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Developing New Methods, Techniques to Improve Heavy-Duty Natural Gas Engine Performance
By: Mehrzad KaiadiSupervisor: Associate Prof. Per Tunestål
GERG ACADEMIC NETWORK EVENT - 2010
Division of Combustion Engines, Dept. of Energy Sciences
Lund UniversitySweden
Gas Engine @ Lund University
Contents
BackgroundObjectivesExperimental setupResults ConclusionFuture Work
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Gas Engine @ Lund University
Background
World Energy Consumption World CO2 Production
Source: Energy Information Administration (EIA)
3
Gas Engine @ Lund University
Background
The main fuel in transporttation sector are Diesel & Gasoline
Natural Gas is a good alternative fuel
Availability
Reliability of resources
Costs
Bridge to “Hydrogen Society”
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CH4 + H2O --> CO + 3H2
Gas Engine @ Lund University
Background
High octane number
Source: Heywood
Cleaner fuel (mainly CH4)
Natural gasGasoline
Source: SwRI
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Gas Engine @ Lund University
Background
Stoichiometric better choiceAlmost same performanceLower emissions (3-way CAT)
Stoichiometric better choiceAlmost same performanceLower emissions (3-way CAT)
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Gas Engine @ Lund University
Objectives
Lower Comp-RatioThrottling losses Lower Comp-RatioThrottling losses
Lower fuel densityLower Comp-RatioHigher Exhaust-TempKnock
Lower fuel densityLower Comp-RatioHigher Exhaust-TempKnock
Narrow A/F windowNarrow A/F window
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Gas Engine @ Lund University
Experimental Setup
Number of Cylinder
6
Displacement 9,4 Liter
Bore 120 mm
Stroke 138 mm
Compression Ratio
10,5:1
Ignition sequence
1-5-3-6-2-4
Fuel Natural Gas
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Gas Engine @ Lund University
New features
Multi-Port fuel injection is designed (Single point injection is replaced)
Why?
Control fuel injection for each cylinder individuallyRapid engine response to change throttle position
Ion-Current measurments
Flexible control system 9
Gas Engine @ Lund University
Results
High performance Model-based controllers to ensure the transient capability
Hythane
Improving Engine Efficiency at Part LoadsClosed-loop dilution limit controlDeveloping new method for calculating combustion stability
Engine modifications to improve efficiency & Extend the Maximum load limit 10
SAE Paper#2008-01-1722
EGR Reduces Throttling Losses
Throttle
1- Without EGRAir
Same load
Air 2- With EGREGR
Using optimum amount of EGR can minimize the losses
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SAE Paper#2008-01-1722
Calculation of COV(IMEP)COV is a normalized standard deviation over large number of
cyclesMean value changes during transients
Replacing mean value by filtered IMEP to remove deterministic changes from COV
( 1) ( ) (1 ) ( )filtered m filtered m netIMEP k IMEP k IMEP kλ λ+ = + −
2( )
100( )
net
imep
IMEP IMEPNCOV
IMEP
⎛ ⎞−⎜ ⎟⎜ ⎟= ×⎜ ⎟⎜ ⎟⎜ ⎟⎝ ⎠
∑
mλ Selected depending on expected time constants
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SAE Paper#2008-01-1722
Calculation of COV(IMEP)
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SAE Paper#2008-01-1722
Control
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SAE Paper#2008-01-1722
Pumping Losses
EGR Valve Position [%]
Thro
ttle
Pos
ition
[%]
PMEP [Bar] @ 1200 RPM
0 20 40 60 80 10026
28
30
32
34
36
38
40
42
44
BMEP 2.5 barBMEP 4 barBMEP 5.5 bar
0.3
0.35
0.4
0.45
0.5
0.55
0.6
Unstable region
Not tested data
10 %PMEP decreases
10 %PMEP decreases
25%PMEP decreases
25%PMEP decreases
36%PMEP decreases
36%PMEP decreases
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SAE Paper#2008-01-1722
Fuel Consumption
EGR Valve Position [%]
Thro
ttle
Pos
ition
[%]
SFC [g/kWh] @ 1200 RPM
0 20 40 60 8025
30
35
40
45
240
260
280
300
320
BMEP 2.5 barBMEP 4 barBMEP 5.5 bar
Unstable region
Not tested data
4.5 %Lower fuel Consumption
4.5 %Lower fuel Consumption
5 %Lower fuel Consumption
5 %Lower fuel Consumption
5.9 %Lower fuel Consumption
5.9 %Lower fuel Consumption
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Gas Engine @ Lund University
Engine Modification
New Piston design Higher compresion ratio Higher turbulence level
New EGR ConfigurationHigher EGR rateFaster & more rebust control of EGR
VGTAdjusting boost pressureMinimizing throttle losses
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Gas Engine @ Lund University
Improving Efficiency
800 1000 1200 1400 1600 18000.38
0.4
0.42
0.44
0.46
0.48
Engine Speed [RPM]
Gro
ss-In
dica
ted
Effi
cien
cy [-
]
Gross-Indicated Efficiency Vs. Engine Speed @ WOT
Original PistonQuarttet Piston
800 1000 1200 1400 1600 180010
12
14
16
18
20
22
24
26
28
Engine Speed [RPM]
Com
bust
ion
Dur
atio
n [C
AD
]
Combustion Duration Vs. Engine Speed @ (WOT)
Original PistonQuarttet Piston
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Gas Engine @ Lund University
Extending the dilution limit
0 5 10 15 200
10
20
30
40
50
60
70
EGR Rate [%]
CO
V [%
]
Cyclic variation Vs. EGR rate / Original Piston
Cylinder 1Cylinder 2Cylinder 3Cylinder 4Cylinder 5Cylinder 6
0 5 10 15 20 25 300
10
20
30
40
50
60
70
80
EGR Rate [%]
CO
V [%
]
Cyclic variation Vs. EGR rate / Quartette Piston
Cylinder 1Cylinder 2Cylinder 3Cylinder 4Cylinder 5Cylinder 6
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Gas Engine @ Lund University
Extending the load limit
800 1000 1200 1400 1600 18009
10
11
12
13
14
15
16
17
18
19
20
Engine Speed [RPM]
BM
EP
[Bar
]Maximum Load Vs. Engine Speed @ (WOT)
Original PistonQuarttet PistonQuarttet Piston & VGT
18% higher load
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Gas Engine @ Lund University
Conclusions
New methods & Techniques are developed to
Improve efficiency @ all operation areaExtend Maximum load limit by ~18%Ensure catalyst high efficiency
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Gas Engine @ Lund University
Future Work
Minimizing throttling losses be means of VGT
Lots of potentials by running on LNGUtilizing the Cold Energy
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