1. Unit IV
Testing of IC Engines
&
Supercharging

2. Syllabus : IC Engines Unit-IV : testing of ic engines
Objective of testing, various performance parameters for
IC engines - indicated power, brake power, friction power, SFC,
AF ratio etc, methods to determine various performance parameters, characteristic curves, heat balance sheet
SUPERCHARGING
Supercharging and turbo-charging methods and their limitations

3. Lecture No 23 Learning Objectives:
To understand objectives of engine testing
To learn about engine performance parameters

4. Objectives of Testing Engine performance during development
Engine performance after development/
sample testing after production by
manufacturers
Engine performance testing by Govt Testing
Agencies for certification like ARAI

5. Objectives of Testing Whether engine is performing as per design?
Indicated Power (IP)
Brake Power (BP)
Frictional Power (FP)
Mechanical Efficiency
Thermal Efficiency
Brake Specific Fuel Consumption (bsfc)
Heat Balance Sheet
Whether engine is meeting emission norms? CO HC
NOx PM
Soot

6. Objectives of Testing Leakage in engine? Smooth running of engine?
Engine performance after overhaul/repairs?

7. Performance Parameters
Brake Power (BP)
Power available at output shaft/ crank shaft
Mechanical Losses/Frictional Power (FP)
Sum of frictional losses and pumping losses incl power required to operate engine accessories like water pump, dynamo etc
Indicated Power (IP)/ Theoretical Power
Power produced within eng cylinder
IP = BP + FP

8. Tests Performed on IC Engines
Indicated Power (IP)
Brake Power (BP)
Frictional Power (FP)
Mechanical Efficiency
Air-Fuel Ratio
Brake Specific Fuel Consumption (bsfc)
Thermal Efficiency
Working out Heat Balance Sheet

9. Engine/ Mechanical Indicator
Indicator Paper
Wrapped Drum
p-V diagram
Stylus
Rope connected
To Piston Rod
Pulleys
Weight
Piston
Coupling Nut
To Combustion Chamber

10. Measurement of IP on Mech/Eng Indicator
To determine IP, p-V diagram is required, the area of
which represents work developed by engine per cycle
Apparatus used for drawing actual p-V diagram is
called Mechanical/ Engine Indicator
Eng indicator consists of a cylinder, piston, piston rod
coupling nut, straight line linkage with stylus, spring
of required stiffness, indicator card wrapped drum,
pulley, rope and weights .
Vertical movement of stylus and horizontal movement
of the cord combines to produce a closed figure
called Indicator diagram
Area of indicator diagram can be measured by
Planimeter to a definite scale giving work developed

11. Mean Effective Pressure
Indicated Mean Effective Pressure (imep)
imep is the average pressure, which if acted over the
entire stroke length, would produce the same work
done by the piston as is actually produced by the
engine during a cycle
Let ‘a’ be the net area of indicator diagram (cm2)
‘l’ be length of diagram (cm) and
‘k’ be spring stiffness N/cm2/cm
Hence, mean height of
diagram = a/l

12. Indicated Power (IP) Let pm= imep (N/cm2); L= Length of stroke (m)
A= Piston top area (cm2)=Лd2/4;
N= RPM
n= Power stroke /min(=N/2 for 4 S eng as one
power stroke per 2 rev & N for 2S eng)
Hence, Force on Piston=
Pm x A (Newton)
WD per Cycle=
pm x A x L (Nm)
Hence, IP = pm x A x L x n (Nm/min)/Cycle/Cylinder

13. Lecture No 24 Learning Objectives:
To learn working out/ measurement of Brake Power (BP) &
Friction Power (FP)

14. Measurement of BP 1. Rope Brake Friction Dynamometer S W
Spring Balance
Rope
Flywheel/Brake Drum W
Weight

15. Brake Mean Effective Pressure (bmep)
Rope Brake Friction Dynamometer (Contd.)
Let W=Dead Weight (mg) in Newton (N)
S=Spring Balance Reading (N)
Rb=Radius of Brake Drum (D+d)/2 (m)
D=Brake Drum dia and ‘d’ rope dia
N=Engine RPM
Hence, net Brake Load= (W – S)
Braking Torque = (W-S) x Rb
Hence, Brake Power (BP) =
Brake Mean Effective Pressure (bmep)

