Engine, Emissions and Vehicle Research DivisionSouthwest Research Institute (SwRI)

SwRI’s HEDGE Technology for High Efficiency, Low Emissions

Gasoline Engines

Terry Alger

DEER ConferenceDetroit, MI

29 September 2010

Current State-of-the-Art Engine Technology Diesel

● World-class efficiency, but expensive NOx & PM aftertreatment

Spark ignited gasoline● Less efficient, but best tailpipe

emissions w/ inexpensive catalyst

Gasoline fuel consumption (g/kWh)

1000 2000 3000 4000 50002468

101214161820

BM

EP (b

ar)

RPM

237 g/kWh

2008 turbopasscar

800 1000 1200 1400 1600 1800 20002468

10121416182022

BM

EP

RPM

Diesel fuel consumption (g/kWh)

2008 on-roadengine

191 g/kWh

At what cost / emissions level can SI and CI engine efficiencies

converge?

SwRI HEDGETM Technology A high efficiency solution for the gasoline engine

● Improved low-load BSFC → high CR and reduced PMEP● Improved high-load BSFC → high CR and reduced knock● Eliminates need for enrichment → cooler PTT at high load● Suppresses low speed pre-ignition (LSPI)

Applicable to many platforms (LD-HD)

0.06 0.08 0.1 0.2 0.4 0.60.8

1

2

4

68

10

20

40

Cylin

der P

ress

ue [b

ar]

Cylinder Volume [L]

0% EGR 5% EGR 10% EGR 15% EGR 20% EGR

Cycle Efficiency Improvement with EGR

0 5 10 15 200

10

20

30

40

Loca

tion

of 5

0% M

FB [0 a

TDCf

]

EGR [%]0 5 10 15 20

1.290

1.292

1.294

1.296

1.298

1.300

1.302

Cyc

le-A

vera

ged γ

[-]

EGR [%]

Improved Charge Properties

Reduced Knock Tendency / Improved

Combustion Phasing

0 5 10 15 20-0.22

-0.20

-0.18

-0.16

-0.14

-0.12

-0.10

PMEP

[bar

]

EGR [%]

Reduced Pumping Losses

(load specific)

Result:~ 10% BSFC improvement at low loads10-30% BSFC improvement at high loads

Emissions Reduction with EGR

Significant emissions reductions possible

May reduce aftertreatmentcosts / PGM use

Lack of enrichment means emissions compliance on highly-loaded cycles

Gaseous emissions reduction is platform independent

GDI PM/PN reduction with EGR may offer emissions compliance without a filter● PM/PN reduction maintained at

high power levels

0 5 10 15 20 25 300

4

8

12

16

20

24

28

EGR [%]

BSCO BSNOx BSHC BSPM [x1000]

Em

issio

ns [g

/kWh]

CO, NOx and PM are reduced at lower combustion temperatures

Reduced post-flame oxidation

TC MPI engine 1500 rpm / 10 bar bmep

TC GDI engine2500 rpm / 7 bar bmep

Reduced Exhaust Temperatures

Reduced exhaust temperatures eliminated enrichment requirement● Can meet emissions at WOT for HD / off-road certification● Immediate 5-30% reduction in BSFC at WOT

Allows for variable geometry turbines May reduce catalyst aging / durability requirements Potentially decrease the cost of exhaust hardware

0 5 10 15 20 25650

700

750

800

850

900

Pre-

Turb

ine

Tem

pera

ture

s [o C]

Cooled EGR [%]

High Speed / High Load Condition

Elimination of LSPI

EGR suppresses LSPI occurrence● > 15% cooled EGR eliminates it completely

Combination of improved phasing / earlier spark and increased ignition delay with EGR

BMEP

No. of PI Events per

30,000 engine cycles

1250 rpm

Advanced Ignition Systems: Electrical Ignition

High EGR mixtures are difficult to ignite● EGR rate limited by combustion

instability SwRI ‘s DCO™* system maximizes

EGR tolerance● Long duration discharge● Energy use can be tailored for operating

conditions Sole ignition source in LD

applications Used in SI mode for dual-fuel

applications

0 5 10 15 200

2

4

6

8

EGR [%]

Low Speed / Low Load

SwRI DCO system

Stock ignition system

CoV

IMEP

[%]

9% reduction in BSFC

* Patent Pending

Advanced Ignition Systems:Pilot Ignition

Typical fuel fractions:● 85-95% gasoline● 15-5% diesel fuel

High pressure not required

For best efficiency, use pilot ignition● Ignition fluid is a “chemical spark

plug” Useful in applications that typically

employ a diesel engine

PFI: Gasoline

DI: Ignition FluidSpark plug

SwRI Dual-Fuel Multi-Mode Concept

Mid-Load Condition

50

1200 1600 2000 2400Engine Speed [rpm]

BMEP

[bar

]

40

1200 1600 2000 2400Engine Speed [rpm]

BMEP

[bar

]

Enabling Technologies: Boost System

1500 RPM

5000 RPM

Boosting at high dilution levels (EGR with or without lean burn) is challenged by● High pressure ratios● Low exhaust temperatures reduce the blade speed ratio and

maximum turbine efficiencies● For LD - broad speed range (800 RPM to 5000 RPM) requires

wide flow range● Transient performance must be maintained

2-stage boosting is required for dilution levels > 25%High dilution engine with 2-stage boosting

> 40% EGR 0.85 < φ ≤ 1

ITE [%]

Air handling realities and transient

requirements rapidlydecrease indicated

efficiencies

BTE [%]

Light Duty Results Fuel consumption

significantly reduced from baseline● 5-11% at low loads● 10-40% at high loads

Demonstrates potential for high-efficiency downsized application

BSFC [g/kWh]

240

1500 2000 2500 3000 3500 4000 4500 50002

4

6

8

10

12

14

16

18

20

22

Engine Speed [rpm]

BMEP

[bar

]

BSFC [g/kW-hr]

MPI application ( > 11:1 CR)

GDI application (> 10:1 CR)

MD Results MD application can match diesel

torque and BSFC with ultra-low emissions● TWC compliant● Packaging and cost benefits for off-

road applications● SwRI working on large-bore, multi-

cylinder application

310270

250240230

220

210

1000 1200 1400 1600 1800 2000 2200 24002

4

6

8

10

12

14

16

18

20

g

Engine Speed (rpm)

BMEP

(bar

)

40

1200 1600 2000 2400Engine Speed [rpm]

BMEP

[bar

]

BTE [%]

Peak BTE ~ 42%

Option for all-electric application with small BTE penalty

Alternative fuel compatible CNG LPG Alcohols

Summary Cooled EGR is a solution

to both efficiency and emissions concerns● Very low cost / benefit

ratio compared to alternative options

● Significant efficiency increases while maintaining or reducing emissions- May present solution for

GDI PM challenge SwRI’s HEDGE

technology addresses many of the issues in cooled EGR performance● Control● Stability● Performance