Diesel Engines Fuelled With Ethanol Diesel Emulsion Engineering Essay

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Fossil fuels are fuels formed by natural resources such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years. The fossil fuels, which contain high percentages of carbon, include coal, petroleum, and natural gas. Fossil fuels range from volatile materials with low carbon hydrogen ratios like methane.

Fossil fuels are non-renewable resources because they take millions of years to form, and reserves are being depleted much faster than new ones are being made. The production and use of fossil fuels raise environmental concerns. A global movement toward the generation of renewable energy is therefore under way to help meet increased energy needs.

1.2 Non Fossil Fuels:

Non fossil fuels are alternative sources of energy that do not rely on burning up limited supplies of coal, oil, or natural gas. Examples of non fossil fuels include: nuclear energy, wind or water generated energy, and solar power. These tend to be renewable energy sources, or means of generating power that can be utilized indefinitely.

Non fossil fuels are considered by many to be extremely important to the future of power creation. This is because they are usually renewable energy sources that could be tapped for hundreds of years and not run out. In addition, non fossil fuel energy production usually generates much less pollution than other energy sources. This is considered crucial by many governments who are looking for ways to reduce the amount of pollution produced by their countries.

Fossil fuel disadvantages include pollution. When a fossil fuel material such as coal is burned to create energy, carbon dioxide is released. This carbon dioxide pollutes the atmosphere and contributes to the greenhouse effect. Non fossil fuels do not have this disadvantage.

The growing concern due to environmental pollution caused by the conventional fossil fuels and the realization that they are non-renewable have led to search for more environment friendly and renewable fuels. For the past few decades, a lot of effort has been made to reduce the dependency on petroleum fuels for power generation and transportation all over the world.

1.3 Diesel ethanol blend:

Diesel engines are widely used as a power source in medium and heavy-duty applications due to their lower fuel consumption and lower exhaust emissions of carbon monoxide (CO) and unburned hydrocarbons (UHC) compared with gasoline engines. Since the invention and successful running of the CI engine, vegetable oil was used as fuel at the time petroleum fuel supply was expensive or difficult to obtain. Later, with the availability and supply of petroleum products, vegetable oil was replaced with diesel (or heavy fuel). This reduced the dependence on vegetable oil as well as directed research interest towards improving the diesel fuel. Diesel engine has received considerable attention because of its high heat efficiency and low emission. However, with the stringent emission standard and limited petroleum reserve, alternative fuels for diesel engine have been used. As a renewable and oxygen-containing bio-fuel, ethanol is a prospective fuel for vehicle, which can be blended with diesel or be injected into cylinder directly. Ethanol, C2H5OH, (also called Ethyl Alcohol) is the second member of the aliphatic alcohol series. It is a clear colorless liquid with a pleasant smell.

There are many studies on the application of ethanol on diesel engine, which focuses on the three aspects:

1. Application techniques of ethanol on diesel engine

2. Fuel properties of ethanol-diesel blends.

3. Effects on the combustion and emission characteristics of ethanol-diesel blends.

Because ethanol is polar molecule and its solubility in diesel is prone to be affected by temperature and water content, high percentage addition of ethanol to diesel is difficult, especially under low temperature. In order to mix ethanol and diesel, an emulsifier or co-solvent should be added. An emulsifier (also known as an emulgent) is a substance which stabilizes an emulsion (mixture of two immiscible liquids) by increasing its kinetic stability. Many literatures indicated that aromatic hydrocarbon, middle distillate and wax content of diesel are important factors of its blend with ethanol. The emulsifier we will use for our project is ENER diesel.

Presently, the application techniques of ethanol on diesel engine can be divided into the following three classes:

(1) ethanol-diesel blend by high pressure pump.

(2) ethanol fumigation to the intake air charge by using carburetion or manifold injection, which is associated with limits to the amount of ethanol due to the incipience of engine knock at high loads, and prevention of flame quenching and misfire at low loads.

(3) dual injection system requiring an extra high-pressure injection system and a related major design change of the cylinder head.

(4) blends of ethanol and diesel fuel by using an emulsifier or co-solvent to mix the two fuels for preventing their separation, requiring no technical modifications on the engine side.

The physical and chemical characteristics of ethanol-diesel blends are very important to its application on diesel engine. The stability, density, viscosity, surface tension, specific heat, heat value and cetane number of blends have great impact on the injection, atomization, ignition and combustion properties, as well as cold-start, power, fuel consumption and emission characteristics of engine. Additionally, the poking and leakage of conventional tank, fuel pipe and sealing part can be rendered. More stringent demands are necessary for the mixture, transportation, storage and usage of fuel because of low flash point of ethanol-diesel blends [9-13].The cetane number is an important fuel property for diesel engines. It has an influence on engine start-ability, emissions, peak cylinder pressure and combustion noise.

For lab testing, there are 5 diesel engines of same specifications. These engines will be fuelled with E7.5, E10, E12.5, E15 and diesel. Each engine will run for 512 hours. After completion of eight cycles (512 hours) readings will be taken. The performance characteristics and emissions will be measured.

