Effect of Compression ratio, Injection Timing and Injection Pressure on a DI Diesel engine for better performance and emission fueled with diesel diesel biodiesel blends Venkatraman.M 1, Devaradjane.G 2 1 Department of Mechanical Engineering, Arulmigu Meenakshi Amman College of Engineering, Vadamavandal, Kanchipuram 2 Department of Automobile Engineering, Anna University, MIT Campus, Chrompet, Chennai mvramcet@yahoo.co.in ABSTRACT In the present investigation test were carried out to examine the performance, combustion analysis and emissions of a direct injection diesel engine coupled with electrical dynamometer fueled with diesel and pungam methyl ester and their blends (, and PME3).From the investigation it is found that the combined increase of compression ratio, injection timing and injection pressure increases the BTHE and reduces BSFC while having lower emissions for. For small sized direct injection constant speed engines used for agricultural applications (4.4 kw), the optimum combination was found as CR of 19:1 with IP of 24 bar and injection timing 27 btdc.the heat release rate are reduced Methyl ester of Pungam oil blended fuel compared to diesel. The harmful pollutants such as HC, CO, are reduced in the pungam oil esters compared to diesel fuel. Key words: Diesel engine, injection timing, injection pressure, pungam oil methyl esters, performance, emission, combustion characteristics Notations used: BSFC : Brake specific fuel consumption BTHE : Brake thermal efficiency BSEC : Brake specific energy consumption HRR : Heat release rate CHRR : Cumulative heat release rate : Blend of biodiesel and diesel having 1% Biodiesel and remaining diesel : Blend of biodiesel and diesel having 2% Biodiesel and remaining diesel PME3 : Blend of biodiesel and diesel having 3% Biodiesel and remaining diesel 1. Introduction With crude oil reserves estimated to last for few decades, there has been an active search for alternate fuels. The depletion of crude oil would cause a major impact on the transportation sector. Of the various alternate fuels under consideration, biodiesel, derived from vegetable oils, is the most promising alternative fuel to diesel due to the following reasons.biodiesel can be used in the existing engine without any modifications.biodiesel is made entirely from vegetable sources; it does not contain any sulfur, aromatic hydrocarbons, metals or crude oil residues. 288
Biodiesel is an oxygenated fuel; emissions of carbon monoxide and soot tend to reduce. The use of biodiesel can extend the life of diesel engines because it is more lubricating than petroleum diesel fuel.biodiesel is produced from renewable vegetable oils/animal fats and hence improves the fuel or energy security and economy independence. A lot of research work has been carried out to use vegetable oil both in its neat form and modified form. Since India is net importer of vegetable oils, edible oils cannot be used for production of biodiesel. India has the potential to be a leading world producer of biodiesel, as biodiesel can be harvested and sourced from non edible oils like Jatropha curcus, pongamia pinnata, neem mahua, castor, linseed, etc. Some of these oils produced even now are not being properly utilized. Out of these plants, India is focusing on Jatropha curcas and pongamia pinnata, which can grow in arid and wastelands. Implementation of biodiesel in India will lead to many advantages like green cover to wasteland, support to agriculture and rural economy and reduction in dependence on imported crude oil and reduction in air pollution. In the present investigation biodiesel is prepared from pungam oil.the performance, combustion and emission characteristics were analyzed on a four stroke single cylinder direct injection diesel engine have been used. 2. Biodiesel production Esterfication of pungam oil comprised heating of oil, addition of sodium hydroxide and alcohol, stirring of the mixture, separation of glycerol, and biodiesel.this esterfied pungam oil is called biodiesel.biodiesel properties are similar to diesel fuel as shown in the Table.1.After esterfication of the pungam oil its properties like density,cetane number,viscosity,calorific value are improved. These parameters induce better combustion characteristics and performance of diesel engine. The biodiesel contain more oxygen and lower calorific value compare than diesel.as a results in lower generation of hydrocarbon and carbon monoxide in the exhaust than diesel fuel. 3. Testing Procedure Table.1 Properties of Bio diesel compared with neat diesel Bio Diesel Properties Diesel Pungam oil (Methyl Ester) Cetane No. 48 56 47 57 Density(kg/m 3 ) 821 934 892 Viscosity (cst) 3.52 45.62 5.42 Calorific value (MJ/kg) 43 36.64 39.15 Flash point C 48 27 156 Figure.1.shows the schematic diagram of the experimental set up and its specification are given in Table.2. Testing was carried out at various loads starting from no load to the full load condition. An Electrical dynamometer was used to apply the load on the engine. A water rheostat with an adjustable depth of immersion electrode was provided to dissipate the power generated. 289