16. 2. Prony Brake Dynamometer
Load
Arm
Flywheel/
Brake Drum
Brake
Shoes
Length, L
Weight W

17. Prony Brake Dynamometer (Contd.)
Let W (=mg) be the weight (N)
Let L be the distance from centre of brake drum to
hanger, called load arm (m)
Then, Torque=W x L (Nm)

18. Frictional Power (FP) Difference between IP and BP is called FP
FP includes:
- Pumping losses due to intake & exhaust processes
- Frictional losses in bearings, rotary/sliding parts
Power required to drive auxiliaries like governor,
water, lub oil, fuel pumps, alternator/dynamo,
valve operating mechanism etc
FP increases as square of N but practically FP ∞ N1.6
Higher FP results in:
- Reduced power output
- Decreased mech efficiency
- Increased bsfc
- Increased requirement of cooling

19. Methods of Measurement of FP
By measurement of IP and BP
Willan’s Line Method
Morse Test
Motoring Test

20. FP by Willan’s Line Method
( Fuel Rate Extrapolation Method )
At Constant Eng Speed, say 1500 RPM 4 3
Fuel Flow
Rate (kg/h) 2 1 A
BP (kW)

21. FP by Willan’s Line Method
A graph between fuel consumption rate (kg/h) taken
on y-axis and BP (kW) on x-axis is drawn, while
engine is made to run at some constant speed, say
1500 RPM
The graph is extrapolated back to zero fuel
consumption, which cuts on –ve x-axis at point ‘A’
The –ve intercept on x-axis represents FP at that
speed of the engine
Although when BP=0, some fuel consumption is there.
This fuel is consumed to overcome engine friction
Only for CI engine to be run at constant speed as
Fuel consumption rate v/s BP plot is almost straight
line in case of diesel engine, hence can be extrapolated

22. FP by Morse Test Morse Test can be used for determining FP/IP of
multi-cylinder IC engines, generally 3 cyl and more
by cutting off each cylinder in turn
In SI engines, each cylinder is rendered in-operative
by short-circuiting the SP or cutting off fuel supply
in MPFI systems. In CI engines, fuel supply is cut off
Consider 4 stroke, 4 cylinder SI engine coupled with
dynamometer
Engine is run at constant speed N throughout one
set of test parameters, as FP ∞ N2
It is assumed that pumping & mech losses are same
whether a cylinder is working or not
Throttle position is kept fixed, however, to attain
same speed N, load is decreased by dynamometer

23. FP by Morse Test Let B=BP of eng when all cylinders are working
B1=BP of eng when Cylinder No 1 is cut off
Similarly, B2=BP of eng when Cylinder No 2 is cut off
B3=BP of eng when Cylinder No 3 is cut off
B4=BP of eng when Cylinder No 4 is cut off
Let I1, I2, I3 & I4 be the IPs developed by Cylinder
Nos 1, 2, 3 & 4 respectively and their corresponding
FPs be F1, F2, F3 & F4
Total BP(B) = (I1+I2+I3+I4) - (F1+F2+F3+F4)

24. FP by Morse Test BP(B) = (I1+I2+I3+I4) - (F1+F2+F3+F4)
Hence, B1=(I2+I3+I4) – (F1+F2+F3+F4)
On subtracting; B – B1 = I1
Similarly, B – B2 = I2
B – B3 = I3
B – B4 = I4
On adding; IP = I1 + I2 + I3 + I4
= 4B – (B1+B2+B3+B4)
B, B1, B2, B3 & B4 can be measured by Dynamometer,
Hence IP can be calculated
Therefore, FP = IP - BP

