Refine Your Search

Topic

Author

Affiliation

Search Results

Technical Paper

Optimisation of Diesel Engines Converted to High Compression Spark Ignition (SI) Natural Gas Operation

1988-03-01
871149
There is a strong interest around the world in natural gas as an alternative fuel. This paper is concerned with the option of converting diesel engines to spark ignition operation. Although this may appear to be an outrageous thermodynamic action, it is preferable to using natural gas in a low compression gasoline engine conversion. An investigation is described in which engine maps were produced for a 5.6 litre direct injection diesel engine converted to CNG. The diesel operating characteristics have been compared with those of the spark ignition conversion at compression ratios of 18:1 (the original diesel value), 15:1 and 13:1. Detailed data are presented for the 15:1 compression ratio. These test results are supplemented by results for other diesel conversions. The use of these engines in bus fleet operations is also discussed.
Technical Paper

Acoustical Selection of Class 8 Truck Floormats

1999-05-17
1999-01-1688
Class 8 truck manufacturers use a wide variety of materials for cab floor construction. These include traditional steel and aluminum plate as well as aluminum honey-comb and balsa wood core composites. Each of these materials has unique transmission loss properties. The acoustical performance of the floor system, (cab floor, decoupler, and barrier) depends not only on the acoustical performance of the decoupler and barrier, but also on the cab floor material. This paper outlines an experimental technique for selecting an acoustical floormat system utilizing vehicle and laboratory tests that takes these factors into account.
Technical Paper

Case History: Engine Timing Gear Noise Reduction

1999-05-17
1999-01-1716
This paper describes the procedures used to reduce the tonal noise of a class eight truck engine timing gear train that was initially found to be objectionable under idle operating conditions. Initial measurements showed that the objectionable sounds were related to the fundamental gear mesh frequency, and its second and third harmonics. Experimental and computational procedures used to study and trouble-shoot the problem include vibration and sound measurements, transmission error analysis of the gears under light load condition, and a dynamic analysis of the drive system. Detail applications of these techniques are described in this paper.
Technical Paper

Accessory Drive Belt Pulley Entry Friction Study and Belt Chirp Noise

1999-05-17
1999-01-1709
Accessory belt “chirp” noise is a major quality issue in the automotive and truck industry. Chirp noise control is often achieved by very tight pulley alignment, a guideline being .33 degree maximum belt entry angle into each grooved pulley. Occasionally belts will chirp at pulleys where the system alignment is this good or better. This study offers an explanation for such occurrences. This is a study to see if fundament groove side sticking theory correlates with the belt entry angle, and how the coefficient of friction relates to this entry angle. The study combines theory with lab data. In summary, the study fundamentally links the coefficient of friction of the belt to the belt chirp noise phenomenon, and allows the projection of a belt's general tendency to chirp to be predicted by the measurement of belt coefficient of friction on a test stand.
Technical Paper

What Fuel Economy Improvement Technologies Could Aid the Competitiveness of Light-Duty Natural Gas Vehicles?

1999-05-03
1999-01-1511
The question of whether increasing the fuel economy of light-duty natural gas fueled vehicles can improve their economic competitiveness in the U.S. market, and help the US Department of Energy meet stated goals for such vehicles is explored. Key trade-offs concerning costs, exhaust emissions and other issues are presented for a number of possible advanced engine designs. Projections of fuel economy improvements for a wide range of lean-burn engine technologies have been developed. It appears that compression ignition technologies can give the best potential fuel economy, but are less competitive for light-duty vehicles due to high engine cost. Lean-burn spark ignition technologies are more applicable to light-duty vehicles due to lower overall cost. Meeting Ultra-Low Emission Vehicle standards with efficient lean-burn natural gas engines is a key challenge.
Technical Paper

