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We have developed a methodology for predicting combustion and emissions in a Homogeneous Charge Compression Ignition (HCCI) Engine. The methodology judiciously uses a fluid mechanics code followed by a chemical kinetics code to achieve great reduction in the computational requirements; to a level that can be handled with current computers. In previous papers, our sequential, multi-zone methodology has been applied to HCCI combustion of short-chain hydrocarbons (natural gas and propane). Applying the same procedure to long-chain hydrocarbons (iso-octane) results in unacceptably long computational time. In this paper, we show how the computational time can be made acceptable by developing a segregated solver. This reduces the run time of a ten-zone problem by an order of magnitude and thus makes it much more practical to make combustion studies of long-chain hydrocarbons.

The specific goal of this project was to determine if there is a difference in the lube oil degradation rates in a heavy-duty diesel engine equipped with an EGR system, as compared to the same configuration of the engine, but minus the EGR system. A secondary goal was to develop FTIR analysis of used lube oil as a sensitive technique for rapid evaluation of the degradation properties of lubricants. The test engine selected for this work was a Caterpillar 3176 engine. Two engine configurations were used, a standard 1994 design and a 1994 configuration with EGR designed to meet the 2004 emissions standards. The most significant changes in the lubricant occurred during the first 50-100 hours of operation. The results clearly demonstrated that the use of EGR has a significant impact on the degradation of the engine lubricant.

The ability of a piston oil ring to conform to liner distortions during engine operation is directly related to its radial stiffness. The ability to conform is also very important for controlling lubricant oil consumption and emissions. This paper describes the procedure utilized to investigate the technical feasibility of using flexible high performance engineering plastics to replace metal as base material for oil rings. Bench tests and engines were used to select and evaluate different types of plastics for wear resistance and structural integrity. Engine test results indicated no structural failures but wear levels were found to be unacceptably high for use in durable heavy duty diesel engines.

Diesel engine builders are faced with a new challenge to lower the weight of engines to increase payload while meeting rigorous durability goals for the engine. Cooling system parts represent a family of components which may be converted to lightweight metallic alloys for significant weight savings. To utilize lightweight alloys, cooling system parts must be engineered to maintain the same durability as the cast iron components they replace. For a modern high speed diesel, the Bl0 design life may be upwards of 1,280,000 kilometers which is a very aggressive target for a new component design. A test program was planned to guide design and development of aluminum (Al) cooling system parts for a new engine. The part must exhibit no corrosion after long duration operating with acceptable coolant. This program included three major phases consisting of bench scale corrosion tests for alloy selection, component rig tests for design verification and engine testing for system reliability.

An engine rig test and a scuffing BOCLE test have been used to investigate the lubricity of low sulfur diesel fuels and its relationship with unit injector wear in heavy duty diesel engines. The rig test effectively ranks 11 selected fuels/fluids according to their actual performance. The scuffing BOCLE test correlates with the rig test by showing the same ranking capability, and it is easy to perform. A similar correlation has been established using ISO reference fuels. The scuffing BOCLE test has been used to study 37 fuels randomly sampled from the field. The data shows that there is indeed a reduction in lubricity of low sulfur fuels. The variation in lubricity of low sulfur fuels is also much greater than high sulfur fuels. Data in this study shows that transition from good to poor lubricity usually occurs between 2500 to 3000 grams in the scuffing BOCLE.

Reports of disabling diesel engine seal failures which accompanied the introduction of low sulfur diesel fuel in October '93 prompted an in-depth survey of diesel fuel chemical and physical properties. The purpose of the survey was to anticipate other possible problems which might arise with the newly introduced low sulfur fuels. The survey will produce a database containing over 1000 number 2 diesel fuels from various parts of the US. About 75% of the samples tested were on-highway low sulfur diesel fuels. Samples analyzed were from the D-A Lubricant Company, Cummins customers failures (truck fleets of various sizes), and a number of retail fueling stations. Properties under investigation are % Sulfur, Cloud/Pour Points, Viscosity, API Gravity, TAN/TBN, Boiling Range, Aromatics content, Heat Content, Lubricity, and Peroxide number.

