A New Dual-type DMA for the Measurement of Nanoparticles from Engines

Kazuo Takeuchi1,2), Junsuke Yabumoto1,2), Yoshiki Okada1,2)

1) Wyckoff Co., Ltd., 2) RIKENAkio Kibayashi3)

3) Shimadzu Co.Terunao Kawai4) and Yuichi Goto4)

4) NTSEL

1. Measurement of Gas-borne Nanoparticles2. Calibration of Size Measurement3. Difficulties in Conventional DMAs4. Dual-type DMA as a Solution5. Experiment6. Conclusion

8th ETH CONF. Zurich 8/16/04

Measurement of Air-Borne Nanoparticles

Nanoparticles: 1 nm < dp < 300 nm

method in-situ? problems

TEM measurement after collection no

• tedious procedure that requires preservation of the size distribution

light scattering yes• scattered light intensity dp

6 • not practically applicable to

nanoparticles

mobility measurement using DMA (yes)

• sensitivity and stability (historically).

• calibration method below 10 nm.

Differential Mobility Analyzer (DMA)Differential Mobility Analyzer (DMA)

Faraday Cup

DMA

Electrometer

Qsh

Qae

Qsa

Qex

Sheath gasLV

RRQZ sh

2

)/ln( 12*

Electrical mobility of particles

V

p

cp

D

eCn

3

Dp: Particle diameter

Cc: Cunningham correction factor

: Gas viscosity

np: Number of elementary charges on a particle

Size distribution of particles

Size-selected particles

Size-selection of nanoparticles using DMASize-selection of nanoparticles using DMA

Problem for Conventional DMAs in Automobile Exhaust MeasurementProblem for Conventional DMAs in Automobile Exhaust Measurement

Typically, conventional DMAs need to scan the voltage for 2

minutes

Cannot cope with the quick transient behaviors in automobile exhaust

DMA with a multi-channel

detector

dual-type DMA with both

• scanning measurement mode and

• transient measurement mode

Typical particle size distribution of nanoparticles in engine exhaust

Num

ber

dens

ityDiameter (nm)

Image reproduced from D.B. Kittelson and W. Watts,

Third Joint ESF-NSF Symposium Abs.,Dublin, Sept. 6 (2000).

Dual-type DMA of WyckoffDual-type DMA of Wyckoff

Sheath gas inlet #1

Central electrode

Aerosol gas inlet

Sheath gas inlet #2

Excess gas outlet #1

Base reservoir

Cover

Mobility analyzer #1

Aerosol gas inlet

Common electrode

Mobility analyzer #2

Housing

Excess gas outlet #2

Vacuum pump

HV

LV

FC2 PA2

PA1FC1

Features of the Dual-type DMA (DDMA)Features of the Dual-type DMA (DDMA)

1) The DDMA can be operated both in scanning measurement mode and in transient measurement mode.

2) In transient measurement mode, voltages are fixed at the peak values of the nuclei mode and the accumulation mode.

3) Particle number density can be obtained by assuming that the shape of the size distribution is unchanged.

4) DDMA can be operated with intentionally reduced resolution.

Generation of model nanoparticles with bimodal size distributionGeneration of model nanoparticles with bimodal size distribution

Qs2

Qs1

Cooler(Air cooled)

SUS Filter (10nm)

Am241Neutralizer

Corona Charger

MFC

NaCl particles generator

Air

Regulator

Smoke particles generator

MFC

MFC

MFM

MFM

Qsh1

Qsh2

Qex1

FC1

PA1

Electro-meter 1

Qex2

3L

Circulation pump

MFC

Furnace

DC Supply 0- ± 3kV

DC Supply0- ± 300V

Electro-meter 2

MFC

MFC

FC valve

FC valve

SUS Filter (15μ m)

Dual- DMA

P3

Press.sensor

T

Temp.sensor

Vacuum pump

P2

P1

Press.sensor

FC2

PA2

Press.guage

Surge tank

2LBack press. valve

Press.guage

非定常排気微粒子数濃度計測結果

0.0E+00

1.0E+06

2.0E+06

3.0E+06

4.0E+06

5.0E+06

6.0E+06

7.0E+06

1 10 100 1000dp (nm)

PN

C [

#/c

c]

Scanning Mode Measurement of Model Nanoparticles

DMA1Model nanoparticles

corresponding to nuclei mode

DMA2Model nanoparticles corresponding

to accumulation mode

Num

ber

dens

ity (

#/cc

)

Transient Mode Measurement of Model Nanoparticles

0.0E+00

2.0E+06

4.0E+06

6.0E+06

8.0E+06

1.0E+07

0 10 20 30 40 50 60 70

time sec【 】

Num

ber

dens

ity#/

cc【

】

DMA1(for nanoparticles of ~10nm)

DMA2(for nanoparticles of ~ 100nm）

ON

OFF

Corona charger

System Schematic

D-DMA

PC

ChassisDynamometer

Fuel

BlowerController

SMPS

PC

System Schematic

D-DMA

PC

ChassisDynamometer

Fuel

BlowerController

SMPS

PC

SMPS

PC

Measurement of nanoparticles from a Automobile EngineMeasurement of nanoparticles from a Automobile Engine

Result for JE-05 Driving Mode

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900

Time second

Con

cent

ratio

n N

/ c

cDMA- 1(10 nm)

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900

Time second

Con

cent

ratio

n N

/ c

c

DMA- 2 (75 nm)

0102030405060708090

100

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900

Time second

Veh

icle

spe

ed

Km

/h

Km/ hr

1) We have introduced the dual-type DMA (DDMA) of Wyckoff.

2) The DDMA is simple and robust, and would be easy to use as a standard apparatus for the measurement of nanoparticles in automobile exhaust.

3) At the completion of this project, Shimadzu Co. will commercialize the DDMA and will be capable of large-scale production.

Acknowledgement: We would like to thank JRTT for financial support. We would also like to thank Dr. Montajir and the scientists and technicians of NTSEL, Wyckoff, RIKEN and Shimadzu for their technical support and advice.

Concluding Remarks