MINUTES OF THE KICK-OFF MEETING for WP 200 and WP 300 of the EU project PARTICULATES. Organisation

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1 Eidgenössische Materialprüfungs- und Forschungsanstalt EMPA Laboratoire fédéral d'essai des matériaux et de recherche Überlandstrasse 129 Laboratorio federale di prova dei materiali e di ricerca CH-8600 Dübendorf Institut federal da controlla da material e da retschertgas Tel Swiss Federal Laboratories for Materials Testing and Research Fax Dübendorf, 16 June 2000 MINUTES OF THE KICK-OFF MEETING for WP 200 and WP 300 of the EU project PARTICULATES Location / Participants The meeting was held at EMPA Duebendorf, CH-8600 Duebendorf on May 11 and on May 12, It was attended by: Name Organisation 1 Mr. David Blaikley (DB) (AEAT) 2 Mr. Claes de Serves (CdS) (MTC) 3 Mr. Andy Feest (AF) (AEAT) 4 Mr. Laurent Forti (LF) (IFP) 5 Mr. Olle Johnson (OJ) (VOLVO) 6 Mr. Jorma Keskinen (JK) (TUT) 7 Mr. David Kittelson (DK) (Uni Minnesota) 8 Mr. Henrik Landälv (HL) (VOLVO) 9 Mr. Urs Lehmann (UL) (EMPA) 10 Mr. Marko Marjamäki (MM) (TUT) 11 Mr. Giorgio Martini (GM) (CONCAWE) 12 Mr. John McAughey (JM) (AEAT) 13 Mrs. Pirita Mikkanen (PM) (DEKATI) 14 Mr. Martin Mohr (Mohr) (EMPA) 15 Mr. Leonidas Ntziachristos (LN) (LAT/AUTh) 16 Mr. Andreas Paul (AP) (EMPA) 17 Mr. Didier Pillot (DP) (INRETS) 18 Mr. George Reischl (GR) (VIENNA) 19 Mr. Zissis Samaras (ZS) (LAT/AUTh) 20 Mr. Janus Urbanus (JU) (CONCAWE) 21 Mr. Urban Wass (UW) (VOLVO) 22 Mr. Roger N. Westerholm (RW) (SU) 23 Mr. Les White (LW) (LWA) Thu only Thursday, 11 th May Welcome and introductions (AP) AP, head of I.C. Engines and Furnaces Department at EMPA, welcomed the participants and gave an overview of the structure, the organisation and the activities of EMPA. Adoption of the agenda Agenda was adopted without modifications. Ending of Thursday the agenda was altered to have only two working groups on Friday (see below). Minutes WP Meeting doc 1 /10

2 Goals of the meeting (JK) In this meeting we have to make a decision what we are going to measure / preliminary decision of the sampling conditions. JK described the goals of the meeting: 1. To choose the basic measured quantities 2. Identify other, possibly measured quantities 3. Decide first line instruments 4. Make clear how the sampling conditions affect the measured quantities 5. Make a preliminary selection of sampling conditions 6. Start work on validation protocol for WP Identify open questions, decide how to tackle them Short Presentations: Some ideas on how we might account for the "end-use" of our work (LW) Annex I At present PM data are based on mass. By modelling on long time range you need to worry about particle numbers À Ideas that might affect the shape of the test matrix Toxicity of PM (UW) Annex II UW presented a concise overview of epidemiological and particle toxicology studies. The toxicological studies performed so far are generating hypotheses rather than providing clear evidence on which properties of PM account for the observed toxic effects. UW s proposal for measured quantities (shortened): 1. Particles should be collected in three size ranges corresponding to nuclei, accumulation and coarse modes (different toxic profiles) 2. Concentration in mass. If mass is too low to be detected, chemical methods 3. Solid core particles and particle size are important factors to health outcome should be sampled 4. Gaseous combustion products with the potential of forming secondary particles in the atmosphere should not be included when the particle mass is determined. Such products should be expressed as NOx, SOx, and HC (VOC) etc. À Look at biological aspects / biological analyses are important Remark of G. Reischl: not only solid particles are important for health effects Some aspects of the particle size measurements (GM reviewed a Ricardo study) Annex III 1. The present testing methodologies for light duty particulate sampling are not ideal for the current low masses and may be inappropriate for particle size distribution and number concentration measurements 2. If particle size and number are to be legislated the influences of the entire system and test environment should be thoroughly evaluated 3. Dilution systems (particularly for particle size and number measurement) should better represent real world conditions 4. If legislation is to address particulates from gasoline and G-DI engines, alternative test methodologies may be required 5. Particles currently attributed to a engine running on a particular fuel from a particular tunnel should be regarded as the product of those variables and the contribution of the entire test environment À Importance of achieving high dilution in a very short time Minutes WP Meeting doc 2 / 10

