The document discusses various types of fuels used in internal combustion engines. It describes the desirable properties of fuels including high energy content, good combustibility, and low pollution. Commonly used fuels are liquids, gases, and solids that have been gasified. The document outlines the chemical structure and hydrocarbon families that make up fuels like petroleum, discussing compounds such as alkanes, alkenes, and aromatics. Alternative fuels are also examined including compressed natural gas, liquefied petroleum gas, producer gas, alcohols, and fuel additives like tetraethyl lead. Fuel specifications for gasoline and diesel are presented relating to properties such as density, heating value, viscosity, and anti-knock quality.

1. TOPIC: I.C.ENGINE FUELS
S K Singh
Centre for Energy Studies
IIT Delhi
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2. I.C.ENGINES FUELS
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3. I.C.ENGINE FUELS Contd…
• Desirable properties of fuel:
• High energy content
• Good combustibility
• Thermal stability
• Low deposits
• Low toxicity
• Low pollution
• Less combustion time
• Commonly used fuels:
• Liquid and gaseous
• Solid fuels may also be used after gasification
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4. CHEMICAL STRUCTURE OF PETROLEUM
• Crude oil - a mixture of many hydrocarbons with
differing molecular structure
• Contains small amount of Sulphur, oxygen, Nitrogen,
Impurities (water and sand)
• C and H atoms are linked in different ways in a
hydrocarbon molecule – which influences the
chemical and physical properties of different
hydrocarbon group
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5. HYDROCARBON FAMILIES
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6. HYDROCARBON FAMILIES Contd..
Alkanes
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VERY STABLE

7. HYDROCARBON FAMILIES Contd..
Alkanes
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8. HYDROCARBON FAMILIES Contd..
Alkanes
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STABLE COMPOUNDS

9. HYDROCARBON FAMILIES Contd..
Alkanes
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10. HYDROCARBON FAMILIES Contd..
Naphthenes
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11. CLASSIFICATION OF FUELS Contd..
Alkenes
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12. HYDROCARBON FAMILIES Contd..
Alkenes
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13. HYDROCARBON FAMILIES Contd..
Aromatics
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14. HYDROCARBON FAMILIES Contd..
Aromatics
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15. Manufacture of engine fuels
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• Formed due to fossilization of organic matter under
ground
• All formed of carbon and hydrogen
• Some with little oxygen + sulphur, mercury + other
minerals and non combustibles

16. FUEL SPECIFICATIONS
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17. FUEL SPECIFICATIONS:
RELATIVE DENSITY
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18. FUEL SPECIFICATIONS:
FUEL COMPOSITIONS
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19. FUEL SPECIFICATIONS:
FUEL COMPOSITIONS
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METHYLCYCLOPENTADIENYL MANGANESE TRICARBONYL

