Preliminary results of the OEMs HDV PN-PEMS validation study B. Giechaskiel Sci. Lab Manager, 13 Nov 2017, Ispra, Italy

Update on HDV PN-PEMS validation program Introduction Experimental Preliminary results Next steps Note: preliminary results as testing is on-going

Introduction PN-PEMS Call of interest (22 Oct 2015) PN-PEMS Technical specifications (based on LDV) (Nov 2015) JRC main evaluation (Feb – June 2016) JRC second evaluation (Sept. 2016) / pre-validation JRC report EUR 28256 EN JRC recommendations and wishlist (Dec 2016) OEMs validation program (Feb 2017+)

Introduction (JRC wishlist) Lab testing At least PMP (+10nm desirable) and one PEMS EFM desirable (to compare vs fuel+air) On-road testing At least 2 PEMS on-road Additional tests CNG vehicles High percentage biofuels Cracked DPF that the emissions are just above the limit

OEMs validation exercise First discussions end of Oct 2016 Final discussions mid Feb 2017 Tests started end Feb 2017 Tests finished end of September Telco 14 Nov status update Extra tests in November (two OEMs)

Objectives Results of Golden instruments vs PMP lab to each other (lab, on-road) Results of rest PN-PEMS vs Golden PEMS (lab, on-road) Results of (valid) on-road tests if only one PEMS (for conformity factors). Database and final analysis (JRC) Open point: EMROAD

PN emissions

OEM period PEMS#2 PEMS#3 PEMS#1 PEMS#4 Comments OEM1 Feb-Mar Y1, Y2 DPF, CNG, lab & on-road OEM2 April Y2 Y1 OEM3 July - DPF on road OEM4 issues CNG on road OEM5 September Y3 CNG lab & on-road JRC Y3 proto CNG lab CPC DC DC CPC

Example experimental set-up From the draft Guide PN- PEMS. Typical setup Due to short heated lines of PN-PEMS it was decided to add an additional 4m sampling line (heated at 120oC) Additional residence time +3 sec

Golden instrument(s) PN-PEMS #2 (CPC) PN-PEMS #3 (DC) Additional sampling (heated) line and splitter to the two instruments

PN-PEMS principles of operation Diffusion Charger or catalytic stripper Condensation Particle Counter Particle size has an effect on the signal wick PMP system (reference) from 23 nm

Technical requirements for PN-PEMS Theoretical differences to PMP

Initial PN-PEMS theoretical uncertainty A 50% difference to “Reference” PMP is expected Two PEMS close to each other should be within 60% assuming similar particle losses

Effect of extra heated line Additional sampling line resulted in 25-30% lower concentrations probably due to diffusion and thermophoretic losses Dilution close to the tailpipe is recommended Directly at tailpipe With heated line

Effect of heated line Results confirmed at a second OEM: PN-PEMS #2 Results confirmed at a second OEM: The sampling line introduced 25-30% particle losses NO correction was applied at the results Texh: 400100oC25%

EFM uncertainty For a few cases (3 labs) test bed data were available (fuel+air) The mean difference to the EFM was better than 3% in all cases

Sub-23nm particles (CNG) at JRC Testing at JRC with PMP systems having evaporation tube (ET) or catalytic stripper (CS) High sub-23nm fraction No evident artifact with ET

Tests at JRC The PEMS systems at the tailpipe were within 16% of the CS system or 29% of the PMP. No indications of artifacts for any of the PEMS systems (both with CS)

PN-PEMS #2 (validation) The first unit had issues during first engine lab testing (CPC measuring 0 after a point) The second unit showed very good results within 30% Better setup could have resulted in better agreement

PN-PEMS #2 (validation) Lab soot (propane diffusion flame) showed similar results: Differences within 30% However concerns were raised for CPC wick drift (needs confirmation) Nevertheless, there was an alarm from the instrument (pulse height)

PN-PEMS #3 (validation) Both units had issues (ET) during on-road tests Nevertheless with a PMP efficiency the results were close to the PMP reference The second unit showed very good results within 50%, overestimating