25. Lecture No 25 Learning Objectives:
To understand working out of heat balance sheet
To learn measurement of air/fuel consumption

26. Theoretical/ Air Std Efficiencies
Otto Cycle:
Diesel Cycle:
Dual Cycle:

27. Some Definitions Thermal Efficiencies: i) Indicated Thermal Efficiency
ii) Brake/Overall Thermal Efficiency
Where mf is fuel consumed in kg/sec
CV is Calorific Value of fuel in kJ/kg
IP/BP is in kW

28. Some Definitions Mechanical Efficiency:
Relative Efficiency : Defined as the ratio of Brake
Thermal Efficiency to Air Standard Efficiency at same
Compression Ratio(CR)

29. Some Definitions Volumetric Efficiency:
Ratio of actual mass of charge inducted during
suction stroke to mass of charge corresponding to
swept volume of the engine at atm pr & temp
Reduced Volumetric Efficiency causes reduction in
Power Output
Volumetric Efficiency puts a limit on the amt of fuel
that can be burnt and hence on its power, since
output of eng depends on amt of air inducted

30. Some Definitions (Brake) Specific Fuel Consumption (bsfc/sfc):
bsfc is defined as the amount of fuel required to be
supplied to eng to develop 1kW of power per hour at
crankshaft
Specific Output:
BP per unit of piston displacement

31. Heat Balance Sheet Heat Balance Sheet is an account of heat released
on combustion of fuel in the combustion chamber
and its utilization in the engine
To draw heat balance sheet, tests are carried out
on engine, while it is run at some constant speed
Heat Supplied:
Heat Supplied = mf x CV (kJ/min)
Where mf = mass flow rate of fuel (kg/min)
CV = Calorific Value of fuel (kJ/kg)

32. Heat Balance Sheet Heat Expenditure/Utilization:
1) Heat Equivalent to BP:
Heat Equivalent to BP = BP x 60 (kJ/min)
2) Heat Rejected to Cooling Water:
Heat carried away by water =mwCpw(Two – Twi) kJ/min
Where mw=cooling water circulation kg/min
& Cpw=4.187 kJ/kgK
3) Heat carried away by Exhaust gases
Heat carried by exh gases=mgCpg(Tge – Tsa) kJ/min
Where mg=(ma+mf) =flue gases flow rate (kg/min)
4) Unaccounted Heat:
By difference

33. Heat Balance Sheet Heat Supplied kJ/ min Heat Utilization 100%
Heat Utilization
100
a) Heat to BP=BPx60
Heat Supplied
by comb of
Fuel
=mf x CV
b) Heat to water
=mwxCpw(Two – Twi)
c) Heat carried away by exhaust gases
=mgxCpg(Tge – Tsa)
d) Heat Unaccounted
(By difference)
100
Total
100

34. Volumetric Fuel Flow Meter(Burette Type)
Fuel from Tank
3-Way Cock
Start
Start
200cc
100cc
Stop
Stop
3-Way Cock
Fuel to Eng

35. Fuel Measurement Time required to supply given volume of fuel is noted
Mass Flow Rate of Fuel Supply:
Density of Fuel = Sp Gravity of fuel x Density of water
This method does not give very accurate mass flow
rate due to variation in density with temp

36. Gravimetric Fuel Flow Meter
Fuel Tank A
Fuel to Engine
Valves B
Flask
Weighing Machine

37. Air Flow Meter Thermometer Air Surge Orifice Plate (A, Cd) Tank
Manometer ΔH
Air Intake to Eng

38. Measurement of Air Consumption by Air Flowmeter
Surge tank is connected to intake side of the engine
Manometer measures the pressure difference
Vol Flow Rate
Cd – Coeff of discharge for given orifice
A – Orifice cross sectional area
ΔHw-Head of water to be converted to air head