At each load, the fuel flow rate various constituents of exhaust gases such as Hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxides (NOx), were measured with a 5 gas MRU Delta exhaust gas analyzer. The analyzer uses the principle of non dispersive infrared (NDIR) for the measurement of CO and HC emissions while NOx measurement was by means of electrochemical sensors. Figure 1: Schematic diagram of Experimental Set Up Combustion analysis was carried out by means of an AVL pressure pick up fitted on the cylinder head and a TDC Encoder fixed on the output shaft of the engine. The pressure and the crank angle signals were fed to a Pentium personal computer. Various combustion parameters like heat release rate, cumulative heat release rate and peak pressure and its accurance were obtained using data acquisition system. The engine was first operated with diesel oil to generate the baseline data followed by Methyl Esters Pongamia and their blends from varying, and PME3 blends and the test were carried out in the same manner. The results of blends are comparable with diesel and are presented. 29
4. Result and Discussion Experimental investigation have been carried to examine the performance and emission at different compression ratio, injection timing and injection pressure the details have been mentioned in Table.3.The engine were set to run at compression ratio 19:1,advanced injection timing 27b TDC and injector pressure 24bar to arrive at the optimum for pungam methyl esters(). From the experimental analysis it was found that at low injector opening pressure 2bar and 22bar and retarded injection timing of 21b TDC and 24b TDC and compression ratio 17.5:1 and 16:1 were also tried but from the investigation it was found that the performance and emission is very poor. Table 2: Specifications of diesel engine Make Kirloskar Model TAF 1 Type Direct injection, air cooled Bore Stroke (mm) 87.5 11 Compression ratio 17.5:1 Cubic capacity.661 lit Rated power 4.4 KW Rated speed 15 rpm Start of injection 24 bºtdc Connecting rod length 22 mm Injector operating Pressure 22 bar Table 3: Range of operating parameters tried in the present testing % Load,25,5,75,1 Speed(rev/min) 15 Compression ratio 16:1,17.5:1,19:1 Injection Timing btdc 21,24,27 Injection Pressure(bar) 2,22,24 Figure.2. shows the comparison of Brake Thermal Efficiency with Brake Power for different fuels. The maximum brake thermal efficiency obtained is about 3.5. % for and 3.1% for diesel. Increase in thermal efficiency due to %of oxygen presence in the biodiesel, the extra oxygen leads to causes better combustion inside the combustion chamber. 291
35 Brake Thermal Efficiency(%) 3 25 2 15 1 IP=24bar PME3 5 1 2 3 4 5 Figure 2: Comparison of Brake Thermal Efficiency with Brake power The thermal efficiency of the engine is improved by increasing the concentration of the biodiesel in the blends and also the additional lubricity provided by biodiesel.the main reason for increasing the thermal efficiency with increase in injection pressure may be due to atomization. Figure.3.shows the comparison of Brake Specific Fuel Consumption with Brake Power for different biodiesel blends. It can be observed that the BSFC of.273kg/kw hr was obtained for diesel and.272 kg/kw hr.it was observed that BSFC decreased with the increase in injection pressure, the increase in BSFC with the increase in concentration of PME in diesel. Figure.4.shows the comparison of Brake Specific Energy Consumption with Brake Power for different biodiesel blends. It was observed BSEC increased with the increase in concentration of PME in diesel and decreases with increasing in injection pressure. The obtained value of BSEC for of 11796kJ/kW hr is lower compared to diesel 122kJ/kW hr. Figure.5.shows the comparison of Hydrocarbon for different biodiesel blends with respect to brake power. It was observed that diesel has the maximum rate of hydrocarbon 36ppm among the tested fuels. It is also found that the hydrocarbon of 29ppm for decreases with increase in concentration of the biodiesel blends. This may be due to improved combustion because of increased in injection pressure and advanced injection timing. Figure.6.shows the comparison of carbon monoxide for various biodiesel blends with respect to brake power. It was noticed that CO emission of.49%vol for diesel and.42%vol for which is maintained due to presence of oxygen in the biofuels. 292