PN-PEMS #1 & #4 Limited data: PN-PEMS #1 overestimating around 50% (1 lab) PN-PEMS #4 underestimating around 20% (1 lab)

PEMS #3 vs PEMS #2 (lab) Lab data Differences -50% to +50% Mean difference 5% at levels >1x10^11 p/kWh Higher relative differences at levels <1x10^11 p/kWh

PEMS #3 vs PEMS #2 (on-road) On-road data (with lab) Mean on-road differences around +50% at levels >1x10^11 p/kWh Partly due to PN-PEMS #2 underestimation PEMS #3 seems to overestimate emissions

PEMS #1 vs PEMS #2 Lab and on-road: Differences around 50% at the critical range >3x10^11 p/kWh Higher difference at lower concentrations Partly due to underestimation of PEMS #3 Generally PEMS #1 overestimating

Real time signals (CNG, lab) Level: 8.5x10^11 p/kWh, differences <15%

Real time signal (ED95, lab) Level: 6x10^10 p/kWh, differences +25% and +85%

Real time signal (DPF, on-road) Cold start 2x10^11 p/kWh, difference <20%

Real time signals (DPF, lab) Emission level: 3x10^11 p/kWh High background of PEMS with diffusion chargers

Real time signals (DPF, lab) Emission level: 6x10^11 p/kWh, +/-30%

Emission levels (DPF) Lab tests WHTC Overall: 14% cold WHTC and 86% hot WHTC On-road tests Integrated emissions (no EMROAD) Cold: First 1200s Overall: 14% cold and 86% average urban, rural, motorway

Emission levels (CNG) Lab tests WHTC Overall: 14% cold WHTC and 86% hot WHTC On-road tests Integrated emissions (no EMROAD) Cold: First 1200s Overall: 14% cold and 86% average urban, rural, motorway

Overview The HDV PN-PEMS OEMs validation phase took place from February 2017 until October 2017 (tbc) 5 OEMs participated until end of October 2017 (tbc) 8 DPF, 5 CNG engines/vehicles 1 golden PN-PEMS was circulated (second had issues) PN-PEMS from 4 instrument manufacturers were tested (8 units) Tests included comparisons of PN-PEMS with PMP systems in the lab and with PN-PEMS on the road

Preliminary conclusions PMP robustness The PMP procedure (evaporation tube and 23 nm CPC, dilution 100x10) gave similar results with a system with catalytic stripper for a CNG vehicle. The sub-23 nm fraction was similar between evaporation tube and catalytic stripper indicating no artifacts. The results confirm previous JRC findings This campaign confirmed that there might be many cases where the sub-23 nm fraction is high and consequently the cut-off curve of the PEMS system is important

Preliminary conclusions Sources of uncertainty for PN-PEMS Exhaust flow rate from EFM <3% Additional sampling line to the golden instruments introduced 30% losses that were not corrected (and wouldn’t happen in commercial systems) Sub-23 nm particles seem to influence more diffusion chargers Initial issues of the Golden instruments probably affected the initial results

Preliminary conclusions Laboratory tests (vs PMP reference) The golden instrument (CPC based) was within 30% with engine or soot generator aerosol for a wide range of emission levels The second golden instrument (DC based) was within -50% and +50% for emission levels >1x10^11 p/kWh A limited number of tests with other PN-PEMS showed similar behavior: a CPC based PEMS was within 30%, a DC based within 50% Second by second comparisons showed excellent agreement with the reference of CPC based PEMS DC based PEMS sometimes show higher spikes and higher background levels

Preliminary conclusions On-road tests The on-road tests didn’t reveal any additional issues not previously seen in the laboratory The relative differences of PEMS were similar on the road as in the lab The relative differences between PEMS were slightly higher than expected The reason was that one system was overestimating the emissions and the others underestimating

Next steps Clarification how OEMs and vehicles will appear. Is the amount of info regarding engines enough (no category N3 etc or engine capacity)? Further confirmation of received data and calculations and how they will be included in the report (i.e. short summary report with results to be sent to each OEM) Update with future additional tests Draft report early 2018?

Any questions? You can find me barouch.giechaskiel@ec.europa.eu