Korrelationen NOx - Home - avl.com

Bertold Arlitt

AVL Emission Test Systems GmbH

Confidential

Korrelationen NOx

NO, NO2 und NOx Analyse mit FTIR und CLD FTIR Anwendertreffen 20. September 2018

Bertold Arlitt | AVL ETS | 20 September 2018 | 2Confidential

Note


Vergleichsmessungen CLD vs. SESAM i60 FT Motorenprüfstand

NOx Korrelationen und NO2 Messwertunterschiede bei transienten Test Zyklen

Reaktionskinetik der NO Oxidation zu NO2 [NOx]

Thema NO, NO2 und NOx in Kalibriergasflaschen

Zertifikate und Rückführbarkeit

Vergleichsmessungen NOx Messwert gut Unterschiede beim NO

Probennahme Verunreinigungen durch Ruß

Messwertvergleiche NOx SESAM i60 FT vs. SII / AMA i60 vs. SESAM i60 FT SII

Zusammenfassung

Inhalt


ENGINE DYNAMOMETER TEST CELL

EMISSION TESTING BY FTIR-SPECTROSCOPY

Development Tool for:

• Engine calibration

• Combustion analysis

• Aftertreatment-systems

• Catalyst efficiency test by the use of different sample points.

Certification Instrument:

• EURO VI und China VI: Ammonia NH3

• EPA CFR 1065 / 1066 : Nitrous oxide N2O

• EPA CFR 1065 CNG Engines: NMHC, NMNEHC

• GTR 15 Flex-Fuel Vehicles (E85) HCHO, MeCHO, EtOH


Global Technical Regulation (GTR 15)Emission component measurement

CO2

CO

NOx

THC

CH4

NMHC

PM

PN

Carbon dioxide

Carbon monoxide

Nitrogen oxides

Total hydrocarbons (by FID)

Methane

Non-methane hydrocarbons

Particulate Matter

Particle Number

CVS Bag

CVS Bag

CVS Bag

CVS Bag/Tunnel

CVS Bag

calculated

CVS Tunnel

CVS Tunnel

NDIR

NDIR

CLD, NDUV

FID, HFID

GC-FID, Cutter-FID

PTS

PNC with CPC

FID all fuels except Diesel, HFID all fuels

THC – CH4

NO2

N2O

NH3

Nitrogen dioxide

Ammonia

Calc. / CVS cont.

CVS Bag

Tailpipe

NDUV, QCL, CLD (NOx-NO)

GC–ECD, FTIR, NDIR, QCL-IR,

FTIR, TDLS, QCL

(NOx,Bag – NO,cont.) or NO2,cont.

FTIR, NDIR with <0.1ppm interference

C2H5OH

NMNEOG

HCHO

CH3CHO

Ethanol

Non-Methane Non-Ethanol Organic Gases

Formaldehyde

Acetaldehyde

CVS

calculated

CVS

CVS

Impinger, Photo Acoustic, FTIR

DNPH-HPLC, FTIR

DNPH-HPLC, FTIR

Reference is CARB

Reference is CARB

Reference is CARB

Emission Component Sample Method Measurement Principle Notes

Sta

ndard

Gaseous

PM

/PN

Additio

nal Polluta

nts

Nitrous oxide


RECORDED DATA

• Fast transient concentration changes during turbo-charged diesel engine-out post DOC measurements.

• Extractive sampling system

• 10 Hz Measurement

• FTIR spectrometer scan speed 5Hz

• Synchronous concentration reading between CLD ChemiluminescenceDetector (Analyzer) and FTIR spectroscopic measurement values.

NOX COMPARISON BETWEEN CLD AND FTIR

[ppm]

Time (s)

APPLICATION ENGINE TESTING

• CLD and FTIR (hot/wet)


REGRESSION ANALYSIS OF THE NOx MEASUREMENT COMPARISON

CLA[ppm]

FTIR i60[ppm]

STATISTICAL EVALUATION

• Linear Regression correlation based on 20000 data points of the different analytical measurement principle.

• Validation measurement data with coefficients of determination to indicate of the correlation results between both analyzer.

• Automotive exhaust emission requirements demands the highest precision and accuracy vs. a pretty fast time resolution.

APPLICATION ENGINE TESTING

• Good agreement


NO2 COMPARISON BETWEEN CLD AND FTIR

Overshoot issues of the CLD indirect NOx-NO calculation to NO2

It depends on:

• t between NOx vs. NO channels

• NO/ NOx ratio in the exhaust

• NOx converter efficiency CLD

(CLA)

• Correlations not possible, artificial reporting of NO2

via CLD technique during fast transient exhaust measurements.


