OCR Document - India Study Channel



1. SYNOPSIS

The world energy crisis forces us to develop a new fuel source for transportation systems. The depletion of petroleum products will be a major problem of tomorrow. Our country loses a lot of foreign exchange for the import of petroleum and its products. The maximum percentage of petroleum imported is used only for transportation systems. So a fuel which is easily available with same potential energy as that of petroleum products chearler cost is needed. Although lots of alternate fuels are being tested for with good combustion properties in internal combustion engines at a and the usage in the internal combustion engines, vegetable oils appears to be an alternate source for India because of its availability. Vegetable oil can be produced in quantities of great enough to power the world's automobiles for the foreseeable future. It can be used in the existing conventional internal combustion engines without any modifications. This project mainly concentrates on vegetable oil blended diesel because it can directly use in conventional diesel engines. The vegetable oil (PINNAl OIL) which is greatly available in India is blended with diesel and used for performance and emission analysis. The smoke level decreased for about 15% to 30% oil in vegetable oil - diesel mixture. NOx emissions usually less or inline with vegetable oil blended diesel as the combustion temperature is same as that of diesel.

2. INTRODUCTION

Dr.Rudolf Diesel first developed the Diesel engine in 1985 with the full introduction of running it on a variety of fuels, including vegetable oil. Diesel showed his engine at the world exhibition in Paris in 1900 using peanut oil as fuel. In 1911 he said, 'the diesel engine can be fed with vegetable oils and would help considerably in the 'development of agriculture of the countries which use it'. In 1912 Diesel said, 'the use of

vegetable oils for engine fuels may seem insignificant today. But such oils may become in the source of time as important as petroleum and the coal tar products of the present time'. Dr. Diesel's words are truer today than ever before.

When Rudolf Diesel showed his engine at the world exhibition in Paris in 1900, he said two words which astonished the gathered engineers, Inventors, and scientists: peanut oil. The patented Diesel engine ran on almost any hydrocarbon from gasoline to peanut oil". The first Diesel engines and fuel systems built in the United States and Europe were so strong that some of them still work. These early Diesel engines were easily powered by straight vegetable oils as there

Since Rudolf Diesel' s time, the Diesel engine has been modified to run on the cheapest fuel available, petroleum. After Diesel's death, the petroleum industry capitalized on the diesel engine by labeling one of the by products of gasoline distillation "diesel fuel". Thus, cheap, dirty "diesel forgotten as a fuel source. During the last three quarters of a century, many fuel became the fuel of the diesel engine and vegetable oil was all but variations of Rudolf Diesel's original engine have been produced. Most of these engines are designed to run on less viscous fuels than the vegetable oil which dowered the original Diesel.

3. ALTERNATIVE FUELS FOR C.I. ENGINES

3.1. ALCOHOLS AS DIESEL FUEL

While S.I. engines can use alcohol fuel with minimal modifications to their fuel delivering systems the diesel engine has not been a good candidate for alcohols. Basically alcohols are unsuitable as diesel fuels for the following reasons.

• That cetane number of alcohol fuels is very low (of the order of zero to eight), which prevents their ignition by compression.

• Alcohol fuels have low lubricating qualities causing trouble in injection pumps and nozzles.

• There are material problems caused by the harsh reaction of methanol towards various plastics and metals.

Because of very low compression ignition quality, alcohols cannot be used alone as fuels for diesel engine without some in-cylinder assistance, like sparkplug, glow plug or other heated surface. Chemical ignition accelerators (usually organic nitrates) may be added to alcohol fuels to give acceptable ignition quality (i.e. increase the cetane number) 5 to 20% additive are required for knock free operation. But additives are expensives and because they contain nitrogen they also increase the NOx emission.

Another method of use of alcohols is in conjuction with conventional diesel oil pure ethanol is completely miscible with diesel fuel at temperatures in excess of about 300C. At lower temperatures, or when the ethanol contains water, miscibility is limited Co. solvents, such as ethyl acetate, may be added to increase the range of miscibility. Methanol, even when (dry, is almost completely immiscible with diesel fuels. The ignition properties of fuel mixtures containing more than about 25% of light alcohol are not generally found to be adequate.

Another method of using alcohol in diesel engines is by dual injection. The alcohol can be injected into the cylinder by a second high pressure system, or into the inlet manifold by a low pressure system; in either case a charge of diesel fuel is used to initiate the combustion process. However, the onset of misfire limits the use of alcohols to about 20% on energy basis.

