ALTERNATE FUEL BIODEISEL
ABSTRACT
The Recent depletion and fluctuation in prices due to uncertain supplies for fossil fuel, make us to search renewable, safe and non-polluting sources of energy. India is not self sufficient in petroleum and has to import about two third of its requirements. Presently Indian Government spend Rupees 90,000 crores for petroleum fuel and annual consumption is around 40 millions tons. One of the solutions to the current oil crisis and toward off any future energy and economic crunch is to explore the feasibility of substitution of diesel with an alternative fuel which can be produced in our country on a massive scale to commercial utilization. Indian Government, research institution and automobile industries are taking interest on bio-diesel from various non-edible oil bearing trees like Jatropha, Karanji, Mahua & Neem. As India is short of edible oils even for human consumption and since the cost of edible oil is also very high, it is preferable to use non-edible oils. Jatropha curcas is one of the prospective bio-diesel yielding crops. This paper highlights our work on alternate fuels and the importance of choosing jatropha. It reduces pollution drastically in terms of sulphates and carbon mono-oxide. 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 Analyser in our thermal laboratory. The pollution levels came down drastically and performance was better with various blends of jatropha and diesel.
INTRODUCTION ABOUT BIO-DIESEL
Bio-diesel is a vegetable oil processed to resemble Diesel Fuel. The first use of peanut oil was made in 1895 by Dr. Rudolf Diesel himself (1858-1913), who predicted- “The use of vegetable oils engine fuels may seem insignificant today. But such oils may become in course of time as important as petroleum and the coal tar products of the present time.” Bio-diesel is the ethyl or methyl ester of fatty acid. Bio-diesel is made from virgin or used vegetable oils (both edible and non-edible) and animal fats through trans-esterification. Just like diesel, bio-diesel operates in compression ignition engines, which essentially require very little or no engine modifications up to require very little or no engine modifications up to 20% blends, and minor modifications for higher percentage blends because bio-diesel is similar to diesel but is very eco-friendly.
PROBLEMS OF USING JATROPHA
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
The above mentioned difficulties cause fluctuation of load after some period of operation and ultimately lead to breakdown of the engine. Hence it is difficult to use Jatropha oil without further processing as fuel in a direct injection engine. 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.
TRANS-ESTERIFICATION:
Trans-esterification, also called alcoholysis, is the displacement of alcohol from an ester by another alcohol in a process similar to hydrolysis, except than an alcohol is used instead of water. This process has been widely used to reduce viscosity of triglycerides.
PROCESS EXPLANATION
If methanol is used in the above reaction, it is termed methanolysis and fatty acid methyl esters are generated, which are called biodiesel.
Three consecutive and reversible reactions are believed to occur in the transesterification which are given below:
The first step is the conversion of triglycerides to diglycerides, followed by the conversion of diglycerides to monoglycerides, and finally monoglycerides to glycerol, yielding one methyl ester molecule from each glyceride at each step. When methanol is used in the esterification A catalyst and excess alcohol are used to increase rate of reaction and to shift the equilibrium to the product side, respectively.
CATALYSTS FOR TRANSESTERIFICATION PROCESS
v Acid catalyst (HCl, H2SO4)
v Alkali catalyst (NaOH, KOH, sodium alkoxide, potassium alkoxide, etc.)
v Enzyme catalyst (lipase)
From an economic point of view, alkali catalyst is better with KOH the more efficient one. The catalyst must be pure and free from moisture.
Process variables for transesterification reaction
v Reaction time and temperature
v Molar ratio of alcohol / oil
v Catalyst type and concentration
v Mixing intensity
v Purity of raw materials (reactants)
DESCRIPTION OF THE TRANS-ESTERIFICATION PROCESS
The measured quantity of neat refined vegetable oil is taken in a three neck flask. 15% of methanol and 0.5% sodium hydroxide by mass for 1 lit. of vegetable oil are thoroughly mixed together first. This mixer is added with the oil, which is taken in the flask. Constant stirring is done at the speed rate of 200 rpm and the flask is heated and maintained at the temperature range of 60oC to 65oC for nearly 2 hours. Heating is stopped after 2 hours. The flask is allowed for natural cooling for nearly 24 hours. After the cooling is over, the ‘Glycerin’ that is present in the vegetable oil is settle down at the bottom of the flask and the ‘fatty acid esters’ are separated from the Glycerin by using the separating funnel. Adding Hcl or NaHCO3 with the fatty acid ester neutralizes it to the pH value of 7.
