The document discusses the cooling system of internal combustion engines. It explains that the cooling system maintains the engine's temperature at optimal levels by removing around 30% of the heat generated. It cools the engine faster when it is hot but provides minimum cooling during starting. The cooling system prevents engine damage by dissipating the high temperatures produced during combustion. It describes the types of cooling systems as liquid/water-cooled or air-cooled. The key components of the liquid cooling system are also outlined, including the radiator, thermostat, water pump, and fan.

1. INTERNAL COMBUTION ENGINE
Made by:
Assistant Professor : NAPHIS AHAMAD
MECHANICAL ENGINEERING
6/10/2017 Naphis Ahamad (ME) JIT 1

2. 6/10/2017 Naphis Ahamad (ME) JIT 2
UNIT IV

3. Cooling system for IC Engines
An automobile's cooling system is the collection of parts and substances (coolants)
that work together to maintain the engine's temperature at optimal levels. Comprising
many different components such as water pump, coolant, a thermostat etc. the system
enables smooth and efficient functioning of the engine at the same time protecting it
from damage
The following are the two main characteristics desired of an efficient cooling system
1. It should be capable of removing about 30% of heat generated in the combustion
chamber while maintain the optimum temp of the engine under all operating
conditions of engine.
2. It should remove heat at a faster rate when engine is hot. However during starting
of the engine the cooling should be minimum, so that the working parts of engine

4. Necessity of Cooling
The cooling system is provided in the IC engine for the following reasons:
• The temperature of the burning gases in the engine cylinder reaches up to
1500 to 2000°C, which is above the melting point of the material of the
cylinder body and head of the engine. (Platinum melts at 1750 °C, iron at
1530°C and aluminum at 657°C.) Therefore, if the heat is not dissipated, it
would result in the failure of the cylinder material.

5. • Due to very high temperatures, the film of the lubricating oil will get oxidized, thus
producing carbon deposits on the surface.This will result in piston seizure.
• Due to overheating, large temperature differences may lead to a distortion of the engine
components due to the thermal stresses set up. This makes it necessary for, the
temperature variation to be kept to a minimum.
• Higher temperatures also lower the volumetric efficiency of the engine

6. Effects of overcooling
(a) Increased cylinder wear.
(b) Dilution of oil due to poor vaporization of petrol
(c) Greater formation of sludge.
(d) Oil does not thin out properly and fluid friction losses are increased.
(e) Engine does not achieve full power.
(f) Burnt gases, which leak past piston, condense in the crankcase to form
corrosive acids in oil.
(g) Lower thermal efficiency i.e. more consumption of fuel

7. Type of cooling system
In order to cool the engine a cooling medium is required. This can be either air or
a liquid accordingly there are two type of systems in general use for cooling the
IC engine. They are…..
Liquid or indirect cooling system
Air or direct cooling system

8. Air Cooling
In this type of cooling system, the heat, which is conducted to the outer parts of
the engine, is radiated and conducted away by the stream of air, which is obtained
from the atmosphere. In order to have efficient cooling by means of air, providing
fins around the cylinder and cylinder head increases the contact area. The fins are
metallic ridges, which are formed during the casting of the cylinder and cylinder
head
The amount of heat carried off by the air-cooling depends upon the following
factors:
(i) The total area of the fin surfaces,
(ii) The velocity and amount of the cooling air and

9. TYPES of Air Cooling
System
1. Natural flow type
2. Forced Convection type

10. Advantages of Air Cooled Engines
1. Its design of air-cooled engine is simple.
2. It is lighter in weight than water-cooled engines due to the absence of water
jackets, radiator, circulating pump and the weight of the cooling water.
3. It is cheaper to manufacture.
4. It needs less care and maintenance.
5. This system of cooling is particularly advantageous where there are extreme
climatic conditions in the arctic or where there is scarcity of water as in
deserts.
6. No risk of damage from frost, such as cracking of cylinder jackets or radiator
water tubes.

11. limitations of Air Cooled Engines
 Can be applied only to small and medium sized engines.
 Cooling is not uniform.
 Higher working temperature compared to water-cooling.
 Produce more aerodynamic noise.
 Specific fuel consumption is slightly higher.
 Lower maximum allowable compression ratios.
 The fan, if used absorbs as much as 5% of the power developed by the engine.

