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Ethanol Optimized Engine
Ford Motor Company
AVL Powertrain Engineering, Inc.
Ethanol Boosting Systems LLC
USDA Biofuel Seminar Series March 29, 2011
This work was partially funded by the US
Department of Energy
2
Ethanol Optimized Engine
Public domain sources used for the slides in this presentation:
DOE merit reviews and annual reports
SAE 2009-01-1490, "Optimal Use of E85 in a Turbocharged Direct
Injection Engine”
SAE 2010-01-0585, “Development of the Combustion System for a
Flexible Fuel Turbocharged Direct Injection Engine”
Paper not referenced in this presentation, but written based on work
performed during the course of the project:
SAE 2011-01-0337, “Blowdown Interference on a V8 Twin-
Turbocharged Engine”
3
Presentation Outline
• Project overview and objectives
• Background
• Charge cooling with direct injection of ethanol
• Dual fuel (E85 DI + gasoline PFI) concept and leveraging
• E85 optimized engine initial targets and approach
• Optical engine and single cylinder engine development
• Multi-cylinder engine development
• Comparison to baseline gasoline engine
• Summary
4
Project Overview
• Joint project with Ford (project lead), AVL, and EBS to design and develop an ethanol optimized engine including dual fuel capability for the F-Series pickup.
• Timeline• Project start date – Oct 2007• Project end date – Dec 2011
5
Initial Project Objectives
• Develop a roadmap to demonstrate a minimized fuel economy penalty for a F-series FFV pickup truck with a highly boosted, high compression ratio spark ignition engine optimized to run
with ethanol fuel blends up to E85.
• Develop and assess a dual fuel concept for on-demand direct
injection of E85.
• Reduce FTP 75 energy consumption by 15% - 20% compared to an equally powered vehicle with a current production gasoline
engine.
• Meet ULEV emissions, with a stretch target of ULEV II / Tier II Bin 5.
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Background - Ethanol Properties
base.64 x baseCO2 emissions (gCO2/L)
base0.65 x baseNHV volumetric basis (MJ/L)
base.97 x baseCO2 emissions (gCO2/MJ)
~ 43.526.9NHV (MJ/kg)
base3.9 x baseHeat of vaporization at stoich1
~ 0.7450.785Density (kg/L)
base1.0 x baseNHV of stoich fuel quantity1
~ 14.69.0Stoichiometric A/F
~ 350840Heat of vaporization (kJ/kg)
91 - 98108Octane (RON)
GasolineE100
SAE 2009-01-1490
1per quantity of air
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550
600
650
700
750
800
850
900
950
1000
1050
1100
-40 -30 -20 -10 0 10 20 30 40 50 60
Crank Angle [°BTDC]
Un
bu
rned
Gas T
em
p [
K]
PFI Gasoline NA 10:1 CR
DI Gasoline NA 10:1 CR
DI Gasoline 2.35 bar Boost 12:1 CR
DI Ethanol 2.35 bar Boost 12:1 CR
PFI, 10 CR, naturally aspirated
DI, 10 CR, naturally aspirated
DI, 12 CR, boosted
DI, 12 CR, boosted, Ethanol
gasoline
130 C
DOE 2009 Merit Review
Background – Charge Cooling with Direct Injection of Ethanol
Lower peak unburned gas temperature directly correlates with reduced knock.
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5 10 15 20 25 30
CA50 (deg aTDC)
Bra
ke
Th
erm
al E
ffic
ien
cy
(%
)
Background – Combustion Phasing
Peak Brake Thermal Efficiency
Thermal efficiency penalty of spark retard
Retarding spark timing
CA50% Burned (deg aTDC) or CA50 (deg aTDC):Location in Crank Angle degrees after TDC where 50% of the air-fuel mixture has burned. Optimum CA50 for best thermal efficiency occurs ~ 5 - 7 aTDC.
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Background - Effect of E85 DI on Knock
Direct injection of E85 is very effective in suppressing knock!
