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A test series was conducted on a six-cylinder diesel engine to study the impacts of controlled factors (i.e., oxygen content of the combustion air, water content of the fuel, fuel-flow rate, and fuel-injection timing) on engine performance and emissions using Taguchi techniques. Separate experiments were conducted using a commercial-grade No. 2-diesel and a lower-grade No. 6-diesel fuel. This paper reports the test results for No. 6 fuel. Oxygen enrichment improved the combustion process with the lower-grade fuel. There was no observable change in turbocharger performance due to oxygen enrichment. The results showed significant reductions in smoke and particulate emissions, a small increase in thermal efficiency and a large increase in NOx emissions when oxygen-enriched air was used. The effect of water-emulsified fuel on NOx emissions was negligible.

A hybrid bus powered by a diesel engine and a battery pack has been analyzed over an idealized bus-driving cycle in Chicago. Three hybrid configurations, two parallel and one series, have been evaluated. The results indicate that the fuel economy of a hybrid bus, taking into account the regenerative braking, is comparable with that of a conventional diesel bus. Life-cycle costs are slightly higher because of the added weight and cost of the battery.

Analytical studies of oxygen-enriched diesel engine combustion have indicated the various benefits as well as the need for using cheaper fuels with water addition. To verify analytical results, a series of single-cylinder diesel engine tests were conducted to investigate the concepts of oxygen enriched air (OEA) for combustion with water emulsified fuels. Cylinder pressure traces were obtained for inlet oxygen levels of 21% to 35% and fuel emulsions with water contents of 0% to 20%. Data for emulsified fuels included no. 2 and no. 4 diesel fuels. The excess oxygen for the tests was supplied from compressed bottled oxygen connected to the intake manifold. The cylinder pressure data was collected with an AVL pressure transducer and a personal computer-based data logging system. The crank angle was measured with an optical encoder. In each data run, 30 consecutive cycles were recorded and later averaged for analysis.

This paper presents the results of an analytical study to identify the essential features of a futuristic engine for cars. A combination of several advanced features in one engine package results in a dramatic increase in the fuel economy of the car while maintaining all other essential features at comparable levels to current cars on the market. This advanced adiabatic diesel (AAD) engine is expected to give 78.8 mpg in the Federal Combined Driving cycle in a 3,000-pound vehicle. This compares to 37.7 mpg and 30.0 mpg obtained in current diesel and gasoline engine powered cars, respectively. The study identified the research and development efforts needed to bring this concept to fruition and concluded that an aggressive 10-year program will result in production availability of these cars.

DEMAND FOR HIGHER SPECIFIC OUTPUT FROM DIESEL ENGINES has resulted in virtually all heavy duty engines being turbocharged. To obtain further increases in specific output, turbocharged engines can be coupled with a charge air cooling system. All major engine manufacturers now offer at least some models employing charge air coolers. The favorable impacts of charge air cooling on fuel consumption, emissions, altitude performance, thermal loading of engine components and the capability for higher specific output have encouraged several investigators to undertake in-depth studies of optimum charge air cooling system. This paper reviews the evolution and trends in charge air cooling systems. The advantages and concerns connected with the various methods are discussed. Some test and analytical results of the effect of charge air cooling on various engine performance parameters are presented.