39. Lecture No 26 Learning Objectives:
To learn about engine characteristic curves

40. SI Engine Characteristic CurvesIP BP FP
POWER
(kW)
Speed

41. SI Engine Characteristic Curves
Lab tests carried out to determine eng performance
During tests, throttle is kept full (full /rated load,
max fuel consumption) and speed is varied by
adjusting the brake load
IP, BP, FP, bsfc, mechanical & volumetric efficiencies
etc are worked out
Same tests can be repeated at half load
At rated output, max p-V diagram area, hence max
imep; For given torque; power ∞ N

42. SI Engine Characteristic Curves
IP increases when imep or speed or both increase
IP initially increases faster with speed, if inlet
conditions are kept constant
However, after certain limit, rate of increase of IP
reduces with speed due to reduction in vol efficiency
as air/charge velocity increase results in inlet pr drop
Mech losses increase with
increase in speed(FP∞ N2)
due to which increase in
IP is off-set by steep
increase in FP

43. SI Engine Characteristic CurvesIP IP BP
bsfc
Mech Eff BP
bsfc x
Mech Efficiency
Speed

44. SI Engine Characteristic Curves
As FP ∞ N2, mech efficiency reduces due to steep
increase in FP
At lower speeds, due to lower charge velocity because
of low piston speed, bsfc reduces since volumetric
efficiency increases and mech efficiency also increases
After certain speed, bsfc
increases due to
reduction in volumetric
efficiency and increase
in mech losses x
Point x represents
economical speed of eng
for min fuel consumption

45. SI Engine Characteristic Curve
Vol
Efficiency
Speed

46. SI Engine Characteristic Curve
Volumetric Efficiency reduces with increase in speed
due to increase in intake velocity resulting in drop of
suction pressure
Higher the speed, lesser the time available for
induction of charge
Suction valve fully opens
only when pressure inside
cylinder slightly below
the surrounding pressure,
thus reducing effective
suction stroke

47. CI Engine Characteristic CurvesBP
Power
bsfc
bsfc
Speed

48. CI Engine Characteristic Curves
IP and BP increase with speed but due to steep
increase in FP, IP and BP start coming down
For bsfc curve, same reasons as in SI engine

49. Engine Characteristic CurvesSI
bsfc CI BP

50. CI Engine Characteristic Curve
Stoichiometric Mixture
Brake/
Overall
Efficiency
Lean
Mixture
Rich
Mixture
A/F Ratio

51. Lecture No 27 Learning Objectives:
To understand working out of engine parameters through
numerical problems

52. Q1. Obtain cylinder dimensions of a twin-cylinder, 2-S
IC engine from the following data:
Engine speed=4000RPM; Volumetric efficiency=77%;
Mech Efficiency=75%; Fuel consumption=10 lit/hr;
Sp. Gr. Of fuel=0.73; A/F ratio=18;
Piston speed= 600m/min; imep=5 bar.
Also, determine power output at STP conditions
(p= N/m2; Ta=25˚C; R for air=0.287 kJ/kgK)
Solution:
Cylinder Dimensions=?
D & L
Piston speed=2LN
Since speed & N are given, L=?
Now, to find out D=?

53. Solution(Contd):

54. Solution(Contd):

55. Solution(Contd):

56. Q2. A 6 cylinder gasoline engine operates on 4 stroke
cycle. Bore of cylinder is 80mm and stroke 100mm.
Clearance volume per cylinder is 70CC. At 4000 RPM,
Fuel consumption is 20kg/hr and the torque developed
is 150Nm. Calculate:-
BP (b) Brake mean effective pressure (c) Brake
thermal efficiency
If CV of the fuel is 43000kJ/kg, find relative efficiency
on brake power basis, assuming engine works on
Constant volume cycle and gamma for air =1.4.
Solution:

59. Lecture No 28 Learning Objectives:
To understand working out of engine parameters and heat
balance sheet through numerical problems

