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Technical Paper

Conceptual Design of the South Coast Alternative Motor Fuels Demonstration Project

1991-11-01
912665
The conceptual design for a large scale, alternative motor fuels demonstration using delivery vans in the Los Angeles area is described. Vehicles built by Chrysler, Ford, and General Motors will be demonstrated on compressed natural gas, methanol (M-85), ethanol blend, reformulated gasoline, and liquefied petroleum gas. Control vehicles will run on unleaded gasoline. About 20 vehicles will run on each fuel. A smaller number of electric vehicles from other sources will also be demonstrated. Data will be collected over a 24-month period on speciated emissions, safety, performance, reliability, maintenance, and durability. An economic assessment of the use of each of the fuels will be performed from a fleet operator's perspective. Federal Express Corporation will serve as the host fleet.
Technical Paper

Total In-Cylinder Sampling Experiment on Emission Formation Processes in a D.I. Diesel Engine

1990-10-01
902062
An experimental study on emission formation processes, such as these of nitric oxide, particulate and total hydrocarbon in a small direct injection (D.I.) diesel engine was carried out by using a newly developed total in-cylinder sampling technique. The sampling method consisted of rapidly opening a blowdown valve attached to the bottom of the piston bowl, and quickly transferring most of the in-cylinder contents into a large sampling chamber below the piston. No modification of the intake and exhaust ports in a cylinder head was required for the installation of the blowdown apparatus. The sampling experiment gave a history of spatially-averaged emission concentrations in the cylinder. The effects of several engine variables, such as the length-to-diameter ratio of the nozzle hole, the ratio of the piston bowl diameter to the cylinder bore and the intake swirl ratio, on the emission formation processes were investigated.
Technical Paper

Ambient Temperature and Driving Cycle Effects on CNG Motor Vehicle Emission

1990-10-01
902069
This paper describes an emissions study of two vans powered by compressed natural gas (CNG). One van was relatively new, while the other had been driven more than 120,000 mi. The purpose of the study was to obtain emissions information which could be used to predict the impact of CNG use on ambient air quality and air toxic concentrations, and to develop a better understanding of the effect of ambient temperature variations on CNG emissions. Using four different driving cycles, emission tests were carried out at 20°F, 75°F, and 105°F. Test results agree with previous findings that document low emissions of nonmethane hydrocarbons from CNG vehicles. Results also confirm the expectation that CNG emissions are not significantly affected by ambient temperature variations, although an increase in formaldehyde emission was noted for the 20°F cold-start tests.
Technical Paper

Swirl Effects on Mixing and Flame Evolution in a Research DI Diesel Engine

1990-10-01
902076
An optically accessible, DI Diesel engine was used to investigate the effect of swirl on fuel-air mixing and flame evolution. Quiescent and swirling conditions were studied at three different fuel-air ratios at an engine speed of 900 RPM. For the mixing studies, performed with nitrogen to prevent combustion, a mirrored piston was used to permit double pass shadowgraph imaging within the combustion chamber. High speed shadowgraph cinematography, using an Argon ion laser, yielded insight into the temporal evolution of the fuel jet and permitted the calculation of penetration speeds and area of the fuel jet as a function of time. With swirl, the penetration rate of the fuel jets was reduced, and the area of the over which fuel was observed increased by 25 percent. Combustion phenomena were studied using backlighting so that the spray and visible light from combustion could be recorded on high speed video.
Technical Paper

Natural Gas-A Rational Approach to Clean Air

1990-10-01
902228
In the quest for cleaner air, there are numerous approaches in various stages of study, development and implementation. Despite stringent clean air regulations, which have reduced previously uncontrolled engine exhaust emissions by more than 10 fold, the population of pollution sources is growing faster than the reduction in the pollution rate per source. Various alternatives include cleaner fuels and alternative fuels, cleaner engines and alternative engines, as well as bold proposals such as electrical power or hydrogen as a fuel, which offer some measure of improvement. However, most efforts to date appear to fall in the category of too little, too late or too costly. It is concluded that a major changeover to natural gas as an alternative fuel for use in most engines, with a program that includes retrofit of old engines and modification of new engines to utilize natural gas, offers an effective and rational solution.
Technical Paper

