EVALUATION OF THE EUROPEAN PMP METHODOLOGIES USING CHASSIS DYNAMOMETER AND ON-ROAD TESTING OF HEAVY- DUTY VEHICLES

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1 12 th ETH-Conference on Combustion Generated Nanoparticles June 23 rd 25 th 2008 EVALUATION OF THE EUROPEAN PMP METHODOLOGIES USING CHASSIS DYNAMOMETER AND ON-ROAD TESTING OF HEAVY- DUTY VEHICLES Heejung Jung, Kent C. Johnson, Thomas D. Durbin, Ajay Chaudhary, and David R. Cocker III College of Engineering-Center for Environmental Research and Technology (CE-CERT), University of California, Riverside, CA Jorn D. Herner, William H. Robertson, Alberto Ayala, and Tao Huai California Air Resources Board (CARB), 1001 I Street, Sacramento, CA David B. Kittelson Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN ABSTRACT As regulatory limits in California and the US for 2007 heavy-duty diesel engines introduce dramatic reductions in PM emissions, there is considerable interest in new emission metrology that can more accurately measure low PM levels. One such metrology, particle number measurement, has been extensively investigated in Europe as part of Europe s Particle Measurement Program (PMP) for light-duty diesel vehicles. This program has put forth a new methodology, including instrument specifications and sampling protocols, for solid particle number measurements. While counting only solid particles may not be indicative of all of diesel PM health effects, this still represents a significant advancement as it is currently the only methodology with low enough detection limits to produce precise measurements of DPF equipped engines. The specific objective of this study was to critically evaluate the proposed PMP method for determining solid particle number emissions from heavy-duty vehicles in the laboratory and during over-the-road driving. This study is complementary to the investigation by CARB involving the PMP Golden Vehicle and presented last year. For this program, testing was conducted on the chassis dynamometer at the CARB heavyduty vehicle emissions laboratory in Los Angeles and over the road with the CE-CERT mobile emissions laboratory (MEL). Testing over the road is a novel idea uniquely enabled by the MEL and where the interest rests on the investigating the plausibility of real-world, yet rigorous emission measurements with the PMP method. One or two PMP compliant dilution systems for measuring solid particle number were tested and compared directly with filter-based PM measurements on two heavy-duty trucks equipped with a DPF. A full suite of other particle measurements and instruments were also used in conjunction with this testing including an EEPS, a Cambustion DMS, CPCs with cut-off size ranges from 3 to 20 nm, a Dekati DMM, and a TSI Dustrak. The test cycles included a 50 mph cruise, UDDS, idle, and some European driving schedules. On-road testing showed that gravimetric PM filter mass measurements were near detection limits for most of driving cycles, which makes it desirable to explore the new PM measurement

2 protocol. The CPC particle number count levels follow a trend that is consistent with the size cuts of the respective instruments, with the particle counts for the 3760s (~11 nm) and the 3790 (20 nm) being considerably less than those of the 3022 (7 nm) and the 3025As (3 nm), suggesting the presence of sub-20nm solid particles making it through the PMP sampling train. The 3022 CPC, which was connected to the primary tunnel as opposed to below the PMP system, also showed higher counts than the other CPCs below the PMP system when volatile nucleation particles formed as shown in Figure 1. The particle number measurements using PMP method showed a lower coefficient of variation than the PM filter mass measurements as shown in Figure 2. One key advantage of particle number measurements is better repeatability at low mass levels. The results of this study including on-road and laboratory testing on chassis dynamometer will be presented. MD 3790 MD 3025 MD 3760 MEL 3025 MEL 3760 CVS E+16 1.E+15 1.E+14 Low Cut CPCs Saturated #'s EURO # Standard 8E11 #/mi (light duty) Particles Count (#/mi) 1.E+13 1.E+12 1.E+11 1.E+10 1.E+09 1.E+08 OnRoad I10 OnRoad SR86 ETC URBAN ETC CRUISE ARB CREEP UDDS Figure 1. Particle number rate (#/mile) on driving cycles for on-road testing MD_3790 MD_3025 MD_3760 MEL_3025 MEL_3760 CVS_3022 NOx PM 100% 90% CPC data COV Based On #/mi 80% COV Percent (%) 70% 60% 50% 40% 30% 20% 10% 0% ETC URBAN ETC CRUISE ARB CREEP UDDS Figure 2. Coefficient of variation for all CPCs and PM mass on driving cycles for on-road testing

3 EVALUATION OF THE EUROPEAN PMP METHODOLOGIES USING CHASSIS DYNAMOMETER AND ON-ROAD TESTING OF HEAVY-DUTY VEHICLES Heejung Jung, Kent C. Johnson, Thomas D. Durbin, Ajay Chaudhary, and David R. Cocker III College of Engineering-Center for Environmental Research and Technology (CE-CERT), University of California, Riverside Jorn D. Herner, William H. Robertson,Tao Huai and Alberto Ayala California Air Resources Board (CARB) David Kittelson Department of Mechanical Engineering, University of Minnesota