In-Use Emissions from Natural Gas Fueled Heavy-Duty Vehicles

1999-05-03
1999-01-1507
The objective of the work described here is to test the performance of closed-loop controlled, heavy-duty CNG engines in-use, on fuels of different methane content; and to compare their performance with similar diesel vehicles. Performance is measured in terms of pollutant emissions, fuel economy, and driveability. To achieve this objective, three buses powered by closed-loop controlled, dedicated natural gas engines were tested on the heavy-duty chassis dynamometer facility at the Colorado Institute for Fuels and High Altitude Engine Research (CIFER). Emissions of regulated pollutants (CO, NOx, PM, and THC or NMHC), as well as emissions of alde-hydes for some vehicles, are reported. Two fuels were employed: a high methane fuel (90%) and a low methane fuel (85%). It was found that the NOx, CO, and PM emissions for a given cycle and vehicle are essentially constant for different methane content fuels.
Technical Paper

Emissions from Buses with DDC 6V92 Engines Using Synthetic Diesel Fuel

1999-05-03
1999-01-1512
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.
Technical Paper

Interim Results from Alternative Fuel Truck Evaluation Project

1999-05-03
1999-01-1505
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.
Technical Paper

Methylal and Methylal-Diesel Blended Fuels for Use in Compression-Ignition Engines

1999-05-03
1999-01-1508
“Gas-to-liquids” catalytic conversion technologies show promise for liberating stranded natural gas reserves and for achieving energy diversity worldwide. Some gas-to-liquids products are used as transportation fuels and as blendstocks for upgrading crude-derived fuels. Methylal (CH3-O-CH2-O-CH3), also known as dimethoxymethane or DMM, is a gas-to-liquid chemical that has been evaluated for use as a diesel fuel component. Methylal contains 42% oxygen by weight and is soluble in diesel fuel. The physical and chemical properties of neat methylal and for blends of methylal in conventional diesel fuel are presented. Methylal was found to be more volatile than diesel fuel, and special precautions for distribution and fuel tank storage are discussed. Steady state engine tests were also performed using an unmodified Cummins B5.9 turbocharged diesel engine to examine the effect of methylal blend concentration on performance and emissions.
Technical Paper

Two-Dimensional In-Cylinder Flow Field in a Natural Gas Fueled Spark Ignition Engine Probed by Particle Tracking Velocimetry and Its Dependence on Engine Specifications

1999-05-03
1999-01-1534
An experimental study was made to investigate in-cylinder flow field in a natural gas fueled spark ignition engine and the effects of engine specifications on in-cylinder flow field. The instantaneous two-dimentional flow fields in a single-cylinder visualization engine, which has 75mm bore and 62mm stroke, were measured in various cross sections perpendicular to the cylinder axis by using the laser light sheet PTV method at various crank angles during intake, compression, and expansion strokes over the wide range of piston combustion chamber configuration, top clearance, and nominal swirl ratio. Flow fields during compression and expansion strokes were also calculated using KIVA2 simulation code for better understanding of the measured results. The results showed that induction-generated swirl is getting concentric to the cylinder center in compression stroke, and is shifted in the radial direction in expansion stroke.
Technical Paper

AQUAZOLE™: An Original Emulsified Water-Diesel Fuel for Heavy-Duty Applications

2000-06-19
2000-01-1861
1 Since 1997 the ELF group has been working on a new fuel designed in priority for use with urban services (buses, lorries). Basically, it is a diesel/water emulsion stabilised by a series of new additives. A lot of testing programmes on engine and vehicles test benches was carried out. They have clearly shown that with this new fuel there is a reduction of nitrogen oxide emissions by up to 30% and black smoke by up to 80%, without any technological modifications being necessary as against EN 590 diesel fuel marketed normally. The water content is, however, the cause of a certain loss in engine performances. Nevertheless, hydrocarbon consumption is reduced by up to 4%. The use of an oxidation catalyst is compatible with a water-diesel emulsified fuel and results in larger emission benefits. Furthermore, a 50 ppm sulphur emulsion with a continuously regenerating particle filter give a particle reduction of 90%.
Technical Paper

