RECENT DEVELOPMENTS IN LEAN-BURN IC ENGINES R.L. Evans Department of Mechanical Engineering The University of British Columbia Vancouver, B.C., CANADA

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

INTRODUCTION • Problems with both SI and DI engines • Engine combustion technology is “converging” • Lean combustion increases engine efficiency • Lean combustion reduces Nox emissions • The “Partially Stratified-Charge Engine”

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

Engine “Convergence” • Engine technologies may “converge”, particularly for vehicle applications • Combustion configuration may vary, depending on operating conditions • Stoichiometric homogeneous charge • Lean-burn homogeneous charge • Direct injection – stratified charge • Partially stratified charge • HCCI (Homogenous Charge Compression Ignition)

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

Engine Characteristics Homogenous Charge

Direct Injection

•Low Efficiency

•High efficiency

•Low PM

•High PM

•High Nox

•High Nox

•Medium loads

•High loads

Lean-Burn

HCCI

•Higher efficiency

•High efficiency

•Low PM

•Low PM

•Lower Nox

•Low Nox

•Lower loads

•Low loads

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

Load

Engine Operation as a Function of Speed and Load Homogeneous Charge Direct Injection

Lean- Burn & Partially Stratified-Charge HCCI Speed

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

THE “PARTIALLY STRATIFIEDCHARGE” ENGINE • Spark-ignited combustion • Main mixture is homogeneous & ultra-lean • Enriched mixture near spark plug • Engine control strategy is critical • Natural Gas or gasoline fuel THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

How it works… 1. Ultra-lean homogeneous charge of natural gas and air

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

How it works… 1. Ultra-lean homogeneous charge of natural gas and air 2. Fuel is injected in the region of the sparkplug

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

How it works… 1. Ultra-lean homogeneous charge of natural gas and air 2. Fuel is injected in the region of the sparkplug 3. Flame kernel forms, and propagates through lean airfuel charge THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

ADVANTAGES OF PARTIAL CHARGE STRATIFICATION • Engine operates in “fuel control” mode, similar to a Diesel engine • Limited use of throttling increases efficiency • Only one fuel is required • No requirement for on-board gas compression • No need for expensive and complex fuel injection equipment THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

Partially Stratified-Charge Control Concept THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

Partially-Stratified Charge Spark Plug •

Lean homogeneous main charge of fuel and air

•

Injection of fuel near ignition source

•

Spark initiates stable flame in fuel-rich area

•

Flame propagates rapidly through lean charge

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

SINGLE-CYLINDER EXPERIMENTS • Ricardo Hydra single-cylinder engine • Bowl-in-piston design • Flat fire-deck cylinder head • Compression ratio of 10.2:1 • 450 cc engine displacement • Natural gas fuel

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

UBC Ricardo Hydra Test Engine Facility

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

BSFC vs. Air-fuel Ratio Injection Duration Optimisation (WOT, 2500 rpm, EOI at MBT-10) 300.0 290.0

Homogeneous-charge

BSFC (g/kW-hr)

280.0

25 deg. inj. duration 270.0

30 deg. inj. duration 260.0

35 deg. inj. duration

250.0

240.0 230.0 220.0 1.40

1.45

1.50

1.55

1.60

1.65

1.70

1.75

1.80

Relative Air-Fuel Ratio THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

Total Hydrocarbons vs. Air-fuel Ratio (WOT, 2500 rpm, 35 deg. Injection pulse width) 40.00 35.00

tHC-wet (g/kW-hr)

30.00

Homogeneous-charge EOI at MBT-5 EOI at MBT-10

25.00

EOI at MBT-15 20.00 15.00 10.00 5.00 0.00 1.40

1.50

1.60

1.70

1.80

Relative Air-Fuel Ratio

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

CO vs. Air-fuel Ratio (WOT, 2500 rpm, 35 deg. Injection pulse width) 14.00

12.00

CO-dry (g/kW-hr)

10.00

Homogeneous-charge EOI at MBT-5 EOI at MBT-10

8.00

EOI at MBT-15

6.00

4.00

2.00

0.00 1.40

1.50

1.60

1.70

1.80

Relative Air-Fuel Ratio

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

NO vs. Relative Air-fuel Ratio (WOT, 2500 rpm, 35 deg. Injection pulse width) 18.00 16.00

Homogeneous-charge

NO-dry (g/kW-hr)

14.00

EOI at MBT-5

12.00

EOI at MBT-10

10.00

EOI at MBT-15 8.00 6.00 4.00 2.00 0.00 1.40

1.50

1.60

1.70

1.80

Relative Air-Fuel Ratio

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

Mass-Burned Fraction Comparison (WOT, 2500 rpm) 100%

Mass Fraction Burned (%)

Homogeneous fuelling, RAFR = 1.65 (MBT Spark = -54) PSC fuelling, RAFR = 1.65 (MBT Spark = -50)

75%

50%

25%

0% -60

-40

-20

0

20

40

60

Crank Angle Degrees THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

Bsfc & BMEP vs. Lambda (WOT, 2000 rpm) 300

8

BMEP 275

6

BSFC

250

4

225

2

1 0 % e x t e n s io n o f le a n lim it w it h P S C 200

0 1

1 .2

1 .4

1 .6

1 .8

L a m b d a (m a s s b a s is )

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

Bsfc vs. BMEP (WOT, 2000 rpm) 300

1 0 % m o r e lo a d c o n t r o l t h r o u g h P S C le a n in g a t W id e O p e n T h r o t t le ( W O T )

275

250

225

W O T , L e a n in g , n o P S C W O T , L e a n in g , w ith P S C 200 4

6

8

B M E P (b a r)

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

NOx vs. BMEP (2000 rpm, Injection at MBT -10) 10 9

PSC 8

No PSC (May 21)

BS NOx (g/kW-h)

7 6

35%, L1.35 5

45%, L1.49 4

Wide Open Throttle, Lambda 1.55

3

45%, L1.52

2 1

Wide Open Throttle, Lambda 1.68

0 0

1

2

3

4

5

6

7

8

BMEP (bar) THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

Combustion Stability (WOT, 2000 rpm) 7 6 5 4 3

E n g in e M is fire s

2

N o P S C - L a m b d a 1 .6 1

1

W ith P S C - L a m b d a 1 .7 4 TDC

0 -5

0

5

10

15

20

-1

C ra n k a n g le o f P m a x (d e g )

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

COV of IMEP vs. Lambda 30

25

Hom ogeneous

20

PSC 15

10

5

0 1 .0

1 .2

1 .4

1 .6

1 .8

L a m b d a ( m a s s b a s is )

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

CONCLUSIONS •

Partially stratified-charge approach extended the lean limit, and reduced Bsfc by up to 10% at a given airfuel ratio

•

PSC approach reduced NOx emissions at part-load conditions

•

Combustion stability is improved with PSC approach

•

PSC may be one component of a multi-component operating strategy due to “convergence”

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004

The End ! Any Questions?

THE UNIVERSITY OF BRITISH COLUMBIA Department of Mechanical Engineering

ECI – Lean Combustion Technology II R.L. Evans - April, 2004