Some studies on the production and use of bio-diesel as CI engine fuel

Abstract

Abstract During the last decade, India has maintained a high growth rate, which has also led to increasing energy demand / consumption. The share of hydrocarbons in the primary energy consumption of the country has been increasingly over the years and presently estimated as 44.9% (36% for oil & 8.9% for Natural Gas). Drive for alternative fuels gathered momentum with the introduction of CNG and LPG and setting up of an ethanol-petrol blending projects in selected states in India. Alternative sources for diesel has been also explored. To cope up with the highly skewed situation of the demand for fossil fuel, vegetable oil is found to be the most promising solution. Biodiesel is an alternative fuel made from renewable biological resources such as vegetable oil and animal fat. It can both act as a substitute and an additive to diesel fuel. The study of non-edible vegetable oil compared to edible oil is very significant in developing countries like India. It is also reported by few researchers that, there are many tree species that been seeds rich in non-edible vegetable oils on which much attention is not made so far. The present study is initiated to investigate the potential of vegetable oil as a source of bio-diesel and feasibility of vegetable oil for the production of biodiesel by optimizing different parameters. For finding a solution to these problems it has been decided to study the two non-edible vegetable oils, e.g. jatropha curcas and karanja (pongamia pinnata) which is converted into biodiesel. The baseline data has been set up from the measured physiochemical properties of the diesel. Certain equations have been developed for predicting different physiochemical properties and that are compared and validated with the existing values. The research activity is started with the conversion of raw jatropha and karanja oil, collected from local market into Jatropha Oil Methyl Ester (biodiesel, known as JOME) and Karanja Oil Methyl Ester (biodiesel, known as KOME) respectively by transesterification process. In next phase a test rig has been developed for a detailed investigation on straight diesel operation as well as with diesel biodiesel blend and pure biodiesel. The engine chosen for this experiment is a single cylinder, air cooled, direct injection engine in which additional fuel and air measuring systems are incorporated for measuring the amount of fuel burnt for a particular time period against a fixed load and also for measuring their respective air-fuel ratios. Then Physiochemical properties of the biodiesel prepared are measured and compared with the standard values of fossil diesel fuel. Next, a mathematical model has been developed to find the cetane number which is highly essential for determining the performance of CI engine and the cetane number obtained through the developed model is quite comparable with the published experimentally obtained cetane number. Separate mathematical models have also been developed to predict some of the fundamental fuel properties like viscosity, density and High Heat Value (HHV) and the values obtained from the model are validated with the published experimentally obtained values. The next step is the experimental phase where the necessary data’s are generated for analyzing the engine performance over a wide range of load variation. The comprehensive experimental activities are carried out for baseline diesel, dieselbiodiesel blend and pure biodiesel. The engine performance, combustion and exhaust emission characteristics at various diesel-biodiesel proportions are also analyzed at different loads for finding the optimum performance of fuel blends. The results of this research work showed that both the biodiesel (jatropha oil methyl ester and Karanja oil methyl ester) are the comparable substitute for replacing the diesel oil in terms of performance and emission characters. In a long duration running situation, blending of biodiesel (JOME and KOME) are the preferred choice for the replacement of diesel in CI engines as it shows a stable mixture. For blended biodiesel, KB25 and JB50 are found to be the optimum choices for the diesel fuel replacement. The brake thermal efficiency of diesel is found to be 34.41% whereas for the KB 25 and JB50 the values are 31.31% and 31.28 respectively which are quite comparable. The CO emission of diesel at full load is 0.024% whereas that of optimum karanja derived biodiesel is 0.016% i.e. there is a reduction in 34% CO emission in case of KB 25 than diesel fuel. For optimum jatropha derived biodiesel (JB 50), the reduction is found around 50% less than the diesel fuel. The HC emission of diesel at maximum load is 32 ppm whereas that of JB100 is 16 ppm i.e. 50% reduction in HC emission for pure biodiesel in comparison to diesel fuel. For karanja derived biodiesel the HC emission at full load is found 23 ppm i.e. around 35% less than diesel fuel. The effect of delay period could be considered as another selection criteria for diesel, diesel biodiesel blend and pure biodiesel which is not the scope of our present study. The metallurgical effects of the engine during long run by using biodiesel have also not been included in the present work. The further research may be carried out considering those parameters.