1. DIESEL ENGINE
POWER PLANT
&
MISCELLANEOUS
TOPICS

2. Introduction
 Good for medium and small outputs
 Used where price comparison and
availability is made to coal power
plants
 Main element is a diesel engine

3. Classification of Engines
 Method of Ignition
– Spark Ignition
– Compression Ignition
 Cycles of Operation
– Two Stroke
– Four Stroke
 On basis of fuel
– Petrol
– Diesel

4. 4
Physical Principles
related to Engine
Operation
 Energy conversion
 Vacuum
 Pressure
 The relationship between temperature,
pressure and volume.
 The three states of matter.

5. 5
Basic Parts of the
Gasoline Engine Cylinder block
 Piston
 Piston rings
 Piston pin
 Connecting rod
 Crankshaft
 Cylinder head
 Intake valve
 Exhaust valve
 Camshaft
 Timing gears
 Spark plug

6. 6
Cylinder Block
 Basic frame of
gasoline engine.
 Contains the
cylinder.

7. 7
Piston
 A sliding plug that
harnesses the force
of the burning gases
in the cylinder.

8. 8
Piston Rings
 The rings seal the
compression gases
above the piston
keep the oil below
the piston rings.

9. 9
Piston Pins
 Also known as the
wrist pin, it connects
the piston to the
small end of the
connecting rod.
 It transfers the force
and allows the rod
to swing back and
forth.

10. 10
Connecting Rod
 Connects the piston
and piston pin to the
crankshaft.

11. 11
Crankshaft
 Along the the piston
pin and connecting
rod it converts the
up and down motion
(reciprocating) of the
engine to spinning
(rotary) motion.

12. 12
Flywheel
 Carries the inertia
when there is no
power stroke.

13. 13
Lower End Action

14. 14
Cylinder Head
 Forms the top of the
combustion
chamber.
 Contains the valves,
the passageways for
the fuel mixture to
move in and out of
the engine.

15. 15
Intake and Exhaust
Valves
 Doorway that lets
the gases in and out
of the engine.

16. 16
Camshaft
 Through the use of
an eccentric the
cam lobes push the
valves open.
 The valve springs
close them.

17. 17
Spark Plug
 Electric match used
to begin the
combustion process
of burning air and
gasoline to create
heat.

18. 18
Engine Related Terms
 TDC (top dead center)
 BDC (bottom dead center)
 Stroke
 Bore
 Revolution
 Compression Ratio
 Displacement
 Cycle

19. 19
Four Stroke Cycle
 Intake
 Compression
 Power
 Exhaust

20. 20
Intake Stroke
 Intake valve opens.
 Piston moves down, ½
turn of crankshaft.
 A vacuum is created in
the cylinder.
 Atmospheric pressure
pushes the air/fuel
mixture into the
cylinder.

21. 21
Compression Stroke
 Valves close.
 Piston moves up, ½
turn of crankshaft.
 Air/fuel mixture is
compressed.
 Fuel starts to
vaporize and heat
begins to build.

22. 22
Power Stroke
 Valves remain
closed.
 Spark plug fires
igniting fuel mixture.
 Piston moves down,
½ turn of crankshaft.
 Heat is converted to
mechanical energy.

23. 23
Exhaust Stroke
 Exhaust valve
opens.
 Piston move up,
crankshaft makes ½
turn.
 Exhaust gases are
pushed out polluting
the atmosphere.

24. 24
Four Stroke Cycle
Animation

25. 25
Two Stroke Animation

26. 26
Diesel Animation

27. Diesel Engine
Intake Stroke:
•Piston moves from TDC to BDC
creating vacuum in the cylinder
•Intake valve opens allowing only
air to enter the cylinder and
exhaust valve remains closed

28. Diesel Engine
Compression Stroke
•Both valves stay closed
•Piston moves from BDC to TDC,
compressing air to 22:1
•Compressing the air to this extent
increases the temperature inside the
cylinder to above 1000 degree F.

