REGENERATION ISSUES Institute for Energy and Transport Joint Research Centre B. Giechaskiel, J. Andersson, G. Martini 3 April 2014

Overview Legislation Heavy duty R-49 Light duty WLTP Literature survey / Past experience PN emissions / Robust protocol Pre-conditioning procedure / effect on repeatability Open issues Next steps

Legislation GTR 4, Regulation 49 (Heavy duty) Continuous  Oxygen with temperatures >550°C  NO 2 with temperatures >250°C Declared regeneration conditions (soot load, temperature, exhaust back-pressure) At least 3 WHTC with regeneration, emissions within 15% Periodic  in cylinder or post injection exhaust  active heating Measurement during regeneration, (before and after). Number of cycles between regenerations Alternatively emission within 15% between regenerations then 1 test

Legislation (Light Duty, WLTC) Continuous (no special procedure) Periodic Single regenerative system Multiple periodic regenerative system Procedure If emissions during regeneration below limit not necessary If emissions between regeneration events within 15%, Type I value can be used Otherwise arithmetic mean of equidistant Type I tests. At least before and after regeneration. Loading with WLTC

PMP robustness No issues with PMP systems (eg due to high temperatures) Indications for volatile artifact below 23 nm, especially below 10 nm Mamakos et al. 2011, PMP Zhang et al. 2012

PMP robustness Confirmation of volatile artifact below 10 nm Between 10 and 23 nm no clear indications of volatile artifact No immediate need to move below 23nm Monitoring advisable Giechaskiel et al. 2014, PMP 30 CVS PCRF 100x10 Tailpipe: PCRF 15x15

PCRF selection PCRF at least 1000 (PND1>100) Sulfuric acid might re- nucleate Important not to grow to >10nm HCs at inlet of PND1 For sub10nm even higher PCRF is needed Yamada 2013

Background Tailpipe: PCRF=225 PN=3.3x10^9 p/km CVS: PCRF=1000 PN=5.5x10^9 p/km

Ki factor NEDC Golden vehicle: Negligible increase Cold start very high emissions EUDC higher but over 1000 km negligible effect WLTC or CADC: DPF1: Msi=1x10^11 (D= km), Mri=4x10^12 (d=8.2 or 23.2)  Mpi= x10^11 p/km, Ki= DPF2: Msi=2x10^10 (D= km), Mri=2x10^12 (d=8.2 or 23.2)  Mpi=<1.4x10^11 p/km, Ki=4-7 With Msi=2x10^9  Mpi=<1.4x10^11, Ki=35-65 or Ki~Mpi (offset method) Emissions always below 6x10^11

DPF 3 Msi=5x10^9 p/km (D=300 km), Mri=7x10^12 p/km (d=23.2) Mpi=5x10^11 p/km, Ki=100

Nature of particles Probably soot due to the decreased efficiency of the filter as it regenerates Metal from fuel additives and lubricant cannot be excluded Heavy molecular hydrocarbons that do not evaporate at 350°C and residence time s. Mamakos et al. 2013

Open issues High temperatures Release (volatiles, ash) from DPF Higher penetration of DPF Ash that was previously attached on the soot Release from tubes due to high temperatures More porous DPFs Loading might affect nature of deposited material

Loading of DPF / Pre-conditioning WLTC  Frequency? DPF fill status affects filtration efficiency and repeatability Difference for small – large engines Andersson et al. 2007, PMP report Yamada 2013

Pre-conditioning (setup) No studies discussing effect of sampling system preconditioning However there could be an effect from contaminated tunnels Dobes et al. 2011, Vienna symp. Recommendation: 120 km/h >20 min

Durability Light-duty Diesel vehicles with DPF are durable and effective to at least km (AECC 2006) VERT procedures at least 2000 h Accumulation of ash: Release during regeneration

GPF GPFs will experience different temperatures Passive regeneration very likely Mamakos et al. 2013

GPF Lower efficiencies are needed More porous DPF are possible (Eff >50%) Mamakos et al. 2013

Partial Filters Still high efficiency for <23nm No special issues for sub23nm particles Heikila et al. 2009

Summary Protocol: PCRF >1000 for regenerations Measurement of >10nm in parallel Absolute PN levels should be monitored for many vehicles Recommendations for WLTC exist Preconditioning Setup: Ensure no desorption from vehicle, transfer tube Loading of DPF / GPF Continuous systems: DPF fill state (repeatability) Periodic system: Extremes: Small – Large vehicle

Discussions slides

Areas for investigation Targets (testing) Test many vehicles Euro 6+ Confirm robustness of PMP Confirm weighted emissions do not exceed limit Ki factor, Frequency Levels of emissions during regeneration

Areas for investigation How (measurement protocol) >23nm and >10nm, PCRF >1000 (PND1>100) Looking for differences >50% System with Catalytic stripper in parallel if possible Addition of a system at the tailpipe (for pre-con study) Organics, sulfates, nitrates, ammonium if possible (at least for regeneration tests) Pre-conditioned (clean) tunnel, pipes etc. At least the temperature that will be experienced Recommendation: Gasoline vehicle at high speed eg 130 km, no low particle concentration measured by VPR For measurements below 10 nm see ‘Sub23nm’ presentation For nature of sub23nm particles see report

Areas for investigation Special attention on the following: LNT: Stored sulfates etc… FBC: Solid sub 23 nm (needs robust protocol) SCR: Formation of solid particles, desorption of material SCRF: Similar with SCR GPF: Different filtration efficiency DPF with SCR coating Hybrids

Areas for investigation Extra tests Prolonged high speed operation /lean spikes (Gasoline) Fuel shut off: <23nm metal oxides from ash, oil (Gasoline) Pre-conditioning effect on fill state / emissions levels GPFs need more info Monitoring of background / Effect of regenerations

Collection of data Euro 6 testing from OEMs (NEDC data) JRC can test if Euro 6 available (focus on WLTC) Preparation of a test plan/protocol Info from OEM (e.g. when regen is about to start) Investigation of worst case (e.g. high loading with Granny cycle) Loading effect: without passive regeneration vs WLTC loading (focusing on Gasoline)