19/8/2017

Engine Performance Monitoring

&
Trend Analysis

PARAMTERS NECESSARY FOR PERFORMANCE

MONITORING
ENGINE PERFORMANCE MONITORING
 Engine revolution
Cylinder cooling condition  Average mean indicated pressure (MIP)

Combustion performance  Fuel pump index

 Load Indicator
Specific fuel consumption  Exhaust temperature

Fuel injection system  Compression pressure (Pcomp)

 Max. Combustion pressure (Pmax)
Cylinder mechanical condition
 Indicated power (Pi)

Turbo-charger performance  Scavenge pressure (Pscav)

 Turbo-charger speed (Ntc)
Air cooler & Filter condition
 Air cooler diff. pressure (p)
Hull effect on engine condition  Air cooler temp difference (t)
(Air outlet and water inlet)

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Sea trial results Sea trial results

Engine data is recorded at
•50% Effect of Ambient temperature :
•75%
•90% • Scavenge pressure - Pscav
•100% load • Maximum pressure - Pmax
• Compression pressure - Pcomp
This data is used to develop • Exhaust temperature
performance curves after
correcting to ISO ambient
condition.

Sea trial Performance Curve

Indicator Cards
Performance curves plotted
Generally used to determine…
from sea trial data.
These curves are used for Compression pressure
comparison of current
performance of ship Peak pressure
with sea trial condition,
Engine Power
when ship’s performance was at
its peak. Engine Fault

Vital for assessing condition of cylinders.

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Indicator Cards Indicator Cards

Four types of indicator cards:

Power card
Draw card/Out of phase card
Light spring card
Compression card

Power card and draw card are generally used to assess the
performance of the engine.

But draw card is the most useful one as it provides more

information of the cylinder condition than a power card .

Indicator Cards Power Diagram

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Power Measurement Power Measurement

Brake Power ( PB )
Indicated power ( PI )
It is the measure of engine shaft power available at the
It is the theoretical power of an engine and measured by taking engine flywheel
indicator diagram from engine cylinder. It is less than indicated power by an amount equal to the
power necessary to overcome the engine’s internal friction.
Indicated power PI = Pm . L . A . N
It can be measured by using a hydraulic dynamometer or
L = stroke, A = piston area, N = number of working stroke/sec torsion meter

Pm is mean effective pressure i.e average pressure in engine

cylinder during complete cycle Brake Power = Indicated Power – Friction Power

Mechanical Efficiency Thermal Efficiency

The ratio of the power delivered by the engine to the total The thermal efficiency of an engine is the ratio of
power generated within the engine is known as mechanical work done by gases in moving the piston to the
efficiency of an engine. thermal heat energy of fuel injected for combustion.
Brake Power (PB)
Mechanical Efficiency =  x 100 %
Indicated Power (PI)

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Power Measurement

An engine indicator is
used to record pV or pwer
indicator diagrams

The areas of these

indicator diagrams
represent the work done
per cycle.

Draw Card - Normal

Planimeter for

Measuring Area of

Indicator Card

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Draw Card Interpretation Draw Card Interpretation

Advanced Ignition: Retarded Ignition:

Pcomp Normal Pcomp Normal

Pmax High Pmax Low

Causes: Poor fuel quality

FQS
Causes: Injection timing early
Fuel p/p suction v/v defective
Faulty p/p / injection timing
VIT incorrect
Faulty injector
Low fuel pressure

Draw Card Interpretation Draw Card Interpretation

Poor Cyl Mechanical Cond: Overloaded Condition :

Pcomp Low Pcomp High

Pmax Low Pmax High

Causes: Leaky Exhaust valve

Too low scav air pressure/ Scav port fouled
Burnt piston crown
Blw-by
Liner/cyl head crack
Effective load lower than normal

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Bar TYPICAL CYLINDER PRESSURE DIAGRAM Bar CYLINDER PRESSURE DIAGRAM

EFFECTS OF DEFECTIVE PISTON RINGS,
Cylinder T ign WORN LINER, BURNT PISTON CROWN
Pmax Tmax
pressure
Compression
35 bar IGNITION DELAY 70 pressure
Pcomp LOW P max

60
LOW P comp
T injo
Pexp 50
LOW P exp
o
36 40

30
LOW P mi

20
Pscav
P mi
10

o o o o o o o o o o o o
-180 -150 -120 -90 o -60 -30 o 0 +30 +60 +90 +120 +150o +180 o
-180o-150 -120 -90 o -60
o
-30
o
0 o +30 o +60
o o
+90 +120 +150 +180 o
Crank angle degrees o Crank angle degrees
36
Check combustion condition in all cylinders

Bar TYPICAL FUEL PRESSURE DIAGRAM

FUEL PRESSURE DIAGRAM
PUMP SPILL OPEN
P injo
EFFECTS OF WORN FUEL PUMP
Bar
Injection
pressure

FUEL VALVE OPENS LOW

INJECTION
PRESSURE

P injo

LATE
LOW RATE OPENING
FUEL VALVE OF
CLOSES OF RISE
L injo INJECTOR

REFLECTED DAM
PUMP SPILL PED
PRESSURE PRES
CLOSES S WA
T injo WAVE VE

REDUCED DURATION
P r
OF INJECTION

Crank
Crank angle
-20
o
-10
o
0
o
+10
o
+20
o
+30
o angle
degrees
0o degrees
TDC
Check that all cylinders are getting equal quantity of atomized
fuel at the right time.