High Pressure Injection of Natural Gas in a Two Stroke Diesel Engine

1990-10-01
902230
Three methods of introducing gas into the DDC 8V92TA engine were evaluated: post-pilot in-cylinder injection; early in-cylinder injection just after exhaust valve closure; and port injection through an air inlet port. Post-pilot injection consistently produced the best combustion and HC emissions. Early in-cylinder injection often resulted in severe end gas knock, but gave higher thermal efficiency than diesel in some conditions. HC emissions were considerably higher than for post-pilot injection. Port injection gave smoother combustion than early in-cylinder injection but higher HC emissions. Its full load thermal efficiency tell between, and part load efficiency below, the other methods.
Technical Paper

Influence of Engine Buildup Variables on the ASTM Sequence VI Fuel Efficient Oil Test

1990-10-01
902164
Using a seven-step quality improvement process, some of the engine build-up factors adversely influencing the severity and precision of the Sequence VI dynamometer test were examined. Insights from engineering (theory) and database (statistical) analyses enabled a 23 factorial experiment to identify oil ring tension, piston ring side clearance, and piston fit as critical parameters in a 3-oil, 9-engine, 28-test program. High ring tension was shown to emphasize the friction reducing capability of higher performing oils and the deficiency of a lower performing oil. Interactions were noted. A helpful correlation of test severity with the engine calibration indicators was shown.
Technical Paper

Transit Bus Operation with a DDC 6V-92TAC Engine Operating on Ignition-Improved Methanol

1990-10-01
902161
The use of methanol as a fuel in transit buses is being demonstrated through the use of diesel engine retrofits and an ignition improver to methanol. This project is aimed at retrofitting the Detroit Diesel Corporation (DDC) 6V-92TAC diesel engine in a GM RTSII bus to operate on methanol. The engine is modified by installing higher compression ratio pistons, higher flowrate mechanical fuel injectors, and a different blower. The bus fuel system is also modified to accommodate the properties of methanol. New fuel lines are installed, and the diesel fuel tank is replaced with two stainless steel tanks. A high-pressure electric fuel pump and a fuel cooler are used to prevent methanol from boiling in the engine. Currently, three buses have been retrofitted. The buses operate at the Southern California Rapid Transit District (SCRTD) in Los Angeles, California.
Technical Paper

Methanol-Fueled Caterpillar 3406 Engine Experience in On-Highway Trucks

1990-10-01
902160
A variety of “alternative” fuels are being considered as potential future replacements for petroleum-based fuels. One of the leading contenders for replacing diesel fuel in some heavy duty applications is methanol, since methanol can be made from abundantly- available materials such as natural gas, coal, and biomass, and because neat methanol can result in reduced NOx and particulate exhaust emissions relative to diesel fuel. Because of various fuel property differences between methanol and diesel fuel, engine modifications must be made to the conventional diesel engine to allow it to utilize methanol fuel. A patented (1) ignition-assist combustion system initially applied to a 2 valve, 4 stroke Caterpillar 3306 DIT engine (121 mm bore) demonstrated methanol combustion feasibility in a tractor application (2).
Technical Paper

Applications of High Performance P/M Aluminum in Internal Combustion Engines

1991-02-01
910156
Powder Metallurgy (P/M) renders the possibilities to tailor material properties using rapid solidification or mechanical alloying processes totally different to the options of ingot metallurgy (I/M). For demanding applications in internal combustion engines new materials have become more important because of environmental and/or performance reasons. Weight reductions to improve the performance or reduce the consumptions and consequently the amount of exhaust gases and increase of temperatures at different locations of an engine need better aluminum materials. P/M solutions are described from the point of view of material's processing and general properties. The potential for automotive pistons is discussed with several examples.
Technical Paper

