1

PM REMOVAL SYSTEM FOR DIESEL PASSENGER VEHICLEUSING NON-THERMAL PLASMA

PM REMOVAL SYSTEM FOR DIESEL PASSENGER VEHICLEUSING NON-THERMAL PLASMA

Kazuhiko Madokoro, Y. H. Kim, K. Naito, T. OgawaH. Fujikawa, K. Hasegawa, H. Tanaka

Research Institute of Innovative Technology for the Earth (RITE), Japan

S. Yamamoto, S. Kodama, C. MineS. Yao, Y. Fujioka

Daihatsu Motor Co., Ltd., Japan

S. Soma, T. Nakajima, G. SugiyamaJapan Automobile Research Institute (JARI), Japan

2

Introduction

- Diesel emission regulations

- What is plasma?

- Advantages and problems of plasma technology

Experimental

Results

Conclusion

OutlineOutline

3

Diesel emission regulations (Passenger vehicles)Diesel emission regulations (Passenger vehicles)

USUSEUEUJapanJapan

0.00

0.02

0.04

0.06

0.08

0.10

0.0 0.2 0.4 0.6 0.80.14 0.40.28

0.052

0.013

1997

2002

2005

2009

PM

[g

/km

]

0.080

0.005 0.08

NOx [g/km]

11, 10 ･ 15 , JC08 mode

Our target

0.00

0.02

0.04

0.06

0.08

0.10

0.0 0.2 0.4 0.6 0.80.00

0.02

0.04

0.06

0.08

0.10

0.0 0.2 0.4 0.6 0.8

0.05

0.025

0.005 0.50.18 0.25

2005 Euro4

2000 Euro3

1994 Tier1

2004 ～ 06 Tier2 (Bin#9)

2007 Tier2 (Bin#5)

　　　　　　

0.062

0.037

0.006

0.044 0.780.19

2009 Euro5

NEDC mode FTP mode

NOx [g/km] NOx [g/km]

Stricter regulations for emission control are being set all over the world. The Japanese post new long-term emission regulation comes into force.

A newly established emission test mode (JC08) has also been introduced.

0

20

40

60

80

0 200 400 600 800 1000 1200

Elapsed time [ s ]

Veh

icle

spe

ed [

km/h

]

Japanese JC08 Japanese JC08 modemode

4

Plasma is called a "Fourth State of Matter". Plasma is a partially ionized gas mixture and contains electrons, ions, neutral atoms,

molecules, reactive free radicals and photons.

Liquid GasMelting Evaporati

on

PlasmaElectrolyticdissociation

Solid

Fourth stateThree states of matter

Exhaust gases

O2, NO, H2Oetc

O3, O, NO2

etc

Discharge plasma

PM

It is generally known that highly reactive species such as O3, O, NO2 and OH are generated in the plasma of diesel exhaust gases. These reactive species can lead to oxidation of PM.

CO2

CO

Application of the plasma to diesel exhaust Application of the plasma to diesel exhaust gasesgases

Lightning Aurora

What is Plasma ?What is Plasma ?

5

Successive PM removal irrespective of ambient temperature No using Platinum-Group Metals Easily controllable of PM removal rates by power management Simple reactor configuration for low pressure drop

Designing of a novel plasma reactor Reduction of energy consumption Improvement of power supply system & power delivery for plasma generation Elucidation of PM removal mechanism Durability of the system

AdvantagesAdvantages

Hurdles to overcome before practical useHurdles to overcome before practical use

Advantages and problems of plasma technologyAdvantages and problems of plasma technology

PM emission : below 0.005 g/kmPM emission : below 0.005 g/km Pressure drop: below 5 kPaPressure drop: below 5 kPa Fuel penalty : below 2.5%Fuel penalty : below 2.5% (at Japanese JC08 mode) (at Japanese JC08 mode)

TargetTarget

6

Introduction

Experimental

- Discharge system

- Emission measurement system

- Modal emission test

Results

Conclusion

OutlineOutline

7

Discharge systemDischarge system

Oscilloscope

AC 100V Plasma Reactor

High voltage probe

Current Transformer

Pulse PowerSupply

DC PowerSupply

Dielectric barrier discharge reactorDielectric barrier discharge reactordriven by high-voltage pulsesdriven by high-voltage pulses

Discharge

Ref: S. Yao (RITE), AIChE J., Vol. 53, 1891-1897 (2007)

8

Non-thermal plasma reactorNon-thermal plasma reactor

Dielectric plate Electrode

Highvoltage

Earth

Dielectric (General flat plate of alumina)

Electrode

Gas flow

CO2

(CO)

Temporary trapOxidation

(Combustion)

PM(c)

Gas flow

9

Dilution Air

Samplingbag

PM filter

CFV-CVS

Engine Exhaust Particulate Sizer(EEPS-3090)

Full flow dilution tunnel

Emission measurement systemEmission measurement system

Dilutor

Chassis dynamometer

Particle numberParticle numberconcentrationconcentration

PM mass emissionPM mass emission

Engine 1.5 L 4-cycle diesel engine

Original Emission level Euro4

Original aftertreatment Diesel oxidation catalyst (DOC)

Vehicle data

Vehicle emission measurement was carried out at JARI.

