UNIT-4 Alternate fuels types and performance.pptx

Alternate fuels

1. UNIT IV ALTERNATE FUELS  

2. NEED FOR ALTERNATE FUELS Conventional fuels are going to run out One day, our sources for traditional fuels including petroleum would be depleted. Owing to the fact that these fuels are typically not renewable To reduce pollution The use of alternative fuels considerably decreases harmful exhaust emissions (such as carbon dioxide, carbon monoxide, particulate matter and sulfur dioxide) as well as ozone-producing emissions. To protect against global warming According to a commonly accepted scientific theory, burning fossil fuels was causing temperatures to rise in the earth’s atmosphere (global warming).

3. NEED FOR ALTERNATE FUELS To save money Alternative fuels can be less expensive to use not just in terms of the fuel itself but also in terms of a longer service life. This in turn means savings for the long term. Can reuse waste Biofuels , bio products, and bio power provide modern and fresh relevance to the old belief that trash for one person is a treasure for another. That’s good news considering that Americans produce in excess of 236 million tons of waste each year. More choices People are different. Each person has his own requirements, opinions, and preferences. One great thing about alternative fuels and the corresponding vehicles that run on them is that there is something to suit any lifestyle.

4. NEED FOR ALTERNATE FUELS You’ll be helping the farmers The use of biofuels that depend on crops produced and processed locally help to support farmers for their dedicated and hard labor. Biodiesel and ethanol cooperatives are a result of the great outmoded farmer cooperatives that assist with returning power to the hands of the people. Can frequently be produced domestically Often, alternative fuels can be developed domestically, utilizing a country’s resources and thereby strengthening the economy.

5. NEED FOR ALTERNATE FUELS Fuel economy Vehicles driven on hydrogen fuel cells and diesel are more economical with respect to fuel compared to an equivalent gasoline vehicle. Meeting Current Global Energy Demand; Alternative fuels are receiving attention because of the following reasons: Alternative fuels are mostly produced from domestic resources that reduce the energy dependence. Use of locally available resources for fuel purposes can reduce crude oil import bill. Most of the alternative fuels, for example, alcohols, biodiesel can be produced from biomass resources and agricultural wastes and electricity for battery operated vehicles can be produced from solar and fuel cells.

6. Parameters are to be considered while deciding the alternative fuel The fuel should have high volumetric and mass energy density. Ease of transportation from production site to delivery points. Long-storage life of fuel, minimum handling, and distribution problems. Environmental compatibility: While using alternative fuel, the engine performance is expected to improve significantly with regard to regulated emissions and unregulated emissions. Manufacturer’s warranty: The alternative fuel must guarantee the lifetime of the equipment; its reliability and operational capability are not modified. Investment cost: Additional investment on an existing engine must be small to ensure that the operation is competitive with petroleum fuel.

7. ALCOHOLS Alcohol is an attractive alternative fuel because it can be obtained from a number of sources, both natural and manufactured. There are two kinds of alcohol. They are: Methanol (or) Methyl alcohol (CH3OH) Ethanol (or) Ethyl alcohol (C2H5OH)

8. METHANOL AS ALTERNATIVE FUEL Methanol is one of the most promising substitute for petroleum fuels. It can be produced from a wide range of available raw materials like coal, lignite and municipal solid wastes. Pure methanol and mixtures of methanol and gasoline (petrol) in various percentages have been extensively tested in several engines and vehicles. The most common mixtures are M85 (85% Methanol and 15% gasoline) and M10 (10% methanol and 90% gasoline).

9. METHANOL AS ALTERNATIVE FUEL Production of Methanol from Lignite or Coal A schematic diagram for producing methanol from lignite or coal is shown in figure 4.1 Pulvarized coal is fed into gasifier where oxygen is supplied and combustion takes place. Synthesis gas which consists of CO and H 2 is produced due to combustion of coal. All H 2 S and most of the CO 2 are removed by passing amine solution. The carbon monoxide (CO) reacts with hydrogen and produces methanol. CO + 2 H 2 → CH 3 OH The raw methanol is then purified to remove water.

10. METHANOL AS ALTERNATIVE FUEL Production of Methanol from Lignite or Coal

11. METHANOL AS ALTERNATIVE FUEL Methanol from Municipal Solid Wastes

12. METHANOL AS ALTERNATIVE FUEL Performance of Methanol Figure shows the performance of petrol, diesel and methanol engines. It shows that pure methanol engine has about 20% greater output compared to that of the standard petrol engine. This is due to the higher compression ratio and more efficient thermodynamic process of methanol engines.

