This document provides information on heat engines and boilers. It defines a heat engine as a device that converts heat energy to mechanical energy. Heat engines are classified as internal combustion engines where fuel combustion occurs inside the engine cylinder, or external combustion engines where combustion occurs outside the cylinder. Details are given on common internal combustion engine types like diesel, petrol, and gas engines. The document also discusses boiler types like fire tube boilers, water tube boilers, and fluidized bed combustion boilers. Key components, workings, and examples of different engine and boiler classifications are described over multiple pages of detailed text.

1. BE 8252- BASIC CIVIL AND
MECHANICAL ENGINEERING

2. HEAT ENGINES
Heat engine is a device used for
converting heat energy into
mechanical energy.
Heat energy is obtained by
combustion of fuel
Classification of Heat engines :
 Internal combustion engine (I.C Engine)
 External combustion engine (E.C Engine)

4. Internal combustion engine
(I.C Engine)
• In I.C engines, the combustion of
fuel takes place inside the engine
cylinder
Examples :
Diesel engine
Petrol engine
Gas engine

5. External combustion engine
(E.C engine)
• In E.C engines, the combustion of
fuel takes place outside the
working cylinder
Examples :
Steam Engines
Steam turbines

6. Classifications of I.C Engines
Number of strokes
 Two stroke engine
 Four stroke engine
Fuel used
 Petrol (or) Gasoline engine
 Gas engine
 Diesel engine
 Dual fuel engine
Working cycle
 Otto cycle
 Diesel cycle
 Dual combustion engine

7. Classifications of I.C Engines
Cylinder arrangement
Inline engine
V engine
Radial engine
Vertical and horizontal engine
Fuel supply
Carbureted type
Injection type
Methods of ignition
Spark ignition
Compression ignition

8. Classifications of I.C Engines
 Cooling system
 Air cooled engine
 water cooled engine
 Lubrication system
 Wet sump lubrication engine
 Dry sump lubrication

9. Basic components of I.C engine

10. I.C Engine Terminology
• Bore : The inside diameter of the
cylinder is known as bore,
measured in mm
• Stroke : Distance travelled by the
piston between two dead centres
(TDC & BDC)
• TDC : The extreme position
reached by the piston at the top of
the cylinder in the vertical engine
is called as Top Dead Centre

11. I.C Engine Terminology
• BDC : The extreme position
reached by the piston at the Bottom
of the cylinder in the vertical
engine is called as Bottom Dead
Centre
• Compression ratio:
– Maximum cylinder volume
Clearance volume
• For Petrol engine : 6:1 to 10:1
• For Diesel engine : 16:1 to 26:1

12. Compression ratio:
video

13. Petrol engine
• Petrol engine is also known as
spark ignition (SI) engine
• Four stroke petrol engine requires
four strokes of the piston for one
cycle of operation
• Number of strokes:
– Four stroke petrol engine
– Two stroke petrol engine

14. Four stroke petrol
engine
• In four stroke engine, one power
stroke is completed for every four
strokes of the piston or during two
revolutions of the crankshaft.
• Four strokes are,
– Suction stroke
– Compression stroke
– Expansion stroke
– Exhaust stroke

15. Suction stroke
Valve position :
Inlet valve : open
Outlet valve : closed
Piston movement : TDC to BDC

16. Compression stroke
Valve position :
Inlet valve : closed
Outlet valve : closed
Piston movement : BDC to TDC

17. Expansion stroke
Valve position :
Inlet valve : closed
Outlet valve : closed
Piston movement : TDC to BDC

18. Exhaust stroke
Valve position :
Inlet valve : closed
Outlet valve : open
Piston movement : BDC to TDC

21. Two stroke petrol engines
• In two stroke engines, the cycle of
operation is completed in two
strokes of the piston (or) one
revolution of the crankshaft
• A two stroke engine has no valves
and only ports are present
• Three ports :
– Inlet port
– Exhaust port
– Transfer port

22. Two stroke petrol engines
Two strokes :
• First stroke : ( upward movement of piston)
– compression , suction and ignition
• Second stroke : Expansion and Exhaust

23. 2 stroke petrol engine
Exhaust port
Inlet port
Transfer port
1.Upward
movement of piston
2.Downward
movement of piston

24. First stroke :
( upward movement of piston)

25. Second stroke
( downward movement of piston)

26. Four stroke Diesel engine
• Diesel engine is also known as
compression ignition ( C.I ) engine.
• The working is similar to that of a
petrol engine and the only difference
is a fuel injector is present instead of
a spark plug.
• This is known as “ Diesel cycle”

27. Four strokes are,
Suction stroke
Compression stroke
Expansion stroke
Exhaust stroke

28. Suction stroke
Valve position :
Inlet valve : open
Outlet valve : closed
Piston movement : TDC to BDC

29. Compression stroke
Valve position :
Inlet valve : closed
Outlet valve : closed
Piston movement : BDC to
TDC

30. Expansion stroke
Valve position :
Inlet valve : closed
Outlet valve : closed
Piston movement : TDC to BDC

31. Exhaust stroke
Valve position :
Inlet valve : closed
Outlet valve : open
Piston movement : BDC to TDC

33. Two stroke Diesel engine

36. BOILERS

37. Boilers
• Boiler also known as steam
generator is a closed vessel in
which steam is generated from
water by the application of heat
and pressure being higher than
the atmospheric
• The main function of a boiler is to
evaporate water into steam at a
higher pressure

38. Requisites of a boiler
• A good boiler should be capable of
producing maximum amount of steam
with minimum initial cost
• It should be compact in size and safe
in working
• The components and parts should be
easily accessible for inspection and
repair
• The heat produced by the fuel in the
furnace should be utilized maximum

