PERFORMANCE OF I.C.ENGINE USING VEGETABLE OILS
Bio-diesel fuel for diesel engines is produced from vegetable oil or animal fat by the chemical process of esterification. This paper presents a brief history of diesel engine technology and an overview of biodiesel, including performance characteristics, economics, and potential demand. The performance and economics of biodiesel are compared with those of petroleum diesel. The term “biodiesel” means the monoalkyl esters of long chain fatty acids derived from plant or animal matter which meet (A) the registration requirements for fuels and fuel additives established by the Environmental Protection Agency under section 211 of the Clean Air Act (42 U.S.C. 7545), and (B) the requirements of the American Society of Testing and Materials D6751.6 There is therefore little reason to see vegetable oil as the primary fuel of the future. On the other hand PVO is a fuel, which does have its benefits, and therefore should be given equal treatment as compared to other CO2 neutral fuels.
The idea of using vegetable oil for fuel has been around as long as the diesel engine. Rudolph Diesel, the inventor of the engine that bears his name, experimented with fuels ranging from powdered coal to peanut oil. In the early 20th century, however, diesel engines were adapted to burn petroleum distillate, which was cheap and plentiful. In the late 20th century, however, the cost of petroleum distillate rose, and by the late 1970s there was renewed interest in biodiesel. Commercial production of biodiesel in the United States began in the 1990s.
The most common sources of oil for biodiesel production in the United States are soybean oil and yellow grease (primarily, recycled cooking oil from restaurants). Blends of biodiesel and petroleum diesel are designated with the letter “B,” followed by the volumetric percentage of biodiesel in the blend: B20, the blend most often evaluated, contains 20 percent biodiesel and 80 percent petroleum diesel; B100 is pure biodiesel. By several important measures biodiesel blends perform better than petroleum diesel, but its relatively high production costs and the limited availability of some of the raw materials used in its production continue to limit its commercial application.
Bio-diesel has gained much attention in recent years due to the increasing environmental awareness. It is produced from renewable resources and, more importantly, is a clean burning fuel that does not contribute to the net increase of carbon dioxide.
1.1 Pure Vegetable oil fuel characterization
The interest in plant or vegetable oils originated in the late 70's and came from the agrarian sector, which is still one of its main drivers. Initially, it was believed to be possible to use these oils directly with a low processing level. Extensive testing by the engine industry has shown that unmodified engines, while operating satisfactorily, would quickly develop durability problems, due to problems with fuel injectors, piston rings and lubrication oil stability. For this reason the engine must be modified. Such modifications can at present be made by a number of facilities mainly in Germany. More than 5000 vehicles are presently using pure vegetable oil in Germany. [ELS] Nevertheless one can still find examples of claims that PVO can be used in any unmodified engine. As an example the TV program Top Gear on BBC presented the claim in November 2002, but without showing any durability test of the concept.
1.2 The major advantages of natural veg etable oil
Ø High calorific value: high energy density
Ø Liquid in form and thus easily to be handled
Ø When burned it emits less soot
Ø When burned it has high energy efficiency
Ø It is neither harmful nor toxic to humans, animals, soil or water
Ø It is neither flammable nor explosive, and does not release toxic gases
Ø It is easy to store, transport and handle
Ø It does not cause damage if accidentally spilt
Ø Its handling does not require special care to be taken
Ø It is produced directly by nature: it does not have to be transformed
Ø It is a recyclable form of energy
Ø It does not have adverse ecological effects when used
Ø It does not contain sulphur it does not cause acid rain when used
Ø All types of forestry machinery (preservation of ground water)
Ø Lorries, vans, pick-ups, etc. (fuel efficient)
Ø Private cars (no CO2 increase, save, non inflammable fuel)
Ø Mixers, mills, pumps, ventilators, and other stationary industrial and agricultural machinery (no toxic gases or inflammable liquids)
1.3 Market Position
PVO today represents a marginal niche in the transport fuel market. The majority of vehicles running on PVO are converted regular vehicles, and conversion equipment sets are available for many common engine models [VW]. Thus in theory most diesel engines can be converted to pure PPO operation, including advanced TDI versions, and as such the technology much be counted as available on a broad basis. One of the main suppliers of conversion equipment (Elsbett in Germany) also sells an engine specifically designed for PVO operation. Additionally the tractor manufacturer Deutz-Fahr markets a tractor specifically adapted for PVO operation as part of a market introduction program.
