super-lean burn concept for high efficiency si engine burn concept for high efficiency si engine ......

Results from Japanese Industry/Academia Joint Research Project

Super-Lean Burn Concept for High Efficiency SI Engine

Challenge for Innovative Combustion Technology to achieve 50% thermal efficiency

Norimasa Iida Keio University

“Impact of Future Regulations on Engine Technology”ERC 2017 SymposiumJune 14-15th, 2017University of Wisconsin Madison

A grave project as Innovative Combustion Technology was organized in theCross-ministerial Strategic Innovation Promotion Program (SIP) by the Cabinet Office.This (presentation) gives an introduction to Research and Development on the Super Lean Burn Concept for Gasoline Engines by the Gasoline Combustion Team with 28 cluster members.

1

What is SIP?

The Cross-ministerial Strategic Innovation Promotion Program (SIP) is a national project under the Council for Science, Technology and Innovation to promote the advancement of science, technology and innovation in Japan.

2

25

30

35

40

45

50

55

1990 2000 2010 2020

Ther

mal

Effi

cien

cy（

%）

Year

SIP - Innovative Combustion Technology -

Transition of thermal efficiency of gasoline engine

HV

Thermal efficiency target : 50%

Innovative combustion technology

Mass-produced engine: max.~40%

・Purpose of SIP “Innovative Combustion Technology”

To cope with social issues such as a climate change and energy security, the enhancement of the engine thermal efficiency is required.

3

SIP - Innovative Combustion Technology -

・Development of “Super-lean burn”technologies

Leader : Keio Univ. Prof. Iida

Gasoline Combustion Team

・Development of innovative controlsystems and CAE tools

Leader : Tokyo Univ. Prof. Kaneko

Controls Team

・ Development of high speedcombustion with low noise andcooling losses technologies

Leader : Kyoto Univ. Prof. Ishiyama

Diesel Combustion Team

・Development of exhaust energyutilization and mechanicalfriction reduction technologies

Leader : Waseda Univ. Prof. Daisho

Loss Reduction Team

¥10 billion ($100 million) /5 years (2014-2018)

4

5

University of TokyoShigehiko Kaneko

Diesel Combustion/Control SubcommitteeCAE/PM Subcommittee

Controls Team

Cluster of Universities

Kyoto UniversityTakuji Ishiyama

Diesel Combustion/Control Subcommittee

Diesel Combustion Team


Keio UniversityNorimasa Iida

Gasoline Combustion Subcommittee



Waseda UniversityYasuhiro Daisho

Exhaust Energy Utilization SubcommitteeFriction Loss Reduction Subcommittee

Loss Reduction Team


PartnershipAgreement

JST Funding(Management) Agency

Cabinet Office ＰＤ（Masanori Sugiyama）

PromotingCommittee

ProgramCouncil

Project Management

The Research Association ofAutomotive Internal Combustion Engines

Combustion Research Committee

DieselCombustion/Control

Subcommittee

FrictionLoss ReductionSubcommittee

Exhaust EnergyUtilization

Subcommittee

GasolineCombustion

Subcommittee

CAE/PMSubcommittee

Chair: Masanori Sugiyama (PD)Members: Shigeo Furuno (Sub-PD), Ministry of Economy, Trade and Industry, Ministry of Education, Culture, Sports, Science and Technology, JST, Experts from industry and academia

Chair: Masanori Sugiyama (PD)Members: Shigeo Furuno (Sub-PD), Experts from industry and academia

Advice to PD for planning

4 teams from approx. 80 universities

Research and Development ofSuper-Lean Burn for

High Efficiency Gasoline EngineGasoline Combustion Team

Graduate School of Science and TechnologyKeio University

Project ProfessorNorimasa Iida

Research and Development are conducted to realize the super-lean burn technology. Specifically,1） Ignition system enabled under super-lean and high intensity flow conditions, 2) Acceleration of the flame propagation by optimizing the tumble flow, 3) Cooling loss reduction based on the analysis of a wall heat transfer mechanism, 4) R&D for the creation of a knock control concept by an approach through

chemical kinetics.

