# I. Introduction upplement to the petroleum fuels becomes a common practice and needful for reducing the usage of fossil fuel resources. Enhancing the production of vegetable oil supports the fuel demands. Biodiesel is methyl or ethyl ester of fatty acid derived from vegetable oils (both edible and non-edible) and animal fat. The main resources for biodiesel production can be non-edible oils obtained from plant species such as Jatropha curcas, Pongamia pinnata, Calophyllum inophyllum, hevea brasiliensis (Rubber) etc. Biodiesel can be blended in any proportion with mineral diesel to produce a biodiesel blend or can be used in its pure form like petroleum diesel [1]. Biodiesel operates in compression ignition (diesel) engine, and essentially require very little or no engine modifications because biodiesel has properties similar to neat diesel [2]. It can be easily stored and transported because of its higher flash point temperature [3]. The use of biodiesel in conventional diesel engines results in substantial reduction in emission of unburned hydrocarbons, carbon monoxide and particulate matters [4]. Environmental factor is the major concern for an alternate fuel. In India adoption of Euro V equivalent emission norms are under consideration. Implementation of emission norms will focus on to reduce the sulphur content and increase the Cetane number of the fuel [5]. Biodiesel derived from rice bran oil, Mahua oil, Neem oil, Jatropha oil, Pongamia oil etc.are suitable alternative fuels for DI diesel engine. The performance of diesel engine depends on blends percentage, Ignition timing and it reduced with increasing the blends percentage beyond 50% [6], [7]. The performance and emission characteristics study was carried out for non-edible vegetable oil such as linseed oil, rice bran oil and its methyl ester. Operational and durability problems were occurred because of high viscosity, low volatility and poly unsaturated character to overcome this vegetable oil methyl ester blends were used instead of straight vegetable oil [8]. Higher viscosity of vegetable oil affects the atomization results in poor combustion and it is prevented by transesterification process. 25 percentage of cotton seed methyl ester blends performance almost same as the neat diesel while used as a fuel in diesel engine [9]. Processed cooking oil was used as a biodiesel through transesterification process. The effect of cooking oil diesel blends like B20, B50, and B100 was compared with neat diesel. 20% of blends produce the lowest carbon monoxide emission than 50 percentage of blends exclude at high engine speed [10]. Straight vegetable oil (Jatropha) used in diesel engine reduce the brake thermal efficiency and increase the smoke. Use of vegetable oil blend with methanol increase the brake thermal efficiency similarly smoke was significantly reduced [11]. Ignition delay, peak pressure and heat release rate were studied compression ignition diesel engine was operated with duel fuel such as karanja methyl ester and hydrogen fuel. Ignition delay increased at full load and it decrease considerably with lower loads. During the combustion process, karanja methyl ester burns with hydrogen results it increase the Year 2014 ume XIV Issue VII Version I ? ? ? heat release rate. Low viscosity of fuel with hydrogen burns quickly and produces high pressure [12]. A cold pressed cashew nut shell liquid blend with diesel was used as an alternative fuel in internal combustion engine. 20 percentages of CNSL blends produce closer value of brake thermal efficiency as neat diesel. Cylinder pressure and heat release rate gets reduced with increasing the Cashew Shell Nut Liquid (CSNL) proportions. Operating engine with 40 percentage of CSNL blends engine knocking was observed [13]. Mahua oil and its blend were used as a fuel in direct injection diesel engine and the performance, emission and combustion characteristics was studied. Ignition delay, cylinder pressure and heat release rate was taken for combustion analysis. The output results for Mahua blends almost comparable with diesel hence; it can be used in diesel engine without any modifications [14]. The present work was approached to study the effect of increase in compression ratio (CR) of a conventional diesel engine operated with different percentage of Jatropha methyl ester and Pongamia methyl ester blends with neat diesel. Peak pressure, heat release rate and ignition delay characteristics for different compression ratio and different biodiesel blends were studied. Also the effect CR with brake thermal efficiency was studied for different percentage of biodiesel blends. # a) Esterification Process Transesterification is a suitable method of utilizing vegetable oils in Compression Ignition engine without any long-term operational and durability problems. Vegetable