13. METHANOL AS ALTERNATIVE FUEL Thermal efficiency Vs fuel air ratio

14. ETHANOL AS ALTERNATIVE FUEL Ethanol has been used as alternative fuel for many years in various regions of the world. Brazil is probably the leading user, wherein the early 1990s, 5 million vehicles operated on fuels that were 95% ethanol. For a number of years gasohol (Mixture of 90% gasoline and 10% ethanol) has been available at service stations in the United States. The most common mixtures are E85 (85% ethanol and 15% gasoline) and E10 (10% ethanol and 90% gasoline

15. ETHANOL AS ALTERNATIVE FUEL Production of Ethanol Ethanol can be produced from sugar or grain. In contrast with methanol production, the process does not require extreme temperature and pressure. Hence very small unit is needed to produce ethanol . Production of Ethanol from grains

16. Production of Ethanol from sugarcane A schematic diagram of producing ethanol is shown in figure 4.10 Production of ethanol from sugarcane requires simple processes since the fermentable sugar is obtained directly from the sugarcane. The sugarcane is first cut and ground, and the cane juice is extracted. This sugarcane juice is then fermented with yeast to produce raw ethanol. Ethanol is produced by fermentation of carbohydrates by the Gay Lussac relation. ETHANOL AS ALTERNATIVE FUEL

17. ETHANOL AS ALTERNATIVE FUEL Production of Ethanol from sugarcane

18. ETHANOL AS ALTERNATIVE FUEL Performance of Ethanol Figure 4.11 shows the performance of petrol and ethanol engines which is based on mean effective pressure. It is observed that the mean effective pressure of ethanol is greater than petrol.

19. COMPARISON ON PROPERTIES OF ALCOHOLS (METHANOL AND ETHANOL) AND GASOLINE (PETROL) Air Fuel Ratio: The alcohol molecule contains fixed oxygen. So, the quantity of air required for combustion of the alcohol is considerably lower than that required for petrol. Calorific Value: Because of the fixed oxygen, the calorific value of alcohol is lower than that of petrol. To produce equal amount of energy more than double the weight of methanol is needed when compared to petrol and 65% greater weight of ethanol is required when compared to petrol.

20. COMPARISON OF ETHANOL AND METHANOL It can be seen from the property tables that most of the properties of ethanol and methanol resembles with each other with hardly change of 10%. Ethanol is superior to methanol since it has wide ignition limit, higher calorific value, and high cetane number compared with methanol. So, ethanol is widely used as S.I engine fuel in many countries.

21. ALCOHOL IN C.I. ENGINES (DIESEL ENGINES) C.I. engines can use alcohol fuel with minimum modifications to their fuel delivery systems. But alcohols are unsuitable for diesel engines for the following reasons. The cetane number of alcohol fuel is very low, which prevents their ignition by compression. Alcohol fuels having low lubricating qualities, which cause trouble in injection pumps and nozzles. Alcohol is much corrosive.

22. ALCOHOL-GASOLINE FUEL BLENDS Alcohols cannot be used directly as fuels in automobile engines except methanol in racing cars. But it can be used as blend with gasoline. Some common alcohol - gasoline fuel blends are: E85 (85% ethanol and 15% gasoline) E10 (10% ethanol and 90% gasoline) M85 (85% methanol and 15% gasoline) M10 (10% methanol and 90% gasoline)

23. ADVANTAGES OF ALCOHOL (METHANOL AND ETHANOL) Higher thermal efficiency. Higher volumetric efficiency. Good internal cooling. The alcohols can also be blended with gasoline (petrol) to form the gasol (80% petrol and 20% alcohol) and it is widely used in USA. Sulphur content in the fuel is low. Less overall emission when compared with gasoline.

24. DISADVANTAGES OF ALCOHOL Alcohol is much corrosive than gasoline (petrol). So, special metals should be used for the engine part to avoid corrosion. Poor cold weather starting characteristics due to low vapour pressure and evaporation. Ignition characteristics are poor. Since alcohols have invisible flames, it is dangerous to handle Vapour lock in fuel delivery systems. Energy content of the alcohol is low. So, almost twice the amount of alcohol compared to gasoline is required to give the same energy.

25. VEGETABLE OILS AS DIESEL FUELS Vegetable oils have two broad classifications: Edible oils (sunflower, soy bean, palm oil, etc.) Non-edible oils ( jatropha , karanji , rubber seed oil, etc.). Edible type oils are mainly used for food purposes whereas nonedible oils are used for food purposes.

26. Table - Physical and Chemical properties of test methods

27. Advantages of Vegetable Oils Vegetable oils can be used as substitute fuel for diesel engine application. Use of vegetable oil for fuel purposes reduces the import of costly petroleum and improves the economy of agricultural countries. They are biodegradable and nontoxic. Vegetable oils are of low aromatics and low sulfur content and hence reduce the particulate matter emissions. They have a reasonable cetane number and hence possesses less knocking tendency.

28. Disadvantages of using vegetable oil as C.I. Engine fuel The high viscosity of vegetable oils leads to pumping and atomization problems in the normal diesel fuel injection systems. High carbon residue causes heavy smoke emission and carbon deposition on the injection nozzle tips and in the combustion chamber. There are also problems of incompatibility with engine lubricants. The poor volatility makes the vegetable oil difficult to vaporize and ignite. This leads to thermal cracking resulting in the heavy smoke emission and carbon deposits in the combustion chamber. This tendency is partly due to higher fuel viscosity.

