PARTICULATES Characterisation of Exhaust Particulate Emissions from Road Vehicles

Deliverable 4: PROTOTYPE: Dilution Sampling System

Final Draft - April 2001

A project sponsored by:

EUROPEAN COMMISSION Directorate General Transport and Environment

In the framework of:

Fifth Framework Programme Competitive and Sustainable Growth Sustainable Mobility and Intermodality Contractors

LAT/AUTh: Aristotle University of Thessaloniki, Laboratory of Applied Thermodynamics - EL CONCAWE: CONCAWE, the oil companies' European organisation for environment, health and safety - B VOLVO: AB Volvo - S AVL: AVL List GmbH - A EMPA: Swiss Federal Laboratories for Material Testing and Research - CH MTC: MTC AB - S TUT: Tampere University of Technology - FIN TUG: Institute for Internal Combustion Engines and Thermodynamics, Tech. University Graz - A IFP: Institut Français du Pétrole - F AEA: AEA Technology plc - UK JRC: European Commission – Joint Research Centre - NL REGIENOV: REGIENOV - RENAULT Recherche Innovation - F INRETS: Institut National de Recherche sur les Transports et leur Securité - F DEKATI: DEKATI Oy - FIN SU: Department of Analytical Chemistry, Stockholm University - S DHEUAMS: Department of Hygiene and Epidemiology, University of Athens Medical School - EL INERIS: Institut National de l’ Environment Industriel et des Risques - F LWA: Les White Associates - UK TRL: Transport Research Laboratory - UK VKA: Institute for Internal Combustion Engines, Aachen University of Technology - D

2 Publication data form

1. Framework Programme 2. Contract No European Commission – DG TrEn, 5th Framework Programme 2000-RD.11091 Competitive and Sustainable Growth Sustainable Mobility and Intermodality 3. Project Title 4. Coordinator Characterisation of Exhaust Particulate Emissions from Road Vehicles LAT/AUTh (PARTICULATES) 5. Deliverable Title 6. Deliverable No PROTOTYPE: Dilution Sampling System 4 7. Deliverable Responsible 8. Language 9. Publication Date Dekati Ltd. English April 2001 10. Author(s) 11. Affiliation Pirita Mikkanen Dekati Ltd. 12. Summary This deliverable describes the prototype of Particulates primary diluter. As set for design criteria, this unit rapidly dilutes and cools the sample at tip of the sampling probe. Subsequently, the sample is transported via porous tube to an ageing chamber to obtain proper residence time. The prototype included primary diluter, dilution air and cooling agent flow controls, flow dividers, Vortex tube for cooling, sensors for monitoring temperature and pressure in several locations. In addition, a data acquisition and control program was developed to the prototype. Two of these units were delivered: the first one in August 2000 and the second in November 2000. Detailed drawings of the primary diluter as well as manual for the user program are included in the Appendices.

13. Notes This is the final draft version to be published on the PARTICULATES web-site. 14. Internet reference http://vergina.enag.auth.gr/mech/particulates 15. Key Words 16. Distribution statement FREE 17. No of Pages 18. Price 19. Declassification date 20. Bibliography 13 (w/o Annexes) FREE NO

3 Table of Contents

Publication data form...... 3 Table of Contents...... 4 1 Design Criteria...... 5 2 Construction...... 5 2.1 Mechanical Construction ...... 5 2.2 Control Unit...... 8 2.3 Software...... 10 3 Results...... 10 3.1 Delivered units...... 10 3.2 Reporting ...... 13 Appendix I – Drawings of Primary Dilution Unit Appendix II – Manual for User Program

4 1 Design Criteria

This prototype diluter was constructed under criteria set by Particulates project. The purpose of the new dilution method was to dilute the sample in a manner that maximum nucleation of the sulphur compounds and hydrocarbon vapour is achieved and simultaneously particle losses in the sampling system are minimised. During controlled cooling in the diluter, compounds with tendency to form new ultrafine particles nucleate. As a consequence, particles existing prior to sampling may be distinguished from particles forming during dilution by their size. The nucleated new particles form a nuclei mode, which can be defined as smaller than 50 nm, and the soot based carbonaceous particles form an accumulation mode, which can be defined as 50-500 nm. The values to create a high nucleation rate are shown in Table 1-1. These values were experimented, e.g., by Kittelson and Abdul-Khalek1.

Table 1-1: Design criteria for dilution

Variable unit value Dilution ratio - 10-20 Residence time s 1 or 1.5 Dilution air temperature °C 30-50 Relative humidity % Controlled

2 Construction

Construction of Particulates primary diluter can be described in three parts: Ø mechanical construction, which includes design and manufacturing of the hardware, Ø control unit, which includes data acquisition and control of the device, and Ø software, which monitors and records data and controls the unit.

