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Inter-Laboratory Comparison ExerciseCPC CALIBRATIONCALIBRATION AEROSOLS AND LABORATORY SETUPS

2016-10-12Alexander Terres

Intermediate Status Report

MOTIVATION

- Comparison of Calibration Aerosols

- Comparison of Laboratory Setups

- Suitability for Calibration sub-23nm ?

Terres: CPC Calibration Round Robin | Calibration Aerosols and Laboratory Setups | 2016-10-12 Page 2

CPC CALIBRATION ROUND ROBIN SCHEDULE

TIME LABORATORY Type

02 / 2016 TSI Germany Instrument Manufacturer

03 / 2016 JRC Research Institute

04 – 05 / 2016 AVL Austria Instrument Manufacturer

06 – 07 / 2016 PTB National Metrological Institute

07 – 08 / 2016 BMW Vehicle Manufacturer

09 – 10 / 2016 Ricardo Energy & Environment Calibration Service

11 / 2016 VW Vehicle Manufacturer

12 / 2016 TSI Germany Instrument Manufacturer

Terres: CPC Calibration Round Robin | Calibration Aerosols and Laboratory Setups | 2016-10-12 Page 3

We are here

REFERENCE DEVICES & CALIBRATION

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LABORATORY REFERENCE INSTRUMENT CALIBRATION TYPE

TSI Germany Aerosol Electrometer National Metrological Institute

JRC Aerosol ElectrometerCPC

Manufacturer CalibrationIn-house

AVL Austria Aerosol Electrometer Manufacturer Calibration

PTB Aerosol Electrometer In-house

BMW Germany Aerosol ElectrometerCPC

Manufacturer CalibrationManufacturer Calibration

Ricardo Energy & Environment CPC National Metrological Institute

VW Germany Aerosol ElectrometerCPC

Manufacturer CalibrationIn-house

LABORATORY SETUPS

Terres: CPC Calibration Round Robin | Calibration Aerosols and Laboratory Setups | 2016-10-12 Page 5

Device under test

Reference

Dilutionbridge

Source DMA

Y-Splitter

Splitter-type: ISO 27891 compliant setup

Device under test

Reference

Source DMA

Sampling volume-type: not ISO 27891 compliant

Device under test

Sampling volume

Dilu

tion

Air

TESTING PROCEDURES: COUNTING EFFICIENCY

Terres: CPC Calibration Round Robin | Calibration Aerosols and Laboratory Setups | 2016-10-12 Page 6

0%

20%

40%

60%

80%

100%

120%

0 20 40 60 80 100 120 140 160

Co

un

tin

g Ef

fici

ency

Mobility Diameter [nm]

Reference Electrometer

Extra Engine Exhaust CPC

Mobility Diameter 10 15 23 41 70 100

Corresponding Diameter,Double Charges

- - 33 59 103 150

Burner Operating Point A A B C D E

Motivation Sub-23 Sub-23 PMP PMP Linearity PN-PEMS

TESTING PROCEDURES: COUNTING EFFICIENCY

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Measurement

• Recording uncorrected Raw Data

• No K-factor on devices under test

• Averaging time: 60-240 seconds

Flow

• Correction: Nominal / actual Flow

• Flow measurement: Volume or Mass

Charges

• Correction for double charges

• Charge distribution: Wiedensohler

• No correction for triple charges

• No correction <23nm

Splitter Bias: Only corrected in certain labsrequired in ISO 27891

Electrometer Zero: Not correctedTo be applied in the future?

Critical when using reference Electrometer

Influenced by:Aerosol characteristicse.g. size distribution, chemistry etc.

TESTING PROCEDURES: EXEMPLARY EVALUATION

Terres: CPC Calibration Round Robin | Calibration Aerosols and Laboratory Setups | 2016-10-12 Page 8

Reference Electrometer Device under Test (CPC)

Raw Concentration 8255/cm³ 6904/cm³

Zero Offset 116/cm³ 0/cm³

Nominal Flow : measured Flow 3 l/min : 2,87 l/min 1 l/min : 1,01 l/min

Flow correction 1,045 0,99

Flow corrected concentration 8629/cm³ 6836/cm³

Flow corr. concentration @59nm 3170/cm³ 2864/cm³

Double charge ratio (Theory) 5,7% 5,7%

Double charged particles 181/cm³ 163/cm³

Double Charge Correction 8629-2*181 6836-163

Charge corrected concentration 8267/cm³ 6673/cm³

CPC Counting Efficiency 6673 : 8267 = 80,7%

Example: Calibration at 41nm

TESTING PROCEDURES: LINEARITY

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Target ConcentrationReference Device

0 1.000 2.000 4.000 6.000 8.000 10.000

Linearity Measurement & Linear Fit

y = 0,84x + 17,73R² = 1,00

0

2000

4000

6000

8000

10000

12000

0 2000 4000 6000 8000 10000 12000

Test

Dev

ice

Co

nce

ntr

atio

n [

1/c

m³]