2. LITERATURE REVIEW:

2.1 'Performance and Emission Characteristics of Diesel Engine Fueled with Ethanol-diesel Blends in Different Altitude Regions' by Faculty of Transportation Engineering, Kunming University of Science and Technology, Kunming (650224, China)

2.2 'The effects of ethanol-diesel blended fuels on the performance and emissions of

unmodified diesel engines' by J. I. Dominguez, E. Miguel CIDAUT, Parque Tecnológico de Boecillo, Parcela 209, ES-47151 Boecillo, Valladolid, Spain R. Arjona, C. Millán Abengoa Bioenergía, Av. Buhaira 2, ES-41018 Seville, Spain

2.3'Solubility of a diesel-biodiesel-ethanol blend, its fuel properties, and its emission characteristics from diesel engine' by Prommes Kwanchareon a, Apanee Luengnaruemitchai by:

a) The Petroleum and Petrochemical College, Chulalongkorn University, Bangkok 10330, Thailand

b) The Royal Thai Navy, Bangkoknoi, Bangkok 10700, Thailand

Received 6 June 2006; received in revised form 25 September 2006; accepted 28 September 2006.

3. NEED OF THE PROJECT:

Nowadays, the growing concern due to environmental pollution caused by the conventional fossil-based fuels and the realization that they are non-renewable have led to the search for more environmental friendly and renewable fuels. Ethanol is a renewable source of energy obtained from sugarcane, molasses etc. Thus, to reduce the dependence on fuel imports and non- renewable sources of energy, this test is performed.

This test will also help us to find the performance characteristics of diesel engine, effect on emissions.

4. OBJECTIVES:

4.1) Evaluation of physicochemical properties of diesel ethanol and their blends.

4.2) Development of engine test rig for endurance test.

4.3) Performance and emission analysis by using diesel E7.5, E10, E12.5, and E15 as test fuel blends.

5. METHODOLOGY PROPOSED:

5.1) Preparation of test fuels.

5.2) Physicochemical properties of ethanol and diesel.

5.3) Schematic diagram of engine test rig.

5.4) Performance parameters

5.5) Emissions measurement.

5.1) Preparation of Test fuels:

The fuels used are diesel, E7.5, E10, E12.5and E15.

E7.5 is prepared by mixing 7.5% of ethanol to diesel. Emulsifier added is 1.05% of ENER Diesel.E10 is prepared by mixing 10% ethanol to diesel and the amount of emulsifier (a substance which stabilizes an emulsion) added is 1.4%. Similarly, the other two blends are prepared.

5.2) Physicochemical properties of ethanol and diesel:

By this test, the properties which we are going to measure are:

Viscosity

Density

Calorific value

Surface tension

Exhaust gases

Smoke

Cloud Point

Flash Point

Pour Point

5.2.1) Viscosity:

Viscosity is a measure of the resistance of a fluid which is being deformed by either shear stress or tensile stress or it describes a fluid's internal resistance to flow and may be thought of as a measure of fluid friction.

The instrument used for measuring viscosity is known as viscometer. Viscometers only measure under one flow condition. In general, either the fluid remains stationary and an object moves through it, or the object is stationary and the fluid moves past it.

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Figure .1- Viscometer

5.2.2) Density:

The mass density or density of a material is defined as its mass per unit volume. The mass density of a material varies with temperature and pressure. (The variance is typically small for solids and liquids and much greater for gases.) Increasing the pressure on an object decreases the volume of the object and therefore increases its density. Increasing the temperature of a substance decreases its density by increasing the volume of that substance.

Density of diesel fuel oil at 15 °C is 820 - 950 kg/cum.

Density of Ethanol is 789 kg/cum at 20 °C.

A hydrometer is an instrument used to measure the specific gravity (or relative density) of liquids; that is, the ratio of the density of the liquid to the density of water. A hydrometer is usually made of glass and consists of a cylindrical stem and a bulb weighted with mercury or lead shot to make it float upright. The liquid to be tested is poured into a tall container, often a graduated cylinder, and the hydrometer is gently lowered into the liquid until it floats freely. The point at which the surface of the liquid touches the stem of the hydrometer is noted. Hydrometers usually contain a scale inside the stem, so that the specific gravity can be read directly. A variety of scales exist, and are used depending on the context.

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Figure 1.2- Hydrometer

5.2.3) Calorific Value:

The heating value or calorific value of a substance, usually a fuel, is the amount of heat released during the combustion of a specified amount of it. The calorific value is a characteristic for each substance. It is measured in units of energy per unit of the substance, usually mass, such as: kcal/kg, kJ/kg, J/mol, Btu/m³.

