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The low auto-ignition temperature, rapid evaporation and high cetane number of dimethyl ether (DME) enables the use of low-pressure direct injection in compression ignition engines, thus potentially bringing the cost of the injection system down. This in turn holds the promise of bringing CI efficiency to even the smallest engines. A 50cc crankcase scavenged two-stroke CI engine was built based on moped parts. The major alterations were a new cylinder head and a 100 bar DI system using a GDI-type injector. Power is limited by carbon monoxide emission but smoke-free operation and NOx < 200ppm is achieved at all points of operation.

Many of the materials which have been developed for use as particle filters in the exhaust of diesel engines have characteristics which give rise to significant problems in practical use. Due to its special characteristics, it is shown that SiC is very well suited for use as the base material for particulate filters. The physical and thermal properties of porous SiC substrate material as applied to diesel particulate filters have been determined and are presented. Experimental results from several types of filter regeneration processes in exhaust gas systems confirm the improvements in the area of thermal load and reduction in temperature level during regeneration. The reduction in temperature during regeneration is shown to be consistent with the high thermal conductivity of SiC.

Mean Value Engine Models (MVEMs) are dynamic models which describe dynamic engine variable (or state) responses as mean rather than instantaneous values on time scales slightly longer than an engine event. Such engine variables are the independent variables in nonlinear differential (or state) equations which can be quite compact but nevertheless quite accurate. One of the most important of the differential equations for a spark ignition (SI) engine is the intake manifold filling (often manifold pressure) state equation. This equation is commonly used to estimate the air mass flow to an SI engine during fast throttle angle transients to insure proper engine fueling. The purpose of this paper is to derive a modified manifold pressure state equation which is simpler and more physical than those currently found in the literature. This new formulation makes it easier to calibrate a MVEM for different engines and provides new insights into dynamic SI engine operation.

Studies were performed with three commonly used additive metals, cerium copper, and iron, with a conventional and a low sulfur fuel in order to investigate fuel additive effects on engine particulate emissions before a particulate filter. Measurements were made on a 4 cylinder direct injection diesel engine and included total particulate mass, soluble organic fraction for both fuels, and polynuclear aromatic hydrocarbon emissions for the low sulfur fuel. The cerium based additive reduced the emissions with both fuels, with the largest effect being on the non-SOF fraction. With the other additives and the high sulfur fuel, non-SOF emissions were increased, increasing total particulate emissions. Copper was found to reduce the polynuclear aromatic hydrocarbons, and cerium was found to have the least effect. The use of an SiC wall flow filter reduced particulate and polynuclear aromatic emissions by over 90%.

Mean Value Engine Models (MVEMs) are simplified, dynamic engine models which are physically based. Such models are useful for control studies, for engine control system analysis and for model based engine control systems. Very few published MVEMs have included the effects of Exhaust Gas Recirculation (EGR). The purpose of this paper is to present a modified MVEM which includes EGR in a physical way. It has been tested using newly developed, very fast manifold pressure, manifold temperature, port and EGR mass flow sensors. Reasonable agreement has been obtained on an experiemental engine, mounted on a dynamometer.