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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.

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.

Considerable amounts (400 ∼ 600 thousand tons) of waste vegetable oil in Japan are still flushed down the drain every year. Utilization of waste vegetable oil for diesel fuel leads to two advantages for environmental protection, to reduce CO2 emission from engines and to avoid water pollution of rivers. In this study, combustion characteristics of waste vegetable oil methyl ester (WME) are investigated in detail by not only engine test run but also observation of burning flames in a visual engine. As results indicate, WME shows rather better combustion state in the visual engine and lower smoke emission from a high-speed DI test engine than gas oil. Moreover, by emulsifying WME with water, further improvement of combustion and more than 18 % reduction of NOx emission is carried out.

In Japan, about 750 million liters of lubricating oil from automobiles and marine engines become waste per year. The authors propose a plan to convert such used lubricating oil (ULO) to effective energy. In detail, some special diesel generator plants should be built and ULO should be burned there after some process. This plan has at least two advantages, i.e. to save the petroleum energy and to avoid the environmental pollution. Aim of this study is to develop the way to utilize ULO for diesel fuel at such a generator plant. Combustion characteristics of ULO are in detail investigated by observation of burning flames in a visual engine and by engine test run. As results of comparison between ULO and heavy fuel oil (HFO), ULO shows rather better ignition quality in the visual engine and lower smoke emission from the running test engine than HFO.

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.