2. VEGETABLE OIL TO BIODIESEL – PROCESS
The process of converting vegetable oil to biodiesel Fuel is called Transesterification. Chemically Transesterification means taking a triglyceride molecule or a complex fatty acid, neutralizing the free fatty acid, removing the glycerin and creating an alcohol ester. This is accomplished by mixing methanol with sodium hydroxide to make sodium methoxide. This liquid is then mixed into the vegetable oil. After the mixture has settled, glycerin is left on the bottom and methyl esters or bodies is left on top and is washed and filtered. The final product biodiesel Fuel when used directly in a diesel engine will burn up to 75% cleaner than mineral oil Diesel fuel.
2.1 Plant oils used for Biodiesel:
A variety of bio-liquids can be used to produce biodiesel. The main plants whose oils have been considered as feed stocks for bio fuel are soyabean oil, rapeseed oil, palm oil, sunflower oil, safflower oil and jatropha oil. Others in contention are mustard, hemp, castor oil, waste vegetable oil, and in some cases even algae. There is going on research into finding more suitable crops. A list of oils that appear to have the potential for biodiesel is provided below in alphabetical order of the plant name:
1) Algae 2) Artichoke oil 3) Canola oil 4)Castoroil 5) Coconut oil 6) Corn oil 7) Cottonseed oil 8) Flax oil 9) Hemp oil 10) Jatropha oil 11) Jojoba oil 12) Karanj t oil 13) Kukui nut oil 14) Milk bush shrub 15) Mustard oil 16) Neem oil 17) Olive oil 18) Palm oil 19) Peanut oil 20) Radish oil 21) Rapeseed oil 22) Rice bran oil 23) Safflower oil 24) Tung oil
25) Sunflower oil 26) Soyabean oil 27) Waste vegetable oil
3. JATROPHA OIL
Considering all options in India, Jatropha Curcas has been identified as the most suitable source. The key features of Jatropha are:
Ø Low cost seeds
Ø High oil content
Ø Small gestation period
Ø Growth on good and degraded soil
Ø Growth in low and high rainfall areas
Ø Seeds can be harvested in non rainy season
Ø Plant size is making collection of seeds more convenient
Effective yield: The jatropha plant bears fruit from the second year after its plantation and the economic yield stabilizes from the fourth or fifth year onwards. The plant may live for more than 50 years with an average effective yielding time of 50 years. The economic yield can be considered as 0.75-2.0 kg/plant and 4.0-6.0 tonnes per hectare per year depending on the agro-climatic zone and agricultural practices. The cost of plantation has been estimated at Rs.20,000 a hectare inclusive of plant material, maintenance for one year, training, overheads and the like. A selling price of Jatropha seeds at Rs.12 a kg would be an economically attractive proposition for farmers. 12 million jobs: India has vast stretches of degraded land, mostly in areas with adverse agro climatic conditions, where species of Jatropha can be grown easily. Use of 11 million hectare of wasteland for Jatropha cultivation can lead to generation of a minimum of 12 million jobs. India with its huge waste/non fertile lands, has taken a well-noted lead in Jatropha cultivation and commercial production is what the industries have to focus on for sustainable development.
