response of the research engine indicates that an increase in cetane number of the fuel with cetane improvers reduced NOx emissions but increased particulate emissions.
Technical Paper

A Parametric Study of Knock Control Strategies for a Bi-Fuel Engine

1998-02-23
980895
Until a proper fueling infrastructure is established, vehicles powered by natural gas must have bi-fuel capability in order to avoid a limited vehicle range. Although bi-fuel conversions of existing gasoline engines have existed for a number of years, these engines do not fully exploit the combustion and knock properties of both fuels. Much of the power loss resulting from operation of an existing gasoline engine on compressed natural gas (CNG) can be recovered by increasing the compression ratio, thereby exploiting the high knock resistance of natural gas. However, gasoline operation at elevated compression ratios results in severe engine knock. The use of variable intake valve timing in conjunction with ignition timing modulation and electronically controlled exhaust gas recirculation (EGR) was investigated as a means of controlling knock when operating a bi-fuel engine on gasoline at elevated compression ratios.
Technical Paper

Exhaust Emissions and Combustion Stability in a Bi-Fuel Spark Ignition Engine

1995-02-01
950468
A Saturn 1.9 liter engine has been converted for operation on either compressed natural gas or gasoline. A bi-fuel controller (BFC) that uses closed-loop control methods for both fuel delivery and spark advance has been developed. The performance and emissions during operation on each fuel have been investigated with the BFC, as well as the performance and emissions with the stock original equipment manufacturer (OEM) controller using gasoline. In-cylinder pressure was measured at a rate of 1024 points per revolution with piezoelectric pressure transducers flush-mounted in the cylinder head. The in-cylinder pressure was used in real time for ignition timing control purposes, and was stored by a data acquisition system for the investigation of engine stability and differences in the combustion properties of the fuels.
Technical Paper

Development and Testing of a Second Generation ULEV Series HEV at West Virginia University

1998-02-23
980489
As a part of the 1996 FutureCar Challenge competition, West Virginia University converted a 1996 Chevrolet Lumina to a series hybrid electric vehicle. This technical report summarizes the modifications made to the vehicle during 1997, the second year of the competition, and details the present state of development of this second-generation hybrid electric vehicle. In particular, the vehicle's powertrain configuration, component selection, control strategy for all modes of operation, emissions control strategies, vehicle structure and design modifications, and suspension design and modifications are all detailed. Also discussed, are the operational use of this vehicle and its intended market. The projected performance of the vehicle, obtained from computer simulations, is discussed in the light of results obtained from testing during 1996 and 1997.
Technical Paper

Effects of Cetane Enhancing Additives and Ignition Quality on Diesel Engine Emissions

1997-10-01
972968
The effects of cetane number and the cetane enhancing additives on diesel exhaust emissions were investigated on a single cylinder DI research engine. The engine used in this study incorporates the features of contemporary medium-to-heavy duty diesel engines and is tuned to US EPA 1994 emission standards. The engine experiments were run using the AVL 8-mode steady-state simulation of the U.S. EPA heavy-duty transient test procedure. The experimental fuels included diesel fuels obtained from different sources with various natural cetane ratings as well as a number of fuels blended by adding two cetane improvers into three base fuels. The two cetane improvers we used were a nitrate-type additive and a peroxide-type additive. Increasing the cetane number resulted in a general decrease in NOx emissions. Similar reductions in NOx emissions were observed with increasing cetane number for all the base fuels irrespective of the cetane improver used in the fuel.
Technical Paper

Potential Applications of the Stiller-Smith Mechanism in internal Combustion Engine Designs

1987-11-08
871225
With few exceptions most internal combustion engines use a slider-crank mechanism to convert reciprocating piston motion into a usable rotational output. One such exception is the Stiller-Smith Mechanism which utilizes a kinematic inversion of a Scotch yoke called an elliptic trammel. The device uses rigid connecting rods and a floating/eccentric gear train for motion conversion and force transmission. The mechanism exhibits advantages over the slider-crank for application in internal combustion engines in areas such as balancing, size, thermal efficiency, and low heat rejection. An overview of potential advantages of an engine utilizing the Stiller-Smith Mechanism is presented.
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