0
5
10
15
20
25
30
6 8 10 12 14 16 18 20 22
BMEP (bar)
CA
50
% b
urn
ed
(°A
TD
C)
E85
98 RON
Gasoline
MBT
Slight spark
retard to
control peak
pressure
700
750
800
850
900
950
1000
6 8 10 12 14 16 18 20 22
BMEP (bar)
Tu
rbin
e in
let te
mp
(d
eg
C)
E85
98 RON
Gasoline
SA
E 2
009
-01
-14
90
BMEP = Brake Mean Effective Pressure:A measure of torque per unit of engine displacement expressed in units of pressure (bar).
10DOE 2009 Merit Review
Background - Dual Fuel Concept
Rationale:
E85 provides large octane benefit with direct injection due to high heat
of vaporization and high inherent octane.
This allows knock-free operation at high compression ratio and high
BMEP with very high thermal efficiency.
but…
Low E85 heating value per volume is a disadvantage for mpg fuel
economy and fuel tank range.
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Dual Fuel (E85 DI + Gasoline PFI) Concept
Combines high load E85 octane benefit with part load gasoline heating value advantage
First proposed by Cohn, Bromberg, and Heywood of MIT
Gasoline, with its high heating value per volume, is the primary fuel
E85 used only as required to avoid knock
Compression ratio and boost increased
Higher CR, downsizing, and downspeeding improve efficiency
Provides maximum leveraging of available ethanolSAE 2009-01-1490
E85 Tank
E85 DI
Gasoline Tank
Gasoline PFI
E85 Tank
E85 DI
Gasoline Tank
Gasoline PFI
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Example Leveraging – EPA M/H Cycle
40
45
50
55
60
65
70
75
5.0L GTDI9.8:1 CR
Gallo
ns U
sed in 1
000 M
iles
Gallons E85 UsedGallons Gasoline Used
50.0 gal gas
SAE 2009-01-1490
40
GTDI = Gasoline Turbocharged Direct Injection
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Example Leveraging – EPA M/H Cycle
5.0L TDI FFV9.8:1 CR
72.5 gal E85
1 gal E85
replaces
0.7 gal
gasoline
40
45
50
55
60
65
70
75
5.0L GTDI9.8:1 CR
Gallo
ns U
sed in 1
000 M
iles
Gallons E85 UsedGallons Gasoline Used
50.0 gal gas
SAE 2009-01-1490
40
GTDI = Gasoline Turbocharged Direct Injection
14
Example Leveraging – EPA M/H Cycle
5.0L TDI FFV9.8:1 CR
72.5 gal E85
1 gal E85
replaces
0.7 gal
gasoline
5.0L Dual Fuel12:1 CR
47.5 gal gas
0.5 gal E85
40
45
50
55
60
65
70
75
5.0L GTDI9.8:1 CR
Gallo
ns U
sed in 1
000 M
iles
Gallons E85 UsedGallons Gasoline Used
50.0 gal gas
SAE 2009-01-1490
40
GTDI = Gasoline Turbocharged Direct Injection
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Example Leveraging – EPA M/H Cycle
The Dual Fuel (E85 DI + gasoline PFI) concept:
� Makes the engine more efficient in its use of gasoline
� Thereby leveraging the benefit of the available ethanol in reducing gasoline consumption
5.0L TDI FFV9.8:1 CR
72.5 gal E85
1 gal E85
replaces
0.7 gal
gasoline
5.0L Dual Fuel12:1 CR
47.5 gal gas
0.5 gal E85
1 gal E85
displaces
5 gal
gasoline
Extra 2.5 gal gas
40
45
50
55
60
65
70
75
5.0L GTDI9.8:1 CR
Gallo
ns U
sed in 1
000 M
iles
Gallons E85 UsedGallons Gasoline Used
50.0 gal gas
SAE 2009-01-1490
40
GTDI = Gasoline Turbocharged Direct Injection
Note: Leveraging effect is dependent on
the drive cycle, and on the amount of compression ratio increase and engine
downsizing / downspeeding. 5:1
leveraging is not a general rule-of-thumb.
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Design and develop a new V8 engine for the ethanol optimized
engine project.
• Dual fuel (E85 Direct Injection + gasoline Port Fuel Injection)
• Twin-turbocharged
• Structure designed for 150 bar peak cylinder pressure
• Twin-Independent variable cam timing
• Roller finger follower valvetrain
Ethanol Optimized Engine Project
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Ethanol Optimized Engine ProjectFueling Alternatives
Fueling alternatives used during engine testing:
• Dual Fuel: E85 direct injection combined with gasoline port fuel
injection
• E85 is used only as required to avoid knock, either at the CA50 for best thermal efficiency or at a specified CA50.
