Alternative fuels for diesel engines have become highly important in the automotive industry due to the depleting fossil fuel sources and increased environmental concerns. Biodiesel fuel has a good combustion characteristic because of their long-chain hydrocarbon structure but the higher density and viscosity of the fuel can contribute to several engine problems such as low atomization, carbon deposit formation and injector clogging. The production of biodiesel with additives can help with the performance and emissions of diesel engines. There are many types of additives on the market but the extent of the additives on engine performance is unknown and lack of research has been done in studying the performance, emissions and fuel consumption together with B100 biodiesel. In this research, there are five types of B100 palm oil methyl ester biodiesel with various additive compositions need to be identified. The density, viscosity and calorific value of biodiesel samples were measured to study the thermo-physical properties as a simulation input. Simulation of the combustion engine is conducted using CONVERGE CFD software; based on single-cylinder, direct injection, YANMAR TF90 diesel engine parameters to study on the combustion characteristics and exhaust emissions. The simulation results were compared with the experiment results. From the simulations, biodiesel with diethyl ester and n-butanol additives give better results compared to other additives because the present of n-butanol PME is believed to reduce CO, CO2 and NOx emissions while diethyl ether can improve the spray characteristics when it blends with B100 biodiesel due to its low density and viscosity.

Biodiesel can be used as an alternative fuel for the diesel engine and have a good combustion characteristic because of their longchain hydrocarbon structure. However, biodiesel possesses few disadvantages such as lower heating value, higher viscosity, higher density and will contribute to several engine problems such as low atomization during injection and carbon deposit formation. There are many types of additives on the market but the extent of the additives on engine performance is unknown and only several researches has been done in studying the performance, emissions and fuel consumption of 100% palm oil methyl ester (B100 biodiesel). In this study, there is five type of B100 biodiesel. The objectives of this research are to identify individual composition in each biodiesel samples, such as the identification of additives and fatty acids methyl esters using gas chromatography (GC-FID). The experimental measurements of density, viscosity and calorific value of B100 biodiesel were conducted. The results showed that a blend of biodiesel with diethyl ether and n-butanol has the closest calorific value to fuel diesel followed by the combination additives of ethanol, butanol and methyl pyrrolidone. Engine performance and emission were also investigated by determining the BSFC, BTE and CO, HC, and NOx gas emissions by simulation using CONVERGE CFD software based on single-cylinder, direct injection YANMAR TF90 diesel engine parameters. Performance results show that the combination of diethyl ether and n-butanol as an additive with crude palm oil will give a higher brake power and lower NOx and brake specific fuel consumption among all samples. The emission studies revealed that the addition of n-butanol additive can reduce carbon monoxides (CO), nitrogen oxides (NOx), particulate matter (PM) emission while diethyl ether can improve the spray characteristics when it blends with B100 biodiesel due to its low density and viscosity.