20. FUEL SPECIFICATIONS:
SPECIFIC HEATING VALUE
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21. FUEL SPECIFICATIONS:
FLASH POINT
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22. FUEL SPECIFICATIONS:
VISCOSITY
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23. FUEL SPECIFICATIONS:
FREEZING POINT
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24. FUEL SPECIFICATIONS:
SURFACE TENSION
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25. FUEL SPECIFICATIONS:
FOR GASOLINE
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26. PETROL
• PETROL: Used in relatively small displacement
Spark Ignition engines (Petrol Engines)
• HCV around 48000 KJ/Kg
• Density around 737.22 Kg/m3 at 15.5oC
• Indian Petrol Octane rating 89 to 91
• BP = 35 to 200 oC
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27. FUEL SPECIFICATIONS:
FOR GASOLINE- VOLATILITY
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28. GASOLINE DISTILLATION CURVE
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29. GASOLINE DISTILLATION CURVE
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30. GASOLINE DISTILLATION CURVE
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31. COLD STARTING
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32. MEASUREMENT OF GASOLINE VOLATILITY
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33. ANTI KNOCK QUALITY OF GASOLINE
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34. ANTI KNOCK QUALITY OF GASOLINE
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35. ANTI KNOCK QUALITY OF GASOLINE
MEASUREMENT
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36. ANTI KNOCK QUALITY OF GASOLINE
MEASUREMENT: OCTANE NUMBER
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37. ANTI KNOCK QUALITY OF GASOLINE
MEASUREMENT: OCTANE NUMBER
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38. ANTI KNOCK QUALITY OF GASOLINE
MEASUREMENT: OCTANE NUMBER
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39. INCREASING OCTANE NUMBER
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40. DIESEL FUEL SPECIFICATIONS
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41. DIESEL FUEL VISCOSITY
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42. DIESEL FUEL SURFACE TENSION
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43. DIESEL FUEL: CETANE NUMBER
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44. CETANE NUMBER MEASUREMENT
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45. CETANE NUMBER MEASUREMENT
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46. CETANE NUMBER MEASUREMENT
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47. 47
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48. DIESEL
• DIESEL: Used in relatively large displacement
Compression Ignition engines (Diesel Engines)
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49. DIESEL contd..
• DIESEL
• Indian diesel Cetane No. Around 48
• High speed diesel Cetane No. around 49 to 50
• HCV = 44800 KJ/Kg LCV = 43400 KJ/Kg
• Density around 820 to 950 Kg/m3 at 15oC
• The High Speed diesel contains additives like-
• Detergents
• Cetane /lubricating improvers
• Rust/corrosion inhibitors
• Defoamers
• Demulsifiers
• BP = 250 to 350 oC
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50. Fuel types (Alternative)
1.Compressed natural gas (CNG)
- Is a fossil fuel substitute for gasoline (petrol), diesel,
or propane/LPG
- Although its combustion does produce greenhouse gases,
it is a more environmentally clean alternative to those
fuels, and it is much safer than other fuels in the event of
a spill (natural gas is lighter than air, and disperses
quickly when released).
- CNG may also be mixed with biogas, produced
from landfills or waste water, which doesn't increase the
concentration of carbon in the atmosphere.
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51. • Compressed natural gas (CNG)
• CNG is made by compressing natural gas (which is mainly
composed of methane [CH4]). [Self Ignition temp 580oC]
• It is stored and distributed in hard containers at a pressure of 200–
248 bar (2900–3600 psi), usually in cylindrical or spherical
shapes.
• CNG is used in traditional gasoline internal combustion
engine cars that have been converted into bi-fuel
vehicles (gasoline/CNG).
• Natural gas vehicles are increasingly used in the Asia-
Pacific region (especially Pakistan), Latin America, Europe,
and North America due to rising gasoline prices. In response to
high fuel prices and environmental concerns, CNG is starting to be
used also in tuk-tuks and pickup trucks, transit and school buses,
and trains.
Fuel types (Alternative) contd..
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52. 1. Due to the absence of any lead or benzene content in CNG, the lead fouling of
spark plugs is eliminated.
2. CNG-powered vehicles have lower maintenance costs when compared with other
fossil fuel-powered vehicles.
3. CNG fuel systems are sealed, which prevents any spill or evaporation losses.
4. Increased life of lubricating oils, as CNG does not contaminate and dilute the
crankcase oil.
5. CNG mixes easily and evenly in air being a gaseous fuel.
6. CNG is less likely to auto-ignite on hot surfaces, since it has a high auto-ignition
temperature (540 °C) and a narrow range (5%-15%) of flammability.
7. Less pollution and more efficiency: CNG emits significantly less pollutants such
as CO2 unburned hydrocarbons (UHC), carbon monoxide (CO), nitrogen
oxides (NOx), sulfur oxides (SOx) and particulate matter (PM), compared to petrol.
For example, an engine running on petrol for 100 km emits 22,000 grams of CO2,
while covering the same distance on CNG emits only 16,275 grams of CO2
Advantages of CNG
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53. • Compressed natural gas vehicles require a greater amount of space for
fuel storage than conventional gasoline powered vehicles. Since it is a
compressed gas, rather than a liquid like gasoline, CNG takes up more
space for each gasoline gallon equivalent (GGE).
• Therefore, the tanks used to store the CNG usually take up additional
space in the trunk of a car or bed of a pickup truck which runs on
CNG.
• This problem is solved in factory-built CNG vehicles that install the
tanks under the body of the vehicle, leaving the trunk free (e.g. Fiat
Multipla, New Fiat Panda, Volkswagen Touran Ecofuel,Volkswagen
Caddy Ecofuel, Chevy Taxi - which sold in countries such as Peru).
• Another option is installation on roof (typical on buses), requiring,
however, solution of structural strength issues. CNG-powered vehicles
are considered to be safer than gasoline-powered vehicles
Drawbacks of CNG
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54. • Compressed Natural Gas is often confused with liquefied
natural gas (LNG). While both are stored forms of natural
gas, the key difference is that CNG is gas that is stored (as a
gas) at high pressure, while LNG is stored at very low