12. liquid cooled system
 In this system mainly water is used and made to circulate through
the jackets provided around the cylinder, cylinder-head, valve ports
and seats where it extracts most of the heat.
 It consists of a long flat, thin-walled tube with an opening, facing the
water pump outlet and a number of small openings along its length
that directs the water against the exhaust valves. The fits in the
water jacket and can be removed from the front end of the block.
 The heat is transferred from the cylinder walls and other parts by
convection and conduction. The liquid becomes heated in its
passage through the jackets and is in turn cooled by means of an
air-cooled radiator system. The heat from liquid in turn is transferred
to air. Hence it is called the indirect cooling system.

14. TYPES OF WATER COOLED SYSTEMS
•Direct or non-return system
•Thermo siphon system
•Forced circulation cooling system
•Evaporative cooling system
•Pressure cooling system

15. Thermo-siphon system
 This system works on the principle that hot water
being lighter rises up and the cold water being
heavier goes down. In this system the radiator is
placed at a higher level than the engine for the easy
flow of water towards the engine. Heat is conducted
to the water jackets from where it is taken away due
to convection by the circulating water. As the water
jacket becomes hot, it rises to the top of the radiator.
Cold water from the radiator takes the place of the
rising hot water and in this way a circulation of water
is set up m the system. This helps in keeping the
engine at working temperature.
Disadvantages of Thermo-Siphon System
1 Rate of circulation is too slow.
2. Circulation commences only when there is a marked
difference in temperature.

16. FORCED or PUMP system
 This system is similar in construction to the
thermo-siphon system except that it makes
use of a centrifugal pump to circulate the
water throughout the water jackets and
radiator
 The water flows from the lower portion of the
radiator to the water jacket of the engine
through the centrifugal pump. After the
circulation water comes back to the radiator,
it loses its heat by the process of radiation.
Advantages
 Cooling is ensured in all conditions
Disadvantages
 Cooling is not temperature dependent
 Cooling stops as soon as the engine is
stopped, which is undesirable

17. Thermostat cooling

18. Thermostat
 Placed between the cylinder head and top radiator
hose.
 Regulates engine coolant temperature
 The temperature that the thermostat opens is called
thermostat rating. (85-900 C most common)
 Solid Expansion design – wax pellet expands as
temp increases, valve begins opening at rating & is
completely open within 10 degrees
 If it fails in open position, engine runs cold resulting
in poor mileage and high wear & tear. If it fails
closed, creates temperature in the engine well
beyond normal limits. Many types of damage may
occur. (Can be checked by placing in the boiling
water)

19. Pressurized cooling
 In pressure cooling system moderate
pressure, say up to 2 bar, are commonly
used. As shown in fig a cap is fitted with
two valves which are loaded by a
compression spring and a vacuum valve.
 When the coolant is cold both valves are
shut but as the engine warm up the
coolant temperature rises until it reaches a
certain preset value corresponding to the
desired pressure when the safety valve
open. But if the coolant temperature falls
during the engine operation the valve will
close again until the temperature rises to
equivalent pressure value. When the
engine is switched off and the coolant cool
down vacuum begin to form in the cooling
system but when the internal pressure fall
below atmosphere the vacuum valve is
opened by the higher outside pressure
and the cooling system then attains
ADVANTAGES
1. Can take overload very easily
2. The placement of radiator is
not critical
3. Corrosion is lo because of the
pressurized coolant
4. No loss of water due to boiling
or evaporation

20. Evaporative cooling
 This is predominately used in stationary
engine. In this the engine will be cooled
because of the evaporation the water in
the cylinder jackets into the steam.
Here the advantage is taken from the
high latent heat of vaporizing of the
water by allowing evaporating in the
cylinder jackets. If the steam is formed
at a pressure above atmospheric the
temperature will be above the normal
permissible temperature.

21. Components of water cooling system
Water cooling system mainly consists of :
(a) Radiator,
(b) Thermostat valve,
(c) Water pump,
(d) Fan,
(e) Water Jackets,
(f) Antifreeze mixtures.

22. Radiator
 It mainly consists of an upper tank and lower
tank and between them is a core. The upper
tank is connected to the water outlets from
the engines jackets by a hose pipe and the
lover tank is connect to the jacket inlet
through water pump by means of hose pipes.
 There are 2-types of cores :
(a) Tubular
(b) Cellular
(c) Gilled tube radiator:
 When the water is flowing down through the
radiator core, it is cooled partially by the fan
which blows air and partially by the air flow
developed by the forward motion of the
vehicle.
 As shown through water passages and air
passages, wafer and air will be flowing for
cooling purpose.
 It is to be noted that radiators are generally
made out of copper and brass and their joints

23. Water pump
 It is used to pump the circulating water.
Impeller type pump will be mounted at the front
end.
 Pump consists of an impeller mounted on a
shaft and enclosed in the pump casing.
 The pump casing has inlet and outlet
openings. The pump is driven by means of
engine output shaft only through belts. When it
is driven water will be pumped.

