1. Technologies for low emission light duty powertrains
HORIZON 2020
Call: H2020-GV
Technologies for low emission light duty powertrains
Action: “Measuring automotive exhaust particles
down to 10 nanometres – DownToTen”
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

2. In collaboration with:
Project Partners
In collaboration with:
The University of California at Riverside,
National Traffic Safety and Environmental Lab (Japan)
and
National Metrology Institute (Japan)
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

3. Aim of the project
To propose a robust approach for the measurement of particles from about 10 nm both for PMP and RDE, complementing and building upon regulation development activities and addressing topics not tackled so far
The objective is a PN-Portable Emission Measurement System (PEMS) demonstrator with high efficiency in determining PN emissions of current and future engine technologies in the real world
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

4. Why measure sub-23nm Particle Number?
<23nm particles detected on regulatory cycles; levels relatively low (except 2T!) – but are there unexplored cases where levels are high?
Sub-23 nm fraction of solid particles
estimated by differences between 10 nm & 23 nm CPCs
Loss corrected (between x1.7 and x2)
Vertical dashed line
6x1011 p/km limit for particles >23 nm
Other line indicates 6x1011 p/km limit for particles >10 nm
All mopeds were 2-stroke unless otherwise specified in the figure
B. Giechaskiel, J. Vanhanen, M. Väkevä & G. Martini (2017): Investigation
of vehicle exhaust sub-23 nm particle emissions, Aerosol Science and Technology
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

5. Some interesting results: <23nm non-volatile PN from diesel fuel cuts and >23nm particles derived from urea-SCR
Driving events and ECT can produce <23nm particles: further investigation required
Light-duty (1.4L, 66kW) turbocharged diesel engine Amanatidis et al. (2017) J Aerosol Sci
Amanatidis et al. (2014) ES&T
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

6. Questions to be answered within the new size range
What is the number fraction of exhaust particles below 23 nm?
What is the specific chemistry of the particles?
How to define the particle species: accumulation – nucleation mode, volatile – non-volatile, solid –liquid, Black Carbon – Elemental Carbon (BC-EC)
What fraction of exhaust particles corresponds to which species?
Which is the appropriate exhaust particle cut size?
How potentially un-regulated particles are linked to secondary aerosol formation
How to robustly correlate raw exhaust sampling suitable for both RDE engine development with dilution methods and sampling approaches employed during engine and vehicle type approval?
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

7. Exhaust emission related particle types
Manifold out (ms) …
Tailpipe out/dilution (s) …
Atmosphere (h)
Time lag?
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

8. DownToTen structure and WP interaction
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

9. Synthesis and evaluation of testing results, incl. metrology (WP5)
Concepts and approach
Equipment and sampling set-up (WP2 & WP3)
Modelling particle transformation (tailpipe-out to the inlet of the measurement equipment) (WP3)
Synthesis and evaluation of testing results, incl. metrology (WP5)
Testing (emphasis on technologies that will be developed in the parallel projects (WP4)
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

10. Exhaust aftertreatment Fuels Cycles Source of the test vehicles
Vehicle class
Engines
Exhaust aftertreatment
Fuels
Cycles
Source of the test vehicles
Passenger cars
GDI & PFI
3WC with and without GPF
Reference Petrol and biofuel admixtures
NEDC, WLTC, 3 RDE cycles; real PEMS trips
uPGrAdE, PaREGEn
SI-Hybrid
A hybrid from GV
Diesel
SCR and/ or NSC with DPF
Reference diesel and biofuel admixtures
DiePeR
CI-Hybrid
SCR/NSC with DPF
CNG
Different qualities
GasON
HDV
SCR and DPF
WHVC, standard CO2-vehicle test cycles; PEMS trips
To be decided
Not decided yet
2-wheelers
>500ccm
3WC
WMTC, RDE cycles, PEMS test for >500ccm
Suggestions from the German programme
50ccm
AVL Research Networking Day 2017