60. Q3. During trial of a single cylinder, 4 stroke oil engine
the following results were obtained:
Cyl bore=200mm, Stroke=400mm, mep=6 bar,
Torque=407Nm, speed=250 RPM,
Oil consumption=4kg/hr, CV of fuel=43MJ/kg,
Cooling water rate=4.5kg/min, Air used per kg of fuel=
30kg, Rise in cooling water temp=45°C, Temp of
Exhaust gases=420°C, Room temp=20°C, mean sp.
heat of exhaust gases=1kJ/kgK, Sp. Heat of water=
4.18kJ/kgK, Barometric pressure= bar
Find IP, BP and draw up heat balance sheet in kJ/hr.
Solution:

61. Heat Balance Sheet 1. Heat supplied by fuel to eng =mfxCV
=4x43000kJ/hr=172,000kJ/h

62. 2. Heat utilized
(i) Heat to Power Output=BPx3600kJ/h
=10.65x3600=38,358kJ/h
(ii) Heat to cooling water=mw x Cpw x ∆Tw
=4.5x60x4.18x45 = 50,787 kJ/h
(iii) Heat to exhaust gases=mg x Cpg x (Te-Ta )
To find mg : ma=30kg/kg of fuel; hence mg=31kg
Since fuel consumption is 4kg/h; mg=31x4kg/h
Hence, Heat to exhaust gases=31x4x1(420-20)
=49,600kJ/h
(iv) Unaccounted Heat=33,255kJ/h (by difference)

63. Heat Balance Sheet Heat Supplied kJ/hr % Heat Utilized
Heat supplied by fuel= mfxCV
172,000
100
To BP= BPx3600
38,358
22.3
To Cooling Water =mw.Cpw.∆Tw
50,787
29.5
To exhaust gases =mg.Cpg.∆Tg
49,600
28.8
Unaccounted Heat
33,255
19.3
Total

64. Q4. During a test on a 4 stroke oil engine,
the following data were obtained:
Mean height of indicator diagram = 21mm
Indicator spring number/stiffness=27kN/m2/mm
Swept volume=14 lit, effective brake load=77kg,
Effective brake radius= 0.7m, speed=6.6 rev/s,
fuel consumption=0.002kg/s, CV of fuel=44MJ/kg,
Cooling water rate=0.15kg/s, water inlet temp=38°C,
cooling water outlet temp=71°C, Sp. heat of water=
4.18kJ/kgK, energy carried by exhaust gases=33.6kJ/s
Determine IP, BP and mech efficiency and draw up
heat balance sheet in kJ/s and %.
Solution:

66. Heat Balance Sheet Heat Supplied kJ/s % Heat Utilized
Heat supplied by fuel=
mf x CV =
0.002x44000
(=88kJ/s) 88
100
To BP
21.92
24.9
To Cooling Water =mw.Cpw.∆Tw
0.15x4.18x (71-38)
20.69
23.5
To exhaust gases (given)
33.6
38.2
Unaccounted Heat
11.79
13.4
Total

67. Q5. A 4 cylinder 4 stroke SI engine has a bore of
5.7cm and stroke 9cm. Its rated speed is 2800 RPM
and it is tested at this speed against a brake which
has a torque arm of 356mm. The net brake load is
155N and fuel consumption is 6.74 lit/hr. Sp gravity of
petrol is and CV is 44200kJ/kg. A Morse test is
carried out and cylinders are cut off in order of 1, 2, 3
& 4 with corresponding brake loads of 111, 106.5,
104.2 and 111N. Determine engine torque, bmep,
brake thermal efficiency, sfc, mech efficiency and imep.
Solution:
Engine torque= (W-S).Rb=WxL
= 155x0.356=55.18Nm

