Proceedings of the 19th National Conference on I.C. Engines and Combustion, Annamalai University, Chidambaram. Dec. 21 - 23, 2005. pp. 59 - 63. 59 GHHGEV QH DNGPF TCVKQU QH EQEQPWV OGVJ[N GUVGT ( FKGUGN QP VJG RGTHQTOCPEG CPF GOKUUKQPU QH E0K0 GPIKPG M0U0 Ujcpmct 3 . D0 Tcijcxgpftc Djcv 4 . E0X0 Uwfjkt 5 and R0 Oqjcpcp 6 1 Dept. of Mechanical Engineering, P. A. College of Engineering, Mangalore. shanksks@yahoo.co.in 2 Dept. of Mechanical Engineering, NMAM Institute of Technology, Nitte. 3 Dept. of Mechanical and Manufacturing Engineering, Manipal Institute of Technology, Manipal. 4 Dept. of Mechanical Engineering, National Institute of Technology Karnataka, Surathkal. ABSTRACT Efforts are under way in many countries, including India, to search for suitable alternative diesel fuels that are environment friendly. Among the different possible sources, diesel fuels derived from triglycerides (vegetable oils/animal fats) present a promising alternative. Fatty acid methyl esters, known as biodiesel, derived from triglycerides by transes- terification with methanol have received the most attention. This paper investigates suitability of different biodiesel blends for diesel engine operation. Edible coconut oil was subjected to transes- terification process to reduce its viscosity and the resulting coconut methyl ester known as biodiesel was used in a single cylinder direct injection C.I engine. The various properties of coconut oil, its methyl ester and ester blends with diesel oil were estimated. The performance and emission studies on 10%, 20%, 30%, 40%, 50% and 100% blends of coconut methyl ester with diesel (by volume) has indicated that the 20% biodiesel blended with 80% diesel (referred as B20) gave better performance and produced lower exhaust emissions. INTRODUCTION The world is presently confronted with the double crises of fossil fuel depletion and environmental degradation. The fact that petroleum based fuels will neither be available in sufficient quantities nor at a reasonable price in future has revived interest in exploring alternative fuels for diesel engines. Thermodynamic tests based on engine performance evaluations have established the feasibility of using a variety of alternative fuels such as CNG, LPG, alcohols, biogas and vegetable oil etc. Vegetable-oil-based fuels have considerable potential as an appropriate alternative, since the fuel properties are similar to that of petroleum diesel. The major problem associated with direct use of raw vegetable oils is their viscosity. One possible method to overcome the problem of high viscosity is transesterification of oils to produce esters (commonly known as Biodiesel) of respective oils [1]. Biodiesel is a non-polluting fuel made from organic oils of vegetable origin. Chemically it is known as free Fatty Acid Methyl Ester (FAME). The esters of fatty acids derived from transesterification of vegetable oils have properties closer to petroleum diesel fuels. These fuels tend to burn cleaner; perform comparably to conventional diesel fuel, and combustion is similar to diesel fuel [1, 2]. Present work focuses on the use of blends of transesterified coconut oil (Biodiesel) with diesel fuel. The objective of this study is to investigate the performance and emission characteristics of the C.I Engine fueled with biodiesel blends. During this investigation, the C.I engine was fueled with the different blends of Biodiesel and neat diesel in proportions varying from 10:90 (by volume) to 100:0 (i.e., full Biodiesel). In order to determine the optimum blend ratio, different blends were employed viz. B10, B20, B30, B40, B50 & B100. EXPERIMENTAL WORK I. Transesterification of Coconut Oil Widely used and accepted process to reduce the viscosity of triglycerides in vegetable oil is transesterification. In the transesterification of vegetable oils, a triglyceride reacts with an alcohol in the presence of a strong acid or base, producing a mixture of fatty acid alkyl esters and glycerol [3]. About 4 gm of catalyst (NaOH) was dissolved in 100 ml of methanol to prepare alkoxide, which is required to activate the alcohol. Around 20 minutes vigorous stirring was done in a closed container until the alkali was dissolved completely. The alcohol-catalyst mixture was then transferred to the reactor containing moisture free coconut oil. Stirring of the mixture was continued for another one hour while the temperature was maintained between 60 o and 65 o C. The resulting mixture was then taken out and poured into the separating funnel and the glycerol was separated from the mixture to get methyl ester of coconut oil. Water