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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.