HV用エンジン

1990 2000 2010エンジン熱効率

(%)

SIPプロジェクト

2020年30

35

40

45

50

YearEngi

ne T

herm

al E

ffici

ency

(%)

Background and Position of R&D Plan

・High expansion ratio・Cooled EGR(Exhaust Gas Recirculation)

・Low friction

Thermal efficiency of hybrid vehicle(HV) engines: approx. 39%(at the beginning of SIP)

This project drives the research for the following objectives for output with super-lean burn as a core technology① Creation of technologies for elements to achieve 50% thermal efficiency② Modeling from the analysis of innovative combustion technologies

Innovative technology is indispensable

Realization of 50% Thermal Efficiency→Innovative combustion

technology is indispensable.

Current main technologies

Transition of Thermal Efficiency of Gasoline Engines

Goal of SIP

SIP Project

HV engines

7

Supercharging

Innovative control

Waste heat recoveryFriction reduction

Loss Reduction Team

■ Scenario of Thermal Efficiency Improvement

Mass productionvehicles

Target

Fuel heat release：100

Brake work35

Thermalefficiency

35%

Exhaust loss31

Cooling loss25

Friction loss 5Pumping loss1

Unburned gas 3

Compression ratio 11Excess air ratio λ1.0

Cooling loss reduction

(Thermal insulation)

High intensity air flow(Tumble)

Technologies of Elements

Super-lean burn system

Research Direction

Development of knock suppression

technologies

Combustion technology

development driven under super-lean,

high intensity turbulence and high

EGR

Cooling loss reduction technologies

Ignition model forSuper-lean burn

Submodel

Super-lean, high intensity

turbulence, high EGR combustion

model

Heat transfermodel

Gasoline CombustionTeam

ObjectivesIncreasing indicated work・Knock control

improvement

OUTPUTto Control

TeamCycle variation control

technologies

Fuel heat release：70

Compression ratio13～14

Excess-air ratio λ 2.0EGR20%

Reducing cooling loss・Low temperature

combustion・Low S/V ratio・Thermal insulation

Reducing exhaust loss・High expansion ratio

・Knock control improvement

Reducing friction loss

Reducing loss in gas exchange ・Turbocharger

efficiency improvement

Ignition system applicable to high

intensity airflow field

Output

Strong ignition

Control Team

Knock control improvement

(Cooling optimization)

In addition to driving the research to enhance a potentiality of hardware related to combustion, 50% thermal efficiency is targeted in collaboration with other research teams

Scenario of 50% Thermal Efficiency for Gasoline Engines

Knock predictionmodel

Brake work35

Thermalefficiency

50%

Exhaust loss19

Cooling loss11

Friction loss 3

Unburned gas 2

8

Goal Setting

1st year 2nd year 3rd year 4th year 5th year30

35

40

45

50

Indi

cate

d Th

erm

al E

ffici

ency

(%)

Single cylinder(Prototype)

Single cylinder (Improved)

・Combustion improvement

・Combustion chamber improvement(+1.0p)

Single cylinder(Specifications

change)・Cooling loss

reduction・High comp.

ratio(+1.1 p)

Single cylinder(Verification

engine)・Combustion

improvement・Knock control

improvement・Fuel utilization(+2.9 p)

・Fuel reforming・Turbocharger

improvement・Friction loss

reduction・Thermoelectric

generator(+2.0 p)

Japan’s originality

Strong ignition device

Surrogate fuels ・λ= 2, EGR20%・Flow rate：20-50m/s・Pboost：100kPa・ε =13・S/B=1.5Catch up

・Piston shape・ε = 13 → 15 → 18・S/B= 1.5 → 1.7

Mass production level

0

5

10

15Ta

rget

s dr

iven

by

eac

h te

am(p

oint

)