3 Experience when sampling from raw exhaust (LN) Annex IV LN shared his experience with raw exhaust sampling. He also reviewed the differences between CVS and mini dilutions systems. Results of ELPI measurements: À increase of nanoparticles or ultrafine particle distribution by using a CVS-tunnel À dilution tunnel is not representative for particle number measurement A mini dilution system is more flexible in that respect and can be combined with a number of different configurations: - rotation-diluter / ejector-diluter with variable dilution ratios - preheating the sample by heating the transfer line to the dilution unit - use a thermodesorber to isolate the solids Review for DGIII (JM) Annex V Particle emissions measurement in the context of health and legislation À PM mass and Particle size are important issues Strategy how to dilute (PM) Annex VI PM described the possibilities of designing/realising a new dilution system. Proposal: 1. Two-stage system (hot and cold) 2. Ejector pump 3. Acoustic flow measurement if necessary Need of À Defined dilution ratio for transient conditions À Flexible dilution ratio À Well defined dilution temperature (influence on nucleation, condensation) Summary of our current understanding of the nanoparticle problem (DK) Annex VII 1. Often up to 90% of the particle number that we count and a significant fraction of the particle mass are formed in the dilution process 2. New particles are formed by nucleation. - chemically formation: sulphuric acid - water nucleation - gas-to-particle conversion: growth by hydrocarbon absorption to sulphuric acid nuclei 3. Total number concentration will be changed by a factor of 100 by changing sampling and dilution conditions 4. shorter residence time (10ms) smaller nuclei mode À Nanoparticle measurements are very strongly influenced by the sampling and dilution techniques employed À Currently most of the particles in the nanoparticle size range are volatile. As engines become cleaner, metallic particles may become more important. How is the relationship to the atmosphere? Measurements of particle size distribution in atmosphere behind modern diesel trucks were carried out in the CRC project. À atmospheric size distributions shows a big nucleation mode Not hydrocarbons (HC) but sulphur gases seems to be the primary cause of nucleation process Minutes WP Meeting doc 3 / 10

4 À sulphur content is clearly playing a very important role in production of nucleation Introduction WP 200 (JK) JK described his view of what should be decided in WP 200, what quantities could be measured and how. JK made a proposal for discussion. The proposal in short: Measure mass by weighing - Distinguish volatile/non-volatile - Possibly use pre-cut - In WP300 study the indirect mass measurement methods Number and size - Use CPC and ELPI - SMPS if stable condition measurements Composition: leave details open until WP300. Let this not restrict sampling for size distribution measurement. The main discussion question was: How detailed characterisation is needed for the possible nucleation mode? DK was of the opinion that both concentration and size distribution should be characterised, even if crudely. Although there is no certainty of the health impact of these particles, they should be characterised to be on the safe side. Introduction WP 300 (Mohr) Mohr pointed out that decisions for a concept of instrumentation and sampling procedure have to be taken in WP200. Task of WP300 is to prove the applicability of the concept and to evaluate the crucial parameters and their limits. A list of parameters was presented that have to be consider for a study in WP300: Sampling parameters: dilution ratio humidity flow velocity residence time temperature distribution initial charge of the particles pressure drop pressure fluctuations losses Parameters concerning the emission source: combustion spark ignition, diesel system engine, vehicle fuel diesel, petrol, CNG, LPG, RME, sulphur, aromatic content, metal additives aftertreatment system trap, DeNOx injection urea operation mode transient, constant pre-conditioning time, load Things that have to be agreed for the protocol for WP500 Correction of losses Comparability of different types and versions of instruments Software version of instruments Proposed concept for WP300: Measurements - Total mass - Mass of solid particles - MSD of particles - NSD of solid particles/at elevated temperature of sampling system - Chemical analysis of total mass (SOF, WSF, EC/OC, PAH) Minutes WP Meeting doc 4 / 10

