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Repeatability and Reproducibility Analysis of the Round Robin Results

Repeatability and Reproducibility Analysis of the Round Robin Results. The familiarization of the participating laboratories within the project with the specific sampling system use (“particulates” system)

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Repeatability and Reproducibility Analysis of the Round Robin Results

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  1. Repeatability and Reproducibility Analysis of the Round Robin Results

  2. The familiarization of the participating laboratories within the project with the specific sampling system use (“particulates” system) • The examination of the consistency of the results obtained when applying this methodology in different physical environments Round Robin Objectives

  3. VTT Energy (VTT) – Finland • MTC – Sweden • IFP – France • EMPA – Switzerland • Technical University Graz (TUG) – Austria • AEA Technology (AEAT) – UK • SHELL – UK • Lab of Applied Thermodynamics (LAT) - Greece Participating Laboratories

  4. Round robin execution table

  5. VW Golf TDI 1.9 l, M Y 1996 with the oxidation catalyst removed • Fuel: Fulfilling the specification EN590 (Year 2000 specs) • Lubricant: BP Vanellus C4 multi SAE 20W – 50 grade (pre aged for 874 km) Test Vehicle

  6. Primary Porous Diluter • TYLAN MFC 2920 dilution air mass flow controller • Ageing Chamber • Thermodenuder • Dekati’s Electrical Low Pressure Impactor (ELPI) & ELPI Filter Stage • Vacuum Pump • 2 Ejector dilutors • Dekati’s Diffusion Charger (DDC) • TSI’s 3022 Condensation Particle Counter (CPC) • Dekati’s Gravimetric Cascade Impactor (DGI) Instrumentation

  7. Transient Cycles: • NEDC • Artemis Road • Steady State Modes: • 50 km/h • 120 km/h • (road loads) Testing

  8. Particulates System • Mass emission rate (mg/km) [DGI] • Active surface (cm2/cm3) [DDC] • Number Concentration (cm-3) [ELPI stages 1 to 8] • Number Concentration (cm-3) [ELPI end filter stage] • Mean aerodynamic diameter (nm) • Number concentration (cm-3) [CPC] • Total number concentration (cm-3) – mean & median mobility diameters [SMPS] • Regulated emissions: • NOx • CO2 • CO • HC • PM Properties measured in round robin

  9. Inspection of the repeatability and reproducibility of the results obtained from each laboratory. • Derivation of a precision statement in terms of the total within laboratory and between laboratories variances. Repeatability – Reproducibility Analysis proposed in ASTM E691-99 Standard

  10. The equipment used • The calibration of the equipment • The operators using the equipment • The environmental conditions Factors affecting the outcome of a test method

  11. Precision and Accuracy Accurate but imprecise results True Value Precise but inaccurate results

  12. Within Laboratory Variability: (σ2). • Between Laboratories Variability (στ2). • Within Laboratory – Between Laboratories Variances reflect: • The precision of the test method • Any vagueness in the protocol • Departures from the protocol • Coefficient of Variance: σ/μ Within Lab and between laboratories variability

  13. Repeatable Results Average value

  14. Reproducible Results Overall mean value

  15. Repeatability Index: k • x… laboratory • Reproducibility Index: h • Critical h* and k* values. Repeatability – Reproducibility Statistics and their critical values

  16. h plots by laboratories(reproducibility)

  17. h plot by driving cycles

  18. k plots by laboratories(repeatability)

  19. k plots by driving cycles

  20. Repeatability problems in regulated emission results

  21. Reproducibility problems in regulated emission results

  22. Within Laboratories Coefficients Of Variance for Regulated Emissions Results

  23. Between Laboratories Coefficients Of Variance for Regulated Emissions Results

  24. Repeatability Problems in Particulates instruments results

  25. Reproducibility Problems in Particulates instruments results

  26. Within laboratories Coefficients Of Variance for Particle properties

  27. Between Laboratories Coefficients of Variance for particle properties

  28. Comparison of the Within Laboratory Coefficients of Variance of the particulates instruments results with the regulated PM ones

  29. Comparison of the Between Laboratory Coefficients of Variance of the particulates instruments results with the regulated PM ones

  30. Great variability observed in ELPI results (possibly thermodenuder?). • DDC results were the most repeatable and reproducible. • Possible dilution ratio determination problems. • Indications that the method is robust. • Importance of conducting another round robin now that all laboratories are familiar with the protocol. Conclusions - Recomendations

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