Conformity of Production Testing for Particle Traps - a Model ExperimentKasper. M., Mosimann. T.

Currently, Type Approval of new DPF systems is covered by acknowledged standards,such as the VERT protocol or the CARB certification procedure. While Type Approvaldemonstrates the quality of a single product sample (or a very limited number), itremains the manufacturer's responsibility to ensure that mass-produced units have -within narrow limits - exactly the same properties as the approved specimen. Theconformity of DPF substrates with their Approved Type is best demonstrated with ameasurement of particle precipitation efficiency.For this purpose, a model set-up for conformity of production (CoP) testing was realised,consisting of a soot particle generator and several particle measuring instruments; twolight-duty particle traps were mounted onto this model test rig and characterised.Measurements were carried out before and after DPF regeneration; then, holes weredrilled into the plugged filter channels to simulate defects.Particle concentrations downstream of the DPF units were found to be far below ambientconcentrations as long as the filters were intact. After regeneration, particle emissionswere observed to shortly increase by approximately two orders of magnitude, but theyreturned to low levels within a few minutes. With a defect of less than 1 mm2 in place,the filtration efficiency dropped from >99.995% to ~99%, further dropping as the size ofthe defect was increased, but independent of exhaust gas flow direction.The model experiment demonstrates the applicability of particle based measuringmethods to the challenge of CoP testing for DPF substrates.

N a n o p a r t i c l e M a n a g e m e n t

Matter Engineering

www.matter-engineering.com

Conformity of Production Testing for Particle Traps - a Model Experiment

Markus Kasper and Thomas MosimannMatter Engineering AG, Wohlen, Switzerland

background• DPF type approval established (e.g. VERT)• DPF market and production grow fast• quality control at end of production needed• conformity of production with approved specimen required

(e.g., 2007 FOEN Filter List)

• CoP testing should use diesel-like particles• particle measurement must be reliable even at post-DPF

concentrations• CoP method must be simple, reproducible, reliable

SiC based filter structure

CoP test set-up

• REXS soot generator

• MD19-2E diluter• SMPS, DiSC, PAS, DC

• DPF samples

summary

• CoP testing possible with compact set-up

• typical DPF penetration < 0.001%

• measurable with nanoparticle (standard) equipment

• even small defects increase penetration significantly

• particle penetration increases almost linearly with leak cross section area

• no effect of leak location in DPF sample

• distinction of smallest defects in new DPF substrate?

results - DPF ok

• DPF in normal condition: used, no defects

• particle penetration < 0.001%

Total Concentration: Before filter After filter Penetration Deposition

[-] [%]

Concentration [1/cm3] 8.03E+07 2.28E+03 0.000028 99.9972

DiSC Mean [1/cm3] 5.94E+07 1.13E+03 0.000019 99.9981

Stdv. [%] 1.02 253.64

PAS2000 Mean [µgEC/m3] 1.96E+05 6.31 0.000032 99.9968

Stdv. [%] 2.38 1.15

LQ1-DC Mean [µm2/cm3] 39.1

Stdv. [%] 46.62

SMPS

Measurement 1 - DPF Test using REXS Soot generator

Filter: FAP/Citroen, delivery condition, used, no defects

Measurement with SMPS, DiSC, PAS2000 and LQ1-DC

0.0E+0

2.0E+7

4.0E+7

6.0E+7

8.0E+7

1.0E+8

1.2E+8

10 100 1000diameter [nm]

0.0E+0

5.0E+3

1.0E+4

1.5E+4

2.0E+4

2.5E+4

3.0E+4

3.5E+4

4.0E+4

1. Sample

2. Sample

3. Sample

co

nc.

dN

/dlo

gD

p [

cm

-3]

SMPS Spectrum

after filterbefore filter

0.00001

0.00010

0.00100

0.01000

0.10000

1.00000

10 100 1000diameter [nm]

penetr

ation [-]

SMPS Penetration

N a n o p a r t i c l e M e a s u r e m e n t

Matter Engineering AG

0.0E+0

5.0E+3

1.0E+4

1.5E+4

2.0E+4

2.5E+4

0 100 200 300 400 500 600Time [s]

0

20

40

60

80

100

120PAS2000 [ugEC/m3]

LQ1-DC [um2/cm3]

Sensor signals: Measurement over time after DPF- DiSC [1/cm3]

0.000001

0.000010

0.000100

0.001000

0.010000

0.100000

1.000000

0 100 200 300 400 500 600Time [s]

DiSC

PAS2000 [ugEC/m3]

Sensor signals: Penetration

Measurement1-Citroen.xls Anhang 1

• DPF in normal condition: regenerated, no defects

• particle penetration < 0.001%

• note "refill" period (3 min)!