24. FAN
•It is driven by the engine output shaft through same belt that drives the pump.
It is
provided behind the radiator and it blows air over the radiator for cooling
purpose.
WATER JACKETS
Cooling water jackets are provided around
the cylinder, cylinder head, valve seats
and any hot parts which are to be cooled.
Heat generated in the engine cylinder,
conducted through the cylinder walls to the
jackets. The water flowing through the
jackets absorbs this heat and gets hot.
This hot water will then be cooled in the
radiator

25. Purpose of LUBRICATION
 Lubrication produces the following effects: (a) Reducing friction effect (b)
Cooling effect (c) Sealing effect (d) Cleaning effect.
(a) Reducing frictional effect: The primary purpose of the lubrication is to
reduce friction and wear between two rubbing surfaces. Two rubbing
surfaces always produce friction. The continuous friction produce heat
which causes wearing of parts and loss of power. In order to avoid friction,
the contact of two sliding surfaces must be reduced as far a possible. This
can be done by proper lubrication only. Lubrication forms an oil film
between two moving surfaces. Lubrication also reduces noise produced
by the movement of two metal surfaces over each other.
(b) Cooling effect: The heat, generated by piston, cylinder, and bearings is
removed by lubrication to a great extent. Lubrication creates cooling effect
on the engine parts.
(c) Sealing effect: The lubricant enters into the gap between the cylinder
liner, piston and piston rings. Thus, it prevents leakage of gases from the
engine cylinder.
(d) Cleaning effect: Lubrication keeps the engine clean by removing dirt or
carbon from inside of the engine along with the oil.

28. Dry Sump Lubrication System

30. FUELS
Introduction
 The increase in energy consumption particularly
in the past several decades has raised fears of
exhausting vital natural resources
 Rapid industrialization and massive growth in
population has increased the dependence and use
of natural fuels
 Approximately 90% of our energy requirement are
met by fossil fuels

31. Alternative Fuel Sources
 Ethanol
 Hydrogen
 Natural Gas
 Propane
 Methanol

32. Ethanol
• Ethanol is an alcohol-based alternative fuel produced by fermenting and
distilling starch crops that have been converted into simple sugars. Feedstock
for this fuel include corn, barley, and wheat.
• Ethanol can also be produced from "cellulosic biomass" such as trees and
grasses and is called bioethanol. Ethanol is most commonly used to increase
octane and improve the emissions quality of gasoline.

33. Hydrogen
•It is the simplest and lightest fuel with atomic no. 1.
•Hydrogen burns more efficiently and creates energy more than gasoline.
•Hydrogen is extremely reactive with oxygen and makes it highly flammable
•Hydrogen mixed with natural gas can be used in internal combustion engine.
•Hydrogen is the perfect fuel to run fuel cells cause pure hydrogen reacts only
with oxygen releasing water thus no emissions.

34. Properties
 Does not occur to any significant extent on earth in its free,
elemental form.
 Found in chemical compositions such as water and hydrocarbons,
and dry coal.
 Pure hydrogen contains no carbon thus burns to form water with
no CO2 or CO emissions.
 One kg of hydrogen contains roughly equivalent energy to one
gallon of gasoline.
 Can be stored as compressed hydrogen at 5,000 – 10,000 psi or
liquid hydrogen (cooled to -4230
F, -2520
C).

35. There are two types of Hydrogen engine
 Hydrogen IC engine
 Hydrogen fuel cell engine
Hydrogen IC engine emits zero CO2 and minimal Nox when compared to other
engines. The SI engine can be used for it.
 Generation of Hydrogen – Electrolysis of water
H2OH2 + ½ O2
 Supply Hydrogen gas to intake valve of SI engine
 Vary voltage of DC supply to control electrolysis process.

36. • Natural gas is a mixture of hydrocarbons, mainly methane, and is
produced either from gas wells or in conjunction with crude oil
production.
• Natural gas is consumed in the residential, commercial, industrial, and
utility markets.
• Natural gas can either be stored onboard a vehicle as compressed
natural gas (CNG) or as liquefied natural gas (LNG). Natural gas can
Natural Gas

37. CNG
 In India CNG costs are at Rs. 40/kg much cheaper than petrol at Rs. 70/ltr.
 The cost saving is immense along with reduced emissions and environment
friendly.
 The use of CNG is mandatory for public transport in New Delhi as well as
for Ahmedabad.
 The Delhi Transport Corporation operates the world’s largest fleet of CNG
buses.