Low temperaturecombustion

Low temperaturecombustion

DIS/V Ignition Improvement Team

Flame Propagation Acceleration Team

Cooling Loss Reduction Team

Knock Suppression Team

Loss Reduction Team

Demonstration withsingle-cylinder engine

4.65.6

6.6

9.5

Gasoline Combustion Teamand Loss Reduction Team

11.5

6.017.63

Setting targets among teams Gasoline Combustion Team

Cre

atio

n of

tech

nolo

gies

for e

lem

ents

to a

chie

ve 5

0% th

erm

al e

ffici

ency

Prop

osal

of m

odel

s us

eful

for e

ngin

e de

velo

pmen

t (Fi

ve g

oals

)

9

Concept of Low Temperature Combustion technology

Super-Lean burn

Super-Lean burn Ordinary combustion（Stoichiometric combustion）

Increase of Specific heat ratio

100

80

60

40

20

0

Hea

t bal

ance

(%)

Exhaust loss

Unburned fuel loss

Ordinary

Cooling loss

Friction loss

Thermal efficiency

Super-Lean burn

Reduction of cooling loss

Operating condition targets for super-lean burn;・Super-Lean （λ ＝2.0）・High turbulent flow （ u = 20～50 m/s, u’ = 5 m/s ）・High EGR （EGR rate = 20 %）

10

Newton’s cooling equation𝑞𝑞 𝜃𝜃 = 𝐴𝐴・ℎ 𝜃𝜃 {𝑇𝑇𝑔𝑔𝑔𝑔𝑔𝑔 𝜃𝜃 − 𝑇𝑇𝑔𝑔𝑠𝑠𝑠𝑠𝑠𝑠𝑔𝑔𝑠𝑠𝑠𝑠 𝜃𝜃 }

Goal・Tasks and Solution Methods

Goal Concept Assignments Solutions

Attainm

ent of 50% therm

al efficiency

Realization of super-lean burn

No ignition

Engine knock

Heat loss on combustion chamber wall

UnburnableExtinguished

Creation of technologies from

science by the w

isdom of industry-academ

ia

Strong ignition system(Optimal ignition method)

Ignition at flow rate> 20m/s

High efficiency tumble portImprovement of combustion

chamber shape(High intensity turbulence flow

utilization)Flame propagation acceleration with

turbulence intensity > 5m/s

Temperature controlin combustion chamber

Approach based onreaction theory(Understanding

of elementary reaction)Knock suppression at γ ≥15

Improvement of surface shapein combustion chamber

Low temperature combustion(Investigation of heat

exchange phenomena)Cooling loss 50% reduction

11


We investigated the thermal efficiency of a test engine designed for the super-lean burn operation as a project of the SIP “Gasoline combustion team.” In order to advance to the super lean burn condition,

・ignition energy

・tumble intensity

were improved and those effects on thethermal efficiency were examined.

Objectives

12


To realize innovative combustion technology to drastically increase the thermal efficiency for energysavings and the CO2 emission reduction, while producing the world-leading researchers and building asustainable industry-academia collaboration in the field of engine combustion technology.

13

Fukui Univ.

Osaka Inst. of Tech.

Yamaguchi Univ.

Kyusyu Univ.

Osaka Prefecture Univ.

Okayama Univ.

Tokyo Inst. of Tech.

Tokyo Univ.

Chiba Univ.

Nihon Univ.

Sophia Univ.

Tohoku Univ.

Tokyo Univ. of Agriculture & Tech.

Tokyo City Univ.

Meiji Univ.

Keio Univ.

Tokushima Univ.

ONO SOKKIKeio SIP Engine

Lab.

Hokkaido Univ.

Nagoya Inst. of Tech.

AIST

Ibaraki Univ.

Hiroshima Univ.

Team leader:Prof. Norimasa Iida(Keio Univ.)