70. We know that IP
= 4BP - (BP1+BP2+BP3+BP4)

71. Q6. During trial of a 4 cylinder 4 stroke SI engine
running at 50 rev/s, the brake load was 267N when all
cylinders were working. When each cyl was cut off in
turn and speed returned to same 50 rev/s, brake
readings were 178N, 187N, 182N and 182N.
Determine BP, IP and mech efficiency of the engine.
For brake, BP=F.N/455(kW), where F is brake load in
Newtons and N rev/s. The following results were
obtained: Fuel consumption=0.568lit in 30 seconds,
SG of fuel=0.72, CV=43000kJ/kg, A/F ratio=14:1,
Exh temp=760°C, Cpg=1.015kJ/kg, Water inlet temp=
18°C and outlet temp=56°C, water flow rate=0.28kg/s,
Ambient temp=21°C. Draw heat balance sheet in kJ/s.
Solution:

72. We know that IP
= 4BP - (BP1+BP2+BP3+BP4)
Therefore IP= 4x ( )
=37.25kW

73. Heat Balance Sheet Heat supplied =mfxCV Heat utilized
(i) Heat to BP=BP= 29.34kJ/s (5%)
(ii) Heat to cooling water=mw x Cpw x ∆Tw
=0.28x4.187x(56-18) =44.55 kJ/s (7.6%)
(iii) Heat to exhaust gases=mg x Cpg x (Te-Ta )
To find mg :(ma +1)xmf=(14+1)x =0.204kg/s
Hence, Heat to exhaust gases=0.204x1.015(760-21)
=153kJ/s (26.1%)
(iv) Unaccounted Heat=356kJ/s (61%) (by difference)

74. Supercharging
&
Turbocharging

75. Syllabus : IC Engines SUPERCHARGING
Supercharging and turbo-charging methods and their limitations

76. Lecture No 29 Learning Objectives:
To learn effects of supercharging /turbo-charging and
limitations

77. How can engine power be increased?
Increasing Eng speed (BP= T x 2πN)
(FP ∞ N2 & Volumetric η ↓ )
Higher CR (Peak Pr increases; Thermal Load
increases; Weight to Power ratio increases)
(HUCR limited due to knocking/detonation in SI
engines and heat load in CI engines)
Utilization of exh energy in gas turbine, thus ↑ BP
Use of 2-stroke cycle; but cooling, emission
problems, lower volumetric & thermal efficiency
Increasing charge density by
- Lowering charge temp (Cooling) and / or
- Increasing induction pressure

78. Objectives of Supercharging
To increase power output
To reduce bulk size of engine
To increase power to weight ratio
To compensate loss of power at high altitude

79. Supercharging Supplying air /Air-Fuel mixture at higher pressure
than the pressure, at which the engine naturally
aspirates, by a boosting device is called
supercharging
The device which boosts the pressure is called
supercharger.
Purpose of supercharging to have small displacement
engines but developing more power and to meet
emission legislation on fuel consumption for emission
control
More power is achieved by raising density of charge,
thus more mass of air making available more oxygen
for combustion

80. Supercharging & Turbo Charging Systems

82. Effects of Supercharging
Increased Eng Output (p-V diagrams)
Turbulence Effect (Higher BP)
Power required to drive supercharger, thus ↓ BP
Mech Efficiency increases
bsfc ↑ for SI (due to reduced delay) but ↓ for CI
engines due to better combustion & higher
mechanical efficiency
Better scavenging; Increase in power output
SI Engines→ Knocking tendency as ign delay ↓
For CI Engines→ Smoother running, low F/A
ratio, ↑ durability & reliability and lower bsfc

83. Effects of Supercharging
Better atomization
Better mixing of air and fuel
Reduced exhaust smoke
Better torque characteristic over whole speed range
Better and smoother combustion
Increased thermal stresses
Increased gas load
Increased valve overlap period of 60° to 160° of
crank angle
Increased cooling requirements of piston and valves

84. P-V Diagrams of Naturally Aspirated & Supercharged Engines4 3 p p
+(c) 4 3 5 6 2
+(a) 5 6 2 7 1
+(d)
patm
patm 7 1
-(b) V V
Naturally Aspirated Engine
Supercharged Engine