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Light Spring Diagram Chocked Scavenge Port

1
Blow down 1 Fault
on opening of
exhaust valve Blow down Normal
4 3
P Scavenge pressure
inside cylinder
on opening of
exhaust valve 4 3
P Scavenge pressure
inside cylinder
2

2
V
1 - Exhaust valve open V
2 - Scavenge port open
3 - Scavenge port closed
4 - Exhaust valve closed

High Exhaust Back Pressure Engine RPM vs Average MIP

1 Fault
Normal 100 Loaded vessel
Blow down 90
Engine Revs (RPM)

on opening of Ballast
80 Test bed
exhaust valve 4
P 3 Scavenge pressure
inside cylinder
70

60

50
2 0 5 10 15

Average MIP (bar)

Torque rich/ overload
V Normal

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Max Pressure vs Average MIP Average Fuel Pump Index vs Average MIP

100 100
90 80

Av Fuel Pump Index

80 60
Pmax

70 40
60 20
50
0 5 10 15 0 5 10 15
Average MIP (bar) Average MIP (bar)

• All unit Pmax must be nearly equal Worn fuel pump  low calorific value
plunger
• If individual unit Pmax varies by 3 bar, it must be corrected  high specific gravity
leaky suction/spill
• Pressure rise Pmax – Pcomp must not exceed 35 bar valve  high water content

Average Fuel Pump Index vs Average MIP Average Exhaust Temp vs Effective power

100
450
80
Av Fuel Pump Index

60 400

40
Texh (C)

350

20
300
0
0 5 10 15 8000 10000 12000 14000 16000 BHP
Average MIP (bar)
Indicated Power (Kw/cyl)
It is recommended to overhaul the fuel pumps when index has
increased by about 10%
Incase the engine is operating with excessively worn fuel pumps, Majority of faults in air supply, combustion and gas systems manifest
the starting performance of the engine will be seriously affected. as increase in exhaust temperature level

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Increase in exhaust temperature

Checking mechanical condition
Item Cause Find out if compression pressure has
reduced due to mechanical condition or
Fuel injection Fuel injectors, worn fuel
pump, timing
scavenge pressure reduction
Cylinder condition Blow by, Exhaust valve leak
Mechanical condition will manifest as
Air coolers Fouled airside, fouled reduction in pressure ratio
waterside
Ambient conditions Extreme condition
Pressure ratio = Pcomp + Pbaro
Turbocharger Fouling turbine side
Fouling compressor side
Pscav + Pbaro
Fuel oil Type & quality

Mechanical defects Diff Press Across Air Filter vs Scavenge Pressure

Item Causes 10
∆Pc(air-filterr) (mmWC)

8
Piston rings Leaking 6

4
Piston crown Burnt
2

Cylinder liner Worn 0

1.5
0.5 1.0 2.0

Scavenge Air Pressure (Bar)

Exhaust valve Leaking
Timing • Filter elements must be cleaned if pressure drop is 50% higher
than testbed value

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Diff Temp Across Air Cooler vs Scavenge Pressure Diff Press Across Air Cooler vs Scavenge Pressure
(Temp Air Out – Temp Water In)

10 10

∆Pc(air-cooler) (mmWC)
8 8
∆T(air-water) (oC)

6 6

4 4

2 2

0 0
0.5 1.0 1.5 2.0 0.5 1.0 1.5 2.0

Scavenge Air Pressure (Bar) Scavenge Air Pressure (Bar)

• Fouling of air side & or fouling of water side

• Air cooler must be cleaned if pressure drop is 50% higher
• Heat transmission can be reduced by an oily film on tubes and fins than test bed value

Plotting the trends

Deviation of Fuel Pump Index vs Av MIP
Deviation of RPM vs Av MIP
100
Indicates : 100

90 80
Indicates :
Av. Fuel Pump Index
Engine Revs (RPM)

80 60

70 Hull fouling 40

60 20
Worn fuel pump
50 Propeller plunger
0 5 10 15 0 5 10 15
Average MIP (bar) Average MIP (bar)
Fouling leaky suction/spill
valve
(+ ve) Sea condition (+ ve)
low viscosity fuel
Loading
Deviation

Deviation

low calorific value

condition
(- ve) 01-Jan 15-Jan 01-Feb 15-Feb 01-Mar 15-Mar 01-Apr 15-Apr (- ve) 01-Jan 15-Jan 01-Feb 15-Feb 01-Mar 15-Mar 01-Apr 15-Apr
high specific gravity

high water content

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Engine Margin

&
Engine
Sea Margin
Layout
Diagram

If the engine & propeller are matched at 100% output, any weather or hull fouling will result
in reduction of engine speed to avoid overloading.

By including Sea Margin and Engine Margin full speed can be given with fouled hull or bad weather.

Ship Propulsion Running Points and Engine Layout Engine Load Diagram
Power

 Heavy propeller curve -

fouled hull and heavy weather
 Light propeller curve -
clean hull and calm weather
MP
MP: Specified propulsion MCR point
SP: Service propulsion point Engine margin
PD: Propeller design point (10% of MP)
SP
PD`: Alternative propeller design point PD´
LR: Light running factor Sea margin
HR: Heavy running (15% of PD)
PD

2 6 HR

Engine speed

< 47 >

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Load Diagram – Light Propeller Curve Load Diagram – Heavy Propeller Running
Engine shaft power, % A Engine shaft power, % A
Propeller design conditions: 110
Clean hull Fouled hull and
100 Very heavy seas
Calm weather 110
90 100

80 90
Light propeller curve Heavy propeller curve
where the propeller Where the engine is 80
70
is optimised optimised
70
60
60

50
50

40
40
60 65 70 75 80 85 90 95 100 110 60 65 70 75 80 85 90 95 100 105
< 49 > Engine speed, % A < 50 > Engine speed, % A

ENGINE

LOAD

DIAGRAM

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