5 - Chemical analysis of size fractionated samples - - (Photoactivity of particles) Some mass size distribution should be carried out in WP300 to clarify the question of existing mass fraction above 1 µm or 2.5 µm Proposed concept for WP 500 Measurements - total mass - NSD of solid particles - chemical analysis of total mass Calculations - solid surface area - - mass of solid particles - mass of volatile material Discussion WP 200 & 300 Key question: Do we need to know the size distribution of the non-solid nucleates, or is volatile mass data enough? JK: Do we need to measure the size distribution of nucleation mode? AF: Question of minimum size to measure. DK: It is not enough to measure the volatile mass. There is no information about adsorption to the accumulation mode particles and nucleation. The number of particles is not simply related to the amount of HC precursor. The number is related to the primary nucleation of the sulphuric cases. All the atmospheric measurements show that there is a significant nucleation mode. Nuclear mode is a relatively stable thing out there in the atmosphere. We don t know how to predict the formation of that nuclear mode JK: We need to do size distribution measurement at transient cycle. ZS: Size distribution measurement at transient cycle is content of contract. Thus there is no question. DK: What are the calibration standards? The program has to think early on what kind of standardisation/calibration we need. GR: Question of optical measurement technique (smoke numbers/opacity). Friday, 12 th May Starting of working groups WG A: WG B: Definition of instrumentation and sampling (Object of WG200). Chair: Martin Mohr, Jorma Keskinen Creation of a validation protocol for instrument, sampling, emission source, data reduction for WP300 (Object of 300). Chair: Zissis Samaras WG A: Definition of instrumentation and sampling Andy Feest (AF) AEAT Laurent Forti (LF) IFP Jorma Keskinen (JK) TUT Giorgio Martini (GM) Concawe Pirita Mikkanen (PM) DEKATI Martin Mohr (Mohr) EMPA Mr. Leonidas Ntziachristos (LN) LAT/AUTh Urban Wass (UW) VOLVO Roger N.Westerholm (RW) SU John McAughey AEAT Olle Johnson Volvo David Kittelson UofM It was observed that the quantities to be measured, instrumentation, and sampling system must be thought of as interdependent. The WP200 introduction presentation of JK was revised. JK pointed out that preliminary decisions have to be done immediately. It is well understood that the decision of measured quantities should be based on Minutes WP Meeting doc 5 / 10