11. Overview of key project resultsWP
Exploitable knowledge
Exploitable product(s) or measure(s)
Sector(s) of application
Timetable for commercial use
Owner & other partners involved
WP2
Proposal for system to generate laboratory-grade exhaust-type of aerosol
Device and method to generate aerosol (demonstrator in month 14)
Calibration institutes, users of aerosol instruments
2020
TUT, TUM
Instrument benchmarking below 23 nm
Knowledge on instrument performance
Exhaust aerosol measurement labs
Not relevant
TUT, AVL, LAT/AUTh, RICARDO
WP3
Understanding formation, properties and characteristics of PN <23 nm
PN <23 nm definition for regulatory purposes
Standardization and regulatory bodies
2018
Entire consortium
PN <23 nm sampling configuration for laboratory testing and PEMS
Demonstrator (in month 17)
PN <23 nm measurement configuration
Instrumentation to be proposed
WP4
DownToTen PN PEMS demonstrator unit
Device and Test protocol (demonstrator in month 22)
Exhaust aerosol measurement labs, regulatory authorities
TUG, AVL, LAT/AUTh, RICARDO, TUT
Evaluation procedures for RDE particle number
Software code and method (demonstrator in month 32)
2019
TUG, AVL, LAT/AUTh, RICARDO, JRC
WP5
Emission performance of late and forthcoming vehicle types
Emission factors to be used in models and estimates
Air quality research, policy making
LAT/AUTH, TUG, TUT, TUM
Calibration procedures for measuring PN<23 nm
Calibration test protocols
TUT, TUG, TUM, JRC
Modelling of exhaust particle processes from emission to dilution
Simulation model
Researchers, manufacturers
2021
LAT/AUTH, TUT
Months 1 –Month 14 Currently at Month 14
Months 7 –Month 21 Currently at Month 14

12. Planned progress per work task, including milestones and deliverables
Device and method to generate aerosol - November 2017
PN <23 nm sampling config. Feb. 2018
DownToTen PN PEMS demonstrator unit - July 2018
Evaluation procedures for RDE PN May 2019
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

13. Progress in the first year of the project
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

14. WP2: Sampling setup for testing in the synthetic aerosol laboratory (1)
A setup was designed to maximize the penetration of non-volatile particles below 23 nm, while avoiding the creation of gaseous artefacts
Important factors like robustness against artefacts (re-nucleation, growth of sub-cut particles), losses of (solid) particles, storage/release effects of gas phase compounds are being assessed in detail
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

15. WP2: Testing in the synthetic aerosol laboratory
Silver particle generation
Nano DMA
Sample treatment (CO2 addition, mixing)
CPC, cut size 2.5 nm
Continuous measurement of dilution ratios
Upstream / Downstream measurements with same tube
Sampling systems used in the tests:
HPCE: hot porous tube cold ejector
CPCE: cold porous tube cold ejector
HECE: hot ejector cold ejector
(plus) CS: Catalytic Stripper
Tampere Technical University
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017
PMP Meeting March 2017

16. WP2: Identified losses with the 1st gen
WP2: Identified losses with the 1st gen. system (silver particle tests at TUT)
Temperature 350 ˚C
Thermophoretic losses are mainly caused by cooling down the sample with an ejector diluter (ED).
Use of PTD for cooling reduces thermophoretic losses to almost zero.
The catalytic stripper (CS) is the dominant source of diffusional losses. They are reduced by downsizing the CS.
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

17. WP2 - Conclusions and recommendations
Nonvolatile particle losses
Identified loss issues with components
Diffusion: mostly at the CS
Thermophoresis: in prototype cold ED
Possible solutions
Cooling dilution with porous tube (minimize thermophoresis)
Optimising the CS size
Artefact formation
The HPCE system appeared to be artefact free at 10 nm. However, HC content in real exhaust aerosol could cause particle growth into the measured range. The CS effectively reduced particle growth.
 Secondary aerosol sampling
The system can be used for secondary aerosol emission characterization by using a separate line after the first dilution stage
Meeting on the Particle Measurements Projects (DownToTen, PEMS4Nano, SUREAL-23), Brussels. June 29, 2017

18. 2 systems produced, more on the way…
WP3: 2nd gen. DTT system to contain two porous tube diluters (PD1 & PD2) was built for chassis dynamometer testing purposes (TUG and Ricardo)
2 systems produced, more on the way…
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

19. APG WP3: Preliminary calibration investigations (AVL) Setup 4 nm
Full flow (0.3 lpm)
4 nm
Full flow (0.3 lpm)
TSI 3775
APG
85Kr
85Kr
85Kr
TSI 3775
DMA
3081
DMA
3081
DTT
TSI 3790
23 nm
TSI 3792
10 nm
Two configurations of the DTT system (2nd gen.) were tested:
Porous diluter + CS 350 C + Porous diluter + Ejector
Porous diluter + CS 350 C + Porous diluter
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

20. WP3: Preliminary calibration investigations (AVL) (2) PCRF (particle concentration reduction factor) results
DTT system enables several configurations to achieve required dilution approach
Particle losses are configuration dependent; but main influence is flow rate through CS
Particle penetration is better than commercial 10nm system
PCRF takes into account losses and dilution ratio
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

21. WP3: Further calibration investigations (Ricardo) (1)
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

22. WP3:Further calibration investigations (Ricardo) (2)
PCRF’s in line with expectations of PMP systems
Penetration with ejector diluter ~15% less efficient than the commercial PMP systems
Penetration efficiency is very similar for CS and ET, but evaporation tube performs slightly better when hot
Tests without ejector diluter would be of interest
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