Soluble organic fraction (SOF)Insoluble organic fraction (ISF)

Soxhlet extraction

10

0

20

40

60

80

100

120

-200 0 200 400 600 800 1000 1200

Elapsed time [ s ]

Ve

hic

le s

pe

ed

[ km

/h ]

Warm-up period

Cold mode start (without warm-up)

Emission measurement start

Modal emission testModal emission test

Hot mode start

Japanese JC08 mode (hot and cold Japanese JC08 mode (hot and cold start)start)

Evaluated aftertreatment systemEvaluated aftertreatment system

EngineEngine Without aftertreatment

Original aftertreatment (DOC)　DOC　

EngineEngine

Original & Plasma reactor

　DOC　

EngineEngine Plasmareactor

11

Introduction

Experimental

Results

- Inlet gas temperature of the plasma reactor

- PM mass emission

- Particle size distributions

- Appearance of alumina plates

- Pressure drop of plasma reactor

Conclusion

OutlineOutline

12

Inlet gas temperature of the plasma reactorInlet gas temperature of the plasma reactor

Inlet gas of the plasma reactor was under low temperature Inlet gas of the plasma reactor was under low temperature during mode.during mode.

Hot start mode Maximum : 222.6 ºC Average : 170.4 ºC

Cold start mode Maximum : 222.0 ºC Average : 147.0 ºC

Gas temperature

0

20

40

60

80

100

Veh

icle

spe

ed [

km

/h ] Target vehicle speed

Real vehicle speed

0

50

100

150

200

250

0 200 400 600 800 1000 1200

Elapsed time [ s ]

Gas

tem

pera

ture

[ °

C ]

hot

cold

13

0.00

0.01

0.02

0.03

0.04

0.05

0.06

PM SOF ISF

Em

issi

on

[ g

/km

]

w/o aftertreatmentOriginalOriginal & Plasma

PM SOF ISF

w/o aftertreatmentOriginalOriginal & Plasma

PM SOF ISF

w/o aftertreatmentOriginalOriginal & Plasma

PM mass emissionPM mass emission

Cold Hot Combine*

* Combine emission = Cold mode emission × 0.25 + Hot mode emission × 0.75

51% 62%59%

86% 93% 91%81%86% 8

4%

15%26% 23%

Japanese new regulation(JP 2009)

The plasma reactor showed almost same removal capability in The plasma reactor showed almost same removal capability in both modes.both modes. The oxidative ability of plasma showed elective affinity for soot.The oxidative ability of plasma showed elective affinity for soot. PM emission of our plasma reactor achieved JP2009 regulationPM emission of our plasma reactor achieved JP2009 regulation

(combine emission value 0.0048 g/km).(combine emission value 0.0048 g/km).

79%79%

77%

54%23% 35%

91%(0.0048 g/km)

14

1 10 100 1000

Particle size [ nm ]

0.E+00

1.E+06

2.E+06

3.E+06

4.E+06

5.E+06

6.E+06

7.E+06

8.E+06

9.E+06

1.E+07

1 10 100 1000

Particle size [ nm ]

Par

ticle

con

cent

ratio

n [

#/cm

3 ]Particle size distributionsParticle size distributions

Cold Hot

Particle concentrations after the plasma reactor were clearly reduced. Particle concentrations after the plasma reactor were clearly reduced. Non-thermal plasma could also remove nano-particles.Non-thermal plasma could also remove nano-particles.

Good

87.6%81.3%

w/o aftertreatment

Original

w/o aftertreatment

Original

w/o aftertreatment

Original

Original & Plasma

w/o aftertreatment

Original

Original & Plasma

15

Without plasma With plasma

Area of electrode

Temporarytrap

Oxidation(Combustion)

Appearance of alumina platesAppearance of alumina plates

After about 300 km mode driving

PM was clearly removed on the alumina plate with plasma.PM was clearly removed on the alumina plate with plasma. PM adsorption was observed less at downstream side. PM adsorption was observed less at downstream side. It is suggested that reactive species which came from the It is suggested that reactive species which came from the upstream side upstream side contributed to oxidize PM at the downstream side. contributed to oxidize PM at the downstream side.