6 health and environmental effects, but there is not enough time to wait for the corresponding reviews made in WP200. There was lively discussion. The decision making process was iterative, and the details are omitted here. Decision on quantities and instruments For the quantities to be measured and instruments to be used in WP500, the following was agreed unanimously: 1) Mass is the main quantity describing the particles a) Primary method is weighing b) Regulated mass is measured from CVS c) Mass is also measured from the dilution system, to be used for quality control purposes d) Volatile/non-volatile fraction is distinguished (method to be decided later) e) Possibilities for indirect mass measurement is studied in WP300 2) Number and size a) Total number in wet mode is measured by CPC. The instruments have different cut sizes. Either the instruments are modified/tuned to have the same cut size or a DMA with a wide trapezoidal transfer function is used as a pre-separator. b) Dry particle size distribution is measured by ELPI c) Diffusion charger combined with total current measurement is used in wet condition. d) Additional SMPS measurements are done at stable conditions Decision on sampling The decision on the sampling system was unanimous. The set-up is best described by the figure in Appendix 1. In short, the following ideas support the set-up of the proposed sampling system: 1. The sampling probe is located at the vehicle exhaust outlet and it is either insulated or heated at a relatively low temperature (e.g. 60 C to be defined exactly) to draw a representative sample of raw exhaust. The possibility was also discussed to have the first dilution carried out inside the tailpipe. This approach would minimise the losses by quench sampling when the exhaust gas temperature changes. Standard exhaust system should be used even with engine dynamometer measurements. If this is impossible, at least the muffler should be installed. The residence time from the particles source (i.e. engine) depends on the length of the exhaust line and the sampling probe before the flow enters the first dilution unit. While the residence time in the exhaust line cannot be controlled (and subsequently may result in variation between different vehicles and different speed/loads), the residence time in the sampling probe needs to be exactly defined and should be as short as possible. Parameters to examine: length of probe, diameter of probe and volumetric flow rate of exhaust gas. 2. After sampling, particles enter the first dilution unit, which provides a moderate dilution ratio in the range of 10-20:1. The principle of operation of the dilution unit was not decided and can be a rotation disk, an ejector or other concept. Dekati should make a proposal to this open question. Aim of this first dilution stage is to primarily decrease the concentration (reduce of coagulation effects) and temperature of the sample and to allow for any adsorption, condensation (either homogeneous or heterogeneous) effects to take place. The temperature and dilution-ratio of the first dilution unit, as well as the delay time between first and second dilution unit were agreed following the advice of DK. Obviously, the details of the residence time of the particles in the dilutor and the operating temperature need to be examined. Additionally, the exact dilution ratio of this first unit should probably be continuously monitored by comparing the concentration of CO 2 or NO x upstream and downstream of the unit (probably after the filter of mass measurement). Thirdly, the conditions of the diluting stream (filtration, humidity, etc.) should be investigated. 3. After the dilutor the flow is split to two parts, which by convention may be called wet and dry. In the wet part, the sample leaves the first dilution unit and it is led to both a mass collecting filter (far left branch) and a secondary dilution stage. The mass is collected to cross check with the number and surface measurements and the mass collected from the dilution tunnel, for quality control purposes. The gas flow through the filter and the sampling temperature need to be examined. Also, a few stages Minutes WP Meeting doc 6 / 10

7 cascade impactor can be utilised in this position to collect samples of different particle sizes, which may be used for size-resolved chemical analysis. 4. The second branch of the wet part enters the secondary dilution stage. This is used to freeze (decrease the rate of) further gas-to-particle reactions and particle-to-particle interactions before particle concentration is measured by a CPC and a Diffusion Charger (DC). This dilution stage operates at close to ambient temperature with a dilution ratio again 10-20:1 and a residence time, which will be decided. 5. Depending on the sizes that we need to sample, a DMA operating at a fixed mobility channel or with a trapezoidal response function to cover a range of sizes may be used before the CPC and the DC. Or, depending on the concentration recorded, a third dilution unit may fit. Also the exact type of Diffusion Charger has not been decided (Matter Engineering, Dekati, other?). Those are open questions, which need to be investigated before conclusions are drawn. 6. To achieve a dry part, the sample is drawn after the first dilution stage to the respective sampling line. This consists of a heater, which heats the sample at the desired elevated temperature (e.g. 300 C) to evaporate any condensed material. The sample is then drawn in a thermodesorber (TD) or a catalytic stripper (CS) which are used to adsorb or oxidise respectively potentially condensable species. Both devices need to be specifically designed to handle the relatively high flow required by the ELPI. The use of an additional dilution stage may also be foreseen, preferably before the heater+(td or CS) to decrease the concentration of the sample and increase the efficiency in removing condensables. After such handling the sample, the solid part of the aerosol is introduced in the ELPI. 7. The option to install a filter to also sample mass of dry particles could be discussed. This information may be used for comparison with ELPI and TGA (or SOF/VOF) results. However, sampling of mass at elevated temperature requires a special handling of the filters, is prone to weighing errors due to low mass collected and may bring disproportional complications to the sampling system. The necessity to install such a filter stage needs to be questioned. There are open questions and possible problems we have to tackle Separation of the volatile material by using a catalytic stripper or a thermodesorber. Catalytic stripper no difficulties expected for higher flow rates not sensitive to high particle concentration Thermodesorber temperature adjustable no oxidation processes some experience available Advantages Disadvantages Activities not available at all at the completely new moment development chemical reactions inside (support by DK possible, e.g. conversion needed) of SO 2 in SO 3 narrow temperature range usable only long temperature stabilisation time available for low flow rates only new nucleation at high concentration possible long residence time up-grading of existing smaller units necessary or new development Low mass emissions We could run in a problem for the mass measurement as the sample is taken from an aerosol diluted by a DR: in the first stage. That could happen especially for very modern engines, for measurements downstream of a trap or when soot will be measured ("dry" branch). Free parameters are sampling time and flow rate, only. Minutes WP Meeting doc 7 / 10