3.2. BIO GAS AS DIESEL FUEL

With the development of biogas plants small diesel engines have been modified to run on diesel alone or diesel biogas combustion. The properties of typical biogas are

Composition : 60% CH2, 40% CO2, trace of H2, H2S

Calorific value : 5160 kcal / m3

4250 kcal/kg

Biogas is another alternate fuel tried in diesels. Biogas can be produced by anaerobic digestion of organic matter. Potential raw materials available on a large scale are cow dung, municipal wastes, and plants specially grown for this purpose like water hyacinth, algae, and certain types of grasses. The main advantage of biogas is that it can be produced in rural areas from readily available materials. Biogas consists mainly of methane and carbon dioxide. Its calorific value is low but its knock resistance (octane number) is high and ignition quality (cetane number) is low.

In dual fuel type diesel engine, the gas is mixed with the incoming air and ignited by pilot diesel fuel injection. Similar to the behavior of alcohol diesel oil dual fuel engines, this gas engine also suffers a fall in efficiency at part loads, compared to the diesel engine, but has good efficiency at full

3.3. HYDROGEN AS DIESEL FUEL

Hydrogen is another alternate fuel tried for IC engines. Investigations were carried out extensively in many countries. The most attractive features of hydrogen as an IC engine fuel are that it can be produced from a potentially available raw material, water and the main product of its combustion again is water.

Hydrogen has very low density both as gas and as liquid. Hence, in spite of its high calorific value on mass basis its energy density as a liquid is only one fourth the of gasoline. As a gas it has less than one tenth the density of air and its heating value per unit volume is less than one third that of methane. This is one of its chief disadvantages. Hydrogen has to be stored as compressed gas, as liquid (in cryogenic containers) or in absorbed form (as metal hydrides) none of which is as convenient as gasoline storage.

Hydrogen has extremely wide ignition limits. Only four percent by volume hydrogen in hydrogen air mixture and 75 percent by volume hydrogen in hydrogen air mixture are both ignitable. This allows a spark ignition engine to operate on hydrogen with very little throttling, a decided advantage. Stoichiometric hydrogen air mixture burns seven times as fast as the corresponding gasoline air mixture. This too is a great advantage in IC engines, leading to higher engine speeds and greater thermal efficiency.

Hydrogen has a high self-ignition temperature but requires very little energy to ignite it. Hence, it is very prone to pre-ignition and back flash in SI engines. Adiabatic flame temperature for hydrogen is a little lower than for gasoline but the rapid combustion allows very little heat loss to the surroundings and hence, high, instantaneous, local temperatures are produced. This leads to high nitric oxide formation.

3.4. VEGETABLE OILS AS DIESEL FUEL

Vegetable oils have better ignition qualities for diesel engines than light alcohols, their cetane number being over 30. There are many vegetable oils which can be used in diesel engines like peanut oil, linseed oil, rapeseed oil but the most important in sunflower oil on which maximum work has been done. The difference in properties of sunflower oil and diesel oil leads to the following problems in the use of vegetable oils in diesel engines.

The viscosity of vegetable oil is much higher than that of diesel. It can cause problems in fuel handling, pumping, atomization and fuel jet penetration. This would require modifications in the engine fuel system.

Vegetable oils are slower burning. It can give rise to exhaust smoke, fuel impingement on cylinder walls and lubricating oil contamination. To overcome this; combustion system must be modified to speed up air-fuel mixing.

The in indirect injection (IDI) engines are more suitable than direct injection (DI) engines for vegetable oils because of a single relative large size nozzle. Sunflower oil can be blended with diesel oil, 80% diesel 20% sunflower oil, to extend the availability of diesel oil.

4. CI ENGINE FUELS- IMPORTANT CHARACTERISTICS

The fuels used in diesel engines are liquid fuels. These fuels are obtained mainly from crude oil. As crude oil is refined, the various fuels got are gasoline 44% fuel oil 36% and balance is kerosene, lubricants etc. The diesel fuel is a mixture of different hydrocarbons, which have boiling points in the range of 180 - 360°C.

Fuels for compression ignition engines are classified into light, medium and heavy diesel fuels. Large slow speed engines can handle variety of diesel fuels than small high-speed engines. Specifications of the fuel oil differ depending on the size and type of the engine.

