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This paper describes the effect of DME-LPG blended fuels on the macroscopic spray characteristics in a high pressure diesel injection system. In this work, the DME-LPG blended fuel that 30% LPG (butane) was blended into pure DME by weight ratio. In order to investigate the macroscopic spray characteristics such as spray tip penetration, spray cone angle, and spray area were measured under the various injection parameters. The experimental results were compared the blended fuels with pure DME. In the experiment, a single-hole nozzle injector with nozzle hole diameter of 0.3mm was used to investigate the macroscopic spray behavior characteristics of DME-LPG blended fuel. The experimental results of DME-LPG blended fuels showed that spray tip penetration was increased according to increasing injection pressure. The spray tip penetration and the spray area of DME-LPG blended fuel was slightly shorter than that of DME, and the both fuels showed similar trends of spray angle.

This paper describes the effects of two stage combustion strategy on the engine performance and the exhaust emission characteristics in a compression ignition engine. The two-stage combustion strategy targets reduction of NOx emissions by decreasing oxygen concentration for second stage combustion. Thus, the first injection was provided in order to consume in-cylinder oxygen, rather than generate power. A multi-dimensional CFD code was utilized to predict engine performance and emission characteristics. For the accurate and efficient computational calculation of ignition and combustion characteristics of diesel fuel, the reduced n-heptane mechanism was used in this study. The calculation for two-stage combustion was performed after validating against the experimental result. The KH-RT breakup model and gas-jet model was applied for the prediction of spray behavior and characteristics. To calculate the ignition and combustion process, CHEMKIN II [1] code was used.

The objective of this work is to analyze the macroscopic behavior of spray on the DME blended biodiesel at different mixing ratios by using spray visualization and injection rate system. The fuel spray structure of DME blended biodiesel and the development process of blended fuel spray was taken with the spray visualization system which consisted of a Nd:YG laser, an ICCD camera, high-pressure chamber and high pressure fuel supply system. The spray images were analyzed a spray tip penetration, a spray cone angle and a spray area distribution at various mixing ratio of DME by weight. The influence of different injection pressure and ambient pressure on the fuel spray characteristics are investigated for the various injection parameters.

In this study, Investigation of atomization characteristics and prediction accuracy of hybrid models for high-pressure diesel fuel sprays is performed. To analyze the atomization characteristics numerically, hybrid breakup models that are composed of primary breakup and secondary breakup are used. To model the primary breakup, KH model and turbulence induced breakup models are selected, and RT model, DDB model, and TAB model are considered for the secondary breakup.

The objective of this work was to experimentally determine the effect of premixed fuel on the reduction of exhaust emissions in diesel engine. In order to investigate the effect of premixed ratio on the NOx and smoke in a diesel engine, the reduction effect of exhaust emissions of diesel engine is investigated by means of experimental method. In this work, a direct injection type diesel engine with M-combustion chamber modified by using the supply system of premixed fuel into the intake manifold. The experimental apparatus consist of premixed fuel system, diesel injection system and electronic control system. The injection amount of premixed fuel in the intake port controlled by electronic injection system. The results of this study show that the increase of premixed ratio of supplied fuel reduce the nitrogen oxide and smoke emissions of the engine.

This study describes the results of transient behavior for a six-cylinders four-stroke turbocharged diesel engine during the change in operating conditions of the engine by using the computer simulation with measurements on test bed. In order to obtain the dynamic behaviors of the engine, the transient simulation are conducted with serveral kinds of inertia moment ratio in turbocharger and engine, a rapid large load application to the engine, and changes of governor gain constant. From the results of this study, the following conclusions may be summarized. Turbocharger lag is the main cause of the inferior transient performances of turbochared diesel engines. A reduction in the turbocharger moment ratio of inertia brings about the improvement of acceleration performance of disel engines. An increase of the engine moment ratio of inertia decreases cyclic variations of the engine speed.

The combustion characteristics of a diesel engine were examined by means of cyclic variation of combustion pressure and heat release history. In this paper the gas pressure, the rate of pressure rise, heat release rate and the other combustion characteristics of direct injection type diesel engine are investigated for the various pressure crank angle history using a combustion analyzing apparatus. Statistical analysis of combustion characteristics of diesel engine have been carried out over a various range of speed, fuel injection timing, and the several factors using a combustion data of five hundreds cycles of combustion analyzer. The results of this investigation show that the variations of combustion characteristics does change as cycle conditions are altered. The influences of cyclic parameter and operational factors on the combustion characteristics of engine are discussed also.