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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

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

Plasma-Assisted Catalytic Reduction of NOx

1998-10-19
982508
Many studies suggest that lean-NOx SCR proceeds via oxidation of NO to NO2 by oxygen, followed by the reaction of the NO2 with hydrocarbons. On catalysts that are not very effective in catalyzing the equilibration of NO+O2 and NO2, the rate of N2 formation is substantially higher when the input NOx is NO2 instead of NO. The apparent bifunctional mechanism in the SCR of NOx has prompted the use of mechanically mixed catalyst components, in which one component is used to accelerate the oxidation of NO to NO2, and another component catalyzes the reaction between NO2 and the hydrocarbon. Catalysts that previously were regarded as inactive for NOx reduction could therefore become efficient when mixed with an oxidation catalyst. Preconverting NO to NO2 opens the opportunity for a wider range of SCR catalysts and perhaps improves the durability of these catalysts. This paper describes the use of a non-thermal plasma as an efficient means for selective partial oxidation of NO to NO2.
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 45% Engine Size Catalyst System for MDV2 ULEV Applications

1998-10-19
982553
A catalyst system, consisting of two different catalyst technologies within a single canister, was developed for MDV2 (Medium-Duty Vehicles, Class 2) to meet ULEV targets. The catalyst volume versus engine displacement is less than 50%. Three approaches taken: substrate study, PM loading study and new catalyst technology development are illustrated here. The most promising system features new catalyst technologies coated on high cell density substrates.
Technical Paper

PremAir® Catalyst System

1998-10-19
982728
Traditional approaches to pollution control have been to develop benign non-polluting processes or to abate emissions at the tailpipe or stack before emitting to the atmosphere. A new technology called PremAir®* Catalyst Systems takes a different approach and directly reduces ambient ground level ozone. This technology can be applied to both mobile and stationary applications. For automotive applications, the new system involves placing a catalytic coating on the car's radiator or air conditioner condenser. As air passes over the radiator or condenser, the catalyst converts the ozone into oxygen. Three Volvo vehicles with a catalyst coating on the radiator were tested on the road during the 1997 summer ozone season in southern California to assess performance. Studies were also conducted in Volvo's laboratory to determine the effect of the catalyst coating on the radiator's performance with regard to corrosion, heat transfer and pressure drop.
Technical Paper

The Development of a Close Coupled Plus Underfloor Catalyst for a ULEV Application

1996-02-01
960796
A close coupled plus underfloor catalyst system was developed for achieving the ULEV performance targets. Catalyst technologies of various precious metal combinations, as well as substrates of different cell densities and wall thicknesses were investigated. Catalyst systems with relatively high precious metal loadings were required to achieved the ULEV targets after simulated engine aging. High Pd-based three way catalysts (TWC), including trimetal and Pd/Pt catalysts together with substrates of low thermal mass, were demonstrated as the appropriate selections for the close coupled position. Pt/Rh and trimetal catalysts combined with substrates of high cell density, were shown to be the promising candidates for the underfloor position.
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

Catalytic Converter Development for Motorcycle Emission Control

1997-10-27
978518
Catalytic control of motorcycle vehicle emissions requires that the catalytic element be carefully integrated into the exhaust system. The catalyst element physical parameters are optimized to achieve specific exhaust tuning requirements. Since the converter is located inside the muffler, the peak temperatures can severely stress both the catalytic active washcoat materials and the currently used metal monolith structure under some operating conditions. This paper addresses the development of an alternative ceramic monolithic catalyst that can be used for 2 and 4-stroke motorcycle applications. A new mounting technique was developed to contain the ceramic catalytic unit within a holder or converter shell with sufficient strength and durability to withstand the severe environment of 2-stroke engine exhaust.
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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