WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Subgroup Additional Pollutants Validation of N 2 O measurement

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP A gas chromatograph with an electron-capture detector (GC–ECD) may be used to measure N 2 O concentrations of diluted exhaust by batch sampling from exhaust and ambient bags. Refer to §7.2. in this Annex Nitrous oxide (N 2 O) analysis with IR-absorption spectrometry (where applicable) The analyser shall be a laser infrared spectrometer defined as modulated high resolution narrow band infrared analyser. An NDIR or FTIR may also be used but water, CO and CO 2 interference must be taken into consideration. Methods for Measurement of N2O in GTR draft GC-ECD Laser infrared spectrometer NDIR FTIR

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Instrument availability and availability of data for evaluation Instrument manufacturers Data for validation GC-ECDseveralVP2/industry laser infrared spectrometer QCL Lasar Cavity ring down several 1 industry none NDIRseveralindustry FTIRseveralnone

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Performance criteria for N2O measurement If the analyser shows interference to compounds present in the sample, this interference can be corrected. Analysers must have combined interference that is within 0.0 ± 0.1 ppm. Established by AP working group, not contained in GTR Interference correction contained in GTR

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP N2O vehicle emission results from VP2 Analyser: GC-ECD Lab: AECC Source: WLTP VP2

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP GC-ECD

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP main column pre column sample loop valve 2 valve 1 total flow backflu sh flow make up gas flow carrier gas filtration sampl e pump bachflush valve ECD Argon/Methan (95/5) N2 O2-doting Flow schematic of GC-ECD

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP LOD and LOQ of GC-ECD-Measurement Assuming background is constant the LOD can be estimated as equal or better 3 * STD and LOQ as 10 * STD STD = 0,00164 ppm LOD = 0,0049 ppm LOQ = 0,0164 ppm LOD and LOQ meet the requirements Source: Daimler

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Conclusions GC-ECD Systems are commercially available With proper application method is free of interferences (base line separation of N2O peak LOD and LOQ meet the requirements GC-ECD has proven to be a reliable method Results from VP2 Results from industry Chemistry lab and well trained personal required Complicated and time consuming sampling and analysis

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP laser infrared spectrometer (QCL)

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Correlation of GC-ECD and QCL GC-ECD and QCL show perfect correlation QCL measures approx. 3 % less Source: Daimler

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP LOD and LOQ exceed the requirements by far Measurement of pure N2 for 30 s LOD and LOQ derived from standard deviation Determination of LOD and LOQ for QCL Source: Daimler

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Interference QCL there is no interference from CO but a slight interference from CO2 (or water) can be observed no interference correction is applied the maximum interference requirement of +/- 0,1 ppm is met in all cases Source: Daimler

WLTP-DTP-AP Validation of N 2 O measurement Scatter of mass emission results (NEDC) results from all 6 correlation vehicles where within +/- 0,8 mg/km data pool: 128 emission test (NEDC) performed on 6 different vehicles (Euro 3/4/5) results from 3 different test cells test period: 6 month Korr02Korr03Korr04Korr05Korr06Korr07Korr08 deviation to mean N2O [mg/km ] vehicle N2OGes. [mg/km] Source: Volkswagen

WLTP-DTP-AP Validation of N 2 O measurement ambient N2O concentration ambient N 2 O concentration is about 0,330 ppm on average all analysers are in excellent agreement (± 0,003 ppm) All mesrements are within +/- 0,015 ppm Source: Volkswagen

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Conclusions QCL Systems are commercially available Perfect correlation to GC-ECD LOD and LOQ exceed the requirements Slight interference from CO2/water but well within limits QCL has proven to be a reliable method various installations running without major problems stable operation over more than one year

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP laser infrared spectrometer (LASAR)

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Linearisation results LASAR The instrument is highly linear Source: SEMTECH

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Accuracy, repeatability and noise testing results LASAR Source: SEMTECH

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Interference LASAR Source: SEMTECH no interference from CO2, CO or water no inteference correction applied

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Conclusions LASAR System commercially available Perfect correlation to calibration gas LOD and LOQ exceed the requirements No interference from CO2/water or CO

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP NDIR

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Correlation not entirely satisfactory Deviation of NDIR to GC of up to 25 % Interference correction has large influence on NDIR results Correlation of GC-ECD and NDIR Source: Daimler

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Even with interference correction in place the maximum interference requirement of +/- 0,1 ppm is not met in all cases Interference correction NDIR Source: Daimler

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Conclusions NDIR Systems are commercially available correlation to GC-ECD not entirely satisfactory Pronounced interferences from CO2/water and CO require interference correction. For the NDIR investigated the combined interference did not fulfill the requirements, even when interference correction was applied with great care. NDIR is a comparatively inexpensive analyser. For the analysis of N2O it has to be operated at its limits.

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP FTIR

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Linearity FTIR Linearity requirements are met Source: BMW

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Conclusions FTIR Systems are commercially available LOQ ~ 300ppb ambient air level with typically 30 sec integration time Cross interference CO within LOD 100ppb (optimized spectral method) Cross interference CO2/H2O (optimized spectral method): N2O in 3 rd bag FTP diluted exhaust typically at ambient air level for petrol vehicles with CO2 ~ 1Vol% and H2O ~1Vol%  cross interference below LOD Linearity requirements comparable to other analyzers are met  Analyzer capable to meet legal requirements with increased integration time

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP The California ARB has published a procedure for N2O emission measurement with FTIR

WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP The methods to measure N2O as described in GTR draft have proven to be sufficiently accurate and robust Systems are commercially available from several instrument manufacturers General conclusions