Heating value is commonly determined by use of a bomb calorimeter. A bomb calorimeter is a type of constant-volume calorimeter used in measuring the heat of combustion of a particular reaction. Bomb calorimeters have to withstand the large pressure within the calorimeter as the reaction is being measured. Electrical energy is used to ignite the fuel; as the fuel is burning, it will heat up the surrounding air, which expands and escapes through a tube that leads the air out of the calorimeter

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Figure 1.3- Bomb Calorimeter

5.2.4) Surface Tension:

Surface tension is a property of the surface of a liquid that allows it to resist an external force. This property is caused by cohesion of like molecules, and is responsible for many of the behaviors of liquids. The instrument used for measuring surface tension is called ultrasonic interferometer.

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Figure 1.4- Ultrasonic Interferometer

5.2.5) Exhaust Gases:

Exhaust gases consist of oxides of nitrogen, carbon monoxide, unburnt hydrocarbons, particulate matter & smoke. An instrument used for measuring exhaust gases is gas analyzer.

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Figure 1.5- Gas Analyzer

5.2.6) Smoke:

It is a visible indicator of combustion process and results due to incomplete combustion. The instrument used for measuring smoke is smoke meter.

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Figure 1.6- Smoke Meter

5.2.7) Cloud Point:

Cloud Point is the temperature at which wax crystals start to precipitate out and the fuel becomes cloudy.

5.2.8) Flash Point:

The flash point is the lowest temperature at which the vapour above a liquid will ignite when exposed to a flame (or other ignition source with sufficient energy). It is a measure of both volatility and flammability.

5.2.9) Pour Point:

The pour point is the lowest temperature at which fluid will begin to flow.

5.3) Schematic diagram of engine test rig.

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Figure - Schematic Diagram of Engine Test Rig

5.4) Performance parameters :

5.4.1) Brake Thermal Efficiency:

It is the ratio of energy in the brake power to the input fuel energy in appropriate limits.

ᶯbth=bp / (mass of fuel per sec Ã- calorific value of fuel)

5.4.2) Brake specific fuel consumption:

It is the weight of fuel burned per hour to produce a given amount of brake horse power in a reciprocating engine.

5.4.3) Exhaust gas temperature

Exhaust gas is emitted as result of combustion of fuels. It is discharged into the atmosphere through an exhaust pipe. The temperature of exhaust gas is measured by exhaust gas temperature gauge.

EGT represents the exact temperature of the fuel mixture after it is combusted in the cylinder. This should be measured as close to the outlet valves as possible.

5.5) Emissions Measurement:

The CI engine exhaust gases contain oxides of nitrogen (NOx), carbon monoxide (CO) and organic compounds which are unburned or partially burned hydrocarbons (HC). Specific hydrocarbon compounds in the exhaust gases are the source of diesel odor. Diesel engines are an important source of particulate emissions; between about 0.2 and 0.5 percent of the fuel mass is emitted as small (-0.1 m diameter) particles which consist primarily of soot with some additional absorbed hydrocarbon.

5.5.1) Oxides of Nitrogen

Exhaust gases of a CI engine can have up to 2000 ppm of oxides of nitrogen. Most of nitrogen oxide(NO),with a small amount of nitrogen dioxide(NO2).There are all grouped together NOx, with x representing suitable number. NOx is very undesirable. Regulations to reduce NOx emissions continue more and more stringent year by year. Released NOx reacts in the atmosphere to form ozone and is one of the major causes of photochemical smog.

5.5.2) Carbon Monoxide:

Carbon monoxide (CO) emissions from internal combustion engines are controlled primarily by the fuel air equivalence ratio. For fuel-rich mixtures CO concentrations in the exhaust increase steadily with increasing equivalence ratio, as the amount of excess fuel increases. For fuel-lean mixtures, CO concentrations in the exhaust vary little with equivalence ratio.

5.5.3) Unburned Hydrocarbon:

Hydrocarbon or more appropriately organic emission, are the consequences of incomplete combustion of the hydrocarbon fuel. Diesel fuel contains hydrocarbon compounds with higher boiling points, and hence higher molecular weights, than gasoline.Also, substantial pyrolysis of fuel compounds occurs within the fuel sprays during the diesel combustion process. Thus, the composition of the unburned and partially oxidized hydrocarbons in the diesel exhaust is much more complex than in the spark-ignition engine and extends over a larger molecular size range.

5.5.4) Particulate Emissions:

Diesel particulates consist principally of combustion generated carbonaceous material (soot), on which some organic compounds have become absorbed. Most particulate material results from incomplete combustion of fuel hydrocarbons; some is contributed by the lubricating oil. The emission rates are typically 0.2 to 0.6 g/km for light-duty diesels in an automobile. In larger direct-injection engines, particulate emission rates are 0.5 to 1.5 g/kWh. The composition of the particulate material depends on conditions in the engine exhaust and particulate collection system.

5.5.5) Smoke:

It is a visible indicator of combustion process and results due to incomplete combustion. The instrument used for measuring smoke is smoke meter.

6. TIME PLAN:

Sr. no

Activities

November

December

January

February

March

1

Decided the objective of project

2

Learning the basic knowledge of the project

3

Lab Testing

4

Analysis of performance and emission characteristics of the engine

5

Finalization of Results

6

Conclusion

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