23. WP3: PCRF to PMP requirements + 15nm calibration (Ricardo)
Calibration with CAST soot
15nm, 30nm, 50nm, 100nm monodisperse aerosol
Normal system operating parameters as used from CVS (used without ejector)
PTD1 350°C – CS1 350°C – PTD2 23°C
2 slpm sampled (2 x 1 slpm CPCs)
3 slpm drawn from CVS (mfc flows differ by 1splm)
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

24. WP3: PCRF Results (without ejector dilutor) (Ricardo)
Results similar to AVL (w/o Ej)
100nm PCRF = 141.9
50nm PCRF = 147.0
30nm PCRF = 159.7
15nm PCRF = 230.0
Flow dilution = 140.2
(26dil +3) – (27dil +2)
29/3 * 29/2 = 140.2
Low losses >50nm
Open question: how to apply PCRF correction including <23nm?
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

25. Preliminary chassis dynamometer investigations (Ricardo)
SPCS v DTT correlation with 23 nm PNC
Average concentration data from cumulative transient tests, and sub-cycles
Good linear agreement between DTT system and Horiba 2000SPCS above 1 #/cm3 (at the PNC) across wide concentration range
Larger differences below this point
DTT reports ~ 14% lower than SPCS
No PCRF correction applied to this yet
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

26. Regulatory emission cycles: NEDC, WLTC, JC08, US06
WP3: “Regulatory cycle testing” of diesel technologies and one gasoline vehicle (Ricardo)
Regulatory emission cycles: NEDC, WLTC, JC08, US06
Several emissions control system variants on diesels
Few tests show either > 23 nm or > 4(7) nm levels above 6x1011 #/km
One GDI + TWC test just above limit value
Highest emissions (but less than 10x limit) from test containing DPF regeneration
Ki factor would reduce this to well below the limit
Generally, non regenerating DPF tests < 2% of limit value
< Euro 6c limit
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

27. WP3: Evaluation of the DTT system with real exhaust (AVL)
Cycle-averaged ratios of particle number emission rates
Cycle-average mean particle diameter measured with the EEPS
The mean particle size of all diesel vehicles (66 to 81 nm) was consistently higher from that of the GDI counterparts (26 to 40 nm)
In a first set of tests, the DTT system was connected on the CVS tunnel in parallel with an AVL Particle Counter (APC) plus CS and allowed for parallel measurement with a 10 and a 23 nm CPC.
In addition a TSI Engine Exhaust Particle Counter (EEPS) was connected on the CVS tunnel, sampling downstream of a catalytic stripper (also operating at 350 C) and a subsequent cold dilution of 10:1. The EEPS allowed for a calculation of the cycle-average mean particle size of the emitter particles
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

28. WP3: Raw vs Dilute Particle Sampling Modelling (AUTh)
AIM: To understand the relationship between the final quantification of raw-sampled “regulated particles” and dilute sampled ones
Critical for fundamental understanding and determining influence of measurement approach on conformity factors
Achieved via simulation and modelling
Overall aim: to couple aerosol dynamics model with commercial CFD code
CFD simulations: flow, mixing heat transfer
Aerosol dynamics simulations will address porous tube dilution and aging / mixing stages
2-D and 3_D simulations will address inflow boundary conditions, including impacts of flow instabilities
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

29. Basic CFD analysis of Porous Tube Dilutor (AUTh)
Critical components will be identified, in which to perform CFD. For example, flow and mixing unsteady 3D CFD simulations are performed for the PTD and mixer shown below by TU Graz.
Evaluate pressure fluctuation effects on dilution – no particle impacts assessed yet; work on-going
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

30. Modeling delayed primary: aerosol formation in the exhaust (CFD model) (AUTh)
Modelling of particle formation rates in exhaust requires determining the spatial profiles of temperature, humidity, vapours and particles.
In work by TUT, an in-house model CFD-TUTEAM, was developed and applied to a PTD dilution system with FLUENT.
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

31. Next steps in the project
More engine exhaust aerosol tests for the system (dilute and raw)
Functional pressure/temperature/dilution evaluations in laboratory
Construct several DTT systems for partners to enable more parallel testing at the later stages of the project
For certain identified vehicle technologies: dedicated campaign(s) for characterization of chemical composition, semi-volatile particle emissions, secondary aerosol formation…
Investigate possible <23nm sampling artefacts in CVS-diluted and raw exhaust
Targeting towards PN-PEMS demonstrator, RDE capable measurement system
Implementation and verification of modal approach for homogeneous aerosol Particle Dynamics
Coupling of implemented Particle Dynamics model with CFD code
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017

32. Any questions?
45th PMP Meeting, Joint Research Centre, Ispra, November 7-8, 2017