temperature, becoming liquid in the process.
• CNG has a lower cost of production and storage compared
to LNG as it does not require an expensive cooling process
and cryogenic tanks.
• CNG requires a much larger volume to store the same mass
of gasoline or petrol and the use of very high pressures
(3000 to 4000 psi, or 205 to 275 bar). As a consequence of
this, LNG is often used for transporting natural gas over
large distances, in ships, trains or pipelines, and the gas is
then converted into CNG before distribution to the end user.
CNG compared to LNG
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55. 2. Liquefied petroleum gas (LPG)
• Liquefied petroleum gas, also called LPG, GPL, LP Gas, liquid
petroleum gas or simply propane, is a flammable mixture
of hydrocarbon gases used as a fuel in heating appliances and
vehicles. [Self Ignition temp 470oC]
• It is increasingly used as an aerosol propellant and a refrigerant,
replacing chlorofluorocarbons in an effort to reduce damage to
the ozone layer. When specifically used as a vehicle fuel it is often
referred to as Autogas.
Fuel types (Alternative) contd..
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56. • Varieties of LPG bought and sold include mixes that are
primarily propane (C3H8), primarily butane (C4H10) [Self
Ignition temp 420oC] and, most commonly, mixes
including both propane and butane, depending on the
season — in winter more propane, in summer more butane.
• Propane/butane blends are also listed in these
specifications. Propylene, butylenes and various other
hydrocarbons are usually also present in small
concentrations
• A powerful odorant, ethanethiol, is added so that leaks
can be detected easily.
LPG Contd..
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57. • Uses : Rural heating ,Motor fuel, Refrigeration, Cooking
LPG Vs Natural Gas
• LPG is composed primarily of propane and butane, while
natural gas is composed of the lighter methane and ethane.
• LPG, vaporised and at atmospheric pressure, has a
higher calorific value(94 MJ/m3 equivalent to 26.1kWh/m3)
than natural gas (methane) (38 MJ/m3 equivalent to
10.6 kWh/m3), which means that LPG cannot simply be
substituted for natural gas.
• For use of the same burner controls and to provide for
similar combustion characteristics, LPG can be mixed with
air to produce a synthetic natural gas (SNG) that can be
easily substituted.
LPG Contd…
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58. • Commercially available LPG is currently derived from
fossil fuels. Burning LPG releases CO2, an important
greenhouse gas, contributing to global warming.
• LPG does, however, release less CO2 per unit of energy than
that of coal or oil. It emits 81% of
the CO2 per kWh produced by oil, 70% of that of coal, and
less than 50% of that emitted by coal-generated electricity
distributed via the grid.
• Being a mixture of propane and butane, LPG emits less
carbon per joule than butane but more carbon per joule than
propane.
LPG Environmental effects
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59. 3. Producer gas
• Producer Gas is a generic term referring to:
• Wood gas: produced in a gasifier to power cars with ordinary internal
combustion engines.
• Town gas: manufactured gas, originally produced from coal, for sale
to consumers and municipalities.
• Syngas: used as a fuel source or as an intermediate for the production
of other chemicals.
• In old movies and stories, when describing suicide by "turning on the
gas" and leaving an oven door open without lighting the flame, they
were talking about coal gas or town gas. As this gas contained a
significant amount of carbon monoxide, the gas was quite toxic. Most
town gas was also odorized, if it did not have its' own odour. Modern
'natural gas' used in homes is far less toxic, and has an gassy
odor added to it for identifying leaks.
Fuel types (Alternative) contd..
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60. • Syngas (Synthesis gas) [Self Ignition temp 593.33oC] is the name
given to a gas mixture that contains varying amounts of carbon
monoxide and hydrogen. Examples of production methods
include steam reforming of natural gas or liquid hydrocarbons to
produce hydrogen, the gasification of coal, biomass, and in some
types of waste-to-energy gasification facilities.
• Syngas consists primarily of hydrogen, carbon monoxide, and very
often some carbon dioxide, and has less than half the energy density
of natural gas. The main reaction that produces syngas, steam
reforming, is endothermic with 206 kJ/mol methane needed for
conversion. Syngas is combustible and often used as a fuel of internal
combustion engines or as an intermediate for the production of other
chemicals.
SYNGAS
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61. • The first reaction, between incandescent coke and steam, is
strongly endothermic, producing carbon monoxide (CO), and
hydrogen H2 (water gas in older terminology).
• When the coke bed has cooled to a temperature at which the
endothermic reaction can no longer proceed, the steam is then
replaced by a blast of air.
• The second and third reactions then take place, producing
an exothermic reaction - forming initially carbon dioxide - raising
the temperature of the coke bed - followed by the second
endothermic reaction, in which the latter is converted to carbon
monoxide, CO. The overall reaction is exothermic, forming
"producer gas" (older terminology).
• Steam can then be re-injected, then air etc., to give an endless
series of cycles until the coke is finally consumed. Producer gas
has a much lower energy value, relative to water gas, due
primarily to dilution with atmospheric nitrogen.
SYNGAS Contd….
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62. 4. Alcohols
Methanol (Ch3OH) and Ethanol (C2H5OH) are used as SI
engine fuel
Ethanol due to high heat of vaporization, is used in
racing cars
Alcohols are mainly used as blends
Acetone and diethyl-ether are also used for blending the
gasoline
Fuel Types (Alternative) Contd….
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63. ALCOHOLS Contd..
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64. MONOHYDRIC ALCOHOLS
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65. ETHANOL
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66. ETHANOL
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67. - Used to improve the combustion performance of the
fuels (i.e to avoid knock and surface ignition)
Commonly used additives are:
- 1. TEL (Tetra Ethyl Lead) (C2H5)4Pb is a heavy liquid
weighing 1.7 Kg/litre
- It boils at 200oC and is soluble in gasoline
- Average gasoline blends have octane no. 75 to 85 which
is increased to 90 to 95 by addition of TEL
- 2. TML (Tetra Methyl Lead) (CH3)4Pb boils at 110oC
- Provide knock protection
- Improvement by 6 Octane rate than those obtained by
TEL
I.C.Engine fuels Dopes and additives
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