The following are the important factors, which influence the choice of fuel:

• Viscosity of fuel

• Flash and fire point of fuel

• Water and sediment present

• Pour point of fuel

• Ash content of fuel

• Sulphur content of fuel

• Boiling range of fuel i.e. volatility characteristic of fuel

• Specify gravity of fuel

• Carbon residue that will be formed

• Corrosiveness and acidity

• Ignition quality of fuel

• Fuel viscosity and fuel injection

Viscosity of a fluid is a measure of its resistance to flow or internal friction. Lubrication, friction between moving parts, their wear and leakage all these factors are influenced by viscosity.

Fuel viscosity dampens rate of pressure rise during pumping. Fluid friction in the highly viscous fuel raises its temperature. This also decreases the speed of travel of pressure wave. Hence, an increase in fuel viscosity tends to increase injection lag. When a more viscous fuel is used, residual pressure in the fuel line increase. This aspect may offset the effect of decreased rate of pressure rise on injection lag. An increase of fuel viscosity increases the duration of fuel injection.

Increase of fuel viscosity will give protracted injection and bad atomization. This will result in poor combustion and smoky exhaust.

Lubrication of fuel injection system, chiefly pump plungers and barrels and needle valve and nozzle body depends entirely on the fuel oil. Fuel oil that leaks past these parts lubricates them. Fuel of low viscosity has inferior lubrication property. This will increase wear of the fuel injection pump and nozzle. Further, low viscosity fuels result in greater leakage past worn fuel injection pump plungers and injector needle valves. This in turn reduces the volume of fuel injected and also pressure build up.

High viscous oils have to be heated to lower the viscosity and make them flow. A very flow viscosity is dangerous, as it will have very low lubricating value. Such a fuel may cause excessive wear and even seizing of the fuel pump plungers. Excessive wear will cause greater past the plungers.

1. FLASH POINT OF FUEL

Flash point is a measure of the fire risk of the oil bulk. A minimum flash point of 65°C is specified for safety. For some high-speed engines, flash point value down to 45°C is specified.

4.2. WATER AND SEDIMENT CONTENT:

Gritty matter in the fuel will cause rapid wear of the injection system and cylinder bore. Sediment may cause clogging of fuel system. Water and sediment content should not exceed 0.5 percent. For high-speed engines, the permissible limit is 0.1 percent. Wear of the injection system and cylinder bore may increase due to corrosion if the fuel contains water especially salt water.

4.3. POUR POINT OF FUEL

Pour point of diesel fuel is important in engines, which are to operate under extreme cold conditions. High pour point may interfere with starting a

Cold engine. Pour point is important in handling fuel between storage and engine. Pour point of fuel should be 5.5 to 8.5°C units below the minimum

anticipated temperature. Maximum pour point for diesel is -15.5°C.

4.4. ASH CONTENT OF FUEL:

Ash content in the fuel represents non-combustible material, some of which is abrasive in nature. Ash content in diesel fuel builds up deposits. As such it should not exceed 0.12 percent by weight for the heaviest fuel and 0.01 percent for light fuel used in high-speed engines.

4.5. SULPHUR CONTENT:

when the fuel is burnt, sulphur present in it produces sulphur dioxide and sulphur trioxide. Condensation of water vapor in the exhaust will result in the formation of sulphuric acid. The acid has a highly corrosive action on steel and cast iron at elevated temperatures. Corrosiveness and acidity will cause wear of various engine parts. Thus, slow sulphur content is most desirable.

4.6. BOILING RANGE OF FUEL

Boiling range of fuel represents the temperature range corresponding to beginning and termination of vaporization of fuel and also the quantum of fuel that will vaporize at different temperatures. Volatility i.e. vaporization capacity of a fuel is measured by 90 percent: distillation temperature. This is the temperature at which 90 percent of the fuel sample has distilled off. Lower this temperature higher is the volatility.

High-speed engines require require rapid evaporation of fuel. This stipulates that the fuel should have more of low boiling and less of high boiling constituents compared to fuels meant for low speed engines. For small diesel engines, a higher volatility is necessary than for larger engines in order to obtain low fuel consumption, low exhaust gas temperature and minimum smoke.

4.7. SPECIFIC GRAVITY OF FUEL:

The specific gravity of the fuel has no direct bearing upon the burning

qualities of fuel. However, the above-indicated limitations of viscosity more

or less confine the limits of specific gravity to about 0.83 to 0.90 for airless

injection engines, down to 0.94 for air injection engines.

