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Technical Paper

Diesel Combustion Characteristics of Coconut Oil and Palm Oil Biodiesels

In order to determine the usefulness of coconut and palm oil biodiesels as alternative diesel fuel, the fuel properties, the combustion characteristics and the exhaust emissions were investigated. Therefore, the methyl esters of coconut, palm and rapeseed oils (CME, PME and RME) and the ethyl ester of palm and rapeseed oils (PEE and REE) were processed and tested using a DI diesel engine. From the experimental results, the thermal efficiency of CME is almost the same as the other test fuels and CME has the lowest HC, CO, NOx and smoke emissions among the test fuels. Also PEE has the same ignitibility as PME and the exhaust emissions of PEE are almost the same as PME. From this investigation, we can say that CME and PEE are favorable alternative diesel fuels to substitute for petroleum based diesel fuel.
Technical Paper

Multi-Component Modeling of Evaporation, Ignition and Combustion Processes of Heavy Residual Fuel Oil

The present study introduces a multi-component model for heavy fuel oil combustion based on two component approximation, implemented into KIVA-3V using modified evaporation, ignition and combustion models. The fuel is treated as a blend of residual portion and cutter stocks. Different fuel properties are assigned to each component affecting evaporation behavior in the liquid phase as well as ignition and combustion characteristics in the vapor phase. The model was validated regarding spray and flame appearance using photographs of spray combustion in a visual constant volume combustion chamber. Further the effects of fuel component properties on the ignition and combustion properties of the fuel blend have been investigated based on rate of heat release analysis.
Technical Paper

Visual Study Focused on the Combustion Problem in Gasoline Direct Injection Engine

Combustion phenomena inside the actual Gasoline-Direct-Injection (GDI) engines have been drawing high attention to its emission characteristics as well as its potential to deal with ultra lean mixture. Although the detailed observation is necessary for its improvement, combustion visualization seems to be strangely overlooked for some reason. This study focuses on the direct observation of GDI combustion to clarify the difficulties behind GDI concept by using a test engine of an actual “wall-guided” configuration and by comparing GDI spray quality with diesel spray in a high-pressure constant volume bomb. The results show that some of the problems about GDI combustion seem to be rather essential than easily conquered, which suggests the necessity for another combustion concept.