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Technical Paper

Effect of OCP Structure on Viscosity in Oil

1990-10-01
902092
Viscosities were measured on 1% solutions of olefin copolymer (OCP) VI improvers in oils using a variety of techniques to obtain comparisons under different shear rates. OCPs with 60-70 mole % ethylene were amorphous; those with 80 mole % contained small amounts of crystallinity. Kinematic viscosities at 40 and 100 ° C increased with molecular weights, regardless of OCP composition. Haake Viscometer data showed that at room temperature and low shear rates solutions of all copolymers were Newtonian. When the temperature was lowered, amorphous copolymers remained Newtonian while partially crystalline OCPs became non-Newtonian and gave viscosities that were much lower than expected from molecular weight. At -20 °C, high shear rates in the CCS reduced the dependence of viscosity on OCP molecular weight and viscosity changed very little with increase in Mw from 106,000 to 336,000; at low shear, however, in both the MRV and Haake, viscosities increased appreciably as Mw rose.
Technical Paper

Effect of a Fuel Additive On Emission Control Systems

1990-10-01
902097
Ethyl has conducted extensive fleet testing to investigate the effect of a manganese-based antiknock additive (MMT) on exhaust emissions from production cars. The fleet consisted of 48 cars - six cars each of eight models representing more than 50% of 1988 U.S. sales. Three of each model were tested for 75,000 miles using the base fuel. The other three used the base fuel plus 0.03125 gram manganese per gallon as MMT. Results of this testing show that use of the additive will not cause or contribute to the failure of emission control systems. Exhaust back pressure data for the 48-car fleet as well as a test of a close-coupled catalyst at 80 mph showed no indication of catalyst distress or plugging. Catalyst conversion efficiency was generally higher for units aged on the MMT fuel. Particulate emission data showed that less than 0.5% of the input manganese was exhausted as airborne for the FTP cycle.
Technical Paper

Effects of Gasoline Composition on Exhaust Emissions and Driveability

1990-10-01
902094
A study of the effects of changes in gasoline composition is one area to explore in our effort to reduce tailpipe emissions from vehicles. However, affects on vehicle performances should also be considered from the perspective of practical useage. In this paper, the influence of gasoline composition (aromatics),volatility, and MTBE blending on engine outlet and tailpipe emissions are discussed,in particular,forcusing on distillation properties which have a close relationship to driveability. Under stable driving conditios and without a catalitic converter, the effects of gasoline volatility is small, while aromatics in gasoline affect exhaust HC and NOx emissions. MTBE has a leaning effect on the engine intake air/fuel mixture. During a transient driving cycle, a high gasoline 50% distillation temperature causes poor driveability, as a result, HC emissions increase.
Technical Paper

Vapor Space Flammability of Automobile Tanks Containing Low RVP Gasolines

1990-10-01
902096
As a means of reducing evaporative emissions from gasoline sources, the Environmental Protection Agency (EPA) and other legislative and regulatory bodies have required reductions in gasoline volatility. Further reductions are being proposed. This paper reports the results of an investigation into the resulting flammability potential of low volatility gasolines contained in automobile tanks when low ambient temperatures are experienced. The hydrocarbon composition and the flammability tendency of the vapor in fuel tanks of passenger cars were determined via a matrix of 45 different gasoline volatility, temperature, and tank level combinations. A flammability device was developed and used to ignite vapors drawn from the tanks of in-use vehicles at the test conditions. The Reid Vapor Pressure (RVP) of the test gasolines ranged from 6.5 to 9.4 psi in the near-full tank level and 6.4 to 7.8 psi at a low tank level.
Technical Paper

Fuel Blending and Analysis for the Auto/Oil Air Quality Improvement Research Program