• Synchronization duration issues during fast transient test cycles between the two channels.

• t related NOx vs. NO difference

• Wrong CLA NO2 measurements related to time delay and converter related side reactions.

NO2 COMPARISON BETWEEN CLD AND FTIR

Issues of the CLD indirect NOx-NO calculation to NO2

• Correlations not possible artificial reporting of NO2



NO2 FTIR I60 SII COMPARE W/ CLD (NOX – NO)

• Synchronization duration issues during fast transient test cycles between the two channels.

• t related NOx vs. NO difference

• Wrong CLD NO2 measurements related to time delay

Issues of the CLA indirect NOx-NO calculation to NO2

• Correlations not possible artificial reporting of NO2


[ppm]

Time (s)

• Good results (FTIR)










Zusammenfassung

Inhalt


Reaction of NO with Oxygen to NOx

KINETICS OF THE NITRIC OXIDE OXIDATION

NO + 0.5 O2 NO2

Details

• Keywords: Air pollution, nitrogen oxides, kinetics, oxidation.

• Experimental Setup: N2 + NO gas cylinders,oxygen generator, massflow meter and FT-IR(Jaso 4cm-1) spectrometerwith gas cell.

O2


CALIBRATION GAS STABILITY OF NO AND NO2

Stability evaluation of calibration gas mixtures containing both NO and NO2

• NO gas standard in nitrogen is stabile

• NO2 gas standard only in air is stabile

• NOx gas standards in nitrogen


Calibration Gas NO or NOx Traceability

• Total Oxides of nitrogen (NOx) in nitrogen, 100 µmol/mol - We prepare 100 µmol/mol of nitric oxide in nitrogen. On the certificate there will be value of NO with 0.3 % rel. uncertainty and as an additional information we can add information about amount of NO2 in the mixture. This certificate would include accreditation recognition.

• Air Liquide order from Scott with traceable to VSL (Netherlands) with reference to NIST.

• But the calibration gas NOx value on gas analysis certificates is not certificated!

2










Zusammenfassung

Inhalt


NOX CORRELATION CLA WITH FTIR

• Good agreement

SOOT CONTAMINATION ISSUE IN SAMPLE–LINE AND –FILTER.

• No difference in NOx


Differences in NO peaks

NO Correlation CLD with FTIR (issues)

• Partly higher NO concentrationspeaks over test cycle as reaction of NO2 with soot contamination.

SOOT CONTAMINATION ISSUE IN SAMPLE–LINE AND –FILTER


NO2 CORRELATION CLD WITH FTIR (ISSUES)

• Differences in NO2 peaks

• NO2 Loss Effect on Soot

SOOT CONTAMINATION ISSUE IN SAMPLE–LINE AND –FILTER.

• Partly lower NO2 concentrationspeaks over test cycle as reaction of NO2 with soot contamination.

2

2


SESAM I60 SII COMPARE TO SESAM I60 FT

• Lower noise at 5Hz measurement

• Better data signal processing

• Better low range measurement

• Better detection limits

IMPROVEMENTS SESAM i60 FT SIICOMPARISON NOx CONCENTRATION READING


NOX SESAM I60 FT SII COMPARE AMA I60

Time (s)

[ppm]

• WLTC recording tail pipe

• Good Conc. comparison

• Better low range measurement

• Better detection limits

IMPROVEMENTS SESAM i60 FT SII

Engine OFF * Engine OFF *

*Engine off = No exhaust flow rate


NOX SESAM I60 SII / CLD I60 COMPARE

REGRESSION ANALYSIS OF THE NOx MEASUREMENT COMPARISON

• STATISTICAL EVALUATION

• WLTC recording tail pipe

• Good correlation over full range

• Good dynamic range

• High R2 values low offset

CLD i60[ppm]

FTIR i60[ppm]










Zusammenfassung

Inhalt


ANALYSIS FTIR AND CLD - NO, NO2 AND NOX

Zusammenfassung

• In general the correlation measurements between SESAM i60 FT SII vs. conventional analyzer benchesagree to each other very well.

• NOx correlations between CLD and FTIR show good results, depending on the used CLD with related H2O and CO2 quench differences.

• NOx NO and NO2 measurements could be affected by sample-line, -filter soot contamination issues.

• The NOx value on calibration gases is not a certified, related to instabilities of NO2 in nitrogen mixtures.

• NO2 gas in only stable in synthetic air and NO in only stable in nitrogen.

• Usually the NOx correlations between CLD and FTIR by the use of proper procedure should agree +3% in between different test cycles.

www.avl.com

Thank You

Documents

Korrelationen NOx - Home - avl.com