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In this study, the performance and emissions of a 4 cylinder 2.5L light-duty diesel engine with methane fumigation in the intake air manifold is studied to simulate a dual fuel conversion kit. Because the engine control unit is optimized to work with only the diesel injection into the cylinder, the addition of methane to the intake disrupts this optimization. The energy from the diesel fuel is replaced with that from the methane by holding the engine load and speed constant as methane is added to the intake air. The pilot injection is fixed and the main injection is varied in increments over 12 crank angle degrees at these conditions to determine the timing that reduces each of the emissions while maintaining combustion performance as measured by the brake thermal efficiency. It is shown that with higher substitution the unburned hydrocarbon (UHC) emissions can increase by up to twenty times. The NOx emissions decrease for all engine conditions, up to 53%.

A single cylinder engine was operated in HCCI mode with diesel-range fuels, spanning a range in cetane number (CN) from 34 to 62. In addition to measurements of standard gaseous emissions (CO, HC, and NOx), multiple sampling and analysis techniques were used to identify and measure the individual exhaust HC species including an array of oxygenated compounds. A new analytical method, using liquid chromatography (LC) with electrospray ionization-mass spectrometry (ESI-MS) in tandem with ultraviolet (UV) detection, was developed to analyze the longer chain aldehydes as well as carboxylic acids. Results showed an abundance of formic and butyric acid formation at or near the same concentration levels as formaldehyde and other aldehydes.

Dimethyl Ether (DME) is a potential ultra-clean diesel fuel. Its unique characteristics require special handling and accommodation of its low viscosity and low lubricity. In this project, DME was blended with diesel fuel to provide sufficient viscosity and lubricity to permit operation of a 7.3 liter turbodiesel engine in a campus shuttle bus with minimal modification of the fuel injection system. A pressurized fuel delivery system was added to the existing common rail injection system on the engine, allowing the DME-diesel fuel blend to be circulated through the rail at pressures above 200 psig keeping the DME in the liquid state. Fuel exiting the rail is cooled by finned tubed heat exchangers and recirculated to the rail using a gear pump. A modified LPG tank (for use on recreational vehicles) stores the DME- diesel fuel blend onboard the shuttle bus.

Biodiesel fuels are widely known to yield an increase in NOx emissions in many diesel engines. It has been suggested that the increase in NOx is due to injection timing differences caused by the low compressibility of biodiesel. In this work, comparisons of injection timing and duration were performed for diesel fuel and a range of biodiesel blends (B20 to B100). The fuel injector on a 4-stroke, single-cylinder, four horsepower, air-cooled, direct injection diesel engine was positioned in a spray chamber while the engine was motored and fuel was delivered to the injector by the fuel pump on the engine. Spray visualization and quantification of injection timing were performed in the spray chamber using an engine videoscope, light attenuation from a HeNe laser and fuel line pressure, and were synchronized to crank shaft position.

In this study, performance and emissions characteristics of an LPG direct injection (DI) engine with a rotary distributor pump were examined by using cetane enhanced LPG fuel developed for diesel engines. Results showed that stable engine operation was possible for a wide range of engine loads. Also, engine output power with cetane enhanced LPG was comparable to diesel fuel operation. Exhaust emissions measurements showed NOx and smoke could be reduced with the cetane enhanced LPG fuel. Experimental model vehicle with an in-line plunger pump has received its license plate in June 2000 and started high-speed tests on a test course. It has already been operated more than 15,000 km without any major failure. Another, experimental model vehicle with a rotary distributor pump was developed and received its license plate to operate on public roads.

Several oxygenates have been proposed and tested for use with diesel fuel as a means of reducing exhaust emissions. This paper examines dimethyl ether (DME), which can be produced in many ways including via Air Products and Chemicals, Inc's Liquid Phase Technology (LPDME ™). Modest additions of DME into diesel fuel (2 wt.% oxygen) showed reductions in particulate matter emissions, but the previous data reported by the author from a multicylinder Navistar 7.3L Turbodiesel engine were scattered. In this study, experiments were performed on a multi-cylinder Navistar 7.3L Turbodiesel engine to repeatably confirm and extend the observations from the earlier studies. This is an important step in not only showing that the fuel does perform well in an engine with minor modifications to the fuel system, but also showing that DME can give consistent, significant results in lowering emissions.

Several synthetic fuels derived from shale and coal were evaluated with respect to a reference petroleum-based Diesel fuel. Tests conducted using a single-cylinder DI Diesel engine were designed to quantitatively compare the fuels on the basis of performance, combustion characteristics, gas-phase emissions, particulate emissions, and biological activity of the solid phase soluble organic fraction. The biological activity was assessed using the Ames Salmonella typhimurium test. The shale fuels studied were a Paraho marine Diesel fuel and a light shale oil condensate from the Logan Wash in situ retorting operation. The coal liquids, Solvent Refined Coal-II and Exxon Donor Solvent, could not be run neat; therefore, they were blended 20% and 40% by volume with the certified DF-2 baseline fuel. Of the synthetic fuels tested, only the Paraho marine Diesel fuel exhibited the qualities of a good finished Diesel fuel.

THE effects of introducing a portion of the fuel charge of a diesel engine into the intake manifold in the form of a fine mist are reported in this paper. Laboratory tests with swirl-chamber and open-chamber engines resulted in smoke reduction up to 80%, increase in smoke-limited power output up to 18.5%, decrease in specific fuel consumption up to 9.8%, shorter ignition lag, lower maximum rate of pressure rise, and smoother operation. In running on good-grade diesel fuel approximately 15% of the main fuel proved to be as good a manifold fuel as any. It was also found that a diesel engine could operate satisfactorily on substandard fuels down to zero cetane number when fumigation was employed. Maximum benefits from fumigation accrued when inducting fuel in the form of a very fine mist (not over 4 microns) produced by Micro-Fog. As yet an economical method of producing this finely atomized fuel spray in large quantities has not been found.