Automobile engineering

1. SDC2AU07
Introduction to Automobile
Engineering

2. Syllabus
UNIT I (10 Hours)
VEHICLE STRUCTURE AND ENGINES: Types of automobiles, vehicle construction and different layouts, chassis, frame and body,
resistances to vehicle motion and need for a gearbox, components of engine-their forms, functions and materials.
UNIT II (12 Hours)
ENGINE AUXILIARY SYSTEMS: Electronically controlled gasoline injection system for SI engines. Electronically controlled diesel
injection system (Unit injector system, Rotary distributor type and common rail direct injection system), Electronic ignition system
,Turbo chargers, Engine emission control by three way catalytic converter system.
UNIT III (10 Hours)
TRANSMISSION SYSTEMS: Clutch-types and construction ,gear boxes- manual and automatic, gear shift mechanisms, Over drive,
transfer box, fluid flywheel –torque converter , propeller shaft, slip joints, universal joints, Differential, and rear axle, Hotchkiss Drive
and Torque Tube Drive.
UNIT IV (8 Hours)
STEERING,BRAKES AND SUSPENSION SYSTEMS: Steering geometry and types of steering gear box-Power Steering, Types of
Front Axle, Types of Suspension Systems, Pneumatic and Hydraulic Braking Systems, Antilock Braking System and Traction Control.
UNIT V (5 Hours)
ALTERNATIVE ENERGY SOURCES: Use of Natural Gas, Liquefied Petroleum Gas. Bio-diesel, Bio-ethanol , Gasohol and
Hydrogen in Automobiles- Engine modifications required –Performance ,Combustion and Emission Characteristics of SI and CI
engines with these alternate fuels - Electric and Hybrid Vehicles, Fuel Cell.

4. UNIT V (5 Hours)
ALTERNATIVE ENERGY SOURCES: Use of Natural Gas,
Liquefied Petroleum Gas. Bio-diesel, Bio-ethanol, Gasohol and
Hydrogen in Automobiles- Engine modifications required –
Performance, Combustion and Emission Characteristics of SI
and CI engines with these alternate fuels - Electric and Hybrid
Vehicles, Fuel Cell.

5. ALTERNATIVE ENERGY SOURCES

6. Fuel

7. Fuel Classification
1. Conventional Fuels
These are obtained from Petroleum (Crude Oil) after
processing
2. Alternative Fuel
These fuels are other than petrol or diesel and are being
increasingly used since these fuels are cleaner than
conventional fuels.

8. PROPERTIES OF CONVENTIONAL ENERGY SOURCES
● Volatility
● Specific Gravity
● Calorific Value
● Octane Number
● Cetane Number

9. Why alternative fuels ?
• Conventional fuels are going to run out
• To reduce pollution
• To protect against global warming
• To save money
• Bio degradable and non toxic
• Easy to handle and store

10. • Approximately 90% of our energy requirements are met by
fossil fuels.
• The increase in energy consumption in past several decades
has raised the fear of exhausting vital natural resources.
• Rapid industrialization and massive growth in population has
increased the dependence and use of natural fuels.

11. ALTERNATIVE ENERGY SOURCES
• Natural gas
• CNG
• LNG
• LPG
• Alcohol
• Electricity-Solar
• Hydrogen
• Bio-Fuel

12. Compressed natural gas (CNG)
Compressed natural gas (CNG) is a fossil fuel that can be used
as a fuel in vehicles.
CNG is considered a clean-burning fuel that reduces harmful
emissions.
CNG vehicles can reduce greenhouse gas emissions by 15–
27%.
CNG is also non-corrosive, which can extend the life of spark
plugs.

13. • CNG is made by compressing natural gas (which is mainly
composed of Methane, CH4), to less than 1 % of the volume
it occupies at standard atmospheric pressure. It is stored and
distributed in hard containers at a pressure of 20 -25 MPa,
usually in cylindrical or spherical shapes.