1990-10-01
902098
This paper provides an overview of the blending techniques and analytical methods used to formulate the fuels for Phase I of the Auto/Oil Air Quality Improvement Research Program (AQIRP). Details of the base stocks and final blend compositions and properties are also included. Phase I involves the blending and testing of 30 different fuels in four different fuel matrices. The four matrices included gasoline reformulations, methanol fuels, gasoline oxygenate and RVP effects, and gasoline sulfur effects. Specifications for the gasoline fuels were very tight, with several properties being held constant while varying four main fuel properties. Another goal of the blending program was that the gasolines were to be blended from existing refinery streams and not from pure components. Nine laboratories participated in the certification of the fuels.
Technical Paper

Comparison of Gasoline and Methanol Vehicle Emissions Using VOC Reactivity

1990-10-01
902095
This paper compares the mass, composition and reactivity towards ozone formation of gasoline and methanol vehicle emissions. Methods used to estimate ozone forming potential include published reactivity scales and the EPA-OZIPM model. Evaluation of the available vehicle emission measurement data does not indicate any ozone benefit for methanol. The data show a wide range in the reactivity of gasoline vehicle VOC emissions. Emissions from vehicles with advanced emission control systems and low mileage have the lowest reactivity. Methanol vehicles emit essentially the same amounts of VOC (on a carbon basis), NOx and CO as gasoline-powered vehicles, and their VOC reactivity fails within the range for gasoline vehicles. When methanol fuels are compared directly with gasoline in flexible fuel vehicles, their VOC emissions have the same or higher reactivity.
Technical Paper

Turbulence Length Scale Measurements by Two-Probe-Volume LDA Technique in a Diesel Engine

1990-10-01
902080
Cycle resolved LDA measurements of the tangential velocity component, made along a diameter of two combustion chambers (toroidal and square) during the compression stroke of a diesel engine operating at 600 and 1000 rpm, are discussed. Indirect measurements of lateral integral length scales determined by single point autocorrelation technique are presented. Finally direct measurements of lateral integral length scales made by a new laser doppler velocimeter system based on two probe volume technique are reported.
Technical Paper

Catalytic Effects of Cr2O3 and PSZ on Gas-Phase Ignition Under Diesel Engine Combustion Conditions

1990-10-01
902084
The effect of chromium oxide (Cr2O3) and partially stabilized zirconia (PSZ) surfaces on the gas-phase ignition of hydrocarbon fuels has been studied in a high pressure chemical flow reactor under low heat-loss Diesel engine simulated conditions. Results are presented for propane and n-hexane fuels at 6 and 10 atmospheres and are compared to previously reported results obtained under similar conditions with platinum surfaces. Thermal enhancement of the gas-phase reactions, as evidenced by the catalytic production of CO and CO2, was found to be negligible for both Cr2O3 and PSZ, where as significant thermal enhancement was observed with platinum. Chemical enhancement of the gas-phase ignition reactions, as evidenced by an increase in the production of intermediate hydrocarbons, was observed under fuel rich conditions with both Cr2O3 and PSZ. Oxygen was shown to be essential in that no change in the intermediate hydrocarbon concentration was observed under pyrolysis conditions.
Technical Paper

Data from a Variable Rate Shape High Pressure Injection System Operating in an Engine Fed Constant Volume Combustion Chamber

1990-10-01
902082
In current systems, for a given nozzle and injection pressure (pump speed), the shape of the injection rate is fixed and the injection timing is the only variable the engine designer can vary. For this non-interactive injection system, changing the injector nozzle (number and diameter of holes) will proportionately change the injection shape. New injection systems in which the rate of injection is a controlled variable are being developed. Results from one such injector, called the UCORS (Universal Combustion Optimization and Rate Shaping), are reported in this paper. The system can dynamically control its injection rate shape by controlling the position and size of a pilot injection relative to the main injection. Data and analysis from an out-of-engine and combustion chamber study of the UCORS injection system are presented.
Technical Paper

Evaluation of the Effects of a New Combustion System and Catalyst on Engine Emissions