38. Natural
Gas
Properties
• Lower emissions
• Lower smog producing gases (60-90% Light-Duty use, 90% in Mid to Heavy-
duty use)
• Can be used to make hydrogen to power the future fuel cell technology
Future of natural gas
• Natural gas is now being installed in 1 out of 5 transit buses today
• Fueling systems are being installed in home or public facilities
• Gradually the automobiles shift to natural gas fuel.

39. Propane
• Propane is a liquefied gas made up of propylene, butane, and butylene
from petro chemicals.
• By-product of natural gas processing and crude oil refining.
What are the benefits?
• A 98% reduction in toxic emissions in light-duty bi-fuel vehicles
• In the quantities needed it costs less than gasoline
• Very accessible compared to other alternative fuels.

40. Propane Properties
• HD5, the automotive propane standard, a mixture of 90% propane and
other hydrocarbons(proplyene).
• Contains 33% - 41% less energy content per gallon than gasoline.
• Vehicles can demonstrate a 60% reduction in ozone-forming emissions
compared to gasoline.
• High octane properties (~104) allow vehicles to operate with higher
compression ratios; leads to higher efficiency/fuel economy

41. • Methanol is wood alcohol, which can be made from natural gas, coal, or
wood.
• Methanol is produced from natural gas in production plants with 60% total
energy efficiency.
• Methanol can be made with any renewable resource containing carbon such
as seaweed, waste wood and garbage.
• Methanol fuel cells will greatly reduce carbon dioxide emissions for vehicles
and virtually eliminate smog and particulate pollution.
Methanol

42. Methanol
Properties
• Lower emissions
• Higher performance
• Lower risk of flammability
• Methanol can be used to easily make hydrogen
Conclusion
• The biggest is the lack of vehicles to use it, manufactures have stopped making
vehicles to run on Methanol

43. Characteristics of IC Engines
1. Brake Thermal Efficiency
2. Indicated Thermal Efficiency
3. Specific Fuel Consumption
4. Mechanical Efficiency
5. Volumetric Efficiency
6. Air Fuel Ratio
7. Mean Effective Pressure

44. Brake thermal efficiency
Brake thermal efficiency is defined as break power of a heat engine as a
function of the thermal input from the fuel. It is used to evaluate how well
an engine converts the heat from a fuel to mechanical energy
Indicated thermal efficiency
The thermal efficiency is a dimensionless performance measure of a device that
uses thermal energy, for example engine, a steam turbine, a steam engine, a
boiler, a furnace, etc, . Thermal efficiency indicates the extent to which the energy
added by work is converted to net heat output.

45. Mechanical efficiency
Mechanical efficiency is the measure of effectiveness of a machine's energy
and power that is input into the device into an output that makes force and
movement. Mechanical advantage by comparing the input and output force
you can find the advantage of a machine
Specific fuel consumption
Thrust specific fuel consumption (TSFC) or sometimes simply specific fuel
consumption, SFC, is an engineering term that is used to describe the fuel
efficiency of an engine design with respect to thrust output.

46. Volumetric Efficiency
 Volumetric efficiency in internal combustion engine is defined as the ratio of the
mass density of the air-fuel mixture drawn into the cylinder at atmospheric
pressure (during the intake stroke) to the mass density of the same volume of
air in the intake manifold.
Air Fuel Ratio
Air–fuel ratio (AFR) is the mass ratio of air to fuel present in a combustion
process such as in an internal combustion engine

47. Mean Effective Pressure
 Mean effective pressure is a quantity relating to the operation of a
reciprocating engine and is a valuable measure of an engine's capacity
to do work that is independent of engine displacement.

48. The performance of an engine is evaluated
on the basis of the following;
 (a) Specific Fuel Consumption.
 (b) Measurement of brake Power
 (c) Specific Power Output.

49. Fuel consumption measurement
 Fuel consumption is measured in two ways:
 The fuel consumption of an engine is measured by determining the
volume flow in a given time interval and multiplying it by the specific
gravity of the fuel which should be measured occasionally to get an
accurate value.
 Another method is to measure the time required for consumption of a
given mass of fuel

50. Measurement of brake power
 The brake power measurement involves the determination of
the torque and the angular speed of the engine output shaft.
The torque measuring device is called a dynamometer.
 Dynamometers can be broadly classified into two main types,
power absorption dynamometers and transmission
dynamometer.