2.1 Mechanical Construction Since a porous tube diluter had been applied successfully in combustion studies earlier2,3. This approach was adapted for tailpipe sampling. In a porous tube diluter, the dilution air is introduced at the tip of the sampling probe within the tailpipe. The dilution air flows through a porous tube and mixes with the sample gas. Most of the dilution gas flows through the tip of the probe to improve mixing in the probe. The rest of the dilution gas is introduced through small pores along the transport line in order to minimise losses inside the probe. Simultaneously, the dilution air is cooled with an external cooler and with cooling agent jacket around the probe. This jacket is designed to maintain the dilution gas temperature below 50°C even during transient testing. In Figure 2-1, the operation principle of the porous tube diluter is presented.

1Kittelson, D. and Abdul-Khalek, I. "Formation of Nanoparticles during exhaust dilution" EFI Members Conference: 'Fuels, Lubricants, Engines, & Emissions' (1999) 2 Biswas, P. In: Aerosol Measurement, eds. Willeke and Baron, Van Nostrand Reinhold, NY (1993) 3 Biswas, P; Li, X and Pratsinis, S. Journal of Applied Physics (1989) 5 Sample

Cross section Cooling agent of the probe Dilution air

Figure 2-1: Operation principal and cross section of porous tube diluter applied for Particulates primary diluter

Probe length is 80 mm, inner diameter 8 mm and outer diameter 26.5 mm. The diluter probe is mounted on a flange attached to an expansion of the exhaust line. The diluter is cooled with cooling air or water. The cooling air is cooled with a vortex tube. In addition, outer surface of the probe can be insulated. The temperatures of the cooling agent and dilution gas within the probe are monitored and the dilution gas temperature (30-50°C) controls the cooling agent flow. In addition, the unit can be applied for hot primary dilution. In this case, the dilution air and the diluter can be heated up to 300°C with an air heater.

Dilution gas is purified and its flow is controlled with mass flow controller. The dilution gas flow control and purification has been laboratories own responsibility. Furthermore, each laboratory has been responsible for controlling the humidity of the dilution gas. The total flow downstream the primary diluter is 110 lpm. Thus, if the dilution ratio (10-20) needs altering the dilution gas flow is controlled (100-105 lpm).

A number of ideas have been presented on adjusting the probe tip to match the exhaust gas flow velocity by altering the sample flow rate e.g. 4,5 or by changing dimensions of the tip continuously e.g. 6,7,8. In this method, we chose to keep the sample flow rate as well as the probe dimensions constant. This was done since the particles smaller than 1 µm are practically insensitive to percent of isokinteic sampling e.g. 9 and since moving parts in the tip of the probe may cause entrainment of particles attached to the tip.

4 US Patent US4649760 “Method and apparatus for controlling flow volume through an aerosol sampler 5 US Patent US5526685 “Fluid flow rate measuring and controlling apparatus and method for using SAMS” 6 US Patent US3921458 “Isokinetic sampling probe” 7 US Patent US4091835 “Autokinetic sampling nozzle” 8 US Patent US4159635 “Isokinetic air sampler” 9 Hinds, W. C. “Aerosol Technology” USA: John Wiley & Sons, Inc. 2nd ed. 483 p. ISBN 0-471-19410-7 (1998)

6 Figure 2-2 shows particle penetration in a probe inlet as a function of particle size during isoaxial sampling. The losses are calculated according to Hinds9 for a 3 m/s sampling flow velocity in a 0.6 and 30 m/s exhaust flow velocity. As stated earlier, the losses for particles smaller than 1 µm are negligible in flow rates applicable for vehicle sampling conditions.

40 %

20 %

0 % 0.01 0.1 1 10 -20 %

-40 %

-60 % Vsample/Vexhaust = 0.1 -80 % Vsample/Vexhaust = 5

-100 % Aerodynamic diameter, µm

Figure 2-2: Particle penetration in the sampling probe inlet for velocity ratios 5 and 0.1.

In order to obtain proper residence time in the diluter, an ageing chamber was introduced. This ageing chamber is a tubular volume with an adjustable length. Since the flow rate in the sampling system is constant, turbulent flow was selected in order to minimise artifacts caused by different residence times along the tube radius10. On the other hand, since the diffusion losses increase while the chamber length increases, the flow velocity was set as small as possible for turbulent flow (Re=Vd/v=4000, where V is the gas velocity, d is the tube diameter and v is the kinematic viscosity of the gas)11. In Figure 2-3, particle residence times for laminar and a turbulent tube flows are shown. The figure is presented as a probability of a gas volume to travel through the system in an optimum residence time for laminar flow and for Re = 4000.