29. Diesel Engine
Power Stroke
•Both valves stay closed
•When the piston is at the end of
compression stroke(TDC) the injector
sprays a mist of diesel fuel into the
cylinder.
•When hot air mixes with diesel fuel
an explosion takes place in the cylinder.
•Expanding gases push the piston
from TDC to BDC

30. Diesel Engine
Exhaust Stroke
•Piston moves from BDC to
TDC
•Exhaust valve opens and the
exhaust gases escape
•Intake valve remains closed

31. Diesel Engine
Four Strokes of Diesel Engine

32. 32
Diesel 2 stroke

33. 33
Diesel

34. Diesel Engine
The only difference between diesel engine and a four-stroke
gasoline engine is:
•No sparkplug on Diesel engine.
•Has a higher compression ratio.
(14:1 to 25:1)
•Better fuel mileage.

35. 35
Why not diesel?
1. Diesel engines, because they have
much higher compression ratios (20:1
for a typical diesel vs. 8:1 for a typical
gasoline engine), tend to be heavier
than an equivalent gasoline engine.
2. Diesel engines also tend to be more
expensive.

36. 36
Why not diesel?
3. Diesel engines, because of the weight and
compression ratio, tend to have lower
maximum RPM ranges than gasoline
engines (see Question 381 for details).
This makes diesel engines high torque
rather than high horsepower, and that
tends to make diesel cars slow in terms of
acceleration.
4. Diesel engines must be fuel injected, and in
the past fuel injection was expensive and
less reliable

37. 37
Why not diesel?
5. Diesel engines tend to produce more
smoke and "smell funny".
6. Diesel engines are harder to start in cold
weather, and if they contain glow plugs,
diesel engines can require you to wait
before starting the engine so the glow
plugs can heat up.
7. Diesel engines are much noisier and tend to
vibrate.
8. Diesel fuel is less readily available than
gasoline

38. 38
Advantages
 The two things working in favor of diesel
engines are better fuel economy and longer
engine life. Both of these advantages mean
that, over the life of the engine, you will tend
to save money with a diesel.
 However, you also have to take the initial high
cost of the engine into account. You have to
own and operate a diesel engine for a fairly
long time before the fuel economy overcomes
the increased purchase price of the engine.

39. Important Terms
 Direct and Indirect Ignition
 Glow Plugs
 Engine Performance Parameters

40. DIESEL ENGINES
Indirect and Direct Injection
 In an indirect injection
(abbreviated IDI) diesel
engine, fuel is injected into
a small prechamber, which
is connected to the cylinder
by a narrow opening.
 The initial combustion takes
place in this prechamber.
 This has the effect of
slowing the rate of
combustion, which tends to
reduce noise.
FIGURE 4-3 An indirect injection diesel engine uses
a prechamber and a glow plug.

41. DIESEL ENGINES
Indirect and Direct Injection
FIGURE 4-4 A direct injection diesel
engine injects the fuel directly into the
combustion chamber. Many designs
do not use a glow plug.

42. GLOW PLUGS
 Glow plugs are always used in diesel
engines equipped with a precombustion
chamber and may be used in direct injection
diesel engines to aid starting.
 A glow plug is a heating element that uses
12 volts from the battery and aids in the
starting of a cold engine.
 As the temperature of the glow plug
increases, the resistance of the heating
element inside increases, thereby reducing
the current in amperes needed by the glow
plugs.

43. Engine Performance
Parameters
 IMEP
 IHP
 BHP
 ITE
 BTE
 ME

44. Indicated Mean Effective
Pressure (IMEP)
Indicator Diagram

45. Indicated Mean Effective
Pressure (IMEP)
 In order to determine the power
developed by the engine indicator
diagram should be available
 Area of the indicator diagram shows
power
 But it can also calculate average gas
pressure on piston in any stroke
 This pressure is called IMEP

46. Indicated Horse Power (IHP)
 It can be calculated as
 Pm is the IMPE in kg/cm2
 L is length of stroke in m
 A is area of piston
 N is speed in rpm
 n is number of cylinders
 k is for stroke count of engine
. . . .
4500.
mP L A N n
IHP
k
=

47. Brake Horse Power (BHP)
 It is defined as the net output power
available at the crank shaft.
 It is found by using a dynamometer at
the output of the shaft
where N is speed in rpm
T is torque
2
4500
NT
BHP
π
=

48. Frictional Horse Power (FHP)
 It is the difference between IHP and
BHP
FHP = IHP - FHP

49. Indicated Thermal Efficiency
(ITE)
 It is defined as the ratio of indicated
work to thermal input
 Where W is the weight of the fuel
CV is the calorific value of the fuel
J is the joules equivalent = 427
4500
i
IHP
W CV J
η
×
=
× ×