Heavy Duty Testing Cycles Development: A New Methodology

2000-06-19
2000-01-1860
Testing cycles for heavy-duty vehicles are an important topic for authorities, manufacturers, fleet owners, etc. in order to assess exhaust gas emissions and fuel consumption. A new methodology was developed to derive representative testing cycles from velocity versus time driving information. During the development, the work was focussed on city-buses, but the methodology can be applied to heavy-duty vehicles in general. The testing cycles are ‘distance-based’, meaning they impose goal speeds at each location. This implies that during acceleration phases, the accelerator-pedal - and gear lever in case of manual transmission - can be operated in a realistic way. The techniques for deriving this kind of testing cycle are proposed. Results of on-board emission and fuel consumption measurements employing these testing cycles are presented for two 19 tons, 160kW city buses, equipped with respectively a diesel and a CNG (stoechiometric) engine, and a 10 tons 112 kW diesel delivery truck.
Technical Paper

Tailpipe Emissions Comparison Between Propane and Natural Gas Forklifts

2000-06-19
2000-01-1865
It is commonly stated that natural gas-fueled forklifts produce less emissions than propane-fueled forklifts. However, there is relatively little proof. This paper reports on a detailed comparative study at one plant in Edmonton, Canada where a fleet of forklift trucks is used for indoor material movement. (For convenience, the acronym NGV, ie. Natural Gas Vehicle is used to designate natural gas-fueled and LPG, ie. Liquified Petroleum Gas, is used to designate propane-fueled forklifts). Until recently the forklift trucks (of various ages) were LPG carburetted units with two-way catalytic converters. Prompted partially by worker health concerns, the forklifts were converted to fuel injected, closed-loop controlled NGV systems with three-way catalytic converters. The NGV-converted forklifts reduced emissions by 77% (NOX) and 76% (CO) when compared to just-tuned LPG forklifts.
Technical Paper

Potential of a Natural Gas Vehicle as EEV

2000-06-19
2000-01-1863
The natural gas vehicle has high potential as an Environmentally Enhanced Vehicle (EEV). In order to achieve low-emissions, a precise gaseous injection system coupled with optimized feedback control is necessary for the natural gas engines. An advanced natural gas vehicle, such as the Honda Civic GX, can meet the Super-Ultra-Low-Emission Vehicle (SULEV) emission standard in California and also meet the future European & Japanese emission standards. The low-emission natural gas vehicle emits very low off-cycle emissions, air toxic emissions and has zero-fuel evaporative emissions. The use of natural gas-based fuels achieves CO2 emission reductions relative to use of petroleum-based fuels. Low-emission NGVs are attractive for use in urban and metropolitan city centers to reduce smog.
Technical Paper

The Systematic Evaluation of Twelve LP Gas Fuels for Emissions and Fuel Consumption

2000-06-19
2000-01-1867
The effects on bi-fuel car exhaust emissions, fuel consumption and acceleration performance of a range of LPG fuels has been determined. The LPGs tested included those representing natural gas condensate and oil refineries' products to include a spectrum of C3:C4 and paraffiinic:olefinic mixtures. The overall conclusions are that exhaust emissions from the gaseous fuels for the three-way catalyst equipped cars tested were lower than for gasoline. For all the LPGs, CO2 equivalent emissions are reduced by 7% to 10% or more compared with gasoline. The cars' acceleration performance indicates that there was no sacrifice in acceleration times to various speeds, with any gaseous fuel in these OEM developed cars.
Technical Paper

Improvement of Performance and Exhaust Emissions in a Converted Dual-Fuel Natural Gas Engine