1990-10-01
902083
The present paper reports the results of an experimental investigation carried out on a four-stroke single- cylinder D.I. diesel engine (100 x 95mm bore x stroke) with the aim to evaluate the effects of a four-lobe square combustion chamber on the gaseous and particulate emissions. Fluid-dynamic behaviour of the axisymmetric toroidal and four-lobe square chambers was investigated by Laser Doppler Anemometry. Engine tests at 2000 and 3000 rpm for different start of combustion (SOC) and A/F ratio are reported. Particulate, HC and NOx emission index measured under different operating conditions are given. In addition, the volatile content of the particulates produced from the two chambers at various engine operative conditions was measured by thermogravimetric analysis (TGA). Finally, the catalytic activity of a metal-oxide-based catalyst in the combustion of particulate was also evaluated by TGA.
Technical Paper

Experimental Evaluation of Tappet/Bore and Cam/Tappet Friction for a Direct Acting Bucket Tappet Valvetrain

1990-10-01
902086
Tappet/bore friction and torque at the camshaft were measured for a direct acting bucket tappet using a cam/tappet friction apparatus. Tappet/bore and cam/tappet friction torque and friction coefficient as a function of cam angle were derived from those measurements. The results showed that, for the particular geometry tested, tappet/bore friction torque accounted for about 13% of the total cam/tappet/bore friction torque at 250 cam rpm. This fraction decreased with increasing speed. Tappet bore friction was greatest at about ± 40 degrees of cam angle, where side loads on the tappet bore were highest. In contrast, earlier results for a center pivot rocker arm design showed tappet bore friction to be negligible.
Technical Paper

Real-Time Measurement of Camshaft Wear in an Automotive Engine - a Radiometric Method

1990-10-01
902085
A radiometric method has been developed for the determination of camshaft wear during engine operation. After a radioactive tracer is induced at the tips of one or more cam lobes by the technique of surface layer activation, calibration procedure are performed to determine the amount of radioactive material remaining versus the depth worn. The decrease in γ-ray intensity measured external to the engine is then directly related to cam lobe wear. By incorporating a high-resolution detector and an internal radioactive standard,measurement accuracy better than ±0.2 μm at 95% confidence has been achieved. Without the requirement of engine disassembly, this method has provided unique measurements of break-in wear and wear as a function of operating conditions. Because this approach requires only low levels of radiation, it has significant potential applications in wear control.
Technical Paper

An Investigation of Lubricating System Warm-up for the Improvement of Cold Start Efficiency and Emissions of S.I. Automotive Engines

1990-10-01
902089
Abstract Transient warm-ups of an engine lubrication system are examined using test bench measurements and numerical simulations. It is shown that friction in the bearings is the greatest heat source for oil, but that a major part of the heat received by the oil is transferred to the walls of bearings and passages. It is also determined that the total amount of heat ultimately retained by the oil is a very small part of the engine energy consumption, and that the engine warm-up does not use all the energy made available by combustion heat transfer and friction losses. Within this scope, some systems are examined to properly use available heat and improve lubricant and engine warm-up. Today, automotive engines are well designed for low consumption and pollutant emissions during fully warmed-up periods. However, emission standards are fixed by test-cycles which begin with cold starts.
Technical Paper

Establishment of a Method for Predicting Cam Follower Wear in the Material Development Process

1990-10-01
902087
Many studies have been reported concerning fundamental tribological research aimed at reducing the severe valve train wear that occurs in internal combustion engines. In this paper, cam follower wear was theoretically and experimentally analyzed at the material development stage. Statistical methods have been applied to practical use in determining the material properties quantitatively. Based on the results, a method for predicting cam follower wear has been derived which has made it possible to develop new valve train systems more efficiently. Further, a guideline for developing new wear resistant materials was also clarified. Finally, the precision high chrominum cast iron rocker arm is described, along with its application to a new NISSAN high-performance 4-cylinder DOHC engine, as an example of the use of this method to develop new wear-resistant materials.
Technical Paper

The Composition of Gasoline Engine Hydrocarbon Emissions - An Evaluation of Catalyst and Fuel Effects