Reports of disabling elastomer seal failures across a wide range of diesel equipment, which accompanied the introduction of low sulfur diesel fuel in October '93 prompted an in-depth investigation of low sulfur diesel fuel chemical speciation. The objective of this work was to gain a better understanding of how low sulfur fuels had changed to cause this problem. Mass Spectroscopy (MS) and seal swell data were obtained on a broad geographical sampling of low sulfur diesel fuels obtained during the 4th quarter of '93. Previously available high sulfur (0.25%) data were available for comparison. Elastomer seal swell data were obtained in pure component blends and also in fuels which had caused field failures. Using these data it was possible to determine which fuel components or lack thereof may contribute most heavily to seal swell failures. Further, compression set data were obtained for a number of commonly used fuel system elastomers in a fuel which caused field problems.

Corrosive wear of non-ferrous engine components by lubricants is a concern of all major heavy duty diesel engine manufacturers since warranty on key engine components has been extended to 500,000 miles. Several commercial lubricants have been linked to premature cam and rod bearing failures induced by corrosion in certain fleets. Although the overall failure rate is low, specific fleets have experienced significantly higher failure rates due to the lubricants used. These failures usually occur at high mileages but less than 500,000 miles. This kind of slow corrosion easily escapes detection of engine tests contained in current oil specifications, and it represents a serious issue in long term warranty cost to diesel engine manufacturers. A comprehensive fleet database has been established to identify the most corrosive lubricants. These lubricants have served as reference oils to develop a corrosion bench test.

A high horsepower, low heat rejection diesel engine is being developed to meet future Army heavy combat vehicle requirements. This engine features high power output in a compact design that is oil-cooled allowing for a significant reduction in radiator size. This design requires a lubricant which can survive a sump temperature of 160°C, for 300 hours with transient sump temperature surges to over 177°C. A comprehensive high temperature lubricant development program has been initiated to address the need for this new design. A modified Cummins 10 liter diesel engine was used to simulate the operating condition of this low heat rejection engine. The premium commercial lubricant that was tested survived only 58 hours before completely losing oxidative stability. Several of the experimental lubricants completed the 200-hour peak torque endurance test.

The U. S. Treasury Department recently ruled that the ethanol blenders tax credit applies to ethanol used to make ETBE for blending with gasoline. As a result, ETBE may soon become a popular gasoline blending component. Like MTBE, ETBE adds oxygen to the fuel while contributing to other performance properties of the gasoline. Phillips Petroleum Company has completed limited driveability and material compatibility studies on gasolines containing ETBE and has determined the effect on various performance parameters such as octane, volatility, and distillation of ETBE in gasoline. Levels of ETBE ranging from 0.0 to 23.5 volume percent (3.7 weight percent oxygen) in gasoline were included in the investigation. Use in gasoline is currently limited to only 12.7 volume percent (2.0 weight percent oxygen) by the gasoline substantially similar rule. No detrimental effects of the ETBE on metal or elastomeric parts common to gasoline delivery and fueling system were found.

The Cummins A3.4-125 (rated 93 kW at 3600 rpm) has been developed to meet 1991 US and California light-heavy duty emission standards, replacing the Cummins 6AT3.4 (formerly Onan L634T-A). Compliance with the stringent particulate standard has been achieved by redesigning the combustion chamber, a systematic oil control program, and charge air cooling. The Ricardo Comet combustion chamber was modified to a downstream glowplug configuration. Oil control efforts addressed all sources of oil derived particulate. With charge air cooling, NOx emissions were reduced while improving fuel economy, torque output, altitude capability, and engine durability. THE CUMMINS A3.4-125 is an evolutionary development of the 1988-90 6AT3.4 engine. The development was driven primarily by 1991 US and California light-heavy duty emission standards, but also was the result of a policy of continuous product improvement. The Cummins A Series diesel engine family was conceived as the Onan L Series (1*).

Effective January 1, 1986, regulations by the U.S. Environmental Protection Agency limited the amount of alkyl lead antiknock additives that could be used in “leaded gasoline” to 0.1 gram per gallon. This has led to considerable concern about the potential for serious wear problems in older engines that were designed to run on leaded fuel. Phillips has completed a study to address this concern and identify limits of potential impact. This paper reports the results of this work. The subject test program was completed on a late model 302 Ford V8 engine modified to be equivalent to engines built prior to 1971 (primary engines of concern). The reported results show that fuel containing as little as 0.05 gram per gallon lead is sufficient to protect engines operated at low to moderate speeds against excessive wear.

