On-Board Diesel & Hybrid Diesel-Electric Transit Bus PM Mass and Size-Resolved Number Emissions

Transcription

1 AAAR 2004 October 4-8 Atlanta, GA On-Board Diesel & Hybrid Diesel-Electric Transit Bus PM Mass and Size-Resolved Number Emissions Britt A. Holmén, Derek Vikara, Zhong Chen, Ruben Mamani-Paco Environmental Engineering Program University of Connecticut John Warhola CT TRANSIT, Hartford, CT

2 Overview ConnDOT & CTTransit Transit bus technologies study Environmentally sensitive AND cost-effective Purchase 2 hybrid diesel-electric buses Emissions Testing gases & particles Originally Dynamometer On-road study Particle Mass & Number Emissions On-board emissions testing protocols Preliminary results SMPS (single-diameter), ELPI (w/filter stage) Total Particulate Mass -- filter

3 Motivation Ultrafine (UF) particle health effects Diesel vehicle exhaust = toxic air contaminant Transit buses = significant urban UF sources Tightening HDV regulations CAA Fleet alternative fuel vehicle requirements 2007 Tailpipe emissions limits (PM 0.01 g/bhp-hr) Fuel regulations (June 2006 reduced diesel S) In-use alternatives to conventional diesels Compressed natural gas (CNG) Diesel + diesel particulate filters (DPF) clean diesel Hybrid diesel-electric (currently on-road > dozen cities)

4 Emissions Project Objectives 2 different technologies under 3 configurations: Conventional Diesel (2002) $270k Detroit Diesel Series 40 Engine, 280 hp Hybrid Diesel-Electric (2003) $500k Cummins ISL Engine, 280 hp Allison E p 40 Electric Drive transmission NiMH batteries (6yr); 2 electric motors 2 buses of each, 40-foot low-floor New Flyer chassis test 2x/month, 1 year duration. 3 fuel/aftertreatment configurations: *No. 1 Diesel *ULSD *ULSD+DPF

5 Allison E p Hybrid System Low noise Lower fuel consumption 60% Improved performance 50% on acceleration Lower emissions NOx 50% CO, HC 90% PM 90% (ULSD+DPF) Parallel Hybrid Regenerative braking Creates electrical energy Parallel Hybrid Components Pure mechanical torque -- maintain highway speeds Diesel Engine/ Generator AC DC BATTERY Pure electrical torque -- accel fr. stop Electric Motor/ Generator Regenerative Braking

6 Driving Routes/Sub-routes 1) Freeway Interstate 91 - Hartford to Enfield, CT Enfield Outbound 16.4 miles Enfield Inbound 16.6 miles 2) Local Farmington Avenue, Hartford, CT Farmington Outbound 5.2 miles Farmington Inbound 5.2 miles 3) High Grade/ Surburban Avon Mountain Avon Outbound 8.1 miles Avon Inbound 8.0 miles 4) QA/QC Warmup 13.2 miles roundtrip, freeway to T coolant > 170F Tunnel Blanks before and after routes every day

7 Three Routes Spd, Altitude Vehicle Speed (MPH) Enfield Farmington Avon Altitude (m) Enfield Farmington Avon Seconds in File Seconds in File

8 Instrumentation Horiba OBS-1300 gas emissions, exhaust flow rate & T, GPS, amb. T, RH Mini-diluters for PM instruments (ejector diluters) DR = ELPI Real-time particle number distributions SMPS Sec-by-sec single-diameter number concentrations PM Gravimetric Mass Total particulate mass integrated over route 3-DRUM Impactor Size-resolved mass for chemical analysis ScanTools Vehicle/Engine parameters (coolant T, RPM, veh. Speed, %load)

9 Scanning Mobility Particle Sizer TSI 3080 Classifier, 3025A CPC Q a = 1.5 Lpm Q sh = 15 Lpm Single-diameter scans 10, 20, 40, 80, 100, 130 nm Vibration mounts for CPC

10 Electrical Low Pressure Impactor 30 Lpm ELPI Filter stage (7nm cut) Vibration table 1-2 sec resolution 12 stages: 7nm 8 µm

11 Dual Mini-Diluters One-stage Ejector diluter design compressed air (HEPA, silica gel) see Holmén & Ayala (ES&T, 2002) Orifice meters: sec-by-sec pressure readings ( flow rates) Diluter A: ELPI & SMPS Diluter B: PM Mass & 3-DRUM Dilution Ratio = 27 to 30

