Non-volatile Particulate Matter Measurement Methodology for Aero- Engines. Mark Johnson Rolls-Royce Emissions Measurement Expert

Transcription

1 FORUM-AE Non-volatile Particulate Matter Measurement Methodology for Aero- Engines 10 th January 2014, MMU, Manchester Mark Johnson Rolls-Royce Emissions Measurement Expert SAE AIR6241 document sponsor & Sampling Team lead

2 Aircraft Emission Measurement Certification Methodology Process SAE-E31 committee members include: engine manufacturers, scientists academic/research institutes, regulators Aerospace Information Report (AIR) Information report written in the style of an ARP by a small number of committee members Review and ballot before published Aerospace Recommended Practice (ARP) Comprehensive report written as an industry standard with input from all members Review and ballot before published CAEP (Committee on Aviation Environmental Protection) Relevant Country members with additional observers including: regulators, NGO s, engine manufacturers Steering Group (specifically WG3) adopts SAE-E31 methodology for aircraft engine certification ICAO (International Civil Aircraft Organisation) Government members ICAO adopts CAEP recommendations and published in Annex 16

3 Existing Aircraft Particulate Emissions Measurement Standard Method - Smoke

4 Visibility Smoke Number SAE Smoke Number method determined over 50 years ago based on reflectance of smoke stained filters

5 PM driver: Local Air Quality Human health impact The smaller the particle the deeper it enters the human body Ultrafine particles have a strong impact on human health Ultrafine particles are underrepresented in mass-based metrics Key property is the particle surface area. Interaction mechanisms are not yet understood. Cleaning Mechanisms Dissolution / leaching of soluble matter in the humid environment of the respiratory system. Physical translocation of non-volatile, insoluble particulate matter. Removal from alveolar region by interaction with macrophages -inefficient for particles < 80 nm. Majority of current technology gas turbine (combustion exit) particles fall in this range)

6 SAE-E31 committee originally tasked with: Define and develop a robust repeatable mass measurement methodology for volatile mass*, non-volatile particle mass and number for use at the exit plane of jet turbine exhaust engines. The method will include sample acquisition, transport/conduction, analysis and computations required to provide the desired parameters. *Note: It is current belief that volatile combustion generated particles do not exist at the engine exit. They form only in sampling lines and/or downstream of engine Particle distribution from a combustion source consists of Non-volatile primary and agglomerate particles (solid carbon/smoke) And Volatile (condensation) particles (hydrocarbons and sulfate) The fraction of volatiles present, depends upon temperature, dilution and residence time of the plume

7 Distinction between nonvolatile and volatile particle types is a critical task in the measurement of particles in aircraft engine exhaust Temperature threshold separating volatile organics from nonvolatile matter is set (by SAE E31) at 350 C Elemental Carbon (EC) - All carbon products >350 C and therefore considered to be equivalent to Non-volatile matter. Organic Carbon (OC) All carbon-based particle products produced by condensation and chemical reaction downstream of the exit of an aircraft gas turbine engine. However, it should be noted that the exact definition of organic carbon depends on the applied measurement technique Part of the volatile fraction Volatile fraction Material that is vapor phase at release conditions (In gaseous form known as volatile precursors), but which condenses and/or reacts upon cooling and dilution in the ambient air to form solid or liquid particulate matter after discharge. The distribution between organic carbon (OC) and EC depends on the operating conditions of the engine. The respective fractions may vary between 10% EC and 90% OC at idle conditions to approximately 100% EC at take-off thrust conditions.

8 E31 PM ARP Milestones & Campaigns (i) AIR5892 (nvpm measurement techniques) published APEX 2 APEX 3 Interim JSF EASA Letter to E31 Aug 2007 Suggestion of nonvolatile mass ARP by 2010 Joint regulator letter to E31 May 2008 Regulators become E31 members SAMPLE I AAFEX Task E31 for an ARP for total mass by 2010 Face-to-face meeting Oct 2008 Between regulators and SAE E31 AIR6037 (Aircraft nvpm method development) published SAMPLE II MS&T lab testing EPA testing Joint regulator presentation Nov 2009 Task E31 for Non-volatile PM ARP by end of 2011

9 E31 PM ARP Milestones & Campaigns (ii) nvpm AIR6241 ballotted nvpm ARP ballotted AAFEX 2 OEM testing SAMPLE III.1 SAMPLE III.2 APRIDE 5 FOCA Zurich APRIDE 4 MS&T Zurich MS&T vs OEM Mermose EPA testing EPA testing SAMPLE III.5 CAEP 9 meeting Feb 2013 Draft PM ARP methodology delivered to CAEP CAEP 10 meeting Feb 2016 WG3 Deliver PM standard to CAEP

