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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.

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

Figure 1.Brake power Vs Brake Thermal Efficiency

Figure 3.Brake power Vs CO emission

B. Brake Specific Fuel Consumption

D. Hydrocarobon Emission The effect of compression ratio on HC emissions from the engine at different loads is shown in Fig. 4. The HC emissions start decreasing with increase of CR and reaches minimum at 18.1:1. For MEPPSO fuelled operation, the HC level is reduced by 11 ppm with increase of CR from 14.5:1 to 18.1:1 for maximum loading conditions. Similarly, for no load and part load conditions, the HC level is reduced by 9 ppm and 12 ppm by increasing CR from 14.5:1 to 18.1:1 respectively.

On the contrary, the HC level is increased when increasing CR beyond 18.1:1.

Figure 2.Brake power Vs Brake Specific Fuel Consumption

The effect of CR on BSFC of the engine fuelled with neat MEPPSO (B100) for different loads is shown in Fig.2.The Brake specific fuel consumption decreases from 0.53 to 0.46 kg/kWh during the increase in CR from 14.5:1 to 18.1:1 at the maximum load. This may be due to the increase in pressure of the compressed air, which improves the volumetric efficiency leading to the decrease in BSFC. On the contrary further increase in CR leads to increase in BSFC to about 0.5kg/ kWh. Figure 4.Brake power Vs HC emission

C. Carbon monoxide Emission The effect of compression ratio on CO emission from the engine fuelled with neat MEPPSO at different loads is shown in Fig.3. It is observed that the CO emission decreases with the increase of CR for all the loads. The CO emission is reduced by 0.035% by vol, when CR is increased from 14.5:1 to 18.1:1 at the maximum load and the minimum value is observed at the CR of 18.1:1. Beyond this range of CR, the CO emission slightly increases. Similarly, CO emission is reduced by 0.04% by vol. and 0.035% by vol, when CR is increased from 14.5:1 to 18.1:1 at no load and part load respectively.

E. Exhaust Gas Temperature

Figure 5.Brake power Vs Exhaust gas temperature

Š 2011 AMAE DOI: 02.MIT.2011.01.502

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

The effect of compression ratio on EGT from the engine fuelled with neat MEPPSO at different loads is shown in Fig.5.

The EGT increases with the increase of CR for all the loads.

When the engine is fuelled with neat MEPPSO, EGT level at no load, part load and maximum load increases to about 25oC, 29oC and 46oC respectively during the increase of CR from 14.5:1 to 20.6:1. The delayed combustion of bio-fuel leads to higher NOx emission.

The performance and emission characteristics of a diesel engine fuelled with MEPPSO are analyzed and compared.

Based on the experimental results, the following conclusions are drawn: 1. The Brake Thermal Efficiency for MEPPSO is increased during the increase in CR from 14.1:1 to 18.1:1 at maximum load. Further increase in CR (above 18.1:1) has no positive effect in BTE. 2. The Brake Specific Fuel Consumption for MEPPSO is decreased from 0.53 to 0.46 kg/kWh with the increase in CR from 14.5 to 18.1 at the maximum load.

3. The CO, HC and smoke emissions for MEPPSO are found lower than those for diesel.

4. The NOx emission for MEPPSO is doubled as compared to that with diesel at maximum load.

G. Oxides of Nitrogen The effect of compression ratio over NOx emissions from the engine fuelled with neat MEPPSO at different loads is shown in Fig.6. The NOx emissions increase with the increase of CR and reaches maximum at 18.1:1, for all the loads. For the engine fuelled with neat MEPPSO, the NOx emissions at no load, part load and maximum load increase to about 56, 58 and 155 ppm respectively, when CR increases from 14.5:1 to 20.6:1.

ACKNOWLEDGMENT This experiment has been done in Internal Combustion Engines Laboratory, Department of Mechanical Engineering, Government College of Engineering, Salem-11. The authors would like to acknowledge the equipment support extended by the World Bank under the Technical Education Quality Improvement Programme (TEQIP).

REFERENCES [1] T. Murayama, K. Itow, “Low Carbon Flower Build-up, Low Smoke, and Efficient Diesel Operation with Vegetable Oils by Conversion to Mono-Esters and Blending with Diesel Oil or Alcohols,” SAE Paper, vol. 841161, 1984.

[2] Deepak Agarwal and Avinash Kumar Agarwal, “Performance evaluation of vegetable oil fuelled compression ignition engine”, Renewable Energy, vol. 33, 2008, pp.1147-1156.

[3] Avinash Kumar Agarwal and Atul Dhar, “Performance, emission and combustion characteristics of Jatropha oil blends in direct injection diesel engine,” in SAE Paper, no.2009-01-0947, 2009.

[4] Sivalakshmi, S. and Balusamy, T, ‘Effect of oxygenated organic compounds-neem oil blends on the performance and emissions of a DI diesel engine’, SAE Paper No. 2011-01-0331.

[5] Avinash Kumar Agarwal, K. Rajamanoharan, “Experimental investigations of performance and emissions of Karanja oil and its blends in a single cylinder agriculture diesel engine,” Applied energy, no.86:106-112, 2009.

[6] M. Muralidharan, P.M.V. Subbarao, “Use of Pongamia Biodiesel in CI Engines for Rural Application,” SAE International, 2004-280030, 2004.

[7] Iman Reksowardojo, K. Ichsan Lubis, “Performance and Exhaust Gas Emissions of Using Biodiesel Fuel from Physic Nut (Jatropha Curcas L.) Oil on a Direct Injection Diesel Engine (DI),” SAE Paper, no. 2007-01-2025, 2007.

[8] K. Manikanta, K. Anil, B. Manoj Prabhakar, “Performance Analysis of Variable Compression Ratio Engine Using Diesel,” Proc. of. Int. Conf. on Advances in Mechanical Engineering, 2010, pp.48-49.

Figure 6.Brake power Vs NO x emission

H. Smoke Intensity The effect of compression ratio on smoke intensity from the engine fuelled with neat MEPPSO at different loads is shown in Fig.7. The Smoke intensity decreases with the increase of CR and reaches the minimum value at 18.1:1, for all the loads. For the engine fuelled with neat MEPPSO, smoke intensity level at no load, part load and maximum load decreases to about 7, 17 and 18 BSU respectively when CR increases from 14.5:1 to 20.6:1.

Figure 7.Brake power Vs Smoke Intensity

© 2011 AMAE DOI: 02.MIT.2011.01.502

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