PERFORMANCE TEST ON IC ENGINE
The engine used for the present investigation is a single cylinder “comet” vertical Diesel Engine (1500rpm, 3.5kW, water cooled). Engine is coupled with an eddy current dynamometer. In the present work, the experiments were carried out at constant speed and for varying load conditions i.e., no load, 25%, 50%, 75% and 100% of the rated load. The injection parameters were kept constant for the existing engine for entire test program. The static fuel injection timing and the fuel injection pressure for the given engine the 27o before TDC and 220 bars respectively as specified by the manufacturer. The engine was started and warm-up with diesel fuel and then the diesel fuel line was cut off and simultaneously the fuel line, which connects the fuel under investigation, was opened. No additives were added to the system before conducting the test. Esterified vegetable oil was injected directly to the combustion chamber as conventional fuel injection. The test was done separately for the four fuels, which are taken for the investigation. In each case the observations were recorded after steady state was reached.
RESULTS AND DISCUSSIONS:
The various engine parameters were observed during the experiment for different loads on the engine. After, the experimental part of the project was completed, the calculations were carried out and various graphs were drawn so as to discuss and arrive at specified result. From the analysis of graphs the conclusion were made.
MECHNICAL EFFICIENCY:
\As the percentage of bio diesel in the blend increased, it was noticed that the mechanical efficiency of the engine also increased. 100% bio diesel was found to have the maximum efficiency whereas, HSD was found to have the minimum efficiency.
TORQUE:
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 is not affected much by the bio diesel. Hence there is no effect in the usage of the biodiesel as an alternate for diesel. Biodiesel is more adaptable to the variation in load and hence does not show any fluctuation in torque and runs in a stable condition.
SPECIFIC FUEL CONSUMPTION:
The specific fuel consumption increases with the increase in the blend. But the SFC of the blends up to the limit of 50% are found to be lesser and better than that of the HSD.
EXHAUST GAS EMISSION READING:
CO, NO, Nox, SO2, NO2 are in ppm
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.
USE OF JATROPHA AS A SUBSTITUTE FOR DIESEL
ENVIRONMENTAL BENEFITS
Major advantage of producing Bio-diesel is the recycling of CO2 and consequent reduction in Global warming because of large scale plantation of oil seeds trees, which recycle the CO2.
v The highest cetane no. of bio-diesel compared to petro diesel indicates potential for higher engine performance.
v The superior lubricating properties of bio-diesel increases functional engine efficiency.
v Their higher flash point makes them to safer to stored.
v The bio-diesel molecules are simple hydrocarbon chains, contains no sulphur or aromatic substances associated with fossil fuels.
v They contain higher amount of O2 (upto 10%). That ensures more complete combustion of HC.
v Bio-diesel almost completely eliminates life cycles CO2 emission.
v Production of 1t / ha / year of high protein seed cake that can be used as animal and fish feeds and organic matter that can be used as organic fertilizers.
v Various other products from the plant (leaf, bark and seed extracts) have various other industrial and pharmaceutical uses.
v Restoration of degraded land over a period of time.
v Rural employment generation.
CONCLUSIONS:
From the above results, the following can be interpreted:
i. Mechanical efficiency improves with the increasing percentage of biodiesel in the blend. 100% biodiesel had the best performance in terms of mechanical efficiency.
ii. The brake thermal efficiency was best for the 50% blend and very similar to the brake thermal efficiency of the HSD.
iii. No considerable change in the value of the torque was noticed. The torque remained almost the same for all the blends.
iv. 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.
v. 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.
vi. 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.
SCOPE FOR FUTURE WORK:
Further work in this field can definitely provide a 100% biodiesel with better performance as well better emission standards. The following work can be further carried out to improve the prospects of biodiesel in future:
i. Going for additives like orange oil, Dimethyl carbonate or Diethylether can improve the performance of the engine
ii. A 20% by volume addition of these additives can give very good results.
iii. Brake thermal efficiency can be improved by as much as 3% through the usage of DEE and DMC.
iv. Smoke decreases with all the above additives.
v. Additives can also be added to reduce the amount of the NOx present in the exhaust.
vi. To reduce the viscosity of the oil even further, the process of Micro-emulsification can be taken up.
The present investigation reveals that the ester of vegetable oils can be a valuable supplement or even a full substitute for diesel fuel. Since they perform with acceptable thermal efficiencies. This alternative fuels reduces the environment impacts of transportation, reduces the dependence on crude oil imports and offered business possibilities to agricultural enterprises. Jatropha cultivation should be taken up on large scale on top priority basis as it will be perennial source of income for formers even during drought periods. The use of bio-diesel becomes necessary to achieve BharatII and BharatIII emissions standards by 2005 and 2010 respectively. It will lead to eco-rehabilitation of degraded lands through plantation of Jatropha curcas for ecological, economical, security and sustainable development.