BSFC(kg/kW hr).7.6.5.4.3 IT=27deg btdc IP=24bar PME3.2.1 1 2 3 4 5 Figure 3: Comparison of Brake Specific Fuel Consumption with Brake Power CO emissions decreases with increase in PME in the blends had sufficient time for combustion process because of advanced injection timing. Figure.7.shows the comparison of NOx emissions of diesel fuel with various blends of PME with brake power. It can be observed that NOx emissions increases for (1238ppm) compare to diesel (196ppm).Due to the advancement of injection timing and pressure all the injected fuel burnt as a result higher combustion temperature is attained. The higher temperature promotes NOx formation. Figure.8.shows the Comparison of pressure with crank angle for different pungam methyl ester biodiesel blends and diesel at full load. It was found that the cylinder pressure (82.3bar) Diesel (81) at 19:1.From the figure it is shown that the pressure increases with increase in injection pressure 24bar and advanced injection timing 27degbTDC. Figure.9.Shows the Comparison of heat release rate with crank angle for different pungam methyl ester biodiesel blends and diesel at full load. It can be observed that the value of heat release rate reduces with increase in PME blends see the value of heat release rate is 12J/CA for diesel and heat release rate is 81.6J/CA for. Figure.1.Shows the Comparison of cumulative heat release rate with crank angle for different pungam methyl ester biodiesel blends and diesel at full load. It is observed that the cumulative heat release rate is increased for (1398J) compared to diesel (1458J). This is due to higher exhaust gas temperature and NOx emission. 293
BSEC(kJ/kW hr) 3 25 2 15 1 IT=27deg btdc IP=24bar PME3 5 1 2 3 4 5 Figure 4: Comparison of Brake Specific Energy Consumption with Brake Power 4 35 IP=24bar 3 Hydrocarbon(ppm) 25 2 15 1 5 PME3 1 2 3 4 5 Figure 5: Comparison of Hydrocarbon for different biodiesel blends with respect to brake power 294
.6.5 IT=27deg btdc Carbon Monoxide(%vol).4.3.2 PME3.1 1 2 3 4 5 Figure 6: Comparison of carbon monoxide for various biodiesel blends with respect to brake power 14 12 IP=24bar Nitric Oxide(ppm) 1 8 6 4 2 PME3 1 2 3 4 5 Figure 7: Comparison of NOx emissions of diesel fuel with various blends of PME with brake power 295
9 IP=24bar 8 7 Pressure(bar) PME3 6 5 4 3 2 1 9 8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 Crankangle(deg) Figure 8: Comparison of pressure with crank angle for different pungam methyl ester biodiesel blends and diesel at full load 12 IP=24bar 1 8 HRR(J/CA) PME3 6 4 2 2 1 1 2 2 4 6 Crankangle(deg) Figure 9: Shows the Comparison of heat release rate with crank angle for different pungam methyl ester biodiesel blends and diesel at full load 296
16 IP=24bar 14 12 CumulativeHRR(J) PME3 1 8 6 4 2 4 2 2 4 6 8 1 2 Crankangle(deg) Figure 1: Shows the Comparison of cumulative heat release rate with crank angle for different pungam methyl ester biodiesel blends and diesel at full load 5.Acknowledgements We thank the management of Sri Venkateswara College of Engineering Sriperumbudur,chennai Tamilnadu India for providing us with the necessary experimental set up to perform this research work. 6. Conclusion In this investigation the diesel engine have been set to run at compression ratio 19:1, advanced injection timing 27b TDC and injector pressure 24bar to arrive at the optimum for pungam methyl esters ).At low injector opening pressure 2bar and 22bar and retarded injection timing of 21b TDC and 24b TDC and higher compression ratio 17.5:1 and 16:1 were also tried but from the investigation it was found that the performance and emission is very poor. It is observed that from the experimental investigation while operating single cylinder diesel engine fuelled with biodiesel from pungam oil esters and their blends. The maximum brake thermal efficiency is found to be (3.5%) in 27ºbTDC and 24bar at compression ratio 19:1. The results show that at compression ratio19:1, higher injector opening pressure 24bar and advanced injection timing27ºbtdc and can gives better performance and emission. 297
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