BIODIESEL PRODUCTION AND PERFORMANCE TESTING USING TUMBA (CITRULLUS COLOCYNTHIS) OIL

Abstract

World is facing severe scarcity of fossil fuels and problem of rising pollution level, among several factors such as industrial pollution and vehicular emissions, splurge in vehicular population is the major factor responsible for it. The increase in CO2, CO, HC, PM and NOx emissions are leading to the problem of global warming, health hazards and depletion in ozone layer etc.. To overcome such problems work is under progress on alternative fuels like non-edible oils, ethanol, CNG, LPG etc. In this report vegetable oils can be converted into biodiesel through transesterification process such as–conventional mechanical stirring method, ultrasonic and hydrodynamic cavitation methods using Tumba (Citrullus Colocynthis) vegetable oil. An integrated, clean, facile and ecologically friendly approach of biodiesel production from Tumba (Citrullus Colocynthis) oil focused on lab scaling up is reported in this study. Transesterification was catalyzed by KOH with methanol (assay 99.0%) for Tumba biodiesel production, maintaining the temperature of solution within the range of 40oC to 45oC. Through conventional mechanical stirring method the optimum yields obtained by using alcohol to oil ratio 4.5:1 in reaction time of 90 minutes at 1% catalyst is 91.32% whereas at 6:1, 93.42% yield is obtained in the same reaction time using reduced percentage of catalyst (0.75%). By using ultrasonic method optimum results obtained on the experimentation of alcohol to oil ratio 4.5:1 in 40 minutes using 1% catalyst is 92.11% yield whereas at 6:1, 94% methyl ester conversion is obtained in the same reaction time with reduced catalyst (0.50%). In this work, an experimental test rig based on hydrodynamic cavitation process was developed for production of Tumba biodiesel. The results show that maximum biodiesel, using the molar ratio of 6:1 and 4.5:1, methyl ester conversion of 95.76% and 92.36% can be achieved respectively, within the reaction time of 30 minute, therefore it is industrially viable. The results illustrate that the use of KOH can be minimized in hydrodynamic cavitation. Among all the processes hydrodynamic cavitation method is most efficient and less time consuming. The relatively mild reaction conditions and high yield of methyl esters using this environment friendly method make it viable for practical use in industry. An experimental investigation was also conducted to the performance of Tumba oil and its fuel blends with diesel. Performance study was carried out on a single cylinder, direct injection, four stroke, Kirloskar diesel engine connected to eddy current dynamometer unit and data was obtained through the “Engine soft” software whereas controlling of parameters is done by using National Instruments-Data Acquisition Driver (NI-DAQ) software. The experiment covers a wide range of loads at the compression ratio of 17.5 by using pure diesel, B20, B40, B60, B80 and B100 biodiesel blends of Tumba oil to obtain various parameters such as torque, exhaust temperature, brake thermal efficiency, brake specific energy consumption, mechanical efficiency and smoke opacity. The maximum brake thermal efficiency achieved with Tumba biodiesel and its blends are in the range of 28% to 29% which are comparable with diesel efficiency. The properties of Tumba biodiesel were comparable to conventional diesel fuel. The comparison of performance parameters show that biodiesel produced from Tumba oil (Citrullus Colcynthis) can be used as an alternative fuel in the automobiles with better performance and lower emissions.