Total Concentration: Before filter After filter Penetration Deposition

[-] [%]

Concentration [1/cm3] 8.03E+07

DiSC Mean [1/cm3] 5.94E+07 5.88E+02 0.000010 99.9990

(last 5min) Stdv. [%] 1.02

PAS2000 Mean [µgEC/m3] 1.96E+05 7.52 0.000038 99.9962

(last 5min) Stdv. [%] 2.38

LQ1-DC Mean [µm2/cm3] 0.3

(last 5min) Stdv. [%]

SMPS

Measurement 3 - DPF Test using REXS Soot generator

Filter: FAP/Citroen, filter directly after regeneration, no defects

Measurement with SMPS, DiSC, PAS2000 and LQ1-DC

0.0E+0

2.0E+7

4.0E+7

6.0E+7

8.0E+7

1.0E+8

1.2E+8

10 100 1000diameter [nm]

0.0E+0

5.0E+3

1.0E+4

1.5E+4

2.0E+4

2.5E+4

3.0E+4

3.5E+4

4.0E+4

1. Sample

2. Sample

3. Sample

conc. dN

/dlo

gD

p [cm

-3]

SMPS Spectrum

after filter,no SMPS data available due to problems with DMA

before filter

0.00001

0.00010

0.00100

0.01000

0.10000

1.00000

10 100 1000diameter [nm]

pe

ne

tra

tio

n [

-]

SMPS Penetration

N a n o p a r t i c l e M e a s u r e m e n t

Matter Engineering AG

0.0E+0

1.0E+5

2.0E+5

3.0E+5

4.0E+5

5.0E+5

6.0E+5

7.0E+5

0 100 200 300 400 500 600 700 800Time [s]

0

2000

4000

6000

8000

10000

12000

14000

PAS2000 [ugEC/m3]

LQ1-DC [um2/cm3]

Sensor signals: Measurement over time after DPF- DiSC [1/cm3]

Measurements recorded from start of charging with soot particles

0.000001

0.000010

0.000100

0.001000

0.010000

0.100000

1.000000

0 100 200 300 400 500 600 700 800Time [s]

DiSC

PAS2000 [ugEC/m3]

Sensor signals: Penetration

Measurement3-Citroen.xls Anhang 3

Defect Penetration Deposition

[mm2] [-] [%]

No defect 0.00 0.0000099 99.9990

1 defect channel 0.79 0.0008823 99.9118

2 defect channels 1.57 0.0019846 99.8015

4 defect channels 3.14 0.0040919 99.5908

Summary of DPF Test using REXS Soot Generator

Filter: FAP/Citroen, with various defects

Values from DiSC Sensor

Number concentration

2.43E+05

[1/cm3]

5.88E+02

5.25E+04

1.18E+05

N a n o p a r t i c l e M e a s u r e m e n t

Matter Engineering AG

0.000001

0.000010

0.000100

0.001000

0.010000

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50

DPF Penetrationen of defect cross section

penetr

ation

Defect cross section surface [mm2]

0.0E+00

5.0E+04

1.0E+05

1.5E+05

2.0E+05

2.5E+05

3.0E+05

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50

Defect cross section surface [mm2]

Num

ber

concentr

ation a

fter

DP

F [1/c

m3]

DPF Penetrationen of defect cross section

Nachtrag 1

results - DPF leaky

• leaky DPF: defect simul-ated by one 1 mm hole

• particle penetration > 0.1%

• leaky DPF: defect simul-ated by four 1 mm holes

• exhaust flow direction reversed

• particle penetration > 0.5 %

Total Concentration: Before filter After filter Penetration Deposition

[-] [%]

Concentration [1/cm3] 8.03E+07

DiSC Mean [1/cm3] 5.94E+07 5.25E+04 0.000882 99.9118

Stdv. [%] 1.02 5.16

PAS2000 Mean [µgEC/m3] 1.96E+05 208.66 0.001064 99.8936

Stdv. [%] 2.38 0.36

LQ1-DC Mean [µm2/cm3] 688.1

Stdv. [%] 2.41

SMPS

Measurement 4 DPF Test using REXS Soot generator

Filter: FAP/Citroen, 1 damaged channel (1* bored out d=1mm)