39. Classification of boilers
According to the flow of water and hot
gases
Fire tube boilers – Ex Cochran, Lancashire
Water tube boilers- Ex Babcock, Wilcox boiler
According to the method of firing
Internally fired boilers – Ex Lancashire
Externally fired boilers - Ex Babcock, Wilcox boiler
According to the method of water
circulation
Natural circulation boilers - Cochran, Lancashire
Forced circulation boilers – La-Mont , velox boiler

40. According to the pressure
developed
Low pressure boilers - Ex Cochran, Lancashire
Medium pressure boilers-Ex Lancashire,
Locomotive Boiler
High pressure boilers - Ex Babcock, Wilcox boiler
According to the axis of the shell
Vertical boilers – Cochran boiler
Inclined boilers
Horizontal boilers - Lancashire boiler , locomotive
boiler
According to the use of the boiler
Stationary boilers - Babcock, Wilcox boiler

41. Low pressure boilers
• The boilers producing steam at a
pressure of less than 80 bar are
termed as low pressure boiler.
• Fire tube boilers are generally
preferred for low pressure steam
production
• Eg. Cochran boiler , Lancashire
boiler , locomotive boiler

42. Cochran Boiler

43. Cochran Boiler
• It is a vertical, multi-tubular low
pressure fire tube boiler.
• It is the modification of a simple
vertical boiler.
• It has many horizontal fire tubes
and hence the heating surface
has been increased

44. Specifications
Diameter of the shell 2.75m
Height of the shell 5.8m
Working pressure 6.5 bar – 15 bar
Steam Capacity 3500 kg/hr
Efficiency 72%
Number of tubes Upto 165

45. PARTS
• Shell
• Furnace
• Flue pipe
• Combustion chamber
• Chimney
• Man hole
• Water gauge
• Safety valve
• Steam stop valve
• Blow off cock
• Fusible plug

46. Salient feature
• The dome shape of the furnace
causes the hot gases to deflect
back and pass through the flue
pipe
• The hemispherical shape of the
shell provides maximum volume
of space
• It occupies less floor area and
hence compact

47. LOCOMOTIVE BOILER

49. High pressure Boiler
• The boilers producing steam at a
pressure of more than 80 bar are
termed as high pressure boilers
• The high pressure boiler can deliver
40 to 1600 tonnes/hr superheated
steam.
• Water tube boilers are generally
preferred for high pressure boilers
• Example : Babcock and wilcox
boiler , Lamont boiler, Benson boiler

50. Lamont Boiler
• It is a water tube, forced circulation
type externally fired high pressure
boiler

52. Main parts
• Feed pump
• Economizer
• Steam separator drum
• Circulating pump
• Evaporator
• Convection super heater
• Air preheater

53. • Economizer:
• It a device in which the waste heat
of the flue gases is utilized for
heating the feed water
• Air Pre-heater :
• The function of the air pre-heater is to
increase the temperature of air before it
enters the furnace.
• It is placed after the economizer.
• Flue gases pass through the economizer
and then to the air preheater

54. • Super heater :
• The function of a super heater
is to increase the temperature
of the steam above its
saturation point
• Steam separator :
• The function of a steam
separator is to remove the
entrained water particles from
the steam conveyed to the
steam engine or turbine

56. Specifications
• Capacity – 50 tonnes/hr
• Steam pressure – 170 bar
• Temperature – 500oC

57. Advantages
• It can produce steam at very high
pressure
• Air preheater and economizer
increases the boiler efficiency
• Arrangement is compact
• The weight of the boiler is reduced as
the separator drum is kept outside
the boiler

58. Disadvantages
• The disadvantages of lamont boiler
is the deposition of salt and
sediments on the inner surface of
the waste tubes
• The deposition reduces the heat
transfer capacity and the efficiency

60. Benson boiler
• Specifications
• Capacity – 150 tonnes/hr
• Steam pressure – 210 bar
• Temperature – 650oc

61. LOEFFLER BOILER

62. FLUIDIZED BED COMBUSTION BOILER

63. BUBBLING FLUIDIZED BED BOILERS

64. CIRCULATING FLUIDIZED BED
BOILERS

65. PRESSURISED FLUIDIZED
BUBBLING BED BOILER

66. Low Pressure VS High pressure
Low pressure boiler High Pressure Boiler
This boiler produces steam at a
pressure less than 80 bar
This boiler produces steam at a
pressure of more than 80 bar
Fire tube boilers are generally
preferred for low pressure boiler
Water tube boilers are generally
preferred for high pressure boiler
Dry steam is produced in this
type of boiler
Superheated steam is produced
in this type of boiler
Rate of steam production is low Rate of steam production is high
Lesser risk of explosion
Eg : Cochran boiler ,
Lanchashire Boiler , locomotive
Boiler
More risk of explosion due to
high pressure
Eg: Babcock and Wilcox Boiler,
Lamont Boiler, Benson Boiler

67. Boiler Mountings
Boiler mountings are the devices mounted on the
boiler surface for safe operation , proper
maintenance and control of steam generation.
Boiler mountings include :
Pressure Gauge
Water Gauge
Safe valve
Fusible plug
Steam stop Valve
Blow off cock

68. Boiler Accessories
Boiler accessories are the devices fitted in boiler to
increase the efficiency of the boiler and proper
working of the boiler.
• Boiler Accessories are :
Economizer
Air Preheater
Superheater
Steam separator

69. Pressure Gauge

70. Water Gauge

71. Safe valve

72. Fusible plug

73. Boiler Accessories
• Economizer

74. Air Preheater

75. Super Heater