4 Acknowledgements The funding for this research is from the California Air Resources Board (CARB) under contract No Dr. Marcus Kasper of Matter Engineering Inc. Mr. Jon Andersson of Ricardo Dr. Andreas Mayer of Technik Thermischer Maschinen (TTM). for their assistance in developing the test plan procedures, in carrying out the experiments, and in analysis of the data. Mr. Donald Pacocha, for his contribution in setting up and executing this field project, the data collection and quality control. Joint Research Center (JRC) of the European Commission

5 Background Objectives Experimental setup Results Integrated data Real time data Conclusion Overview

6 Background Current gravimetric method have increasing difficulty quantifying post-dpf PM mass emissions accurately. Background contribution Insensitive to DPF fill state Euro 5/6 standard includes measurement of solid particles (>23nm) as an additional new metric of particles emitted from light-duty diesel vehicle.

7 Objectives Critical evaluation of the proposed European PMP method for determining particle emissions from heavyduty diesels and its potential in California for PM measurement and in-use screening. Particle mass vs particle number.

8 Lab testing (at CARB MTA lab)

9 UCR/CE-CERT s Mobile Emission Lab (MEL) for On-Road Testing Diluted Exhaust: Temperature, Absolute Pressure, Throat ΔP, Flow. GPS: Pat, Long, Elevation, # Satellite Precision. CVS Turbine: SCFM, Variable Dilution. Secondary Probe. Gas Sample Probe. Secondary Dilution System* PM (size, Mass). Drivers Aid. Gas Measurements: CO 2 %, O 2 %, CO ppm, NO x ppm, THC ppm, CH 4 ppm. Other Sensor: Dew Point, Ambient Temperature, Control room temperature, Ambient Baro, Trailer Speed (rpm), CVS Inlet Temperature. Dilution Air: Temperature, Absolute Pressure, Throat ΔP, Baro (Ambient), Flow, Dew Point (Ambient). Exhaust: Temperature, ΔP (Exhaust-Ambient), Flow. Engine Broadcast: Intake Temperature, Coolant Temperature, Boost Pressure, Baro Pressure, Vehicle Speed (mph), Engine Speed (rpm), Throttle Position, Load (% of rated). Cocker et al. Environ. Sci. Technol. 2004, 38,

10 Gravimetric vs PMP measurements CVS Blower Vehicle exhaust 2.5 um size cut Primary dilution at PMP (150 C) Evaporation tube (300 C) 2.5 um size cut Secondary dilution Filter sampling system Secondary dilution at PMP Condensation particle counter (cut-off at 23nm) TSI 3790 Pump Golden system Clone PMP system Courtesy of W. Robertson for MD-19 diagram

11 Alternative PMP system Modified from ISO 8178 partial flow single venturi fractional flow sampler PND1 VPR PND2 PMP Design DR Temp (C) Heat Length (in) Flow (slpm) Temp (C) DR Temp (C) MEL MD

12 Flow diagram of PM measurement system Lab test Primary dilution Secondary dilution Sampling & Measurement CVS PMP diluter (Clone system) Filter sampling train (gravimetric) TSI 3022 CPC (7 nm) TSI 3025A CPC (3 nm) TSI 3790 CPC (23 nm) PMP CPC TSI 3025 CPC (3 nm) On-road test Primary dilution Secondary dilution Sampling & Measurement MEL CVS MEL secondary diluter Filter sampling train (gravimetric) PMP diluter (Clone system) PMP diluter (Alternative system) TSI 3790 CPC (23 nm) TSI 3760 CPC (11 nm) TSI 3025 CPC (3 nm) TSI 3760 CPC (11 nm) TSI 3025 CPC (3 nm) TSI 3022 CPC (7 nm) PMP CPC F-SMPS and EEPS at MEL CVS and PMP diluter

13 Experimental conditions Lab test On-road test Base Chassis dynamometer Mobile Emission Lab PMP system Clone system Clone & Alternative systems Vehicle 1999 International 4900 Freightliner class 8 Engine International DT 466E (7.6L) Caterpillar C-15 (14.6L) Fuel ULSD ULSD Lube oil SAE 15W-40 SAE 15W-40 DPF Engelhard DPX JM CRT Vehicle weight 27,000 lb 65,000 lb Cycles 2x UDDS (35 min) 50 mph Cruise (45 min) Idle (40 min) UDDS (18 min) ETC Cruise (10 min) CARB Creep (4 min) Flow-of-traffic

14 Courtesy of W. Robertson for MD-19 diagram Integrated Results (using Clone PMP system) CVS Blower Vehicle exhaust 2.5 um size cut Primary dilution at PMP (150 C) Evaporation tube (300 C) 2.5 um size cut Secondary dilution Filter sampling system Secondary dilution at PMP Condensation particle counter (cut-off at 23nm) Pump Golden system Clone PMP system

