ethanol optimized engine

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


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.

6

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

7

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.

8

31

32

33

34

35

36

37

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.

9

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.

11

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

12

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

13


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


50.0 gal gas

SAE 2009-01-1490

40


14



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


50.0 gal gas

SAE 2009-01-1490

40


15


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


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


50.0 gal gas

SAE 2009-01-1490

40


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.

16

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

17

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

18

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

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


19DOE 2009 Merit Review

Approach

20

• 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


1Laser Doppler Anemometry

21

CameraEXCIMER

LASER

BeamSplitter

Single CylinderEngine

SAE 2010-01-0585

Optical Engine Development

22

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


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.


Optical Engine2000 RPM Full Load, Ethanol, LIF Images

24

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

25

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.

26

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

27

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.


Multi-Cylinder Engine DevelopmentAlternative Paths

28

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.

29

22

24

26

28

30

32

34

36

38

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

31

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)

32

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.

33

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).

34

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.

35

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.

36


Thank you for your attention.

Questions?

37


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

39

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.

ethanol optimized engine

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