Leader, Research Base

Group Leaders

Doshisha Univ.

Clusters

Research SiteKeio University SIP Engine Laboratory at Ono Sokki Technical Center

14

Supercharger

PIV SystemCH2O-LIFSystem

OH-LIF System

High Pressure Fuel Supply Device

Lubricant Temperature Regulator

Control Room

Fuel Control Device

Coolant Temperature Regulator

Dynamometer

Optical Engine

Metal Engine

Test Facility Single-cylinder metal engine

Engine specifications Bore(mm) 75

Stroke(mm) 112.5

Stroke Bore Ratio 1.5

Compression Ratio 13

Fuel Injection System MPI, DI

Intake Valve Open(deg. BTDC) -28~7

Intake Valve Close(deg. ABDC) 88~58

Exhaust Valve Open(deg. BBDC) 34~69

Exhaust Valve Close(deg. ATDC) -10~-45

Boosted System Electric Supercharger

SIP common high-octane gasolineLHV (MJ/kg) 42.28

RON 99.8

Stoichiometric A/F ratio 14.22

Fuel specifications

Intake port

Exhaust port

Shape of intake and exhaust ports

15

Test Facility High energy ignition system

・Ignition coil : 60 mJ / 1coil Normal use : 1 coil High energy use : 2 × 5 = 10 coils

16

Test Facility Port adapter for High tumble intensity

Port adapter

Normal intake port High tumble intake port

17

-60

-40

-20

0

Ignitio

n t

imin

ig

[ｄeg

ATDC]

10

20

30

40

0-1

0%

com

bust

ion

dura

tion [

CA

]

0

5

10

15

20

Impro

vem

ent

rate

of

indic

ate

d

ther

mal

effici

ency

[%]

10

20

30

40

0.8 1 1.2 1.4 1.6 1.8 2 2.210-9

0% c

om

bust

ion

dura

tion [

CA

]

Air Excess Ratio, λ [-]

0

5

10

15

IMEP C

OV [

%]

0.00

0.05

0.10

CO [

%]

0

500

1000

1500

2000

0.8 1 1.2 1.4 1.6 1.8 2 2.2

NOx [

ppm

]


2000rpm, IMEP=600kPa

◇ ignition coil 1, w/o port adapter

Results Effects of high energy ignition and tumble port adapter

18

-60

-40

-20

0

Ignitio

n t

imin

ig

[ｄeg

ATDC]

10

20

30

40

0-1

0%

com

bust

ion

dura

tion [

CA

]

0

5

10

15

20

Impro

vem

ent

rate

of

indic

ate

d

ther

mal

effici

ency

[%]

10

20

30

40

0.8 1 1.2 1.4 1.6 1.8 2 2.210-9

0% c

om

bust

ion

dura

tion [

CA

]


0

5

10

15

IMEP C

OV [

%]

0.00

0.05

0.10

CO [

%]

0

500

1000

1500

2000

0.8 1 1.2 1.4 1.6 1.8 2 2.2

NOx [

ppm

]


▲ ignition coil 10, w/o port adapter◇ ignition coil 1, w/o port adapter



19

-60

-40

-20

0

Ignitio

n t

imin

ig

[ｄeg

ATDC]

10

20

30

40

0-1

0%

com

bust

ion

dura

tion [

CA

]

0

5

10

15

20

Impro

vem

ent

rate

of

indic

ate

d

ther

mal

effici

ency

[%]

10

20

30

40

0.8 1 1.2 1.4 1.6 1.8 2 2.210-9

0% c

om

bust

ion

dura

tion [

CA

]


0

5

10

15

IMEP C

OV [

%]

0.00

0.05

0.10

CO [

%]

0

500

1000

1500

2000

0.8 1 1.2 1.4 1.6 1.8 2 2.2

NOx [

ppm

]



◇ ignition coil 1, w/o port adapter


-60

-40

-20

0

Ignitio

n t

imin

ig

[ｄeg

ATDC]