• ETDI: Ethanol Turbocharged Direct Injection
• GTDI: Gasoline Turbocharged Direct Injection
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500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500
Engine Speed (rpm)
BM
EP
(b
ar)
GTDI 91 RON
ETDI (FFV & Dual Fuel)
Support flex fuel and dual fuel operation
• Address V8 residual imbalance issues due to blowdown interference
• Maximize low end torque with scavenging with variable cam timing
• Minimize gasoline fuel enrichment at full load (for flex fuel application)
• Minimize cylinder wall wetting with fuel with direct injection
• Develop rapid catalyst heating strategies utilizing dual fuel
Initial Development Targets
DOE 2009 Merit Review
19DOE 2009 Merit Review
Approach
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• 1-D modeling
• Determine initial cam timings and turbocharger match.
• 3-D CFD, LDA1 flow rig, optical engine, and conventional single
cylinder engine
• Optimize in-cylinder charge motion, fuel spray, and piston bowl.
• Multi-cylinder engine
• Develop cam events, variable cam timing strategy, compression
ratio, turbocharger matching, and air induction system.
• Multi-cylinder engine mapping
• Develop vehicle level projections of performance and fuel
economy for various driving cycles.
• Transient cold start multi-cylinder engine
• Optimize starting strategy for low emissions, fast catalyst light-off, and good combustion stability.
Approach
DOE 2009 Merit Review
1Laser Doppler Anemometry
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CameraEXCIMER
LASER
BeamSplitter
Single CylinderEngine
SAE 2010-01-0585
Optical Engine Development
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Planar Double
Sided LIF ImageFlame Image
Raw
Image
Statistical
Image
Evaluation
The optical engine is used to optimize mixture preparation, eliminate
cylinder bore wall wetting, and optimize catalyst heating and cold start.
Optical Engine: Laser Induced Fluorescence and Combustion Photography
DOE 2009 Merit Review
23
pV3iDT1_E85_2015hL
0
1001
100
low
Density
high
Fuel
Probability
[%]
Fuel spray
direction
Air intake
flow
No wall wetting
Satisfactory full load mixture preparation even with E85 flow rates. Significant
beneficial fuel spray/air motion interaction even at low speed (where air motion is
low) leading to no cylinder bore wall wetting issues.
DOE 2009 Merit Review
Optical Engine2000 RPM Full Load, Ethanol, LIF Images
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Gasoline DIGasoline DI
E85 DIE85 DI
0
1001
100
Flame
Probability[%]
Premixed
Flame
Soot Flame
0
1001
100
Flame
Probability[%]
Premixed
Flame
Soot Flame
No sooting flames with E85
• Ethanol has a single boiling
point of 78.3°C, whereas
gasoline has a range up to
200°C. Thus E85 vaporizes
more readily after impingement
on the piston.
• Ethanol is oxygenated which
facilitates combustion of rich
regions without making soot.
Optical Engine: Gasoline vs. E85Combustion During Catalyst Heating
SAE 2010-01-0585
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Single Cylinder Engine Development
DOE 2010 Annual Report
Single cylinder engine was used to finalize the combustion system prior to procuring multi-cylinder engine components.
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Multi-Cylinder Engine Development
Engine Configuration
90°V8 Dual Fuel
Bore-stroke ratio: 0.88 Twin turbochargers
Compression ratio: 9.5:1 and 12:1 Twin Independent VCT
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Two alternative paths investigated for the dual fuel engine.
9.5:1 Compression Ratio
Normal functional performance on gasoline (but reduced relative to E85) if E85 is not available.
12:1 Compression Ratio
Greater improvement in efficiency, but compromised performance on gasoline due to knock if E85 is not available.
Both paths utilize downspeeding/downsizing for improved efficiency.