Exh

au

st g

as

flow

16

Pressure drop of the plasma reactorPressure drop of the plasma reactor

The plasma reactor maintained lower pressure drop during consecutive The plasma reactor maintained lower pressure drop during consecutive mode tests.mode tests. It is suggested that PM was successively removed by the plasma reactor.It is suggested that PM was successively removed by the plasma reactor.

0

1

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4

5

0 200 400 600 800 1000 1200Elapsed time [ s ]

Pre

ssu

re d

rop

[ kP

a ]

0

20

40

60

80

100

Ve

hic

le s

pe

ed

[ km

/h ]

.

Hot

Cold

Vehicle speed

0

1

2

3

4

5

6

7

8

0 5 10 15Number of mode test [ n ]

Ma

xim

um

pre

ssu

re d

rop

[ kP

a ]

.

17

ConclusionConclusion

1. PM emission could satisfy JP2009 emission regulation of 0.005 g/km by installing the plasma reactor after the original DOC.

The plasma reactor showed successive high removal rate for ISF which is not easily oxidized with catalytic reactions compared with SOF.

2. The plasma reactor could remove PM under low temperature. Such a removal ability is a great advantage compared with a catalyst or a DPF which requires active regeneration.

3. The plasma reactor showed low pressure drop during JC08 mode. Such low pressure drop was achieved due to the structural characteristic

of plasma reactor.

This plasma system is expected to be one of the This plasma system is expected to be one of the

promising technologies for diesel emission control.promising technologies for diesel emission control.

18

AcknowledgementAcknowledgement

This work is supported by This work is supported by

Japanese government through NEDO.Japanese government through NEDO.

New Energy Industrial Technology Development Organization

Thank you for your Thank you for your attention !attention !

Thank you for your Thank you for your attention !attention !

We would like to thank We would like to thank

Professor Yoshimasa NiheiProfessor Yoshimasa Nihei [Tokyo University of Science] [Tokyo University of Science]Professor Hajime FujimotoProfessor Hajime Fujimoto [Doshisha University] [Doshisha University]Professor Yoichi HoriProfessor Yoichi Hori [The University of Tokyo] [The University of Tokyo]Professor Yasutake TeraokaProfessor Yasutake Teraoka [Kyushu University] [Kyushu University]

Comprehensive Technological Development of Innovative, Next-Generation,Low-Pollution Vehicles R&D of Innovative After-Treatment Systems

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END END

20

NOx emissionNOx emission

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

NOx CO NMHC

Em

issi

on

[g/k

m]

w/o aftertreatment

DOC

DOC & Plasma

NOx CO NMHC

w/o aftertreatment

DOC

DOC & Plasma

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

NOx CO NMHC

Em

issi

on

[ g

/km

]

w/o aftertreatment

DOC

DOC & Plasma

Cold Hot

Combine

21

Discharge systemDischarge system

Oscilloscope

AC 100V Plasma Reactor

High voltage probe

Current Transformer

Pulse PowerSupply

DC PowerSupply

DC powersupply(DC voltage : 0-600V)

Pulse power supply driven by DC power supply(Pulse peak voltage : ~ 10kV)

22

Electrode

Dielectric

Electrode

Gas flow

Gas flow Gas flow

Glass wool spacerNew electrode

Alumina plate(dielectric)

Discarge

PM

(Mass-produced flat plate of general alumina)

Plasma reactor and new electrodePlasma reactor and new electrode

Ref: S. Yao (RITE), AIChE J., Vol. 53, 1891-1897 (2007)

23

Thermal plasmaThermal plasma : All particles are in state of high temperatures. : All particles are in state of high temperatures.

Gas show high temperatures.Gas show high temperatures. Non-thermal plasmaNon-thermal plasma : Only electrons show high temperatures. : Only electrons show high temperatures.

Gas remains in state of almost 'cold' (ambient temperature).Gas remains in state of almost 'cold' (ambient temperature).

0 5 10 15 20101

102

103

104

105

106

Gas

Tem

pera

ture

Ris

e [C

]

Electron Temperature [eV]

RFJet

ne ~ 1018cm-3

ne ~ 1015cm-3

ne ~ 1012cm-3

Arc

MW Torch

Line of Tgas Telectron

ne ~ 1012cm-3

Pulsed Corona & DBD

MH Cho, postech, 8th APCPST, 2006

Pulsed Corona(+)

cylinderbarrierrodwire cylinder

Dielectric Barrier

Discharge

Thermal and Non-thermal plasmaThermal and Non-thermal plasma

24Our concept for reducing each emissionsOur concept for reducing each emissions

2CD

PlasmaReactorDOC

Cooled EGR

NOx reduction

Soot and SOF reduction

CO, HC and SOF reduction

NOxcatalyst

NOx reduction

NOx is reduced by control of engine combustion or NOx catalyst.NOx is reduced by control of engine combustion or NOx catalyst. CO, HC and SOF are reduced by the diesel oxidation catalyst.CO, HC and SOF are reduced by the diesel oxidation catalyst. Soot and SOF are reduced by the plasma reactor.Soot and SOF are reduced by the plasma reactor.