10

20

30

40

0-1

0%

com

bust

ion

dura

tion [

CA

]

0

5

10

15

20

Impro

vem

ent

rate

of

indic

ate

d

ther

mal

effici

ency

[%]

10

20

30

40

0.8 1 1.2 1.4 1.6 1.8 2 2.210-9

0% c

om

bust

ion

dura

tion [

CA

]


0

5

10

15

IMEP C

OV [

%]

0.00

0.05

0.10

CO [

%]

0

500

1000

1500

2000

0.8 1 1.2 1.4 1.6 1.8 2 2.2

NOx [

ppm

]


▲ ignition coil 10, w/o port adapter◇ ignition coil 1, w/o port adapter


-60

-40

-20

0

Ignitio

n t

imin

ig

[ｄeg

ATDC]

10

20

30

40

0-1

0%

com

bust

ion

dura

tion [

CA

]

0

5

10

15

20

Impro

vem

ent

rate

of

indic

ate

d

ther

mal

effici

ency

[%]

10

20

30

40

0.8 1 1.2 1.4 1.6 1.8 2 2.210-9

0% c

om

bust

ion

dura

tion [

CA

]


0

5

10

15

IMEP C

OV [

%]

0.00

0.05

0.10

CO [

%]

0

500

1000

1500

2000

0.8 1 1.2 1.4 1.6 1.8 2 2.2

NOx [

ppm

]


● ignition coil 10, w/ port adapter▲ ignition coil 10, w/o port adapter ◇ ignition coil 1, w/o port adapter


20

Potential of Super Lean Burn (Keio University)

λ=1.93

Highest performance class ofmass production engine

SIP single cylinder engineS/B = 1.5ε = 13Engine speed = 2000rpmBoosted w/ electric Supercharger

λ=1.6～1.93

46.0%achieved

2015 year

Final goal

35

40

45

50

0.2 0.4 0.6 0.8 1.0 1.2Indicated Mean Effective Pressure [MPa]

30

25

20

Indi

cate

d Th

erm

al E

ffici

ency

[%]

45.0%

Evaluation results fromthe single cylinder engine

21

Experimental result in 2016 48.5%

When boosting with turbocharger in place ofe-supercharger

Results Maximum indicated thermal efficiency

0

0.5

1

1.5

2

Air

exce

ssra

tio

λ[-

]

1000

1500

2000

2500

THC [

ppm

]

0

2

4

6

8

10

0.2 0.4 0.6 0.8 1 1.2

IMEP C

OV [

%]

Indicated Mean Effective Pressure [MPa]

2000 rpmHigh energy ignition

w/ port adapterBoosted w/ electric Supercharger

● Stoichiometric ○ Leanλ～1.9

Near super-lean burn

IMEP COV < 4 %

22

Test Facility Single-cylinder optical engine and PIV system

PIV specifications Laser

Camera

Laser sheet thickness

Interrogation size

Laser interval Δt

Meas. frequency

Seeding Particles

Vector map

23

Results Estimated tumble ratio

0 90 180 270 3600.0

0.5

1.0

1.5

2.0

2.5

3.0

Tum

ble r

atio

TR

[-]

Crank angle [deg ATDC]

w/o port adapter

w/ port adapter

∑

∑ ×

=

),(

2),(

),,(

),,(),,(

zx

zx

zx

zxzxTR

θω

θθ

r

Ur

r

U

Tumble flow was enhanced by the port adapter.

24

0 90 180 270 3600

10

20

30

40

50

60

Mean

velo

city

[m/s]

Crank angle [deg ATDC]

Results Mean velocity and velocity fluctuation at spark plug

w/o port adapter

w/ port adapter

0 90 180 270 360

0

100

200

300

400

500

600

700

800

TKE [m

2/s2

] Crank angle[deg ATDC]

Squar

e o

f ve

locity

fluctu

atio

n [

m2/s2

]

w/o port adapter

w/ port adapter

Mean velocity and velocity fluctuation around the spark plug were increased by the port adapter.