Ethanol Optimized Engine
Multi-Cylinder Engine DevelopmentAlternative Paths
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20
25
30
35
40
1000 2000 3000 4000 5000
Engine Speed (rpm)
BT
E (
%)
10
14
18
22
26
30
34
1000 2000 3000 4000 5000
BM
EP
(b
ar)
Multi-Cylinder Engine Full Load Comparison ETDI (E85) vs. GTDI (91 RON) at 9.5:1 CR
E85 allows stoichiometric operation over the entire engine map:• Maintains TWC function for
US06 and all off-cycle conditions.
• Provides very high power for Dyno Cert applications.
• Achieves high brake thermal efficiency.
• Avoids fuel economy penalty due to enrichment.
91 RON, λ = 0.8
91RON, λ = 1
E85, λ = 1
E85, λ = 1
91RON, λ = 1
91 RON, λ = 0.8
Note: Higher BTE is possible with E85 with increased compression ratio.
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30
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2 4 6 8 10 12 14 16
BMEP (bar)
Bra
ke E
ffic
ien
cy (
%)
Multi-Cylinder Engine at Part LoadE85 Consumption for the Dual Fuel Engine at 1500 RPM
• E85 is directly injected only as required to avoid knock at optimum CA50.
• Enables high brake thermal efficiency as BMEP is increased.
GTDI
Dual Fuel
Dual Fuel
Dual Fuel
GTDI
GTDI
Optimum Phasing
0
5
10
15
20
25
30
2 4 6 8 10 12 14 16
CA
50 (
deg
aT
DC
)
Note: E85 Mass Ratio = E85 flow rate ⁄ total fuel flow rate (E85 + gasoline)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
2 4 6 8 10 12 14 16
BMEP (bar)
E85 M
ass R
ati
o
30
245
250
255
260
265
270
0 5 10 15 20 25 30
CA50 (deg aTDC)
Co
mb
ine
d B
SF
C(g
/kW
h)
30
32
34
36
38
0 5 10 15 20 25 30
Bra
ke
Th
erm
al E
ffic
ien
cy
(%
)
0.0
0.1
0.2
0.3
0.4
0.5
0 5 10 15 20 25 30
CA50 (deg aTDC)
E8
5 R
AT
IO
Dual Fuel Engine: Effect of Combustion Phasing E85 Consumption for High Load Conditions
Moderate combustion phasing retard: • Significantly reduces amount of E85
required to avoid knock.• Increases E85 fuel tank range.• Minimizes combined (gasoline + E85)
fuel consumption.
Heating value penalty of E85 (by mass)
Thermal Efficiency penalty of CA50 retard
~ 60% Decrease
Note: Combined BSFC = (E85 mass flow rate + gasoline mass flow rate) ⁄ brake power
2500 rpm, 16 bar BMEP
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0
2
4
6
8
10
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35
E85 Mass Ratio
E85 T
an
k R
an
ge R
ati
o
Dual Fuel EngineE85 Tank Range in F-Series
Trailer tow is for 15,500 pound trailer at 70 mph in 5th gear
M-H Cycle
Trailer tow with combustion phasing retard
Trailer tow at best BTE
Assumes E85 tank is one third the size of the gasoline tank
E85 tank range ratio = range on E85 tank ⁄ range on gasoline tank
E85 mass ratio = E85 mass flow rate ⁄ total fuel mass flow rate (E85 + gasoline)
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0
4
8
12
16
20
Metro-Highway City-Suburban
Test Cycle
% F
ue
l E
co
no
my
In
cre
as
eComparison to Baseline Gasoline EngineVehicle Simulation Estimated Results for F-Series
Note: City-Suburban is a Ford test cycle for used pickup trucks.
The dual fuel engine provides improved fuel economy (mpg) and dramatically improved performance relative to the baseline gasoline engine.
0
4
8
12
16
20
24
Max Grade at 65 mph
in 6th Gear (%)
0-60 Time with Trailer
(sec)
Performance Metric
Gra
de
(%
) o
r T
ime
(s
ec
) Baseline Gasoline Engine
Dual Fuel Engine
Dual Fuel CR = 12:1
Vehicle simulation results based on multi-cylinder engine data adjusted to 12:1 compression ratio.
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Summary
• A dual fuel twin-turbocharged engine with structure capable of 150 bar
peak cylinder pressure was designed and developed.
• Combined 3D-CFD, LDA flow rig, optical engine, and single cylinder
engine development was used for optimization of direct injection
mixture preparation & combustion processes.