Natural Gas Hybrid Electric Bus

1991-02-01
910248
The design and predicted performance of a hybrid electric powered transit bus is described. The bus is a 7.6 meter (25 ft), 24 passenger vehicle that incorporates a low floor design and rear door accessible to handicap passengers. The low floor and rear door are made possible by the use of individual high power density permanent magnet motors driving the rear wheels. The hybrid electric drive system consists of a compressed natural gas fueled internal combustion engine that drives a generator which in conjunction with storage batteries supply power to the two traction motors.
Technical Paper

Stratification of Swirl Intensity in the Axial Direction for Control of Turbulence Generation During the Compression Stroke

1991-02-01
910261
Control of turbulence during the compression stroke is suggested by both theoretical calculations and experimental results obtained with an LDV measurement in a motored engine. The authors have found experimentally that when an axial distribution of swirl intensity exists, a large-scale annular vortex is formed inside the cylinder during the compression stroke and this vortex generates and transports turbulence energy. A numerical calculation is adopted to elucidate this phenomenon. Then, an axial stratification of swirl intensity is found to generate a large-scale annular vortex during the compression stroke by an interaction between the piston motion and the axial pressure gradient. The initial swirl profile is parametrically varied to assess its effect on the turbulence parameters. Among calculated results, turbulence energy is enhanced strongest when the swirl intensity is highest at the piston top surface and lowest at the bottom surface of the cylinder head.
Technical Paper

The Effects of Ceramic Coatings on Diesel Engine Performance and Exhaust Emissions

1991-02-01
910460
An experimental investigation of the effects of ceramic coatings on diesel engine performance and exhaust emissions was conducted. Tests were carried out over a range of engine speeds at full load for a standard metal piston and two pistons insulated with 0.5 mm and 1.0 mm thick ceramic coatings. The thinner (0.5 mm) ceramic coating resulted in improved performance over the baseline engine, with the gains being especially pronounced with decreasing engine speed. At 1000 rpm, the 0.5 mm ceramic coated piston produced 10% higher thermal efficiency than the metal piston. In contrast, the relatively thicker coating (1 mm), resulted in as much as 6% lower thermal efficiency compared to baseline. On the other hand, the insulated engines consistently presented an attractive picture in terms of their emissions characteristics. Due to the more complete combustion in the insulated configurations, exhaust CO levels were between 30% and 60% lower than baseline levels.
Technical Paper

A Study of Decrease Oil Consumption for NSOR-Two-Ring Package Piston

1991-02-01
910435
Furuhama(1)* proposed the new two ring package consist of a pressure ring and a narrow single-rail oil ring (NSOR) in 1985. Number of studies(2) have been done for the purpose of reducing the oil consumption (OC) in this ring package. However, OC reduction problem has been still remaining to solve as only one serious problem of this ring package. The reasons of a larger OC in the new ring package than the conventional three ring has been hardly understood, considering the OC control ability on second ring in three ring package will not so large since the fact that the oil film thickness is thicker than that of the oil ring. In this study, the mechanism of OC increase in new ring package was found out at last, as a result, OC of new ring package piston was improved up to the same level of conventional three ring package piston.
Technical Paper

Development of Light Weight High Strength Aluminum Alloy Piston with Cooling Gallery Manufactured Using Squeeze Casting Technique

1991-02-01
910434
In recent years, demands for increased output and low fuel consumption in automobile engines have been mounting. Light weight and high performance is demanded of the main operating parts, such as pistons. In response to these demands, the crown thickness and pin boss unit thickness has been reduced by tremendous improvements in the fatigue strength, compared to strength obtained by conventional methods, by utilizing Squeeze Casting techniques. In addition, the thickness of the inside face of the pistons has been reduced by making use of a split core. Furthermore, by manufacturing a cooling gallery, the heat load has been reduced; by introduction of hollow regions, an extremely light weight and compact piston has been developed. Three new techniques are indicated here. Firstly, the technique of attaining soundness in material and excellent fatigue strength by the Squeeze Casting technique, which is superior to those attained by conventional methods.
Technical Paper