14. Advantages of CNG:
• Fuel economy: CNG is more affordable than petrol.
• Emissions: CNG reduces emissions of particulate matter,
nitrogen oxides, and other air pollutants.
• Spark plugs: CNG is non-corrosive, which can extend the life
of spark plugs.
Disadvantages of CNG:
• Range: CNG has limited range.
• Fueling infrastructure: CNG has limited fueling infrastructure.
• Upfront costs: CNG has high upfront costs.
• Safety: There are safety concerns with CNG.

15. Components of a CNG vehicle

16. Working of CNG

17. Compressed natural gas (CNG) vehicles operate much like
gasoline-powered vehicles with spark-ignited internal combustion
engines. The engine functions the same way as a gasoline engine.
Natural gas is stored in a fuel tank, or cylinder, typically at the
back of the vehicle. The CNG fuel system transfers high-pressure
gas from the fuel tank through the fuel lines, where a pressure
regulator reduces the pressure to a level compatible with the engine
fuel injection system. Finally, the fuel is introduced into the intake
manifold or combustion chamber, where it is mixed with air and
then compressed and ignited by a spark plug.

19. Liquefied Natural Gas (LNG)
• Natural gas is converted into a liquid state.
• The gas is cooled to LNG temperature of -162 °C (-260 °F) at
atmospheric pressure.
• This reduces the gas volume by 600 times and makes it
possible to transport very large energy content over short and
very long distances in specially-designed ocean tankers and
trucks.
• Natural gas can also be shipped over long distances as a
liquid, known as Liquefied Natural Gas (LNG).

20. LNG…
• Liquefaction makes natural gas more economical to transport.
This allows it to be shipped safely and efficiently on specially
designed LNG vessels.
• When the shipment of LNG reaches its destination at the
receiving terminal, it is re-heated and converted back to a gas
via a process known as "Regasification". It is then sent
through pipelines for delivery to end-users.

21. LNG…
• Energy density of LNG is 2.4 times greater than that of CNG
which makes LNG more economical to transport.
• The energy density of LNG is comparable to propane (C3H8)
or ethanol (C2H6O) but is %60 of diesel and %70 of gasoline.

22. Auto LNG and LCNG station

23. What are the advantages of LNG over CNG?
• In vehicle applications, the main advantage that LNG has
over CNG is that it is more dense. For two tanks of the same
size, the LNG tank will allow a vehicle to drive further than
the CNG tank. This makes LNG an interesting option for
heavy trucks traveling long distances.

24. Auto Gas (LPG)
• Auto Gas (LPG) is a clean, high-octane, abundant and eco-
friendly fuel. It is obtained from natural gas through
fractionation and from crude oil through refining. It is a
mixture of petroleum gases like propane and butane.
• Autogas is widely used as a "green" fuel, as its use reduces
CO2 exhaust emissions by around 15% compared to petrol.
One liter of petrol produces 2.3 kg of CO2 when burnt,
whereas the equivalent amount of Autogas (1.33 liters due to
the lower density of Autogas) produces only 2 kg of CO2
when burnt.

25. • CO emissions are 30% lower, compared to petrol and NOx by
50%. It has an octane rating (MON/RON) that is between 90
and 110 and an energy content (higher heating value—HHV)
that is between 25.5 MJ/liter (for pure propane) and 28.7
MJ/liter (for pure butane) depending upon the actual fuel
composition.
• Autogas is the third most popular automotive fuel in the
world, with approximately 16 million of 600 million
passenger cars powered using the fuel, representing less than
3% of the total market share. Approximately half of all
Autogas-fueled passenger vehicles are in the five largest
markets (in descending order): Turkey, South Korea, Poland,
Italy, and Australia.

26. Advantages of LPG
• LPG can be burnt directly.
• It can be transported easily through pipe lines.
• It is clean fuels and do not give smoke and harmful gases
when burnt.
• It give sufficiently good amount of heat energy when burnt.
• Less engine wear, high octane rating (105), no carbon
deposits
• Reasonably easy to modify a petrol car to run on LPG.

27. Disadvantages of LPG
• Special fuel system has to be provided.
• Heavy pressure cylinders increases the vehicle weight
unnecessarily.
• Harder to start in winter
• Distribution network is not widespread as that of petrol and
diesel.
• Explosive like petrol
• If used in low compression ratios, high octane rating goes
waste.