100 % 90 % 80 % 70 % 60 % 50 % 40 % Laminar flow

residence time 30 % Turbulent flow

Probability of optimum 20 % 10 % 0 % 0 % 20 % 40 % 60 % 80 % 100 % Volume of flow

Figure 2-3: Particle residence time distribution for laminar and turbulent tube flows.

10 Shapiro, M. and Goldenberg, M. "Deposition of glass fiber particles from turbulent air flow in a pipe", Journal of Aerosol Science (1993) 11 Gomes, M. P. S.; Pui, D. Y. H.; Vincent, J. H. and Liu, B. Y. H. "Convective and diffusive dispersion of particle in laminar tube flow: effects on time-dependent concentration measurements", Journal of Aerosol Science (1993)

7 Assembly of the Particulates primary diluter is shown in Figure 2-4. In this figure, each piece of equipment is shown individually and the detailed drawings of the pieces are shown in Appedix A.

Figure 2-4: Assembly of Particulates primary diluter.

2.2 Control Unit During the tests, the dilution air flow and temperature were monitored and controlled. The dilution air temperature was control input for a cooling agent flow rate. The dilution air flow was controlled by a mass flow controller. In addition, the exhaust temperature and pressure as well as the cooling agent outlet and the sample temperatures were recorded. The sensors, valves and controllers are shown in Table 2-1.

Table 2-1: Sensors, valves and controllers used for dilution unit

Sensor, valve or controller Type Number of type units/diluter Pressure transducers Keller 2 Temperature sensors 1.5 mm K-type 1 Temperature sensors 0.5 mm K-type 1 Temperature sensors joint K-type 2 Mass flow controller Millipore FC2922 1 Propo valve Bürkert 1 Cooling unit ITW Vortex tube 1

8 Multifunction I/O devices were utilised for data acquisition. National Instrument products DAQCard700 and DAQCard1200 were applied for data transfer to a laptop computer via PCMCIA port. In DAQCard700 there were 8 analog input channels, while in DAQCard1200 there were 8 analog input and 2 analog output channels available. In Table 2-2, the channel allocations are shown.

Table 2-2: Channels for analog input and output in PCMCIA connector

Channel Signal Value Range number IN 1,2 Ground IN 3 Reserved 4-20 mA IN 5 Exhaust temperature 0-600°C 1-5 V IN 7 Dilution air temperature 0-200°C 1-5 V IN 9 Coolant exit temperature 0-200°C 1-5 V IN 11 Sample temperature 0-100°C 1-5 V IN 13 Exhaust pressure (differential) ±500 mbar 0-5 V IN 15 Sample pressure (differential) ±500 mbar 0-5 V IN 17 Atmospheric pressure (absolute) 0-5 V OUT 1 Cooling valve control 0-5 V OUT 2 Dilution flow control 0-5 V

The control unit for Particulates primary diluter is shown in Figure 2-1.

Connector block Electronics for pressure transducers

Power supply

Amplifiers for temperature sensors

Figure 2-5: Inside a control unit for Particulates primary diluter

9 2.3 Software User program for particulates primary diluter was designed to monitor and save data from the control unit. In addition, the second program version was designed to control dilution air and cooling agent flows. The program shows measured values in a graphic form and saves the data in a file defined by the user.

This program called PRIMDIL.exe is a National Instruments LabVIEWÔ based. LabVIEWÔ graphical programming language provides large selection of drivers for data acquisition. In our version data acquisition and control are carried out via PCMCIA port in a laptop. PRIDIL.exe is a standard 32 bit WindowsÔ application.

3 Results

The task of WP370 was to develop, test and manufacture a reference sampling system for particulate measurements from exhaust following the recommendations of other WP300 tasks. As a result two Particulates primary diluters were supplied. These units and related manuals and reports are described in the following.

3.1 Delivered units There were two units delivered. The first unit included the porous tube diluter, ageing chamber, flow dividers, Vortex cooling unit and valve as well as pressure transducers and temperature sensors. The second unit was more sophisticated with controlled dilution gas flow and cooling agent valve. In Table 3-1, the pieces of equipment included in the complete Particulates primary diluter are shown.

Table 3-1: Pieces of equipment included in the Particulates primary diluter

Unit Type Number of pieces/diluter Porous tube diluter Dekati 1 Ageing chamber Dekati 1 Flow dividers Dekati 2 Control unit Dekati 1 PCMCIA card NI DAQCard1200 1 I/O Ribbon cable NI PR50-50F 1 User Programme CD Dekati 1 Cooling unit ITW Vortex tube 1 Dekati Thermodenuder Dekati 1

The first unit has been tested at University of Minnesota by professor Kittelson, at AEAT by Dr. David Blaikley and Dr. Colin Dickens and at IFP by Mr. Laurent Forti. The second unit has been tested by EMPA by Dr. Martin Mohr, Mr. Urs Mathis and Mr. Jyrki Ristimäki from Tampere Univeristy of Technology and at LAT/AUTh by Professor Zissis Samaras and Mr. Makis Giechaskel. The complete test results will be reported elsewhere. However, in Figures 3-1 and 3-2 the Particulates primary diluter is shown in operation at EMPA.

