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Recently, for reduction of PM emission from diesel engine, low sulfur diesel fuel was introduced and commercialized. There are some reports for effect of fuel sulfur on PM characteristics by using engine dynamometer tests. However, it is difficult to understand mechanism of PM formation and effect of fuel sulfur on PM formation process. Thus, investigation by a simple flame is effective way for understanding detail PM formation process. In this paper, effect of sulfur content in fuel on PM characteristics was investigated by using laboratory-scale PM generator. Test fuels were diesel and surrogate diesel fuel, and sulfur concentration in the surrogate fuel was controlled with thiophene addition. Effects of fuel sulfur on PM were clarified with characteristics of PM obtained from PM number distribution measurements and PM compositions analysis.

This paper describes the application of inverse boundary element method (Inverse BEM) to vibration identification on surface of Co-generation System enclosure. This method is a kind of matrix inversion using singular value decomposition. Therefore it is significant to select proper tolerance in order to identify vibration accurately. In this study, the tolerance selection method is proposed. First step, the surface velocity of numerical model with unit input was obtained by Finite Element Method. The sound pressure around the model was obtained by BEM. Second step, random noise was mixed with obtained sound pressure. Third step, by using Inverse BEM, the surface velocity was identified from the sound pressure with noise. Next, the error between the identified velocity and the velocity obtained by FEM were evaluated and the tolerance is selected to minimize the error.

This paper describes how use of multi-objective optimization of pulsating noise and backpressure improved an exhaust silencer for diesel drive equipment. Low frequency pulsating noise and backpressure were simultaneously predicted using one-dimensional fluid dynamics and acoustic analysis by BEM. In addition, an experiment was done to investigate the relation between high frequency noise including flow-induced noise and the dimensions of perforations in silencer pipes. Finally, a prototype of the exhaust silencer was built and examined in order to confirm the effects of these design methods mentioned. As predicted, exhaust noise was reduced without increasing backpressure.

In a direct injection diesel engine, liquid fuel was injected through a multi-hole injection nozzle to a combustion cavity. The spray impingement on the cavity wall made the quick mixing of sprayed fuel and air. Then the spray impingement process was considered as the key process of the mixture formation, and this process was widely investigated. Since the cavity had too small space for free movement of plural sprays injected by a multi-hole injection nozzle, sprays after impingement were interacted together on the cavity wall. This movement was generally recognized but the detail behavior was not yet clarified. In this study, single shot diesel spray injected into a high-pressure test vessel, in which the impingement plate was mounted, was used to investigate the above movement.

The demand for the noise reduction of working machines, such as construction machines, tractors, and generators, has been strongly increasing. In order to achieve noise reductions, a low noise fan was developed using the CFD (Computed Fluid Dynamics) technique. The engine enclosure was developed, not only to reduce the noise emitted from the engine efficiently, but also to improve the cooling performance. Finally, the average noise level of working machines was reduced by about 10dB(A).

RITE and three national institutes of Ministry of International Trade and Industry (MITI) have been jointly developing a CO2 mitigation system in “Project of Chemical CO2 Fixation and Utilization Using Catalytic Hydrogenation” since 1990. A conceptual total system of the project is composed of the separation/recovery via membrane separation of a large amounts of CO2 emitted from stationary sources such as power plant, iron-making plants, chemical plans and so on, H2 production by water electrolysis, methanol synthesis from CO2 and H2, and of the transportation of the methanol produced to the sites for energy consumption and/or chemical production. An application of the system to a 1,000 MW coal fired power plant could recover 470 ton/h of CO2 and produce 323 ton/h of methanol. If the methanol produced is used for a power plant in Japan, the energy efficiency and the CO2 reduction rate of the system could be estimated to be around 30%, 36% respectively.

The purpose of this paper is to outline some of the approaches to provide an exhaust gas high temperature sensor with wide temperature detection range and fast responsiveness. Conventional exhaust gas temperature sensors were designed only to detect an overheating catalyst, so they were unable of detecting temperatures below 600°C. Their slow responsiveness prevented them from detecting rapid catalyst temperature changes. The development of a new thermistor material enabled the sensor to measure a wide temperature range of 300°C to 1000°C. This new sensor provides fast response time (x = 8.7seconds.) as well as durability capability to 1000°C Applications for this sensor include in catalyst preheating and OBD-II systems.

In a small high-speed DI diesel engine, injected fuel sprays impinge on the wall of piston cavity. Discussion and analysis of the combustion phenomena in the diesel engine demand the measurement of the characteristics of the impinging spray. In the experiments presented here, diesel fuel oil was injected into a high pressure chamber in which compressed air or CO2 gas at room temperature was charged. The single spray was impinged on a flat wall at a normal angle. The growth of the spray was photographed, not only with transmitted light but also with scattered light through a narrow slit. The temporal and spatial distribution of the droplets density in the impinging spray applying the concentric circle model was calculated using the data of the laser light extinction method. From these results, the detailed information concerning the droplets density in the impinging diesel spray was obtained.