Reference Concentration [1/cm³]

Grimm Engine Exhaust CPC

Linear (Grimm Engine Exhaust CPC)

Reference Device: Aerosol Electrometer or CPC

PossiblyElectrometer offset

Extra Engine Exhaust CPC

Linear Fit

TESTING PROCEDURES: COUNTING EFFICIENCY

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Measurement

• Recording uncorrected Raw Data

• No K-factor on devices under test

• 70nm mobility diameter

• Averaging time: 60-240 seconds

Flow

• Correction: Nominal / actual flow

• Flow measurement: Volume or Mass

Charges

• Correction for double charges

• Charge distribution: Wiedensohler

• Derived from Counting Efficiency test

Splitter Bias: Only corrected in certain labsrequired in ISO 27891

Electrometer Zero: Not correctedTo be applied in the future?

Critical when using reference Electrometer

Influenced by:Aerosol Characteristicse.g. size distribution, chemistry etc.

SOOT GENERATORS: SIZE RANGE

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0

5000

10000

15000

10 100

Part

icle

Co

nce

ntr

atio

n [

1/c

m³]

Mobility Diameter [nm]

0

1000

2000

3000

4000

5000

10 100

Part

icle

Co

nce

ntr

atio

n [

1/c

m³]

Mobility Diameter [nm]

0

10000

20000

30000

40000

50000

Part

icle

Co

nce

ntr

atio

n [

1/c

m³] miniCAST 6204C at BMW

Round Robin APG w miniCAST 6203C

PALAS DNP 3000 with N2

SOOT GENERATORS: SIZE RANGE

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0

5000

10000

15000

10 100

Part

icle

Co

nce

ntr

atio

n [

1/c

m³]

Mobility Diameter [nm]

0

1000

2000

3000

4000

5000

10 100Pa

rtic

le C

on

cen

trat

ion

[1

/cm

³]

Mobility Diameter [nm]

0

10000

20000

30000

40000

50000

Part

icle

Co

nce

ntr

atio

n [

1/c

m³]

PALAS DNP 3000 with N2

Round Robin APG w miniCAST 6203C

miniCAST 6204C at BMW

SOOT GENERATORS: MAXIMUM CONCENTRATION COMPARISON @10NM

EXAMPLE: Maximum Concentration at BMW laboratory setup (sampling volume, 15l/min dilution air)

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On-site miniCAST AVL Particle Generator PALAS DNP 3000

GMD Max. Conc. GMD Max. Conc. GMD Max. Conc.

10nmVery small 2500/cm³ Very small 35/cm³

Small 1300/cm³ Small 600/cm³ Small 200/cm³

Medium 400/cm³ Medium 180/cm³ Medium 250/cm³

15nm

Very small 1700/cm³ Very small 25/cm³

Small 7900/cm³ Small 1020/cm³ Small 700/cm³

Medium 1700/cm³ Medium 1200/cm³ Medium 2000/cm³

10nm: Insufficient concentration for calibration vs. electrometer with example setup

Going to larger sizes (GMD 20nm – 30nm): No need to worry about multiple charges?

SOOT GENERATORS: CAST – INTERCHANGING SETTINGS

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0

1000

2000

3000

4000

5000

10 100

Part

icle

Co

nce

ntr

atio

n [

1/c

m³]

Mobility Diameter [nm]

Round Robin APG w miniCAST 6203C

0

10000

20000

30000

40000

10 100

Part

icle

Co

nce

ntr

atio

n [

1/c

m³]

Mobility Diameter [nm]

miniCAST 6204C with APG burner settings

CAST-settings are not transferable between models!

SOOT GENERATORS: CAST – SINGLE SIZE DISTRIBUTION CALIBRATION

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0%

20%

40%

60%

80%

100%

120%

10 100

Co

un

tin

g Ef

fici

ency

Mobility Diameter

Reference Electrometer

GMD 20nm

GMD 35nm

GMD 50nm

0

10000

20000

30000

40000

50000

10 100

Part

icle

Co

nce

ntr

atio

n [

1/c

m³]

Electrometer OffsetVery low absolute concentration

Size distribution influenceWith double charge correction applied

Especially when comparing Electrometer & CPC

Calibration Aerosols

CPC CALIBRATION ROUND ROBINFIRST FINDINGS

Participants from all areas of the engine exhaust PN –community

Measurements examine CAST soot as a calibration aerosol

Possible concentration issues for sub-23nm calibration

No universal burner settings for different CAST models

Size distribution influences measurement results

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A big “Thank You” to all the labs that are contributing to this Round Robin!

Open questions for calibration with CAST soot

(only partly covered in ISO 27891):

Clear definition of suitable size distributions

Accurate correction for multiple charges / Strategies to avoid multiple charges

Zero correction and Zero drift of Electrometers

Suitability of „Sample volume-type“ test setup for calibration

THANK YOU FOR YOUR ATTENTION

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