Özet:

The purpose of this study is to find out in-cylinder flow characteristics of a four-cylinder, 2,3 liter diesel engine before the fuel injection and also properly simulate the atomization process in order to improve the combustion efficiency and emission parameters. A complete intake stroke with Compressed Bio Gas (CBG) port injection, compression stroke, pilot fuel injection at the end of the compression and exhaust stroke simulated in 3D. Both naturally aspirated and turbo-charged modes of operations were studied. In this study, cold flow structure, fuel atomization for different spray models and dual fuel combustion are investigated. A comprehensive model for atomization of liquid sprays under high injection pressures has been employed. Finally, a calculation on an engine configuration with compression, spray injection and CBG-diesel combustion in a direct injection dual fuel diesel engine is presented. In 3D CFD study, selected proper cases modeled using full geometry of diesel engine. Fine grids were tested with 1,700,000 hexahedral cells. In this paper, fine grid results are evaluated. CBG fuel induced during intake process in dual fuel diesel combustion engine and then mixed with air before the premixed gas enters the cylinder. It is ignited by the injection of pilot diesel fuel near the Top Dead Center (TDC). This lean combustion and diluted gas mixture cause low in-cylinder temperature and resulting in a NOx emission. The results are in agreement qualitatively with the previous studies in the literature.

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