10 AIR6241 published in November 2013 Plus 12 Appendices: Excel calculators PM EI, Sampling system Transport Performance (simple & complex) Standard Operating Procedures mass instrumentation/calibration Volatile Removal Efficiency methodology

11 Mass Measurement Techniques (not sensitive to volatiles) Laser Induced Incandescence (Artium) Photoacoustic (AVL) Filter absorption (Thermo) Secondary traceable transfer calibration via filter burn-off NIOSH 5040 using diffusion flame (>80% EC)

12 Mass Instrument Specifications (note mass measurement obtained after a minimum 8x dilution factor) Performance specification Value Range 1 mg/m 3 Resolution 1 µg/m 3 Repeatability 10 µg/m 3 Zero drift 10 µg/m 3 /hr Linearity 15 µg /m 3 Limit of detection (LOD) 3 µg/m 3 Rise time Sample rate Accuracy - Agreement with EC determined by NIOSH 5040 (at 15 ± 5 µg/cm 2 EC loading) 2 sec 1 Hz 0.90 slope 1.10

13 Number Measurement Technique Condensation Particle Counter Need to remove volatiles...

14 Number Measurement Specifications Volatile Particle Removal: Achieve >99.9% removal of 15 nm and 30 nm tetracontane (CH 3 (CH 2 ) 38 CH 3 ) particles with an inlet concentration of 10,000 particles/cm 3 and 50,000 particles/cm 3 respectively. Condensation Particle Counter: Adhere to ISO27891 recommendations Use reagent grade n-butanol as working fluid Operate under full flow operating conditions (flow splitting inside the CPC is not allowed) single count mode only with upto 10% coincidence correction Linearity 0.90 slope 1.10 Have counting efficiency of 50% at 10 nm and 90% at 15 nm electrical mobility diameter respectively, using an emery oil aerosol or equivalent Note that number measurements are NOT corrected for particle loss in the VPR (different to PMP). However, particle penetration measurement through VPR is required for sampling system transport performance, with minimum specifications of 30%, 55%, 65% & 70% at 15, 30, 50 & 100nm respectively.

15 Difficulties in Aircraft large engine sampling... Aircraft engine sampling systems are much longer than automotive due to: - Harsh (vibration and temperature) environment close to large engines - Complex probes for exhaust representativeness Results in sampling line lengths >25m and therefore significant particle loss Thick Testbed Wall nvpm Measurement system

16 AIR6241 Sampling Methodology

17 Sampling System Particle loss mechanisms

18 Sampling System Particle Transport Penetration calculation at 15, 30, 50 & 100nm

19 Sampling System Particle Transport performance example Multiple Systems

20 nvpm Number measurement CPC lower size cut-off Single component efficiencies:

21 Sampling + detection system efficiency

22 nvpm Measurement Uncertainties nvpm Number similar methodology to PMP thus similar uncertainties (~17 to 20%), plus sampling uncertainties below nvpm Mass theoretically (GUM) similar to number plus sampling uncertainties. Need more confidence due to lack of long term/multiple instrument/multi lab data (only one campaign so far) Sampling Particle losses system standardised as far as possible to reduce differences in particle loss between systems - Ongoing measurements of long term drift on sample loss Experiment comparisons ongoing/planned to understand reproducibility (number/mass plus sampling) between reference and OEM systems SAE E31 are developing an assumption-based theoretical methodology for correcting particle loss (no measurement of size distribution). It is currently unknown what the impact of uncertainty due to this methodology is similar to the measurement uncertainty above.

23 nvpm ARP roadmap (if funding available) 2012 DWD compliant validation/ robustness testing AIR6241 ballotted Reference systems comparison Permanent vs mobile Single / multi system testing Dilution factor sensitivity, Dilutor1 low inlet pressure, line loss drift Ballot ARP SAMPLE III.2 MS&T A-PRIDE 3 A-PRIDE 4 MERMOSE SAMPLE III.3 MS&T A-PRIDE 5 MST SAMPLE III.5 Mass Initial Performance validation, calibration, QC checks 12 months Intercomparison (Mobile Reference vs engine manufacturers) Round-robin testing A-PRIDE 6 Possible delay if: 1) technical problems arise 2) OEM engine availability Engine Manufacturers perform robust system testing in multiple locations/engine types System repeatability / Uncertainty Particle loss correction methodology, uncertainty analysis

24 Conclusions Huge milestone reached with publication of AIR6241, would not have been possible without international collaboration involvement Further work is needed to prove the robustness and operability of AIR6241 methodology (at engine manufacturers) to publish ARP Further work on the nvpm methodology uncertainty is required (including comparison engine testing to assess reproducibility) Current E31 roadmap timeline is only possible if funding and engine resource are available to test. Further development (and uncertainty) of sampling system particle loss correction methodology required (but can be applied retrospectively to nvpm AIR/ARP obtained data)