• Direct injection of E85 allows operation at stoichiometry at very high
BMEP levels with high thermal efficiency.
• E85 results in minimal soot emissions due to increased vaporization
after piston impingement and oxygen content.
• Moderate combustion phasing retard can be used to increase E85 fuel
tank range under towing conditions while minimizing overall fuel
consumption (gasoline + E85).
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Summary (continued)
• The dual fuel engine:
• Combines the heating value per volume advantage of gasoline with the high load octane advantage of E85.
• Provides improved efficiency via higher compression ratio and increased BMEP which allows greater levels of downsizing and downspeeding.
• Significantly leverages the use of ethanol in reducing gasoline consumption and CO2 emissions.
• Successful implementation of the dual fuel engine depends on:
• Convenient availability of E85.• Customer acceptance of filling two fuel tanks.
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Future Work in 2011
• Development and assessment of cold starting strategy for the dual
fuel engine on multi-cylinder transient engine dynamometer.
• Evaluation and mapping of the dual fuel engine at 12:1 compression ratio:• Fuel efficiency• Full load performance• E85 consumption and range
• Refinement and final assessment of vehicle level attributes.
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Ethanol Optimized Engine
Thank you for your attention.
Questions?
37
Ethanol Optimized Engine
Backup Slides
381000 2000 3000 4000 5000 6000
Engine speed [rpm]
Net IM
EP
[bar]
14
18
22
26
30
ISF
C [g/k
Wh]
240
270
300
330
360
Therm
al eff [%
]
25
30
35
40
45
Lam
bda [-]
0.90
0.95
1.00
1.05
1.10
1000 2000 3000 4000 5000 6000Engine speed [rpm]
CO
V [%
]
0
1
2
3
4
MF
B 5
0 [aT
DC
]
0
10
20
30
40
Exh. m
anifold
tem
p [°C
]
600
700
800
900
1000
Pm
ax+
3sig
ma [bar]
60
90
120
150
180
E85
RON91
2.5%
30°CA
150 bar
950°C
DI E85 operation permits MBT ignition (where not peak pressure limited) without requiring fuel enrichment even at much higher loads than gasoline. This leads to significant efficiency increase!
25%
MBT
DO
E 2
009 M
eri
t R
evie
wSingle Cylinder Engine: E85 vs. 91 RON
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20 40 60 80 100E85 [%]
ISF
C [g/k
Wh]
240
270
300
330
360
Therm
al eff [%
]
34.0
35.5
37.0
38.5
40.0
MF
B 5
0 [aT
DC
]
0
5
10
15
20
Pm
ax+
3sig
ma [bar]
90
110
130
150
170
20 40 60 80 100E85 [%]
ISF
C [g/k
Wh]
240
270
300
330
360
Therm
al eff [%
]
34.0
35.5
37.0
38.5
40.0
MF
B 5
0 [deg]
0
5
10
15
20
Pm
ax+
3sig
ma [bar]
90
110
130
150
170
18 bar NMEP24 bar NMEP27 bar NMEP
2000 rpm 3500 rpm
150 bar
Less than 100% E85 DI required to hold MBT ignition at high BMEP – minimizes E85 consumption increasing E85 range. Reduced E85 requirement when Pmax limited at higher speeds.
70-75% E85req’d for MBT 55-60% E85 req’d
MBT
18 bar NMEP24 bar NMEP26 bar NMEP
DO
E 2
009 M
eri
t R
evie
wSingle Cylinder Engine: Dual Fuel E85 DI % Sweeps
40
Energy ratio = energy content of ethanol = 1.671
energy to produce ethanol
EER = Effective energy ratio of ethanol used in Dual Fuel engine
with leveraging of 5:1 (as an example):
EER = energy content of saved gasoline = 14
energy to produce ethanol
For leveraging of 5:1, 14 MJ of gasoline energy are saved for
every 1 MJ of energy used to produce corn ethanol.
SAE 2009-01-1490
Effect of LeveragingNet Energy Value of Ethanol
1Shapouri, Hosein, Duffield, James, McAloon, Andrew, and Wang, Michael, "The 2001 Net Energy Balance of Corn-Ethanol", 2004.