28. Key benefits of LPG

29. Biofuels
...renewable primary
products

30. Definition of biofuels
• Produced from renewable biomass
material
• Fuels that have been extracted
from plants and crops are known
as biofuels.
• Commonly used as an alternative
• Cleaner fuel source
• Much cleaner than petrol/diesel
alternatives
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31. Different types of biofuels
• Bioethanol
• Biodiesel
• Biogas
• Biobuthanol
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33. Importance of Biodiesel
• Environment friendly
• Clean burning
• Renewable fuel
• No engine modification
• Increase in engine life
• Biodegradable and non-toxic
• Easy to handle and store

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Bioethanol

37. Bioethanol - Advantages
• As a result of complete combustion, it burns more cleanly.
• Reduce greenhouse gas emission
• It is carbon neutral
• It is a renewable energy source
• Any plant can be used for the production of bio ethanol, if it
contains sugar and starch.

38. Disadvantages of Bioethanol
• Large amount of arable land is required to grow crops, hence
natural habitat would be destroyed.
• Due to attractive prices of bioethanol, some farmers may
sacrifice food crops for biofuels which may lead to food
shortage and increase in price.
• Large amount of carbon dioxide is released during the
production process.
• Efficiency is less compared to petroleum.
• Difficult in cold starting
• Difficult to transport.

39. Gasohol
Gasohol is a gasoline – ethanol blend used as fuel in vehicles.
About 9 parts gasoline and 1 part ethanol is mixed to form
Gasohol.

40. Advantages
• Domestically produced – reduce foreign fuel dependency
• Typically used in Flex Fuel vehicles as a blend of E85 (85%
ethanol and 15% gasoline)
• Clean burning mixture
• Higher octane rating.

41. Disadvantages
• Required massive use of crop land to supply required power.
• Less energy content as compared with gasoline
• Evaporative emission is more from the fuel tank.
• Evaporative emission forms harmful ground level ozone and smog

42. Hydrogen
• Hydrogen is used as a fuel in many ways, including:
• Rocket fuel
• Fuel cells for electricity generation
• Powering vehicles
• Industrial processes
• Hydrogen is a chemical energy carrier that can be transported
or piped to where it's needed. It stores three times as much
energy per unit of mass as conventional petrol.

43. • Hydrogen is not used as a domestic fuel because it's not readily
available in the atmosphere. It requires processes like
electrolysis of water for its production, which is costly and time
consuming.
• Hydrogen is safer to handle and use than other fuels because it's
non-toxic. It's also lighter than air, so it dissipates quickly if
there's a leak.
• Hydrogen fuel cells are two or three times more efficient than
traditional combustion technologies. For example, a conventional
combustion-based power plant usually generates electricity
between 33 to 35 percent efficiency.
• Hydrogen is not a new source of energy, but rather an energy
storage mechanism. 95% of hydrogen is produced by cracking
natural gas (fossil fuel).

44. Advantages
It is tine simplest clement and occurs in abundance in the
universe. It is considered ideal fuel because of its advantages:
1. It is the cleanest fuel which burns to give energy and
leaves only water as a product of combustion.
2. It does not produce any greenhouse gases, e.g., CO2.
3. It is safe to manufacture.

45. Disadvantages
However, its use is still restricted to space vehicles and concept
cars due to the following disadvantages:
1. Very high cost of manufacture.
2. It is highly flammable and can ignite easily in low
concentrations, which means a small leak in transport on
storage can be a big public safety hazard.

46. Modifications in gasoline engines
for use of ethanol fuel

47. Main jet changes
Main jet allows entry of air fuel in cylinder.
• Greater octane number than petrol
• Requires greater compression ratio.
• Increase in orifice diameter of the main
jet.
• Needs increase of 20 to 40%.

48. Idle Orifice Changes
For entry of fuel in idle mode
• Idle orifice needed for supply of air-
fuel mixture in slow speeds or idle
states.
• Diameter to be increased for proper
supply of mixture.

