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In order to improve the fuel properties and diesel combustion of biodiesel, waste vegetable oil methyl ester (from rapeseed and soybean oil mixture) with 5-20 mass% 1-butanol (BWME) are tested using a DI diesel engine. The viscosity and pour point of BWME decrease by blending 1-butanol. There is no problem in the startability and stability of the engine operation with BWME. Thermal efficiency of BWME is almost the same as that of the gas oil. The smoke emission decreases with increasing 1-butanol although the HC and CO emissions increase due to the longer ignition delay. It is concluded that BWME can be utilized as an alternative diesel fuel. Furthermore, to improve the ignitability and exhaust emissions of biodiesel with 1-butanol, palm oil methyl ester (PME) with high cetane number is tested as a base fuel of the 1-butanl blend. When the 1-butanol content in PME/1-butanol (BPME) is 15 mass%, BPME has almost the same ignition delay and HC and CO emissions compared with the gas oil.

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.

The diesel combustion characteristics and the exhaust emissions of biodiesel are affected by the composition of fatty acid methyl esters (FAMEs). In this study, the combustion characteristics and the exhaust emissions from single compositions of FAMEs, such as methyl palmitate, methyl oleate and the others, are investigated by using a single cylinder DI diesel engine. Experimental five FAME fuels are neat methyl oleate and the rest are blended mixtures based on methyl oleate. From the experimental results, the ignition delays of saturated FAMEs decrease with longer straight chain of the hydrocarbon molecules while in the same carbon number FAMEs, the ignition delays increase by increasing carbon-carbon double bonds. The break thermal efficiencies of the five FAME fuels and the gas oil are almost the same.

The fuel properties, the diesel combustion and the exhaust emissions of palm kernel oil methyl ester (PKME) and a blend of 20% PKME with 80% JIS No.2 gas oil (PK-B20) were investigated. In this study, the fuel properties were measured by laboratory analyses and the engine experiments were carried out by using a single cylinder direct injection diesel engine. To make comparison between biodiesels and conventional diesel fuel, palm oil methyl ester (PME), coconut oil methyl ester (CME), and the gas oil (JIS No.2) were also used as test fuels. From the fuel property analyses and the engine experimental results; the pour point of PKME was -5°C which was the same as that of CME and the pour point of PK-B20 was -10°C, the brake thermal efficiency of PKME was the same as the other test fuels, the ignition ability of PKME was better than that of the gas oil and the exhaust emissions (CO, HC, NOx and smoke) from PKME were almost the same as those of CME and lower than those of the gas oil.