The ongoing need for improved fuel economy, longer engine life, lower emissions, and in some cases, increased power output makes lower charge air temperatures more desirable. In 1983, Cummins introduced the new BCIV engine at 400 H.P. (298 KW) with “Optimized Aftercooling”, and is now introducing this concept to its remaining 10 and 14 Litre premium diesel engines. This Tuned Low Flow Cooling design provides many advantages when compared to the other alternatives studied, which included air-to-air and systems incorporating two radiators. The selection process considered performance, durability, fuel economy, emissions, noise, investment, and total vehicle installed cost. Computer simulations and vehicle tests were used to determine performance for each charge air cooling alternative. The simulations were used to guide prototype development and the selection of production hardware.

Laboratory tests have shown that 40% glass-reinforced PPS is suitable for automotive underhood use where it comes into contact with used engine oil, gasoline/alcohol, gasoline/MTBE, water, water/ethylene glycol, hydraulic fluid, and transmission fluid at elevated temperatures. On exposure to water or water/ethylene glycol at 248° F (120° C) and 257°F (125°C), respectively, there is a sharp decline in mechanical strength in the first few weeks with little change thereafter. The residual strength of the 40% glass-reinforced PPS is comparable to, or better than other materials, such as phenolics, which have proved satisfactory in such usage. These results have been translated to successful applications in heavy duty diesel engines. Piston cooling nozzles and water pump impellers made of 40% glass-reinforced PPS have undergone successful engine component evaluations.

The entire engine lubrication system has been represented by a series-parallel network of flow passages and flow elements. The pressure distribution and flow rates in the network were computed according to pressure-flow characteristics of each element. The pressure-flow relationship for each network element was estimated using empirical pipe friction, expansion, and bend loss coefficients, as well as by using test rig results and a steady-state journal bearing model. The journal bearing model is basically that of the classical short bearing model with provision for heat transfer to the oil and the relative thermal growth of the journal and bearing system. When compared with diesel engine tests, the simulation predicted the pressure distribution throughout the engine and the flow rate through each branch within 10%.

The Instron Capillary Rheometer, with special extremely fine capillaries, has been used to measure the apparent viscosities of non-Newtonian polymer-thickened multigrade oils at temperatures from 100°F to 320°F and shear rates to 106 sec-1. The same apparatus can produce permanent shear under extreme conditions. Temporary shear data at 100°, 150°, 210°, 280° and 320°F are reported for eight commercial oils and five experimental oils formulated with different VI improvers in the same base oil. Permanent shear data are given for a larger set of oils.

Extensive laboratory and field test data are presented on multigrade motor oils formulated with a new VI improver developed by Phillips Petroleum Company. This VI improver is a hydrogenated copolymer of butadiene and styrene. Its unique features are outstanding shear and oxidation stability, and excellent performance in Caterpillar 1-H diesel tests. Attention is focused not only on the unique features but on its overall performance in multigraded oils. Although this VI improver was originally developed for passenger car multigrade oils, data are present to show application in truck multigrade oils, high VI hydraulic oils, automatic transmission fluids, farm tractor hydraulic fluids, and use as a VI improver and thickener in several synthetic oils.

Tests were conducted with several production diesel engines and one prototype low-emission diesel engine to determine the effect of fuel properties on exhaust emissions and engine performance. Fuel cetane number was found to be the most significant fuel property; low cetane fuels resulted in higher hydrocarbons and oxides of nitrogen and increased noise. Conversely, higher cetane fuels produced lower emissions and noise, and also improved engine starting characteristics. The degree of these effects was influenced by engine configuration. Although engine design changes can result in substantial emissions reduction, fuel properties can also influence achieveable levels.

There has been an accelerated growth in power of diesel engines in United States line haul trucking. This paper analyzes the effect of high power on engine-related operating variables that occur under different highway conditions and dissimilar terrain features. When properly applied, high-powered diesel engines can increase average vehicle speed and/or fuel economy.

Differences in the power producing capacities and exhaust emission characteristics of various spark-ignition-engine fuels are frequently obscured by interactions involving the particular engine system used in the comparison. In an attempt to minimize this problem, gasoline, propane, methane, and a hydrogen-methane fuel gas were compared in a single cylinder engine under conditions that were optimum for each fuel. The resulting data, coupled with an estimated duty cycle representative of traffic service, permitted the development of internally comparable data on fuel consumption and exhaust emissions. Smog-inducing hydrocarbon emissions from the exhaust of a propane-fueled engine can be less than 13% of the minimum value obtainable with a gasoline fueled engine. Such emissions would be substantially eliminated with a well designed methane engine.