49. Power Valve Changes
vacuum-controlled valve, spring loaded,
shuts off, to conserve fuel.
• Power valve allows extra fuel to blend
with the air/fuel mixture when the
accelerator is depressed.
• Difficult to alter.
• Valve with approx. 25% greater flow
capacity sufficient for increased power.

50. Accelerator pump changes
Supplies extra fuel on sudden accelerator
pressing
• Used to inject fuel when accelerator is
suddenly depressed.
• Increase the size approximately by
25%.
• Larger size may create difficulty in
reverting back to gasoline.

51. A small gist
• More compression is needed in the cylinder during stroke, to
utilize the full potential of the fuel.
• Hence, the inlet diameters of the orifices which let the fuel in
are to be increase.

52. Compression Ratio Changes
• Ethanol has a good octane rating.
• Compression ratios up to 15 : 1 may be
suitable.
• Difficulty in reversing back to gasoline.
• Remedy: installation of Water injection
system for cooling to revert back to
gasoline.

53. Compression Ratio Changes…
• Use of high compression pistons. Connecting rods and
bearings may not tolerate high ratios.
• May be replaced.
• Installing a turbocharger.
• No excessive compression during engine startup.

54. Cold weather starting
Alcohol does not vaporize as easy as gasoline, hence starting
the vehicle in cold condition is a problem.
Different solutions for this problem are:
• Use extra fuel tank for petrol
• Use of fuel preheater
• Use of air preheater

55. Fuel preheating
• Required in cold climates
• Can be done by making the fuel flow over the hot engine
parts through tubes.
• The process is time consuming
• It is not an effective process

56. Air preheating
• Air from around the exhaust manifold is let the air fuel
mixture through ducts.
• A flap within the air cleaner snorkel shuts off this supply
when engine warms up and allows ambient air enter.
• This flap is usually either thermostatically or vacuum
controlled.
• External type resistance air heater may also be used.

58. • Used to hold coolant in the cylinder head until it reaches a
certain temperature.
• Thermostat decides the temperature at which the coolant will
enter the cylinder head.
• Ethanol engine works at less temperature than petrol engine
of same horse power.
Thermostat change

59. Initial use of Alcohol fuel
• Alcohol will act as a cleansing agent and will clean of the
fuel tank, fuel lines, and filters, remove engine's internal parts
of built up carbon, gum, and varnish deposits.
• Suddenly a lot of filth will be floating around in fuel.
• It may clog fuel filter to the point of not allowing any fuel to
pass.
• Loosened internal engine deposits can foul the spark plugs
badly.

60. Fuel injection system
• Many vehicles equipped with fuel injection systems instead
of carburetors.
• Effect is same as increasing the main jet diameter and idle
orifice diameter.

61. Electric vehicles
Electric vehicles (EVs) are vehicles that are partially or fully
powered by electricity. They use electric motors instead of internal
combustion engines. EVs have low running costs and are
environmentally friendly because they use little or no fossil fuels.
Some types of EVs include:
• Battery Electric Vehicles (BEVs)
• Hybrid Electric Vehicle (HEV)
• Plug-in Hybrid Electric Vehicle (PHEV)
• Fuel Cell Electric Vehicle (FCEV)

62. Battery Electric Vehicles (BEVs)
Fully powered by electricity.
These are more efficient
compared to hybrid and plug-
in hybrids.

63. Hybrid Electric Vehicle (HEV)
The vehicle uses both the
internal combustion (usually
petrol) engine and the battery-
powered motor powertrain. The
petrol engine is used both to
drive and charge when the
battery is empty. These vehicles
are not as efficient as fully
electric or plug-in hybrid
vehicles.

64. Plug-in Hybrid Electric Vehicle (PHEV)
Uses both an internal
combustion engine and a
battery charged from an
external socket (they have a
plug). This means the vehicle’s
battery can be charged with
electricity rather than the
engine. PHEVs are more
efficient than HEVs but less
efficient than BEVs.

65. Fuel Cell Electric Vehicle(FCEV)
FCEVs are also known as
Zero-Emission Vehicles. They
employ ‘fuel cell technology’
to generate the electricity
required to run the vehicle.
The chemical energy of the
fuel is converted directly into
electric energy.