25Equation for PM removal ratesEquation for PM removal rates

Emission w/ oaftertreatment

ー Original orOriginal & Plasma emission

Emission w/ o aftertreatment

× 100 (%)

PM removal ratefrom emission w/o aftertreatment

=

Original DOCemission

ー Original & Plasmaemission

Original DOC emission

× 100 (%)

PM removal ratefrom original DOCemission

=

26PM number emission (CPC)PM number emission (CPC)

0.E+00

1.E+13

2.E+13

3.E+13

4.E+13

5.E+13

6.E+13

7.E+13

8.E+13

9.E+13

w/o DOC DOC &Plasma

PM

nu

mb

er

Em

issi

on

[ #

/km

]

w/o DOC DOC &Plasma

0.E+00

1.E+13

2.E+13

3.E+13

4.E+13

5.E+13

6.E+13

7.E+13

8.E+13

9.E+13

w/o DOC DOC &Plasma

PM

nu

mb

er

Em

issi

on

[ #

/km

]

Cold Hot

Combine

27

Japanese 10-15 mode and JC08 modeJapanese 10-15 mode and JC08 mode

0

20

40

60

80

0 200 400 600 800 1000 1200

Elapsed time [ s ]

Ve

hic

le s

pe

ed

[ km

/h ]

0

20

40

60

80

0 200 400 600 800 1000 1200

Elapsed time [ s ]

Ve

hic

le s

pe

ed

[ km

/h ]

Japanese JC08 modeJapanese JC08 mode

Japanese 10-15 modeJapanese 10-15 mode

28

0

1

2

3

4

5

0 200 400 600 800 1000 1200

Elapsed time [ s ]

Pre

ssur

e dr

op [

kP

a ]

hot

cold

Gas temperature and pressure dropGas temperature and pressure drop

The plasma reactor could remove PM effectively even under low temperatures.The plasma reactor could remove PM effectively even under low temperatures. The plasma reactor showed lower pressure drop below 3.8 kPa during mode. The plasma reactor showed lower pressure drop below 3.8 kPa during mode.

0

20

40

60

80

100

Veh

icle

spe

ed [ k

m/h

]

Target vehicle speedReal vehicle speed

0

50

100

150

200

250

Gas

tem

pera

ture

[ °

C ]

hot

cold

Cold start mode Maximum : 222.0 ºC Average : 147.0 ºC Hot start mode Maximum : 222.6 ºC Average : 170.4 ºC

Gas temperature

Cold start mode Maximum : 3.4 kPa

Hot start mode Maximum : 3.8 kPa

Pressure drop

29PM mass emission (JP2009)PM mass emission (JP2009)

0.00

0.01

0.02

0.03

0.04

0.05

0.06

PM SOF ISF

Em

issi

on

[ g

/km

]

w/o aftertreatmentOriginalOriginal & Plasma

PM SOF ISF

w/o aftertreatmentOriginalOriginal & Plasma

PM SOF ISF

w/o aftertreatmentOriginalOriginal & Plasma

Cold (JC08)

Hot (10-15) Combine*

* Combine emission = JC08 Cold mode emission × 0.25 + 10-15 Hot mode emission × 0.75

Japanese new regulation(JP 2009)

Combine emission value0.0038 g/km

30

0

20

40

60

80

100

Veh

icle

spe

ed [ k

m/h

] Target vehicle speedReal vehicle speed

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

3.0E+06

3.5E+06

0 200 400 600 800 1000 1200

Elapsed time [ s ]

Tot

al c

once

ntra

tion

[ #/

cm3 ] w/o aftertreatment

Original

Original + DBD (200W)

Total particle concentrationsTotal particle concentrations

31

Fluctuation of pressure drop during mode testsFluctuation of pressure drop during mode tests

Maximum pressure drop didn't increase during consecutive Maximum pressure drop didn't increase during consecutive mode tests.mode tests. It is suggested that PM was successively removed by the plasma It is suggested that PM was successively removed by the plasma reactor.reactor.

0

1

2

3

4

5

6

7

8

0 5 10 15

Number of mode test [ n ]

Ma

xim

um

pre

ssu

re d

rop

[ kP

a ]