51. Measurement of friction power
 The difference between indicated power and the brake power output of
an engine is the friction power.
 Almost invariably, the difference between a good engine and a bad
engine is due to difference between their frictional losses.
 The frictional losses are ultimately dissipated to the cooling system (and
exhaust) as they appear in the form of frictional heat and this influences
the cooling capacity required. Moreover, lower friction means availability
of more brake power; hence brake specific fuel consumption is lower.

52. Types Of Dynamometers
Absorption Dynamometers
These dynamometers measure and absorb the power output of the
engine to which they are coupled. The power absorbed is usually
dissipated as heat by some means. Example of such dynamometers
is prony brake, rope brake, hydraulic dynamometer, etc.
Transmission Dynamometers: In transmission dynamometers, the
power is transmitted to the load coupled to the engine after it is
indicated on some type of scale. These are also called torque-
meters.

53. Characteristics of IC Engines
1. Brake Thermal Efficiency
2. Indicated Thermal Efficiency
3. Specific Fuel Consumption
4. Mechanical Efficiency
5. Volumetric Efficiency
6. Air Fuel Ratio
7. Mean Effective Pressure

54. Brake thermal efficiency
Brake thermal efficiency is defined as break power of a heat engine as a
function of the thermal input from the fuel. It is used to evaluate how well
an engine converts the heat from a fuel to mechanical energy
Indicated thermal efficiency
The thermal efficiency is a dimensionless performance measure of a device that
uses thermal energy, for example engine, a steam turbine, a steam engine, a
boiler, a furnace, etc, . Thermal efficiency indicates the extent to which the energy
added by work is converted to net heat output.

55. Mechanical efficiency
Mechanical efficiency is the measure of effectiveness of a machine's energy
and power that is input into the device into an output that makes force and
movement. Mechanical advantage by comparing the input and output force
you can find the advantage of a machine
Specific fuel consumption
Thrust specific fuel consumption (TSFC) or sometimes simply specific fuel
consumption, SFC, is an engineering term that is used to describe the fuel
efficiency of an engine design with respect to thrust output.

56. Volumetric Efficiency
 Volumetric efficiency in internal combustion engine is defined as the ratio of the
mass density of the air-fuel mixture drawn into the cylinder at atmospheric
pressure (during the intake stroke) to the mass density of the same volume of
air in the intake manifold.
Air Fuel Ratio
Air–fuel ratio (AFR) is the mass ratio of air to fuel present in a combustion
process such as in an internal combustion engine

57. Mean Effective Pressure
 Mean effective pressure is a quantity relating to the operation of a
reciprocating engine and is a valuable measure of an engine's capacity to do
work that is independent of engine displacement.

58. The performance of an engine is evaluated
on the basis of the following
 (a) Specific Fuel Consumption.
 (b) Measurement of brake Power
 (c) Specific Power Output.

59. Fuel consumption measurement
 Fuel consumption is measured in two ways:
 The fuel consumption of an engine is measured by determining the
volume flow in a given time interval and multiplying it by the specific
gravity of the fuel which should be measured occasionally to get an
accurate value.
 Another method is to measure the time required for consumption of a
given mass of fuel

60. Measurement of brake power
 The brake power measurement involves the determination of the
torque and the angular speed of the engine output shaft. The
torque measuring device is called a dynamometer.
 Dynamometers can be broadly classified into two main types,
power absorption dynamometers and transmission
dynamometer.

61. Measurement of friction power
 The difference between indicated power and the brake power output
of an engine is the friction power.
 Almost invariably, the difference between a good engine and a bad
engine is due to difference between their frictional losses.
 The frictional losses are ultimately dissipated to the cooling system
(and exhaust) as they appear in the form of frictional heat and this
influences the cooling capacity required. Moreover, lower friction
means availability of more brake power; hence brake specific fuel
consumption is lower.

62. Types Of Dynamometers
 Absorption Dynamometers
 These dynamometers measure and absorb the power output of the
engine to which they are coupled. The power absorbed is usually
dissipated as heat by some means. Example of such dynamometers is
prony brake, rope brake, hydraulic dynamometer, etc.
 Transmission Dynamometers: In transmission dynamometers, the
power is transmitted to the load coupled to the engine after it is indicated
on some type of scale. These are also called torque-meters.