4.8. CARBON RESIDUE

Carbon residue is the carbon left after evaporation and burning off of volatile matter from a sample of oil by heating. It indicates the tendency of the fuel to form carbon deposits on engine parts. A maximum carbon residue of 0.10 percent is allowable.

4.9. CORROSIVENESS

The fuel must not be corrosive, must not contain free acids. Otherwise it may damage the metal surfaces with which it comes in contact in storage and in the engine.

4.10. IGNITION QUALITY OF FUEL

Ignition quality is a measure of the ability of fuel to ignite promptly after injection. A fuel, which ignites slowly, causes diesel knock. In other ensures easy starting and a progressive smooth combustion with less noise. In high speed (automative) diesel engines, time available or allowed for combustion is very short. As such, ignition delay of the fuel must be small. This means, fuel must have good ignition quality.

Ignition quality of a fuel is expressed by different terms:

1. Cetane number of fuel

2. Self-ignition temperature of fuel.

3. Critical compression ratio.

4. Diesel index

5. Aniline point

Knock rating of CI engine fuels is done by comparing the fuel under prescribed conditions of operation in a special engine with primary reference fuels. These reference fuels are n cetane and alpha methylinapthalene. The ignition quality of the fuel is indicated by the term cetane number.

The cetane number of a fuel is the percentage by volume of cetane in a mixture of cetane and alpha methylnaphthalene, which will exhibit the same ignition characteristics of the fuel under test in a standard engine, under a set of standard test conditions. Thus a cetane rating of 60 indicates that the fuel has the same ignition characteristics as a mixture by volume of 60 parts (C16H34) and 40 parts of alpha-methyl naphthalene.

4.11. IGNITION QUALITY AND ANTIKNOCK

CHARACTERISTICS

The chemical structure desired in petroleum fuels for CI engines is opposite to that desirable for spark ignition engines. For a given number of carbon atoms the straight chain paraffin's have the highest cetane numbers. Also within this series, the larger the molecule the higher is the cetane number. Thus fuels having very high octane numbers such as gasoline, good aromatic fuels and alcohols are not well suited for use in compression ignition engines. The best fuels for the CI engine are highly paraffinic with average molecular weights greater than those of gasolines. Commercial kerosene is also a suitable one, but carbon deposit will be more.

Gasoline has got antiknock qualities (desirable in SI engines), but does not ignite readily. As such, gasoline is not suitable for use in diesel engines. Sharp oscillations of pressure, are noted during combustion. The engine will not run smoothly.

4.12. IGNITION ACCELERATORS

In general, the more readily the hydrocarbon molecules break up (chain structure) the better is the ignition quality of fuel. Fuels of poor ignition qualities can be improved by mixing them with fuels, which have good ignition qualities.

The cetane number of such a mixture then lies between the cetane number of the constituents. Ignition accelerators are added to diesel fuels to increase the rate of preflame reactions and reduce the ignition lag. Most ignition accelerators reduce the flash point of the fuels. They also tend to Increase the Conrad son carbon on the 10 percent distillation bottom and the carbon residue.

5. DESIRABLE CHARACTERISTICS OF DIESEL ENGINE FUEL

The desirable character of compression ignition engine fuels are as follows:

• Must be clean, water, grit and all foreign matter must be removed by filtering or by a similar process.

• Should be non-corrosive, or at least without any corrosive agents us free acids.

• Should have sufficient lubricating property so that there will not be undue wear of the fuel pump and the injector parts.

• Should have sufficient viscosity to avoid undue leakage of fuel past fuel pump plunger and injector needle. Should not have a viscosity too high to interfere with the flow of fuel through the high-pressure tubing and with the hydraulics of injection process i.e. build up of pressure and injection.

• Must ignite easily for easy starting and smooth running of the engine.

• Must burnt progressively and smoothly, which will avoid excessive cylinder pressures and a rough running engine.

• Must burn completely and leave no carbon or other deposits and practically no ash in the engine cylinder. High viscosity fuels may cause smoky exhaust.

• Must have low carbon residue. High carbon residue may produce deposits of carbon and a gummy substance on pistons and cylinder liners. Deposits may cause sticking of piston rings and valve stems.

• Must have suitable volatility characteristics. Low volatility reduces maximum power output, increases fuel consumption and gives smoky exhaust. Such a fuel also makes starting of a cold engine more difficult.

