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The depletion of fossil fuels and the increase in the emission levels has caused a concern globally. An eco-friendly alternate was required to fulfill the growing demand. This paper highlights our work on alternate fuels and the importance of choosing jatropha. It reduces pollution drastically in terms of sulphates and carbon monoxide. To start with, we reduced the viscosity problem faced to a large extent by carrying out the transesterification process in our chemistry laboratory. We also studied the cost factor involved in the usage of jatropha. Performance test was conducted on an electrical loaded diesel engine and a study on the emissions was made using Exhaust Gas Analyzer in our thermal laboratory. The pollution levels came down drastically and performance was better with various blends of jatropha and diesel.
Bio diesel is a diesel fuel substitute produced from renewable sources such as vegetable oils, animal fats and recycled cooking oils. Chemically, it is defined as the mono alkyl esters of long chain fatty acids derived from renewable lipid sources. Bio diesel is typically produced through the reaction of a vegetable oil or animal fat with methanol or ethanol in the presence of a catalyst to yield glycerine and bio diesel (Chemically called methyl or ethyl esters).
The major problem in using the raw jatropha oil will be choking of the filter and other parts of the engine. Further, due to its high viscosity, raw jatropha oil can cause a lot of trouble during cold seasons. Also, the following major problems could be faced.
Due to higher density of jatropha oil, the atomization in combustion becomes difficult.
Poor volatility accounts for improper vaporization and ignition incapability. This also cause thermal cracking resulting in heavy smoke emissions and carbon deposits in the engine. Also the durability of the engine will be affected
The presence of wax contents in the oil causes formation of gum in the combustion chamber
It either requires the oil to be processed further or some modifications should be made in the engine. The viscosity of oil was reduced by the transesterification process.
PROCUREMENT OF OIL:
The RCAC (Rural Community Action Centre) in Tamilnadu has taken the lead in promoting Jatropha. It has formulated plans of not only helping the Petroleum industry, but also the women self-help groups and the farmers. The Rural Community Action Centre is a non-governmental, non-profit service organization devoted to the promotion of economy and well being of rural farming community. The polluted environment and health hazards that tend to cripple the rural life are the primary concerns of the organization.The raw oil was purchased from the Rural Action Community Action Center (RCAC), Muthur. And the Tamil Nadu Agricultural University (TNAU), Coimbatore.
The cost of 1 kg of jatropha seeds comes up to Rs 5. After extracting oil, the cost of one litre of oil comes up to Rs 12 per litre. After carrying out the esterification process, the cost of one litre of bio diesel comes up to Rs17/litre. If mass production is taken up, the cost of the same product will come down to Rs 13 per litre.
TRANSESTERIFICATION PROCESS :
The raw OIL to be used.
CATALYST. (Generally NaOH).
ALCOHOL. (Ethanol or Methanol).
A WASHING AGENT. (Generally distilled water)
The catalyst, NaOH (1.2 g) is first added to the alcohol, Methanol (36ml) and dissolved by shaking vigorously. The solution is then mixed with the crude oil (150 ml) to be used. The contents after mixing thoroughly are heated with Water-bath heater with constant stirring at regular intervals for 1-2 hours. Contents are allowed to settle down for 10-12 hours. The contents are separated into 2 parts--Methyl esters (less dense) and glycerine (thicker) by gravitational separation. After that Methyl ester is washed with equal amount of distilled water. This washed solution is allowed to settle for another 24 hours. This settling process will separate the Biodiesel and the soaps. Finally, the Biodiesel is filtered using Wattman filter to get pure Biodiesel.