Fig.No:3.1 Plantation of jatropha and Jatropa seeds
4. PALM OIL
The oil palm, Elaeis guineensis, is native to Africa. Its commercial value lies mainly in the oil that can be obtained from the mesocarp of the fruit - palm oil - and the kernel of the nut - palm kernel oil. Palm oil is used mainly for cooking (cooking oil, margarine, shortening, etc.) and has non-food applications (soap, detergent, cosmetics, etc.)
Palm Oil is the highest yielding oil crop, producing on average about 4-5 tonnes of oil per hectare per year, about ten times the yield of soybean oil. It is already very profitable to invest in the industry, even using existing technology. The price of palm oil is
consequently high - above 24,000 Rs per tonne - and the cost of production relatively low - about 7,200-9,600 Rs per tonne –so investors do not see the need for R&D. There may also be reluctance to embark on R&D, since its results often filter down to end-users eventually, inducing the latter to wait for others to cover the costs.
Fig.No:4.1 Plantation of palm and palm seeds
Two identical diesel engines are running, one on diesel oil and the other on palm oil. It possible by this method to have a continuous comparison of the operation of the two engines thanks to a series of regular measurements. This analysis focuses on the evaluation of the durability of the engine running on palm oil.
5.1 Testing Conditions
Description of the engine used:
Copy of LISTER engine 8/1 manufactured in India and marketed by the company FLAMINGO OVERSEAS PVT. LTD, RAJKOT - 360.001, GUJARAT– INDIA
Table No: 5.1 durability of the engine running on palm oil.
5.2 Appreciation of the service life of the palm oil engine
Evolution of the quantity of oil necessary to provide 1 mechanical kWh:
From the mass consumption of the engine per unit of time and the measure of the electric output by the generator, we deduce the quantity of oil necessary for the mechanical production of one kWh. The evolution in time of this value compared with the engine running on diesel oil will enable us to appreciate the service life of the engine running on palm oil.
Wear of the injection elements:
The acidity or the lack of viscosity of the palm oil is likely to cause a premature wear of certain parts of the injection pump or injector. The disassembling and the comparison of these elements on the engines A and B will allow assessing if the use of palm oil as a fuel really is a problem at this level.
Quality of the combustion in the engine:
The quality of combustion is appreciated mainly by the opacity of the exhaust fumes. They must be colorless. The temperature of these fumes also gives interesting information. Then, the disassembling of the cylinder head and the injector on the two engines and the comparison of their carbon deposit makes it possible to figure out if palm oil causes any problems at the combustion level.
Wear of the engine:
The ovalisation of the cylinder is the most important information. By measuring it before and after the tests and by comparing the values measured on the engines A and B, one can determine if the use of palm oil produces a faster wear in the engine or not. Then, the analyzes of lubricating oil samples taken in the two engines at the end of the tests will allow to complete this comparison.
· The biodiesel fuels produced less smoke than diesel under similar engine operating conditions, probably because palm oil contains oxygen which helps the combustion in the cylinder.
· The biodiesel and reference fuels provided similar combustion pressure patterns at low and medium engine loads, suggesting that the biodiesels had no adverse effect in terms of knocking.
· The biodiesel fuels lowered the premixed combustion of heat release because of the lower volatility.
Ø The viscosity of vegetable oils is much higher than that of diesel.It can cause problems in fuel handeling,pumping,automization& fuel jet penetration.
Ø This would require modifications in the engine fuel system.
Ø Vegetable oils are slower burning.
Ø It can give rise to exhaust smoke,fuel impingement on cylinder walls& lubricating oil contamination.
Ø To overcome this combustion system must be modified to speed up air-fuel mixing.
Ø The indirect injection(IDI) engines are more suitable than direct injection(DI) engines for vegetable oils because of single relative large size nozzle hole.
Ø Azhar Abdul Aziz*; Mohd Farid Said* and Mohamad Afiq Awang* “Performance of Palm Oil-Based Biodiesel Fuels in a Single Cylinder Direct Injection Engine”
Ø . www.card.iastate.edu/.../images/4-1_small.gif