5.1. DIESEL FUELS BIS (ISI) SPECIFICATIONS 1460-1974

|Characteristic |Requirements |

|Flash point (Pensky martens closed), min |55°C |

|Kinematic viscosity centistokes at 37.8°C max |2 to 7.5 |

|Carbon residue (Rams bottom-percent by weight |0.2 |

|Cetane number, min |45 |

|Diesel Index |48 |

|Distillation, percent recovery at 360°C, in |90 |

|Copper strip corrosion for 3 hours at 100°C |Not worse than No. 1 |

|Water content percent by volume, max |0.05 |

|Requirements |Characteristics |

|Percent by weight, max |0.05 |

|Ash, percent by weight, max |0.01 |

|Acidity (total) mg of KOH/g, max |0.5 |

|Sulphur, total percent by weight (max) |1.0 |

|Pour point, max |6°C |

5.2. PROPERTIES OF PINNAI OIL (CALOPHYLLUM INOPHYLLUM)

The density of the oil is 920 Kg / m3

The viscosity of the oil at 30°C is 30 cS

The gross calorific value of the oil is 36000 kJ / kg

The flash point for the oil is 210°C

The fire point of the oil is 235°C

The cetane number by any vegetable oil lies between 30 to 35

6. METHODS OF EXTRACTING VEGETABLES

There are two types of oil presses which are useful for both small and large scale vegetable oil processing. The most common type of oil press is the screw press. This press uses a large diameter screw inside a metal housing. The oil seed is fed into the top of the press and falls into the churning screw. As the seed is churned into a mash by the turning threads of the screw, the oil is squeezed from the meal, or cake. The protein cake from the oilseed oozes from the side of the press and the vegetable oil dribbles from the bottom of the press.

6.1. SCREW PRESSES

Screw presses are available in sizes ranging from table top models to industrial models which can produce 2000 pounds (4400 kilograms) of oil per day. Screw presses are available in electrical powered and diesel powered models. Screw presses tend to be slow and they sometimes produce

oil with bits of meal still in it. A ram Dress is a more efficient oil press design. The press uses a hydraulic piston inside of a cylinder to crush the oilseed. Ram presses can be powered by hand, by an electric motor, or by a diesel engine.

2. OIL SETTLING

After a vegetable oil is pressed, it is often left to settle for a few days in a horizontal settling tank. The vegetable gums and pieces of meal cake will settle to the bottom of the tank. If the vegetable oil is to be used as a fuel, it should be pumped through a series of filters. First, it should be passed through a 150 micron mesh screen, then through a 25 micron filter, and then through a 10-15 micron fuel filter.

3. DIESEL POWERED PRESSES

Most of the mid to large sized oil presses can be powered with diesel engines. When used in conjunction with a diesel engine which has been modified to burn straight vegetable oil, these presses can produce their won fuel, diesel powered presses can provide fuel for entire communities or villages. Diesel powered generators, mills and pumps can pumps can run on the vegetable oil produced from a local resource such as jatropha oil. The combination of a diesel powered press and a diesel generator can offer many people who live in rural or isolated areas an inexpensive sustainable system of generating electricity.

Vegetable oils contain energy which came directly from the sun. Vegetable oil crops such as peanuts, sunflowers, and soybeans concentrate solar energy in their oils. Whereas fossil oil was made over a period of hundreds of millions of years, it takes as little as a few months to grow vegetable oil from seeds. Vegetable oil is a practical diesel engine fuel in many locations. For example, numerous islands produce electricity with diesel generators. These islands import diesel fuel which costs several dollars a gallon while they export coconut and palm oils for a few cents a gallon. By using locally grown vegetable oil for fuel, islands and countless other communities around the world can benefit from reduced fuel costs as well as lower localized emissions.

7. COMMON OIL-PRODUCING CROPS

There are over 350 species of oleaginous, or oil producing plants and thousands of sub-species. This chapter concentrates on ten plants that are commonly found in different regions of the world. The following table gives average annual oil yield in pounds of vegetable oil per acre and kilograms of vegetable oil per hectare for ten common oil seed crops. Many plants species produce more oil in tropical climates and conditions. Some species can be harvested more than once a year.

|PLANT |LATIN NAME |

|Oil Palm |Elaeis guineensis |

|Coconut |Cocos nucifera |

|Jatropha |Jatropha curcas |

|Rapseed |Brassuca napus |

|Peanut |Arachis hypogaea |

|Sunflower |Helianthus annuus |

|Safflower |Carthamus tinctorious |

|Soybeen |Clycine max |

8. FUELING DIESEL ENGINES WITH VEGETABLE OIL

There are three ways to use vegetable oil in a diesel engine. Each method has advantages and disadvantages. Using vegetable oil in a diesel engine is by 3 methods.