Advances in High Temperature Components for the Adiabatic Engine

1991-02-01
910457
An advanced low heat rejection engine concept has been selected based on a trade-off between thermal insulating performance and available technology. The engine concept heat rejection performance is limited by available ring-liner tribology and requires cylinder liner cooling to control the piston top ring reversal temperature. This engine concept is composed of a titanium piston, headface plate and cylinder liner insert with thermal barrier coatings. Monolithic zirconia valve seat inserts, and thermal barrier coated valves and intake-exhaust ports complete the insulation package. The tribological system is composed of chrome oxide coated cylinder, M2 steel top piston ring, M2 steel valve guides, and an advanced polyol ester class lubricant.
Technical Paper

Florida lnstitute of Technology - 1990 Methanol Challenge Experience

1991-02-01
910573
The next decade will show a change in all motor fuels used in public transportation. As of this writing, methanol is viewed as one of the most promising of the new “clean air fuels.” Florida Institute of Technology, in competition with 13 other Universities, designed and completed modification on a 1988 Chevrolet Corsica supplied by General Motors. These modifications included high compression ceramic coated pistons in conjunction with turbochargin. Further research included camshaft testing, ignition and fuel curve changes, and a unique 6/3 cylinder cut-out scheme during low engine load conditions. The Corsica was then entered in the 1990 Methanol Challenge.
Technical Paper

The Effect of Piston Temperature on Hydrocarbon Emissions from a Spark-Ignited Direct-Injection Engine

1991-02-01
910558
Light-load unburned hydrocarbon emissions were studied experimentally in a spark-ignited direct-injection engine burning gasoline where the piston temperature was varied. The test engine was a single-cylinder Direct Injection Stratified-Charge (DISC) engine incorporating a combustion process similar to the Texaco Controlled Combustion System. At a single low load operating condition, the piston temperature was varied by 50 K by controlling the cooling water and oil temperature. The effect of this change on unburned hydrocarbon emissions and heat release profiles was studied. It was found that by carefully controlling the intake air temperature and pressure to maintain constant in-cylinder conditions at the time of injection, the change in piston temperature did not have a significant effect on the unburned hydrocarbon emissions from the engine.
Technical Paper

A Telemetry Linkage System for Piston Temperature Measurements in a Diesel Engine

1991-02-01
910299
A telemetry linkage system has been developed for piston temperature measurements in a direct-injection diesel engine. In parallel with the development of the telemetry linkage system, fast response thermocouples were installed at three piston locations - two on the bowl surface and one on the crown surface. A novel design was used to achieve electrical continuity between the piston and the connecting rod by means of a flexible steel strap pivoted on the piston skirt. The telemetry linkage system was then used to transport the electrical wires from the thermocouples to the external data acquisition system. A series of tests was run to determine the effects of location and load on piston surface temperatures. Surface temperature profiles varied substantially among the three locations, reflecting the differences in the combustion and heat flow characteristics of their surrounding regions.
Technical Paper

Factors Affecting the Fatigue Performance of Metal Matrix Composites for Diesel Pistons

1991-02-01
910833
The mechanical properties of an aluminum silicon alloy reinforced with ceramic fibers has been investigated as part of a much larger program to develop metal matrix composite Pistons for diesel engine applications. Tensile and fatigue tests were carried out over a range of temperatures typical of those experienced during engine operation. The influence on the properties of non-fibrous extrinsic particles, which originate from the fiber manufacturing process, are considered in detail. These data show that the tensile and fatigue characteristics are much improved over those of unreinforced materials at temperatures in the range of the maximum engine operating temperature. The presence of extrinsic defects has little effect on the tensile properties but causes a reduction in the fatigue life, which may be greater than one order of magnitude at a given load.
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