PROPERTY COMPARISON OF HSD AND BIODIESEL
Calorific value MJ/kg
Flash point OC
Fire point OC
EXPERIMENTAL SETUP :
The main processes carried out in the Mechanical department were the performance tests, the exhaust emissions test and the Heat balance test. The performance tests are indicators of the various parameters such as the specific fuel consumption, the thermal efficiency, etc.which will enable the fuel to be compared with the petroleum diesel. The exhaust emissions indicated the percentages of the various gases present in the exhaust and thus helped in comparing the pollution levels of the Bio diesel with the petroleum diesel. The engine used for conducting the mechanical tests was a Kirloskar Electrical Loading Engine. Its specifications are:
SPECIFICATION OF THE KIRLOSKAR ENGINE:
Number of cylinders
Number of strokes
Type of cooling
The schematic arrangement of the experimental set up is shown in figure below. The normenclature of the nos. mentioned are:
1Engine 2.Alternator 3.Fuel Tank 4.Fuel Measuring Tube 5.Cooling Water Inlet and Outlet Thermometer 6.Exhaust Gas Thermometer.
THE EXPERIMENTAL SETUP AT OUR LABORATORTY:
For measuring the mass flow rate of water, a five litre can was used. A stop watch was used to the calculate time taken to fill the 5 litre can. The fuel tank, the burette stand and the stand to carry the fuel tank was also fabricated by us.
SPECIFICATIONS OF FLUE GAS ANALYSER:
The MAESTER 2000 indicated emission levels in the exhaust of the engine
Type x therm
It was decided to test the characteristics of the bio diesel with various blends. We opted for the following blends of bio diesel along with high speed diesel.
As the percentage of biodiesel in the blend increased, it was noticed that the mechanical efficiency of the engine also increased. 100% Biodiesel was found to have the maximum efficiency whereas, HSD was found to have the minimum efficiency.
BRAKE THERMAL EFFICIENCY:
As the percentage of biodiesel in the blend increased, it was noticed that the brake thermal efficiency of the engine decreased. However, the 50% blend was seen to have a value closer to the brake thermal efficiency of the HSD. It was thus understood that the 50% blend would be the optimum blend as far as brake thermal efficiency was concerned. It is also seen from the bar chart that at all the loads, the brake thermal efficiency was best at the 50% blend.
The torque at all the blends was found to be almost same. The change in torque at the blends was found to be negligible suggesting that the torque of the engine isnâ€™t affected much by the biodiesel.
SPECIFIC FUEL CONSUMPTION:
The specific fuel consumption increases with the increase in the blend. But the SFC of the blends upto the limit of 50% are found to be lesser and better than that of the HSD. From the bar-chart, it is clear that the blend that fares best at all the loads in terms of SFC is the 50% blend.
EXHAUST GAS EMISSION READING:
From the above readings, it was clear that the emissions came down drastically with the use of bio diesel. Bio diesel contains higher amount oxygen (up to 10%) that ensures more complete combustion of hydrocarbons. Except the Nox emissions, all other pollutants came down in their percentage.
LEVELS OF CO EMISSIONS (IN ppm)
LEVELS OF NOx EMISSIONS (IN ppm)
Bio diesel almost completely eliminates lifecycle carbon dioxide emissions. When compared to high speed diesel it reduces emissions of particulate matter by 40%, unburned hydrocarbons by 68%, carbon monoxide by 44% and sulphates by 100%.
From the above results, the following can be interpreted:
Mechanical efficiency improves with the increasing percentage of biodiesel in the blend. 100% biodiesel had the best performance in terms of mechanical efficiency.
The brake thermal efficiency was best for the 50% blend and very similar to the brake thermal efficiency of the HSD.
No considerable change in the value of the torque was noticed. The torque remained almost the same for all the blends.
No considerable change in the values of the brake mean effective pressure though the values of the 50% blend and the 25% blend were closer when compared to other blends which had slightly lower values.
The SFC of all the blends was lower when compared to the SFC of the HSD. But the 50% blend had the closest SFC value to that of the HSD.
The emissions came down drastically. Except the NOx emissions which increased slightly, all other pollutants were present in lesser amount in the emissions.
The above results give an indication that the 50% blend of bio diesel and HSD is the optimum blend which gives a better performance as well as better emission standards.