29. BIO-DIESEL This is an alternative to standard diesel fuel. This is made from biological sources instead of petroleum. It is made from plant oils or animal food. Pure bio-diesel is referred by B100 standard diesel is usually mixed with biodiesel. 80% of standard diesel is mixed with 20% of bio-diesel. This blended bio-diesel is referred by B20. National Bio-diesel Board, the technical definition of bio- diesel is "a fuel comprised at mono-alkyl esters of long chain, fatty acids derived from vegetable oils or animal fats, designated B100, and meeting the requirements of ASTMD6751".

30. Biodiesel Production Vegetable oil reacts with alcohol (typically methanol or ethanol) in the presence of catalyst produced biodiesel. Biodiesel production process consists of three steps; namely, Conversion of triglycerides (TG) to diglycerides and one ester molecule Followed by the conversion of diglycerides (DG) into monoglycerides (MG) and one ester molecule Monoglycerides into glycerol and one ester molecule catalyst

31. Advantages It also safer and non-toxic. It has higher flag point than conventional diesel oil. It can be easily stored and transported. It can be also used as engine lubrication assistant. It increases the engine life due to less deposit. It has lesser emissions. The below table gives average emission of biodiesel and composed diesel fuel.

32. Disadvantages NO x emissions will form smoke. Although bio-diesel being solvent helps in better lubrication, yet the loosening deposits from the conventional diesel engine compound may clog the fuel filter. So, filters should be changed often. Cost of the biodiesel is more than the conventional diesel oil. Less availability. Bio-diesel breaks down rubber components. It does not suits all type of engines. In some engines, the reduction in power occurred at 10%. 1.1 litres of bio-diesel oil would be equivalent to 1 litre of conventional diesel oil.

33. NATURAL GAS Natural gas, like petroleum comes from underground reserves. It consists, mainly about 95 percent of methane (CH4). The remaining 5 percent comprises of butane, propane, ethane with small amount of water vapour . Simple chemical structure of methane makes possible for complete combustion, releasing lesser emissions. Two types of natural gas is used as alternative fuel. They are: Compressed Natural Gas (CNG) Liquefied Natural Gas (LNG)

34. Compressed Natural Gas (CNG) Natural gas is compressed and stored in high-pressure cylinders. This is done for ease transportation storage and automation. Hence it is called compressed natural gas. It requires no additives and its production does not need complicated refining processes. It has very low emissions.

35. Liquefied Natural Gas (LNG ) LNG means natural gas in liquid form. It is made by refrigerating natural gas to minus 161°C. It is a clear, colourless , odourless liquid. During the liquefaction process, natural gas is cooled below its boiling point removing most of the water vapour , butane, propane, etc., so that LNG is more than 98 percent of methane (CH4). LNG is much more dense than CNG, which means more energy per unit volume. The implication is the higher vehicle range for the same size of fuel cylinder.

36. LIQUEFIED PETROLEUM GAS Liquefied petroleum gas (LPG), a mixture of propane (C3H8) and butane (C4H10) gas, is a popular fuel for internal combustion engines. It is a nonrenewable fossil fuel that is prepared in a liquid state under certain conditions. This popularity comes from many features of the fuel such as its high octane number for spark ignited engines, comparable to gasoline heating value that ensures similar power output.

37. HYDROGEN FUELS Hydrogen fuel can be produced from water, a potentially available raw material. Hydrogen is best suited for I.C engines since physical delay is almost zero. So number of automobile manufacturers have built with prototype or modified engines which operate on hydrogen fuel. Properties of Hydrogen Fuel It has low emission property. Hydrogen density is low, both when it act as a liquid as well as gas. Calorific value is high .

38. Hydrogen Engines Hydrogen is a highly reactive fuel which is required to handle in a great manner. Flash back arresters have to be provided between the engine and the storage tank to prevent flash back from going to tank. Energy density of hydrogen in liquid state is one fourth that of gasoline. As a gas it has less than one tenth of the density of air. This makes the storage of hydrogen easier. It can be stored easily in a cryogenic container when it is in liquid form.

39. Hydrogen injection in spark ignition engine

40. Liquid Hydrogen storage and gaseous hydrogen injection system

41. Advantages of using hydrogen as a fuel High energy content per volume when stored as a liquid. This increases the vehicle range for a given fuel tank capacity. No toxic gas is produced after the reaction. Availability of the hydrogen fuel is more. It does not pollute the environment. Low emission due to less carbon content in the fuel.

42. Disadvantages of using hydrogen as a fuel Low volumetric efficiency. Fuel cost is high. No possibility of refuel. Size of the system is large due to heavy and bulky storage tank. Storing as a gas makes the system as more tedious one. High NOx emission is due to high flame temperature.

43. Engine Modification System for LPG

44. Engine Modification Using Ethanol

45. PERFORMANCE, COMBUSTION AND EMISSION CHARACTERISTICS OF SI AND CI ENGINES USING THE ALTERNATE FUELS Here we are going to compare the gasoline with the hydrogen fuel. Comparison of Performance Characteristics In analysing the performance characteristics of the gasoline and hydrogen fuel, we can take the brake thermal efficiency factor. The brake thermal efficiency of the hydrogen fuel is more when compared with gasoline fuel.

46. Comparison of Performance Characteristics

47. Emission of CO

48. Emission of NO

49. Emission of HC

50. Comparison of Combustion Characteristics