2000-06-19
2000-01-1866
To improve performance and exhaust emissions of a converted dual-fuel natural-gas engine, the effects of basic parameters were experimentally investigated. The results show that diesel fuel operation is favorable at very low loads and that a small amount of pilot fuel with a moderate injection rate is effective for suppressing knock at high loads. As for the charge air throttling, there is an optimal combination of charge amount and equivalence ratio to obtain high thermal efficiency and reduced emissions. An optimal strategy for fueling is demonstrated based on the results. Adequate control of pilot fuel amount, injection timing and throttle opening area gives diesel-equivalent thermal efficiency with very low smoke emission over a wide range of loads.
Technical Paper

Direct Injection Compressed Natural Gas Combustion and Visualisation

2000-06-19
2000-01-1838
This paper details the development of a compressed natural gas (CNG) engine with ultra lean burn low emissions potential. Hydrogen assisted jet ignition (HAJI) is used to achieve reliable combustion and low NOx emissions, whilst direct injection is used to improve thermal efficiency and decrease hydrocarbon (HC) emissions. It is found that port inducted propane, port inducted CNG and directly injected CNG all produce negligible levels of CO and NOx when operating at air/fuel ratios higher than λ = 1.8. Furthermore, direct injection of CNG produced approximately 100 ppm C6 less HC emissions than port induction of CNG, and port induction of CNG decreased the HC emissions by around a factor of a third to a half in comparison with port induction of propane.
Technical Paper

Supercharged Homogeneous Charge Compression Ignition (HCCI) with Exhaust Gas Recirculation and Pilot Fuel

2000-06-19
2000-01-1835
In an attempt to extend the upper load limit for Homogeneous Charge Compression Ignition (HCCI), supercharging in combination with Exhaust Gas Recirculation (EGR) have been applied. Two different boost pressures were used, 1.1 bar and 1.5 bar. High EGR rates were used in order to reduce the combustion rate. The highest obtained IMEP was 16 bar. This was achieved with the higher boost pressure, at close to stoichiometric conditions and with approximately 50 % EGR. Natural gas was used as the main fuel. In the case with the higher boost pressure, iso-octane was used as pilot fuel, to improve the ignition properties of the mixture. This made it possible to use a lower compression ratio and thereby reducing the maximum cylinder pressure. The tests were performed on a single cylinder engine operated at low speed (1000 rpm). The test engine was equipped with a modified cylinder head, having a Variable Compression Ratio (VCR) mechanism.
Technical Paper

Multi-Dimensional Modeling of Ignition, Combustion and Nitric Oxide Formation in Direct Injection Natural Gas Engines

2000-06-19
2000-01-1839
The heat release and pollutant formation processes in a direct injection natural gas engine are studied by coupling detailed chemistry with a multi-dimensional reactive flow code. A detailed kinetic mechanism consisting of 22 species and 104 elementary reactions is chosen by comparing ignition delay predictions with measurements in a combustion bomb. The ignition model is then coupled with a turbulent combustion model and extended Zeldovich kinetics to simulate heat release and nitric oxide production in a direct injection engine. Parametric studies are conducted to investigate the effect of engine operating conditions which include speed, load, injection timing and level of boost. It is shown that use of detailed chemistry is extremely important to predict the correct ignition delay period as engine operating conditions change. Use of both time and crank angle as the independent variable reveals interesting details of the heat release process as a function of engine speed.
Technical Paper

The Effect of Tire Stiffness Parameters on Medium-Duty Truck Handling

2000-05-01
2000-01-1645
This paper presents the results of a sensitivity study on the effect of tire stiffness parameters on selected handling performance metrics of a medium-duty truck. The tire stiffness parameters considered in the study are radial stiffness, longitudinal or braking stiffness, and cornering stiffness. An ADAMS model of a medium-duty truck was developed to simulate vehicle handling maneuvers. Two handling scenarios were considered: a combined braking and cornering scenario and a split-μ, straight-line braking scenario. The results of the study indicate that all three tire stiffness parameters are important in accurately predicting vehicle handling performance. Furthermore, when conducting design studies on suspension and steering system design variables other than tire stiffness parameters, the choice of specific values used for the tire stiffness parameters can significantly influence the results of the design studies.
X