oils can play a vital role in power generation for developing countries. Esterification is a chemical treatment process performed for treating vegetable oils [15]. Crude Jatropha and Pongamia seed oil was used for Transesterification process to convert crude oil into methyl ester oil. The Esterification process parameters such as reaction condition, type of alcohol, amount of catalysts, reaction time and temperature were controlled by manual mode. Single stage base catalyzed Transesterification was used for Jatropha and Pongamia. Methanol used as a regeant; H2SO4 and KOH used as a catalyst for base reaction. # b) Biodiesel Properties The fuel properties of Jatropha methyl ester (JME) and Pongamia oil methyl esters (PME) blends with diesel are shown in Table1.The biodiesel properties such as density (kg/m3), calorific value (kJ/kg), viscosity (cSt), flash point (0C) was improved by Transesterification process. The property of biodiesel was tested as per IS15607:2005 standards. The methyl esters of Jatropha and Pongamia oil properties relatively closer with neat diesel. From the experimental results, these bio fuels can be used to operate the existing engine without any modifications. Compare with diesel, Jatropha and Pongamia blends contain oxygen molecules in the fuel. Hence complete combustion of fuel in the engine inhibits with the presence of oxygen ions in the biodiesel. Flash point for biodiesel was high, so it is safe to store compare with diesel. Small amount of biodiesel (Jatropha and Pongamia) added with the diesel increase the flash point of diesel blends. # II. Experimental Setup and Procedure AVL software and data acquisition system was used to analyze the combustion characteristics of an engine as shown in Fig. 1. AVL 365C angle encoder was used to measure the crank angle position. AVL GH14D Pressure transducer was used to convert cylinder pressure value into analog signal form to the data acquisition system. Specification of the DI diesel engine was shown in Table 2. Experimental investigations of Jatropha methyl ester and Pongamia methyl ester were carried out in a four stroke single cylinder air cooled direct injection 4.4 kW at 1500 rpm diesel engine as a bore of 87.5 mm and stroke length of 110 mm as shown in Fig. 2 and Fig. 3. Engine test was performed with neat diesel; biodiesel blends (10%, 20% and 30%) for different compression ratios of 17.5:1, 19:1 and 20:1. Electric Dynamometer consists of electrical power bank it applies loads 0%, 25%, 50%, 75%, 100% on engine and it is controlled with the aid current and voltage values. The performance of biodiesel blends experimental values are compared with neat diesel. # III. Error Analysis Error analysis was performed to indentify the accuracy of the measuring instruments. The percentage of uncertainties of a measuring instruments as given in Table . 3 Percentage of uncertainties present in experiments is = square root of ((uncertainty of pressure transducer)2 + (uncertainty of angle encoder)2 + (uncertainty of K-type thermocouple)2 + (uncertainty of stop watch)2 + (uncertainty of manometer )2 + (uncertainty of burette)2)+ (uncertainty of load cell)2 = square root of ((0.20)2 + (1)2 + (0.4)2 + (0.2)2 + (0.5)2 + (0.15)2+ (0.21)2) = square root of (1.566) = ±1.25%. # IV. Results and Discussion # a) Cylinder Pressure i. Pongamia Methyl Ester Blends The variation of cylinder pressure with crank angle for PME blends at different compression ratio as shown in Fig. 4a-c. For compression ratio of 17.5, peak pressure occurs at 67.49 bar at CA of 50 after TDC for diesel and 67.9 bar at CA of 60after TDC for PME10%, 67.67 bar at CA of 60 after TDC for PME20%, 67.68 bar at CA of 70 after TDC for PME30%. For 19 compression ratio, peak pressure occurs at 75.72 bar at CA of 70 after TDC for diesel and 75.78 bar at CA of 60 after TDC, 75.25 bar at CA of 60 after TDC, 76.94 bar at CA of 70 Global Journal of Researches in Engineering ( ) after TDC for PME10%, PME20%, PME30% respectively. For 20 compression ratio, peak pressure occurs at 75.61 bar at CA of 60 after TDC for diesel and 76.62 bar at CA of 60 after TDC, 75.83 bar at CA of 70 after TDC, 75.63 bar at a CA of 70 after TDC for PME10%, PME20%, PME30% correspondingly. It is observed from the figure that biodiesel blends had a higher peak pressure than diesel. The Combustion peak pressure increased with increasing the compression ratio. ii. Jatropha Methyl Easter Blends The variation of cylinder pressure with crank angle for JME blends at different compression ratio as shown in Fig. 6a-c.For compression ratio of 17.5, JME10%, JME20%, and JME30% combustion pressure of 69.28 bars at CA 70 after TDC, 70.67 bar at CA of 70 after TDC, 69.42 bar at CA of 60 after TDC respectively. For compression ratio of 19, JME10%, JME20%, J30% combusts pressure of 77.12 bar at CA 60 after