1990-10-01
902074
Twenty-three hydrocarbon components were analysed in the exhaust emissions from a 2.3 litre gasoline engine. The effect of a three-way catalyst on emission rates was investigated, as was the effect of addition to fuel of specific aromatic and olefinic compounds. The addition of 1-hexene and 1-octene (olefins) caused statistically significant increases in reactive olefins - ethene and propene - in the exhaust. The addition of benzene and toluene led to increases in these compounds in the exhaust, and indicated that whilst fuel-toluene is the main source of toluene emissions, the emission of benzene has sources in addition to fuel-benzene. A three-way catalyst, when operating at > 600°C, eliminated most hydrocarbons except methane and traces of the light aromatics. At idle, however, the catalyst exhibited substantial selectivity towards different hydrocarbons according to their ease-of-oxidation.
Technical Paper

The Effect of Gasoline Aromatics Content on Exhaust Emissions: A Cooperative Test Program

1990-10-01
902073
A cooperative vehicle exhaust emissions test program was conducted by the California Air Resources Board and Chevron Research and Technology Company. The focus of the program was to determine the effect of aromatics content on nitrogen oxides (NOx) emissions. The program consisted of testing nine vehicles on three different fuels. The fuels ranged in aromatics content from 10% to 30%.* Other fuel properties were held as constant as possible. The tests were conducted in two different laboratories. In addition to the measurement of criteria emissions (hydrocarbons, carbon monoxide, and NOx), some of the hydrocarbon emissions were speciated and a reactivity of the exhaust was calculated. Only slight changes in the exhaust emissions and reactivity were observed for a change in aromatics content from 30% to 10%.
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

Numerical Analysis of the Fuel Spray Formation in DI Diesel Engine

1990-10-01
902078
The spray formation for a heavy duty diesel engine is calculated and compared with the direct and Schlieren photography. The calculation is performed by three dimensional numerical analysis based on KIVA computer program. The discrete particle technique is used for the spray modeling. The drag force of the spray droplet in the calculation is adjusted to have a same penetration with the experiment. The calculations are performed to investigate the influence of the evaporation, combustion, and coalesence for the development of the spray. The results of the calculation are visualized using three dimensional iso-surface to compare with the photograph. The comparison shows that the calculated reaults gives the similar feature on the distribution of each property with the experiment.
Technical Paper

Simultaneous Optimization of Diesel Engine Parameters for Low Emissions Using Taguchi Methods

1990-10-01
902075
This paper describes a study which was conducted to simultaneously optimize several diesel engine design and operating parameters for low exhaust emissions using the Taguchi method. A single cylinder, research, diesel engine equipped with a high pressure, cam-driven, electronic unit injector was used in this optimization experiment. The major effects of key engine design parameters on exhaust emissions were quantified and optimum parameter settings were determined. Measurement of exhaust emissions using the optimum parameter settings showed that particulates and NOx emissions were significantly lower than those obtained for the baseline engine. The Taguchi method was found to be a useful technique for the simultaneous optimization of several engine parameters and for predicting the effect of various design parameters on diesel exhaust emissions.
Technical Paper

Development of a New Optical Technique for Measuring Diesel Spray Penetration

1990-10-01
902077
A new optical measuring technique of tip penetration of a diesel fuel spray was developed by detecting the arrival times of the spray tip at several light sheets which were preset at various axial locations downstream. Verified by the instantaneous photographic technique, it was confirmed that this technique is effective, with sufficient accuracy, for measuring the spray tip penetration much more easily than the conventional photographic technique. The tip penetrations of diesel sprays injected through single-hole nozzles with various orifice lengths and diameters has been investigated over a wide range of the operating conditions by this technique. The spray injected through two multihole nozzles, either with or without a sac volume, has also been characterized. The results showed that the spray tip penetration is affected somewhat by the operating conditions. Eventually it is affected by the injected fuel momentum flowrate, nozzle geometry and ambient gas density.
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