8.1. BIO DIESEL

Biodiesel is a fuel made from 80-90% vegetable oil, 10-20% alcohol, and 0.35-1.5% catalysts. It is a stable fuel, performs reliably in all diesel engines, cuts emissions, is mixable with petroleum diesel fuel, is easy to make, safe to handle, and will work with all diesel fuel storage and pumping systems. No engine modifications are needed to use Biodiesel in a diesel engine. Biodiesel can be poured straight into the fuel tank of any diesel vehicle.

8.2. VEGETABLE OIL – DIESEL MIX

Diesel engines can run on a mixture of vegetable oil and kerosene. The method involves “cutting” vegetable oil with kerosene. This method requires careful attention to mixing proportion, does not produce reliable results, and can be damaging to a diesel engine if not done carefully. This method also requires that an extra fuel tank be installed in the vehicle. The vegetable oil and kerosene mix should be considered experimental and potentially harmful to the diesel engine.

8.3. STRAIGHT VEGETABLE OIL

A Diesel engine can run in straight vegetable oil as long as the engine as started in diesel fuel and the vegetable oil is heated. Either used cooking oil or new vegetable oil can be used as fuel. This method involves installing a vegetable oil tank and modifying the heater hoses have been modified, the diesel engine is started on diesel or Bio-diesel fuel and then switched to hot, straight vegetable oil. When the engine is running, the engine coolant is used to heat the vegetable oil so that it has a similar viscosity to diesel fuel. When it is time to turn the engine off, it is cooled down on diesel or Biodiesel fuel. With attention to detail, this system is reliable.

9. EXPERIMENTAL PROCEDURE

The engine used in the experiment to conduct performance analysis is a four cylinder Direct Injection Diesel powered engine. The Engine specifications are given below.

1. Engine Specification

|Make |: |Standard 20 |

|Number of cylinder |: |4 in line, wet liner |

|Bore |: |85.72 mm dia |

|Stroke |: |92 mm |

|Displacement volume |: |2120cc |

|Compression ratio |: |20.1:1 |

|Engine output |: |Maximum 42 BHP @ 3000 RPM |

|Max. Torque |: |10.8 Kgf-m @ 2200 RPM |

|Cooling System 1 |: |Water cooled |

|Charging Dynamo |: |12V, 22A |

|Starter Motor |: |Pre-engaged type –12V |

9.2. PROCEDURE

The engine was started with Diesel and was left idling for 2 minutes. The fuel for the engine is delivered by a fuel tank through gravimetric flow. The set up had a 3-way burette end to measure the fuel consumption time for 10 cc from which the total fuel consumption time can be calculated. At first the performance analysis of the engine when fueled with diesel and then when fueled by blended diesel was noted. The engine was cooled by the coolant water circulation forced by a pump and its flow rate is controlled. The coolant outlet is left out without making it to pass in the radiator.

The engine is allowed to run at a constant speed of 1500 rpm for loads by controlling the accelerator. The coolant flow rate is controlled and its outlet temperature is noted by using a thermocouple. The exhaust gas temperature is also measured by inserting a thermocouple in the silencer following the exhaust manifold. The brake power produced by the engine is measured by a hydraulic dynamometer. The mass flow rate of air is calculated by the pressure difference measured at the inlet manifold by using a water column manometer. The % smoke present in the exhaust gases are noted by a smoke analyzer. These readings are noted for different loads applied by the hydraulic dynamometer.

Then the engine is stopped and allowed to cool by continuously passing cooling water. By this the engine heat is removed by the cooling water and the next fuel sample i.e., 10% oil + 90% diesel is used. For this, the engine is again started with diesel and left idling for some time with diesel and the diesel flow from the tank is cut-off and the fuel sample is poured in the top of the burette and all the above said readings are taken. Like wise the fuel samples up to 50% oil +50% diesel was used.

10. RESULTS

The vegetable oil blended diesel is being used to extent the availability of diesel and to reduce the depletion of petroleum fossil fuels at rapid rate. The vegetable oil blended diesel can be used in conventional diesel engines without any modifications and sacrificing any efficiency.