50. Brake Thermal
Efficiency
 It is defined as the ratio of indicated
work to thermal input
 Where W is the weight of the fuel
CV is the calorific value of the fuel
J is the joules equivalent = 427
4500
b
BHP
W CV J
η
×
=
× ×

51. Mechanical Efficiency
 It is the ratio of BHP to IHP
m
BHP
IHP
η =

52. Example 4.4
 A diesel power station has a supply power demand of
30kW. If the overall efficiency of generating station is
40%, (a) Calculate the diesel required per hour and
also (b) calculate the electrical energy generated per
ton of fuel
 Efficiency = Output/ Input
 0.4 =30/Input
 Input = 0.4*30 = 75kW
 Energy per hour = 75kWh = 75*860 kcal = 64500kcal
 Fuel Required = 64500 / 12000 = 5.37kg

53. Example 4.4 contd.
 (b) calculate the electrical energy generated per ton of
fuel
 Input per ton = 1000 kg
= 1000 * 12000 kcal
= 1000 * 12000 / 860 KWh
= 13954 kWh
 Efficency = Output/Input
Output = Efficiency * Input
= 0.4 * 13954
= 5581 kWh

54. Miscellaneous Topics
 Instrumentation
– Barometer
– Manometer
– Pyrometer
 Running Alternators in Parallel
 Advantages of AC transmission
 Stability of Power Systems

55. AC or DC
 Brief History
 Available standards
 AC 220 or 110 ?
 50Hz or 60 Hz

56. Running Alternators in Parallel
 What is synchronizing
– Connecting of two or more alternators
 Conditions
– Frequency of the systems should be
identical
– Phases of the incoming alternator should
be identical to that of the bus bar
– Voltage of the incoming alternator should
be approximately same as that of the bus
bar

57. Advantages of AC Tx
 Possible to generate voltage as high
as 33kV as compared to 11kV max in
DC
 Stepping up of voltage is much easier
in AC as compared to DC
 Easier to maintain AC substation
 Efficiency is much higher than DC

59. Torricelli Barometer
 The mercury in the tube
pushes down with its
weight.
 The bottom of the tube
is open to the
atmosphere.
 The air pushes on the
open surface of the
mercury.
 On an average day, the
pressure of the air
equals the pressure
exerted by a column of
mercury 760 mm high.
Weight of
mercury

60. Barometer Detail
Why doesn’t the diameter of the
column of Hg make a
difference?
Recall that Pressure =
force/area.
The “force” is the weight of the
mercury, but the pressure that
results is that weight divided
by the area of the column. So
… a bigger column weighs more
but also has a proportionally
bigger area, and the two
factors cancel one another
out.
The pressure caused by the column
of mercury pressing down is
independent of the diameter of

61. Manometer
 A manometer is
comprised of a bulb
containing a gas and
a U-shaped tube.
 The U-shaped tube is
partially filled
with mercury. The
weight of the
mercury puts
pressure on the gas.
 If the U-tube is
OPEN there is also
air pressure acting
on the gas.
 The gas molecules
put pressure on the
mercury.
PHg

62. Manometer
– measures contained gas pressure
U-tube Manometer Bourdon-tube gauge
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

63. lower
pressure
higher
pressure
Manometer
P1
Pa
height
750 mm Hg
130 mm
higher
pressure
880 mm Hg
Pa =
h =+-
lower
pressure
620 mm Hg
P1 = Pa
P1 < Pa

64. Manometer
Pb
Pa
750 mm HgPa =

65. lower
pressure
Manometer
Pa
height
750 mm Hg
130 mm
lower
pressure
620 mm Hg
Pa =
h =-

66. 880 mm Hg
higher
pressure
higher
pressure
Manometer
Pa
height
750 mm Hg
130 mm
Pa =
h =+

67. PYROMETERY
 Pyrometery is the art and science of measurement of high
temperatures. Pyrometery makes use of radiation emitted by the
surface to determine its temperature
 Temperature measuring devices invented are called pyrometers

68. PYROMETERS
 Pyrometer is a device capable of measuring temperatures of objects
above incandescence i.e. objects bright to the human eye).
 It is a non contact device
 A device that measures thermal radiation in any temperature range.

69. PRINCIPLE
A pyrometer has
 optical system
 detector
It is based upon “Stephan Boltzmann law”
E=σ AT4

70. Basic Pyrometer