15 Lab test PM mass (from gravimetric method) On-road test PM (mg/mi), (mg/hr) for Idle PM (mg/hp-hr) In-Use Emission NTE 30mg/hp-hr 2007 Emission Standard 10 mg/hp-hr for an FTP Engine Dynamometer Test Cruise Double UDDS Idle ETC Urban ETC Cruise ARB Creep UDDS Route 1 ETC Urban ETC Cruise ARB Creep UDDS Route PM Mass on Filter (µg) Lab test On-road test 3 σ reference filter weight for on-road testing (3 2.5 = 7.5 µg) 0 Cruise Double UDDS Idle ETC Urban ETC Cruise ARB Creep UDDS Route 1

16 PM number 1e+16 1e (23nm) 3025A (3nm) 3022* (7nm) PMP CPC 1e+15 Particle count (#/mi) 1e+14 1e+13 1e+12 (8 10 #/mi) Lab test Euro5/6 Light DutyStandard 11 On-road test Particle count (#/hp-h) 1e+14 1e+13 1e (23nm) 3025A (3nm) PMP CPC 1e+11 1e+11 1e+10 Cruise 2 UDDS ETC Urban ETC Cruise ARB Creep UDDS Route1 Route2 1e+10 ETC UrbanETC CruiseARB Creep UDDS Route 1 Route 2 1e+7 Particle concentration (#/cc) 1e+6 1e+5 1e+4 1e+3 1e (23nm) 3025A (3nm) 3022* (7nm) PMP CPC * Means at VS and ** means at MEL PMP system 1e+1 1e+0 ETC UrbanETC CruiseARB Creep UDDS Route 1 Route 2

17 Coefficient of Variation (COV) Lab test On-road test 3790 (23nm) 3025 (3nm) 3022* (7nm) PM Mass COV(%) ** 50 0 Cruise 2 UDDS ETC UrbanETC CruiseARB Creep UDDS

18 Results (Real time data) Concentrations normalized to those at CVS for comparison. 2.5 um size cut CVS Blower Vehicle exhaust Primary dilution at PMP (150 C) Evaporation tube (300 C) Secondary dilution at PMP Golden system Clone PMP system Condensation particle counter (cut-off at 23nm) Alternative PMP system

19 European Transient Cycle (ETC) Cruise A spike showed up in the beginning of ETC cruise cycles all the time due to gear shift before the cycle. CPCs Under PMP F-SMPS at CVS Particle concentration (#/cc) 1.00E E E E E (3nm) 3022* (7nm) 3760 (11nm) 3790 (23nm) EEPS (6nm) Exh_temp_C Exhaust temperature (C) 1e+2 1e+3 1e+4 1e+5 1e+6 1e+7 dn/dlogd p (#/cm 3 ) D p (nm) E E :57:00 12:02:00 12:07:00 Time (hh:mm:ss) Cycle time (s) 3 hypotheses: Solid particle penetration- -> Size distribution from previous studies using EEPS and DMS -> Need to confirm with f-smps or nano-smps -> Continuous ash particle emissions at DPF?-> Unlikely Partial evaporation of large particle Re-nucleation of sulfate

20 US EPA Urban Dynamometer Driving Schedule (UDDS a.k.a FTP 72 and LA-4 ) CPCs under PMP F-SMPS at CVS 1.0E particle concentration(#/cc) 1.0E E E (3nm) 3022*(7nm) 3760 (11nm) 3790 (23nm) Particle Size, Dp (nm) e+2 1e+3 1e+4 1e+5 1e+6 1e E E Cycle time (s) Time (s)

21 Real time data (flow-of-traffic) CPCs under PMP EEPS at CVS Hydrated sulfate concentration contributes to 45% of mass 500 Particle Count (#/cc) Comparison of MEL vs MD19 Dilution System For CPC's nm and nm Normalized to MD19 Dilution (MEL DR ~100 MD19 DR~300) CPC3760 MD19 CPC3760 MEL CPC3790 MD19 Vehicle Speed Eng Power Exh Temp Engine Power (bhp) Vehicle Speed (mph) Particle Size, Dp (nm) e+4 1e+5 1e+6 1e+7 1e Time (sec) Time (sec)

22 Real time data (flow-of-traffic) EEPS at CVS F-SMPS under Alternatve PMP system Particle Size, Dp (nm) e+5 1e+6 1e+7 1e+8 Particle Size, Dp (nm) e+5 1e+6 1e+7 1e :06:00 07:11:00 07:16:00 07:21:00 07:26:00 Time Stamps :06:00 07:11:00 07:16:00 07:21:00 07:26:00 Time Stamps

23 Conclusion The overall results indicate that particle number can provide a more repeatable measurement with particle emission levels well below the 2007 U.S. PM mass standard.

24 Conclusion Under more aggressive, on-road driving conditions, significant nucleation was observed, with very high count levels below the PMP system. These particles had a large sulfate contribution that may not have been eliminated by the current PMP dilution system. This finding suggests that certification level tests are not sufficient to understand or characterize particle count levels that may occur on the road. Re-nucleation or penetration under PMP system should be understood and need further study.