25

Integrated Heat Release (Φ=1.0～0.5) IMEP600kPa 26

Strong ignition（10 coils）＋Strong Tumble flow up to 30m/s λ=2.0Strong ignition（10 coils）＋Tumble flow λ=1.9Standard ignition（Single coil） λ=1.6 University Leader： Keio University

In the case of λ =1.0, flame propagation started just after the spark discharge, and the heat release occurred, and with CA=10 at -5deg. ATDC.

In the case of λ = 2.0, when the spark discharge occurs at -40deg.ATDC, propagation of flame kernels may be freezing (partly extinguish?) by stretching effects.The number of kernels increases dispersedly in the chamber.At around -10deg. ATDC, Ka becomes 10 and flame propagation starts.CA10 takes at -5deg. ATDC.

Combustion trajectory on Peters turbulent combustion diagram27

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

Intake Compression(negative)

Compression(positive)

Expansion Exhaust Total

Am

ount

of H

eat F

lux

q[M

J/m

2 ]

Motoring testNe=2000rpmWOT

Effect of tumble flow intensity on the heat flux is small during the expansion stroke 28

Keio UniversityTokyo city University

w/ Tumble adapterw/o Tumble adapter

Heat flow from gas to the wall increases by increasing tumble flow intensity→ Because of wall cooling effects, it can be used for knock improvement.

Heat flux measurement under motoring condition

Heat flow from the chamber wall to gas duringthe first half of the compression stroke

28

・No increase of heat loss during the expansion stroke

Heat flux measurement under firing condition 1/2

29

Intake Compression

Expansion Exhaust

λ=1.0 (φ=1.0)

λ=1.4 (φ=0.7)

Crank Angle θ [deg. ATDC]

λ=1.0 (φ=1.0)

λ=1.4 (φ=0.7)

In-cylinder pressure

Temperature Swing @Surface

In-cylinder gas temperature(mass averaged)

Heat Flux

Temperature Swing @4mm depth

Heat flux measurement under firing condition 2/2

-0.002

-0.001

0

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.008

Intake Compression(negative)

Compression(positive)

Expansion Exhaust Total

Am

ount

of H

eat F

lux

q[M

J/m

2 ]

FiringNe=2000rpmIMEP=400kPa, MBT w/ tumble adapterTwater:350.2K (80deg.C)

λ=1.0 (φ=1.0)

λ=1.4 (φ=0.7)

λ=1.25 (φ=0.8)

30

Prospects of super lean burn engine

2000rpm, Fuel=0.32g/s,IMEP = 0.7 MPa

Cycle-to-cycle variation of indicated thermal efficiency as a function of air excess ratio

50 % by super lean burn !?

31

Summary

The thermal efficiency was examined on the test engine designed for the super-lean burn concept by the SIP Gasoline Combustion Team.

• A high energy ignition system and a high intensity tumble flow generated by aport adapter contributed to the lean limit expansion.

• The test engine demonstrated, an indicated thermal efficiency of 46%.

• The result of the PIV measurement showed that a high intensity air flow wasgenerated during the intake stroke with a port adapter. It generates a highintensity of the turbulence, which is essential to enhance a stable Low-Temperature-Combustion of the super-lean mixture in a short duration afterthe long ignition-delay.

34

Thank you for your attention

This project was supported by Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP) -“Innovative Combustion Technology” (Funding agency: JST).

33

Acknowledgment

Co-Author

28 clusters of SIP Gasoline Combustion Team

AICE Gasoline Combustion Committee

Collaborations

Prof. Takeshi Yokomori, Keio University

34

for more information

http://sip.st.keio.ac.jp/

37

Thank you for your attention

35

super-lean burn concept for high efficiency si engine burn concept for high efficiency si engine ......

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