10 Primary diluter

Tailpipe

To CVS

Figure 3-1: Particulates primary diluter mounted on a tailpipe of a Diesel vehicle at EMPA.

Ageing chamber

Dekati Thermodenuder

Figure 3-2: Ageing chamber of the dilution unit.

In Figure 3-3 a test result of the effect of dilution ratio on the nuclei mode is shown. This test was carried out with a Particulates primary diluter and an Electrical Low Pressure Impactor (ELPI). The result indicates distinct nuclei and accumulation mode and a clear effect of dilution ratio on nuclei mode formation.

11 9000000

8000000 7000000 Nucleation mode 6000000

5000000

4000000

3000000 Number dN/dlogDp [1/cm³] 2000000 DR2»10 1000000

0 0.0100 0.1000 1.0000 10.0000 Dp [um]

900000

800000

700000

600000 Accumulation i.e.

500000 Soot mode

400000

300000 Number dN/dlogDp [1/cm³] 200000

100000 DR2»20

0 0.0100 0.1000 1.0000 10.0000 Dp [um] 500000

450000

400000

350000

300000

250000

200000

150000 Number dN/dlogDp [1/cm³] 100000

50000 DR2»40

0 0.0100 0.1000 1.0000 10.0000 Dp [um]

Figure 3-3: The effect of dilution ratio (DR) on nuclei mode as measured with ELPI for Diesel exhaust.

3.1.1 Manuals Both units were accompanied with a manual folder. In this folder, each piece of equipment was individually described or the user manuals provided by the manufacturer were included. The user manual for Primdilu programme is included in Appendix B.

12 3.2 Reporting SAE Conference Paper: Mikkanen, P.; Moisio, M.; Keskinen, J.; Ristimäki, J. and Marjamäki, M. 'Sampling method for particle measurements of vehicle exhaust', SAE Technical Paper 2001-01- 02192

13 Appendix I – Drawings of Primary Dilution Unit

Appendix II – Manual for User Program PRIDIL7.exe instructions PiM / Dekati Ltd. / 24.10.2000 PROGRAM FOR PRIMARY DILUTION UNIT Dekati Ltd. Pirita Mikkanen 20.10.2000

PRIDIL7 program controls the data acquisition and primary dilution by sending commands to the Mass flow control unit via PCMCIA port. It shows the measured values in graphic form and saves the data in a file defined by the user. PRIDIL7.EXE is standard 32 bit WindowsÔ application made with National Instruments LabVIEWÔ graphical programming language.

Operating system capable of running standard 32-bit WindowsÔ applications (Windows 95Ô, Windows NTÔ Windows 98Ô, Windows 2000™) required. Windows 95 or 08 recommended.

PRIDIL7.exe setup

Program is provided in CD. To install PRIDIL7: 1. Insert the Program CD to a CD-ROM drive 2. Open Windows explorer and run X:data\setup.exe for LabVIEW RunTime engine installation. 3. Follow the instructions given by the setup program. 4. Run PRIDIL7.exe from the CD or copy files to directory

In Windows NT or Windows 2000 systems LabView RunTime engine installation requires administrator privileges

Dekati ltd Osuusmyllynkatu 13 FIN-33700 Tampere Finland Tel: +358-3-3578100 Fax: +358-3-3578140 PRIDIL7.exe instructions PiM / Dekati Ltd. / 24.10.2000 RUN PRIDIL7.exe

Press the white arrow in the upper left corner to start the data acquisition. The data is saved automatically to a file defined in the screen below.

In case the file exists, the replacement is confirmed. PRIDIL7.exe instructions PiM / Dekati Ltd. / 24.10.2000 The data acquisition programme is stopped with the STOP button in the right lower corner. For changes in the screen setup, charts etc. see LabVIEW Manuals.

The dilution air temperature is controlled by the Vortex tube and the magnetic valve. A red led lights when set value is exceeded.

The ambient pressure is an absolute sensor. The exhaust and sample pressures are differential sensors relative to the measured ambient pressure.

Temperatures are measured with K-type thermocouples. The exhaust temperature measurement range is 100-600° C, sample range is 0-100° C, cooling agent and dilution air ranges are 0-200° C.

This is an example of an error message, while the PC cannot find the PCMCIA card. There is a National Instruments NI-DAQ CD-ROM following the PCMCIA-card. With this CD installation of the DAQCard700 ought to be possible. Windows 95 or 98 is recommended.