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Increases in efficiency may be possible by a new technique for non-thermal plasma aftertreatment of exhaust gases. The new technique involves very short risetimes (40ps) high frequency (5Ghz) high power bursts of low duty factor microwaves to generate a dielectric barrier discharge. The technique is illustrated in the simplified example of the dissociation of NO in N2. Electric field distributions and enhancing improvements are briefly described for a number of configurations. The technique is meant to be used in conjunction with material catalyst and can, for a class of catalysts, cause a significant reactivity on the catalyst surface.

Temperature measurement of internal components and surfaces can enhance understanding of thermal processes that occur during engine operation. Such measurements have typically been made with thermocouples, temperature sensitive paints or plugs, or infrared emission methods. Phosphor thermometry, a non-contact measurement technique, is an alternative that can be applied when more traditional methods are not feasible or are too costly. Recent efforts described in this paper have used phosphor thermometry to measure steady state piston crown temperature in a single cylinder engine. Additional testing with this technique included monitoring intake valve temperature in a multicylinder engine under cold start conditions. Packaging of the optical hardware necessary for this technique was substantially refined during these tests for use in modern engine geometries.

A study is carried out here to examine the probable causes for the seemingly contradictory results found in the present-day literature on low-heat-rejection (LHR) engines, provide plausible explanations, and indicate possible directions for future research. Almost all numerical studies predict improved thermal efficiency, increased availability in the exhaust, and reduced in-cylinder heat rejection in the case of LHR engines. The degree of improvement varies considerably from a few percentage points to several, depending on the extent of insulation and whether or not turbocompounding and Rankine bottoming cycle are included. In these simulations, care is taken not to allow the volumetric efficiency to decrease due to higher cylinder temperatures in LHR engines. In addition, air-fuel ratio and, in many instances, peak conditions are maintained constant in both the LHR and conventionally-cooled engines.

A series of tests are conducted in a tubular, continuous flow combustor containing a 15 cm diameter combustion liner. Fuel is supplied to the flame zone through a circular array of 30 equispaced miniature airblast atomizers. The objective is to achieve a sensibly uniform mixture strength in the fuel-air mixture entering the flame zone. This, in turn, ensures uniform conditions of temperature and chemical composition at any given axial distance downstream of the fuel injection plane. A unique feature of this fuel injection system is that it allows the mean drop size of the fuel spray to be varied while maintaining all other flow properties constant. Thus, experimental data on particulates and other pollutant emissions can be acquired under controlled conditions of pressure, inlet air temperature, and fuel mean drop size, at any given axial distance downstream of the fuel injection plane.

Raw oils generated by low-temperature coal pyrolysis were chemically characterized and subjected to tests in three diesel engines of different configuration. The coal liquids were tested as blends with conventional No. 2 diesel fuels, the coal liquids being 20-25% by volume. These tests were performed in support of a broader set of studies on the feasibility of using low-temperature pyrolysis to obtain liquid fuel materials from coal that do not require extensive, costly upgrading. Determination of physical and chemical properties of the pyrolysis liquids indicated a higher hydrogen/carbon ratio and lower aromaticity than typical SRC II and EDS middle distillates. Combustion tests were performed in both direct- and indirect-injection engines at three sites. The results were highly variable, the addition of the oil showing no effect on emissions and performance in some cases, reduced emissions on one engine, and increased emissions in other cases.