12 Tests Completed Jan Sep 04 Hybrids H301 H302 Conventional No. 1 Diesel Ultra-low S Fuel

13 Single Diameter SMPS Particle Concentration #/cm 3 1.0x x x x x Augs04 29Julys04 16Aprs04 21Jans04 21Aprs04 Bus H301 Avon 40 nm Particle Concentration #/cm 3 8.0x x x x10 4 Bus 202 Farmington 80 nm 13Febs03 27Mays03 18Febs03 11Febs :00 00:10 00:20 00:30 00:40 Time in Route Hybrid, 40nm Avon Mountain :00 00:05 00:10 00:15 00:20 00:25 00:30 00:35 Time in Route Diesel, 80nm Farmington

14 Route Mean SMPS Distributions 10 6 Enfield No. 1 DIESEL FUEL/ Enfield IN H302Ein H301Ein D201Ein D202Ein 10 6 Avon Mountain No. 1 DIESEL FUEL/ Avon OUT dn/dlogdp #/cm No. 1 DIESEL FUEL/ Farmington OUT Diameter nm 10 6 dn/dlogdp #/cm 3 Farmington H302Aout H301Aout D201Aout D202Aout Diameter nm Black, Red = Hybrids Green,Blue = Diesels dn/dlogdp #/cm H302Fout H301Fout D201Fout D202Fout Diameter nm

15 Effect of Grade (SMPS) dn/dlogdp [# cm -3 ] Avon Route (Mountain only) SMPS data Uphill Diesel Downhill Diesel Uphill Hybrid Downhill Hybrid Open symbols = Hybrids Diameter, nm

16 Route Mean 10,20 nm 8.0x x10 4 Mean 10, 20nm By Route No. 1 Diesel Hybrid Diesel Ultralow Sulfur Hybrid Diesel Concentration # cm x x Enfield Out Enfield IN Farm Out Hybrid > Diesel on No. 1 Diesel and ULSD up to 50% Less difference where grade Farm IN Avon Out Avon IN

17 Route Mean nm Concentration # cm x10 4 No. 1 Diesel Hybrid Diesel 6.0x10 4 Ultralow Sulfur Hybrid Diesel 4.0x x10 4 Mean nm By Route 0.0 Enfield Out Enfield IN Farm Out Farm IN Avon Out Avon IN For larger diameters, mean ULSD higher than D1 fuel!!! Hybrid > or ~ Diesel

18 PM Filter Mass No. 1 Diesel Fuel Hybrid-D1 Diesel-D1 70 Ultralow Sulfur Diesel Fuel Hybrid Diesel PM Filter Mass micrograms PM Filter Mass micrograms 0 Warm-up Enfield Out Enfield IN Farm Out Farm IN Avon Out Avon IN Warm-up Enfield Out Enfield IN Farm Out Farm IN Avon Out Avon IN Hybrid > or = Diesel 0 Highest PM mass on freeway, Lower on grade ULSD did not produce lower particle emissions.

19 Ratio Diesel to Hybrid Mass 1.2 D1 Fuel ULSD Diesel-to-Hybrid PM Mass Ratio Warm-up Enfield Out Enfield IN Farm Out Farm IN Avon Out Avon IN

20 ELPI, SMPS, Speed MPH H301 speed Hybrid, Farmington Number Conc. Number Conc x10 8.0x10 N 5 TOT ELPI 6.0x x x x10 4.0x x nm SMPS Time in Route

21 Summary 1 No significant difference between hybrid and conventional particulate emissions for: SMPS single diameter 10 to 130 nm PM filter total mass There were some differences between routes. Uphill > Downhill Mean route SMPS number distributions High variability between sampling days. Ambient conditions (T, traffic, dilution ratio)

22 Summary 2 No significant particulate emissions difference between fuels: SMPS single diameter 10 to 130 nm PM filter total mass Could other factors be more important than fuel? ambient T, RH conditions, traffic artifacts in dilution?? (water?) Could source of particulates be from oil, not the fuel??? Implications for real-world, on-road fleets Vehicle maintenance critical.

23 Allison E p Hybrid Systems Seattle, WA (235) Portland, OR (2) St. Paul, MN (3) Hartford, CT (2) Salt Lake City, UT (3) Philadelphia, PA(12) New Jersey (4) Orange County, CA (2) Austin, TX (2) Houston, TX (4) GM Allison E p 40/50 Hybrids by Dec (Indra, 2004)

24 Future Tasks Diesel Particulate Filter (DPF) After-treatment October December testing Scantool Data Analysis Conventional & Hybrid tools differ Writing program to extract data & timestamp it RPM, vehicle speed, % load, %throttle Sec-by-Sec Analysis Data alignment (diluter lags, corrections) Scantool PM Instruments Horiba State of Charge correction (Hybrids)

25 Financial support: CTTransit (Steve Warren) Thank you! The Joint Highway Research Advisory Council project JHRAC 03-8 National Science Foundation BES Testing & Data Analysis: Jimmy Dowd, Andres Chaparro, Jason Lewandowski Brad Harwood