Measurement with SMPS, DiSC, PAS2000 and LQ1-DC

0.0E+0

2.0E+7

4.0E+7

6.0E+7

8.0E+7

1.0E+8

1.2E+8

10 100 1000diameter [nm]

0.0E+0

5.0E+3

1.0E+4

1.5E+4

2.0E+4

2.5E+4

3.0E+4

3.5E+4

4.0E+4

1. Sample

2. Sample

3. Sample

conc. dN

/dlo

gD

p [cm

-3]

SMPS Spectrum

after filter,no SMPS

data availabledue to problems

with DMA

before filter

0.00001

0.00010

0.00100

0.01000

0.10000

1.00000

10 100 1000diameter [nm]

pe

ne

tra

tio

n [

-]

SMPS Penetration

N a n o p a r t i c l e M e a s u r e m e n t

Matter Engineering AG

0.0E+0

1.0E+4

2.0E+4

3.0E+4

4.0E+4

5.0E+4

6.0E+4

7.0E+4

8.0E+4

0 100 200 300 400 500 600Time [s]

0

100

200

300

400

500

600

700

800

900

1000PAS2000 [ugEC/m3]

LQ1-DC [um2/cm3]

Sensor signals: Measurement over time after DPF- DiSC [1/cm3]

0.000100

0.001000

0.010000

0.100000

1.000000

0 100 200 300 400 500 600Time [s]

DiSC

PAS2000 [ugEC/m3]

Sensor signals: Penetration

Measurement4-Citroen.xls Anhang 4

Total Concentration: Before filter After filter Penetration Deposition

[-] [%]

Concentration [1/cm3] 8.03E+07 3.40E+05 0.004238 99.5762

DiSC Mean [1/cm3] 5.94E+07 2.78E+05 0.004678 99.5322

Stdv. [%] 1.02 3.60

PAS2000 Mean [µgEC/m3] 1.96E+05 1015.19 0.005176 99.4824

Stdv. [%] 2.38 0.28

LQ1-DC Mean [µm2/cm3] 3440.8

Stdv. [%] 2.25

SMPS

Measurement 7 - DPF Test using REXS Soot generator

Filter: FAP/Citroen, 4 damaged channels, reverse flow

Measurement with SMPS, DiSC, PAS2000 and LQ1-DC

0.0E+0

2.0E+7

4.0E+7

6.0E+7

8.0E+7

1.0E+8

1.2E+8

10 100 1000diameter [nm]

0.0E+0

1.0E+5

2.0E+5

3.0E+5

4.0E+5

5.0E+5

6.0E+5

7.0E+5

8.0E+5

1. Sample

2. Sample

3. Sample

conc. dN

/dlo

gD

p [cm

-3]

SMPS Spectrum

after filterbefore filter

0.00001

0.00010

0.00100

0.01000

0.10000

1.00000

10 100 1000diameter [nm]

pe

ne

tra

tio

n [

-]

SMPS Penetration

N a n o p a r t i c l e M e a s u r e m e n t

Matter Engineering AG

0.0E+0

5.0E+4

1.0E+5

1.5E+5

2.0E+5

2.5E+5

3.0E+5

3.5E+5

0 100 200 300 400 500 600 700Time [s]

0

500

1000

1500

2000

2500

3000

3500

4000

PAS2000 [ugEC/m3]

LQ1-DC [um2/cm3]

Sensor signals: Measurement over time after DPF- DiSC [1/cm3]

0.001000

0.010000

0.100000

1.000000

0 100 200 300 400 500 600 700Time [s]

DiSC

PAS2000 [ugEC/m3]

Sensor signals: Penetration

Measurement7-Citroen.xls Anhang 7

Reproducible EXhaust Simulator - REXS

• combustion soot generator• 1.5 g/h @ 80 nm / 700 l/min • 65 / 80 / 100 nm mode• backpressure proof up to 500 mbar

Diffusion Size Classifier - DiSC

• on-line measurement of number and size• size range 10-300 nm• portable, 10 hrs battery operation• USB or bluetooth connectivity

Test Set-up:

For photo of Test Set-up, see Appendix 9

acknowledgment

This case study was financially supported by the AKPF - Association of Filter Manufacturers, www.akpf.org

The authors further wish to express their gratitude to Mr. Mayer, TTM, for many fruitful discussions.