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Short Paper Proc. of Int. Conf. on Recent Trends in Mechanical, Instrumentation and Thermal Engineering 2011

Experimental Analysis of a Variable Compression Ratio Engine S.Sivalakshmi1, T.Balusamy1, K.Ramamoorthy2, and U.Udaykrishnan2 1

Assistant professor, Government College of Engineering, Salem-11, India Email: s_sivalakshmi@yahoo.com 2 Student, Government College of Engineering, Salem-11, India Email: {crazyram.mech, udaykrish10}@gmail.com

Abstract— The problem of world energy supply is a hot topic at the moment. This leads to the need for development of renewable energy technologies. Energy from biodiesel is one of the opportunities that could cover the future energy demand. Many early studies indicate the possibilities of the biodiesel produced from Pongamia Pinnata being used as a fuel in compression ignition engine. An attempt has been made in this paper to improve the performance and emission characteristics of a Variable Compression Ratio (VCR) engine fuelled with the methyl ester of pongamia pinnata Seed Oil (MEPPSO) by varying the compression ratio. The results reveal that the performance and emission of the engine fuelled with neat M EPPSO showed an improvement at the compression ratio of 18.1:1.

II. EXPERIMENTAL A. Experimental Setup Experiments have been conducted in a variable compression ratio, fully automated single-cylinder, fourstroke, naturally aspirated, direct injection diesel engine. The main specifications of the engine are: bore 85mm, stroke 82 mm, compression ratio 14.1 to 20.6, maximum power 2.3 kW at 1500 rpm, a three hole nozzle mounted at the center of combustion chamber injects the fuel at the pressure 210 bar. The fuel consumption can be measured with the aid of optical sensor. A differential pressure transducer is used to measure air flow rate. The engine is coupled with an eddy current dynamometer which is used to control the engine torque through computer. Engine speed and load are controlled by varying excitation current to the eddy current dynamometer. An AVL exhaust -gas analyzer and AVL Smoke meter are used to measure the emission parameters and smoke intensity respectively. Load can be changed from no load to the maximum load. The engine is operated at the rated speed i.e., 1500 rpm with varying compression ratio from 14.1 to 20.6. The experiment is carried out at different compression ratios and different loads. Then, the results obtained are presented in the form of graphs.

Index Terms— Methyl ester of Pongamia Pinnata Seed Oil, Performance, Emission, Variable compression ratio engine.

I. INTRODUCTION The word has been confronted with energy crisis due to the decrease of fossil fuel resources and the increase of environmental restrictions. Therefore attention has been focused on developing the renewable or alternate fuels to replace the petroleum based fuels for transport vehicles. There are several alternative sources of fuel like vegetable oils, biogas, biomass, primary alcohols which are all renewable in nature. Among these fuels, vegetable oils appear to have an exceptional importance as they are renewable and widely available, biodegradable and non-toxic, and environmental friendly. In agriculture-based country, like India, the use of vegetable oils has to be identified and initiated in order to prevent environmental degradation and reduce dependence on imported fossil supplies by partially replacing them with renewable and domestic sources. A great deal of research has been conducted on their feasibility and the researchers have concluded that neat vegetable oils hold promise as alternative fuels for diesel engines for short-term use [1-7]. The Compression Ratio (CR) is the key parameter in IC engines. The concept of variable compression ratio promises improved engine performance and emissions [8]. In this study, experimental investigation has been carried out to find the optimum compression ratio for a variable compression ratio engine fuelled with methyl ester of pongamia pinnata seed oil for better engine performance and improved emission.

© 2011 AMAE DOI: 02.MIT.2011.01.502

B. Transesterification The formation of methyl ester of Pongamia Pinnata by transesterification requires raw oil, 15% of methanol and 5% of sodium hydroxide on mass basis. However, transesterification is an equilibrium reaction in which excess alcohol is required to drive the reaction very close to completion. The vegetable oil chemically reacts with an alcohol in the presence of a catalyst to produce methyl esters of pongamia pinnata seed oil (MEPPSO). Glycerol will be produced as a by-product during this reaction. III.RESULTS AND DISCUSSIONS A. Brake Thermal Efficiency The effect of compression ratio (CR) on BTE of the engine fuelled with neat MEPPSO at part load and full load is shown in Fig 1. BTE initially increases with the increase of CR from 14.5:1 and reaches maximum at the CR of 18.1:1. Further increase of CR has no positive effect in BTE. This is due to increase in temperature of the compressed air, which result in better atomization of MEPPSO which causes better combustion leading to increase in brake thermal efficiency of the engine. 17


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