TDC, 79.19 bar at CA of 80 after TDC, 78.85 bar at CA of 60 after TDC respectively. For compression ratio of 20, JME10%, JME20%, JME30% combustion pressure of 76.76 bar at CA 70 after TDC, 77.98 bar at CA of 60 after TDC, 77.83 bar at CA of 50 after TDC respectively. The peak pressure forJME20%, atCR of 20 was 3.57bar, for PME30% at CR of 19 was 1.82bar higher than diesel. The peak pressure takes place after TDC for safe and efficient operation. If it occurs close to TDC or before that causes severe engine knock thus affects engine durability [16]. It is concluded from the results JME 20% with Compression ratio of 20:1 achieves maximum peak pressure of 3.46 bar higher than diesel and JME20% blend was the optimum fuel blends as far as peak cylinder pressure concerned. # b) Heat Release Rate The variation of heat release rate with crank angle for PME and JME blends at different compression ratio as shown in Fig. 5a-c and Fig. 7a-c. Heat release rate indicates that ignition delay for biodiesel blends was shorter compared with neat diesel. Neat diesel produces maximum heat release of 91.93 kJ/m3deg for CR of 17.5, 87.72 kJ/m3deg for CR of 19, and 79.85 kJ/m3deg for CR 20 respectively. It is observed from figure that maximum heat release rate of biodiesel blends are lower than diesel because of their shorter ignition delay compared with diesel. It is also observed from the obtained values that, JME 20% blend produces minimum heat release rate of 62.53 kJ/m3deg at compression ratio of 20:1 among the biodiesel blends tested. # c) Ignition Delay The variation of ignition delay fordiesel, biodiesel blends at different compression ratio as shown in Fig. 8. Ignition delay is one of the important parameters in determining the knocking characteristics of diesel engines. It is a period between start of injection and start of combustion and it depends upon many factors such as compression ratio, the inlet pressure, injection parameters and the properties of the operating fuel. Higher the cetane number (CN), the shorter is the ignition delay, and vice versa [17]. Table. 4 show the ignition delay for biodiesel blends for different compression ratio.It is observed from figure that the ignition delay of methyl esters and its blends is significantly lower than that of diesel and decreases with increase in the percentage of methyl ester in the blend and compression ratio. As the temperature of air in the cylinder is fairly high at the time of injection, esters undergo chemical reactions and polymerization, which result in injection characteristics that are different from those of diesel. A decrease in ignition delay results in smaller amount of fuel accumulation to ignition which results in lower heat release rate during premixed combustion phase. # V. Effect of Biodiesel Blends on Brake Thermal Efficiency The variation of the brake thermal efficiency with compression ratio for diesel, biodiesel blends at full load were shown in Fig. 9. Brake thermal efficiency (BTE) mainly depends on the operating fuel properties such as density and viscosity. In general, BTE was lower for methyl ester derived biodiesels compared to diesel. To achieve better brake thermal efficiency of biodiesel blends, compression ratio of diesel engine was increased. At full load conditions BTE of diesel, PME10, PME20, PME30, JME10, JME20, JME30 are 28.1%, 26%, 27%, 30%, 30.3%, 33.5%, 35.6% respectively. It is observed from the figure that BTE gets increased proportionally with engine loads. JME30% blend produces 7.5% higher brake thermal efficiency than diesel. Increase in compression ratio of engine enhance the complete combustion of fuel in the combustion chamber with the presence of oxygen and hence better thermal efficiency. # VI. Conclusion The experiments reveals that biodiesel from unrefined Jatropha and Pongamia seed oil is quite suitable as an alternative to diesel. Following results were obtained from the bio fuel operated single cylinder diesel engine operation. 12![Figure 1 : AVL Data acquisition system](image-2.png "()Figure 1 :Figure 2 :") 34b4c5a55b![Figure 3 : Test engine setup](image-3.png "Figure 3 :Figure 4b :Figure 4c :Figure 5a : 5 GlobalFigure 5b :") 5c6a![Figure 5c : Crank angle vs. heat release rate for compression ratio of 20](image-4.png "Figure 5c :Figure 6a :") 6b6c7a57b![Figure 6b : Crank angle vs. cylinder pressure for compression ratio of 19](image-5.png "Figure 6b :Figure 6c :Figure 7a : 5 GlobalFigure 7b :") 1 2Year 201429XIV Issue VII Version Iume) A Vol( 3 4)(Journal of Researches in EngineeringGlobal © 2014 Global Journals Inc. (US) ## Acknowledgement Sincere thanks and gratitudeto the Principal & Management of SVCE for granting permission to use the facilities in the college for this research work. Our Sincere thanks to Mr. R. 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