8 WG B: Validation protocol David Blaikley (DB) AEAT Henrik Landälv (HL) VOLVO Marko Marjamäki (MM) TUT Zissis Samaras (ZS) LAT/AUTh Claes de Serves (CdS) MTC Jan Urbanus Concawe Andreas Paul EMPA Urs Lehmann EMPA Georg Reischl UofV Conclusions of WG B for tests in WP 300: 2 LDV 1 Diesel [DI] Euro II 1 Gasoline [MPI] Euro II No engines on a test bench No aftertreatment systems for the diesel Fuel Issue Gasoline: 2000 Gas Diesel: 2000 Diesel ppm Sulphur - EC 1 Swedish Standard lube oil Transient and constant conditions; As the test cycles in Artimes will be decided in September we have to create own (anticipated) cycles. Conditioning of the vehicle has to be analysed Validation of specific combinations over the full driving pattern One single dilution system is going to be used for measuring/calculation/estimation of the losses Measurement of exhaust gas flow via measurement of air consumption and fuel consumption or lambda Determination of diffusion losses in instruments by literature review Procedure of data reduction has to be studied in the framework of the Round Robin test (Need for specification, procedures) Sampling conditions to be investigated: - dilution ratio Yes - residence time of undiluted sample (as short as possible) Yes - humidity of the dilution air (and the aerosol) Yes - pressure drop and pressure fluctuations in the sampling line Yes - conditioning of the sampling system and instruments Yes - specification for dilution air Yes - velocity conditions at sampling No - temperature distribution along the sampling line No - initial charge of the particles No Mohr: Initial charge of the particles might have a significant effect on the results of the diffusion charger Minutes WP Meeting doc 8 / 10

9 Further steps in WP200 and WP300 and schedule of next meeting More information about the Round Robin Test (who is doing what?) Next Meeting (differ between two types): large meeting once a year. small meetings / working groups ad hoc Dekati needs to be contacted to examine the possibility of circulating a thermodesorber between a few labs (AEA, EMPA, IFP, LAT, MTC) for testing Open questions and future work System to distinguish between volatile and non-volatile fraction. Possible methods are Soxhlet extraction, TGA, and a simple oven to heat the samples. A questionnaire will be prepared. To be studied in WP200. Analysis of particle composition. Artefacts were recognised as a possible problem. Which diffusion charger should be used (ELPI or Matter Engineering)? Do we need to calibrate the diffusion charger? The issue of TEM/SEM was not tackled in the meeting. It needs to be addressed in WP200 and preferably be included in TUT s questionnaire. When will the first prototype versions of instruments available? a) dilution unit b) diffusion charger c) heater/ thermodesorber/catalytic stripper for ELPI flow rates Follow-up All presentations to be ed to the co-ordinator of the meeting Questionnaire on chemical analysis (JK) Decision on method to distinguish between volatile and non-volatile fraction (JK and AEAT) Requirements on samples for PAH analysis (RW) First draft of a schedule for activities in WP300 until the 30 th of June (Mohr). Optical techniques for possible incorporation into Task 500 (AEAT). Preparation of a concept for the round robin test until the 25 th of June (PM + ZS). Provisionally the next plenary meeting was set for the end of 2000 beginning 2001 in Tampere. Minutes WP Meeting doc 9 / 10

10 Appendix 1 Proposed experimental set-up (Diesel light duty configuration) engine aftertreatment system TUBE τ: [real world] Τ:? L 20 cm CVS mass DILUTION DR: Τ 30 C mass TUBE τ :? Τ:? TUBE τ 1.5 s Τ:? DILUTION DR: Τ 20 C HEATER τ? Τ:? DILUTION DR:? Τ 20 C mass TUBE τ? Τ 20 C THERMO DESORBER / CATALYTIC STRIPPER τ? Τ:? DILUTION / DMA / - DR: ELPI CPC DC Annex I Annex II Annex III Annex IV Annex V Annex VI Annex VII Annex I to VII can be found in separate files Minutes WP Meeting doc 10 / 10