66. Advantages of EVs
• Low running costs
• Low maintenance costs
• Tax and financial benefits
• Better performance
• Zero tailpipe emissions
• Easy to drive and quiet
• Convenience of charging at home
• No fuel, no emissions

67. Fuel cell
Fuel cells are electrochemical devices that convert chemical
energy into electricity and heat. They are characterized by
high efficiency and low pollutant emissions.
Fuel cells work by combining fuels, such as hydrogen or
methane, with oxygen to generate electricity. The first fuel
cells were invented by Sir William Grove in 1838.
Fuel cells are made up of two electrodes, an anode and a
cathode. The anode is where fuel oxidation takes place, and the
cathode is where oxidant reduction takes place.

68. Fuel cells work like batteries, but they
do not run down or need recharging.
They produce electricity and heat as
long as fuel is supplied. A fuel cell
consists of two electrodes—a negative
electrode (or anode) and a positive
electrode (or cathode)—sandwiched
around an electrolyte. A fuel, such as
hydrogen, is fed to the anode, and air
is fed to the cathode.

69. In a hydrogen fuel cell, a catalyst at the anode separates
hydrogen molecules into protons and electrons, which take
different paths to the cathode. The electrons go through an
external circuit, creating a flow of electricity. The protons
migrate through the electrolyte to the cathode, where they unite
with oxygen and the electrons to produce water and heat.

70. Advantages of fuel cells
More detailed information is available in the applications section,
which offers information specific to each industry.
• High Efficiency- when utilizing co-generation, fuel cells can
attain over 80% energy efficiency
• Good reliability- quality of power provided does not degrade over
time.
• Noise- offers a much more silent and smooth alternative to
conventional energy production.
• Environmentally beneficial- greatly reduces CO2 and harmful
pollutant emissions.
• Size reduction- fuel cells are significantly lighter and more
compact

71. Disadvantages of fuel cells
• Expensive to manufacture due the high cost of catalysts
(platinum)
• Lack of infrastructure to support the distribution of hydrogen
• A lot of the currently available fuel cell technology is in the
prototype stage and not yet validated.
• Hydrogen is expensive to produce and not widely available.

72. Combustion and Emission
Characteristics of SI and CI engines
with alternate fuels

73. Experimental setup

74. Combustion characteristics of SI engines
Bioethanol offers high octane rating and
to reduce fuel consumption, ethanol is
often added to gasoline fuels. The heat of
combustion is compared along with the
various bioethanol and gasoline blends at
different engine speeds are shown in
Figure. The heat of combustion is
increased with increasing engine speed. It
can be observed that due to the higher
mass diffusivity of bioethanol compared
to that of gasoline, the higher blend cases
(ie, E40, E60, and E80) have a higher
heat of combustion as compared to E0.
Moreover, higher engine speed demands
more fuel intake, and therefore the heat of
combustion increases with increasing
engine speed.

75. Engine performance

76. For higher bioethanol blend cases, the brake thermal efficiency
and volumetric efficiency increases when bioethanol fuel is
used in the engine. Above figures show the variation in brake
power and volumetric efficiency. It can be seen from Figure that
maximum brake power is increasing with increasing engine
speed for all the studied cases. Moreover, as demonstrated in
second figure, the volumetric efficiency decreases with
increasing engine speed for lower bioethanol blend cases E0,
E10, and E20. In contrast for the higher bioethanol blend cases
E40, E60, and E80 the volumetric efficiency attain a maximum
in the mid-range of engine speed. It is worth noting that the
volumetric efficiency in higher bioethanol usage is higher than
in pure gasoline fuel and volumetric efficiency decreased at
high engine speed for pure gasoline fuel too.

77. Exhaust gas temperature (EGT)
The EGT provides valuable
insight into the performance of
the combustion process. This can
be achieved by measuring the
temperature of the burned gases
as they exit the combustion
chamber.
The EGT attains a lower value at
higher engine speed (3400 rpm)
for all bioethanol blend cases
than that of pure gasoline
reference case E0, which further
supports the reduction of
emission gases.