85. Limitations of Supercharging
Power o/p limited by knock, thermal & mech loads
For SI engines, knocking reached earlier
In CI Engs, thermal & mech loads reached earlier
Increase in intake pr increases peak pr leading to
increase in weight of cylinder (limitation on peak pr)
Increase in peak pr→ ↑ tendency to detonate (SI)
Increase in peak pr increases friction losses
Increase in peak pr, increases bearing loads
↑ peak pr → ↑ peak T →Reqmt of better cooling sys
↑T → ↑ exh gas temp →overheating of exh valves
Due to the above reasons, supercharging
generally limited to 2.5 bar

86. Limitations of Supercharging In SI Engs.
Detonation is the limitation as it increases with ↑ pr,
↑ T, ↑ CR, ↑ density of charge
Strongest detonation at stoichiometric A/F ratio
CR limited due to detonation for given Octane
Rating of fuel used
Detonation can be reduced by reducing CR but
BP & thermal efficiency decreases & bsfc increases
For the above reasons, SI Engines are normally
NOT supercharged except for aircraft, high altitude compensation or higher power of aero engines required at the time of take off of aircraft at the expense of higher fuel consumption

87. Limitations of Supercharging In CI Engs.
Increased induction pr helps in suppressing
knocking tendency, improve combustion,
higher power output & thermal efficiency and
hence can use lower Cetane fuels
Supercharging is limited by:
- peak pressure →mechanical loading
- peak temp →thermal loading
- thermal stresses developed
- mean temp of cylinder walls
- loads on bearings

88. Lecture No 30 Learning Objectives:
To understand methods of supercharging
To learn various methods of turbocharging

89. Types of Superchargers
Centrifugal Type Supercharger
Root’s Type Supercharger
Vane Type Supercharger

90. Centrifugal Type Supercharger

91. Root’s Type Supercharger

92. Vane Type Supercharger

93. Vane Type Supercharger

94. Arrangements of Supercharging
After Cooler
Air outlet from
Compressor
Inlet to Engine
Exhaust from
Engine
Compressor
Gears
Engine
Load
Air inlet to
Compressor

95. Arrangements of Turbocharging
Air inlet to
Compressor
Exhaust from
Turbine
Compressor
Turbine
After Cooler
Air outlet from
Compressor
Exhaust from
Engine
Inlet to Engine
Engine
Load

96. Method of Super/Turbocharging
After Cooler
Air outlet from
Compressor
Exhaust from Engine
Inlet to Engine
Turbine
Compressor
Load
Engine
Exhaust from
Turbine
Air inlet to
Compressor

97. Method of Super/Turbocharging
Exhaust from
Turbine
After Cooler
Load
Turbine
Air outlet from
Compressor
Inlet to Engine
Exhaust from
Engine
Compressor
Gears
Engine
Load
Air inlet to
Compressor

98. Turbochargers generated in the eng cylinder
Exhaust gases carry about 1/3 of the total energy
generated in the eng cylinder
In order to utilize this energy, hot gases can be
allowed to expand further in a gas turbine and its
work output can be utilized to drive a supercharger.
This system of supercharger coupled to Turbine is
called Turbocharger
Due to cyclic fluctuations of the pressure in exhaust
pipe, turbo charging is not employed in single
cylinder eng, however, system is suitable for
engines having 4 or more cylinders

99. Turbo Charger Advantages Disadvantages
Turbocharger does not consume eng power
No gearing required between turbine and
compressor as both are connected by single shaft
Gain in power at nominal cost
Exhaust energy, which is 1/3 of total energy
generated in the engine, is gainfully utilized
Exhaust noise level reduces
Suitable for high speed engines
Disadvantages
Increase in fuel consumption at low power output
Total cost of unit increases

101. End of Unit - IV