The calorific value of the vegetable oil is about 82% of calorific value of diesel. The diesel is directly blended with vegetable oil as they are completely miscible.

The blended fuel has also led to certain improved performance

characteristics.

• The smoke level decreased for about 15% up to 30% oil in vegetable oil diesel mixture.

• The friction power of the engine remained constant and had not suffered any variation

• As the vegetable oil has no Sulphur in it, the Sulphur dioxide emissions are estimated to reduce without any change in lubrication properties. Therefore Sulphur free diesel can be blended with vegetable oil for improved performance and reduced smoke levels.

• NOx emissions usually remain less or inline with vegetable oil blended diesel as the combustion temperature is same as that of diesel.

• Coolant water and exhaust gas temperatures had not suffered any deviations drastically.

It is also estimated that by using straight vegetable oil blended diesel

may also lead to the following problems:

• There may be a problem in delivering a correct amount of fuel by the injector pump due to the high viscous oil.

• As the wax constituents are estimated to present in the vegetable oil, this may lead to coking of the injectors and nozzles and the spray pattern may not be in the designed order.

• As the viscosity of the oil is high, it may not mix properly with the air inside the cylinder combustion chamber there may be a difficulty in the

• As the oil may have high degree of unburning hydrocarbons constituents, it may lead to high amount of carbon deposits in the cylinder liners and thereby increase the load after certain time of engine running. This may also lead to piston ring failures.

• After running the engine with blended diesel, it has to be again run with pure diesel for some time to wash out the unbumt hydrocarbons that may be present in the injectors and nozzles. Again the engine has to be started with diesel for easy starting.

• In the engine running with blended diesel may require frequent cleaning of the engine parts, as the carbon deposits are more and this may also contaminate the lubricating oil.

WORKS TO BE DONE IN THE FUTURE

The vegetable oil can be converted into ester by the trans-esterification process and this has very low viscosity and has similar properties as that of diesel. This is called as Bio-diesel.

The straight vegetable oil if to be used in diesel engines, it can be tried for indirect diesel engines ( IDI) for better performance characteristics.

The diesel blended with vegetable oil can also be heated above 150°C for reducing the viscosity and this may be injected by using solenoid valves with the diesel along another line.

The vegetable oil blended diesel can be added with suitable additives

for removing the carbon particles in the injector nozzles.

Vegetable oil if to be used alone the engine design should be modified

accordingly by increasing the injector orifice diameter for better injection.

11. CONCLUSION

Satisfactory performance was obtained with the blend containing 30% Pinnai oil. There was no degradation of fuel consumption and smoke readings were less or inline with that of diesel fuel. As the auto ignition properties of the vegetable oils are similar to those of diesel fuel they may be a right alternative fuel for the diesel engines in the near future.

The usage of vegetable oils as alternate fuels will enable the farmers to become self sufficient in diesel fuel, thereby reducing dependency on imported crude oil.

The usage of vegetable oil will also save the considerable amount of foreign currency of our nation and may provide a job for millions.

12. BIBLIOGRAPHY

• Keith Owen and Trevor Coley, “Automative Fuels Handbook”, Society of Automotive Engineers, Inc.

• Reda Moh. Bata, “Alernate Fuels: A Decade of Success and Promise PT – 48”

• H.V. Parekh, “Solvent Extracion of Vegetable Oils”.

• “Alternate Fuels SP – 480”, Society of Automative Engineers, Inc.

• “From the Fryer to Fuel Tank”.

• John B. Heywood, “Internal Combustion Engine Fundamentals”

• K.K. Ramalingam, “Internal Combustion Engines”

• V. Ganesan, “Internal Combustion Engines”.

• M.C. Mathur and R.P. Sharma, “Internal Combustion Engines”.

INTRODUCTION

ALTERNATIVE FUELS FOR

C.I. ENGINES

CI ENGINE FUELS

– IMPORTANT CHARACTERISTICS

DESIRABLE CHARACTERISTICS OF DIESEL

METHODS OF EXTRACTING VEGETABLE OILS

COMMON OIL-PRODUCING CROPS

FUELING DIESEL ENGINES WITH

VEGETABLE OIL

EXPERIMENTAL PROCEDURE

RESULTS AND DISCUSSION

CONCLUSION

BIBLIOGRAPHY

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