Deuxième Congrès Tunisien de Mécanique COTUME’2012 Sousse 19-21 Mars 2012 Page 1/3 Abstract :The main purpose of this research is to study the effect of various blends of a Biodiesel fuel on the performance of a six cylinder diesel engine.The Biodiesel was obtained from the trans- esterification of waste oils (frying oils). Results obtained demonstrate that the biodiesel gives very inter- esting ecological advantages but engine performance was re- duced slightly comparatively to those obtained with a pure diesel fuel. Keywords: biodiesel, diesel engine, performance, emission. 1. Introduction It is recognized that petroleum resources are exhaustible and the world’s present oil reserves may be wiped out in about 40 years. Also the use of petroleum as a fuel gener- ates several environmental problems. Biodiesel, obtained from vegetable oils, could be a good alternative to solve the environmental pollution problems along with providing many other utilities. Several experi- ments have been carried out on these fuels and satisfactory results have been obtained. Lower emissions are produced and other advantages include higher thermal efficiency and low engine noise compared to the diesel engine operating with conventional diesel fuel. Biodiesels are obtained, in general, from transesterification which refers to a catalyzed chemical reaction involving vegetable oil origin, and an alcohol, usually methanol, to yield fatty acid alkyl esters and glycerol (i.e. crude glycerin) [1,2,3]. In this study, we investigated the effect of various blends of “Methyl Ester” biodiesel fuel, obtained from the transesteri- fication of waste oils, on a six cylinder Diesel Engine per- formances. Our results agree well with many experimental results re- ported in literature. These tests demonstrated a significant environmental advantage of the Methyl Ester biodiesel (lower emissions of CO and smoke) however a slight reduc- tion of the engine performances (a decrease of the engine power and torque, and an increase of fuel consumption) are observed. 2. Experimental Set-Up The study was performed on SCHENCK D400 engine test bench .The engine was a 4-stroke, six cylinder, Direct Injec- tion Diesel engine [model OM 352], manufactured by Mer- cedes Benz. The performance and emission tests were conducted under engine full load condition. 3. Results and Discussions 1.1. Engine Performance Preliminary bench-tests have been performed to evaluate the variation of engine performances and emissions versus the percentage of biofuel. Figures 2. and 3. show torque and power evolution vs. engine speed for different blends; the curves represent average results of different test series re- ported to ISO conditions. No modification has been done on engine set-points, in order to allow complete fuel interchan- geability. The increase of biodiesel percentage in the blend involves a slight decrease of both power and torque over the entire speed range. In particular, with pure biodiesel there is a re- duction by about 3% of the maximum power and about 5% of the maximum torque. Moreover, with pure biodiesel, the maximum torque is reached at higher speed; this fact might be related to an increase of the flame velocity observed with biodiesel. This may result in a pressure peak shift to a crank angle closer to TDC [6]. Experimental Study of a Diesel Engine Performance Running on Vegetable Oil Biodiesel Blend R. Ennetta 1,2 , C. Boubahri 1 , R. Said 1 , and J. Bessrour 3 1 Ionised and Reactive Media Study (EMIR), University of Monastir, Avenue of Ibn El Jazzar, Monastir, 5019, Tunisia, +21622179580, chokri.boubahri1@gmail.fr, +21698616789, Rachid.Said@ipeim.rnu.tn. 2 Higher Institute of Industrial Systems of Gabes (ISSIG), University of Gabes, Salaheddine El Ayoubi Street, Gabes, 6011, Tu- nisia, +21698487430, ridha.ennetta@issig.rnu.tn 3 Applied Mechanic, Engineering and Industrialisation, National School of Engineers of Tunis, BP 37, Le Belvédère, 1002 Tuni- sia, +21671874700, jamel.bessrour@enit.rnu.tn Fig.1 Engine test bench. Fig.2 torque vs. speed