TRANSIT BUS EMISSION STUDY COMPARISON OF EMISSIONS FROM DIESEL AND - - PowerPoint PPT Presentation

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TRANSIT BUS EMISSION STUDY

COMPARISON OF EMISSIONS FROM DIESEL AND NATURAL GAS BUSES Nils-Olof Nylund & Kimmo Erkkilä

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THE FINNISH NATIONAL BUS PROJECT 2002-2004

VTT performed more than 200 emission measurements with 34 different buses Some vehicles were subjected to a follow-up program to study emission stability and deterioration Variables in the study were, among others:

– vehicle certification class (Euro 1 to Euro 5/EEV) – vehicle mileage – fuel (diesel, natural gas) – duty cycle (Braunschweig bus cycle, ECE, Orange Country) – vehicle load

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OBJECTIVES OF THE EXPANDED WORK ON CNG BUSES

To provide unbiased emission data on current diesel and CNG vehicles

– extensive emission analysis

Diesel buses

– Euro 3 without after-treatment – Euro 3 with oxidation catalyst – Euro 3 with OEM installed CRT

Natural gas buses (catalyst equipped)

– Euro 3 lean-burn – EEV lean-burn – EEV lean-mix (combination of λ= 1 and lean-burn) – EEV stoichiometric (λ= 1)

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CHASSIS DYNAMOMETER TESTING

Braunschweig Bus Cycle

10 20 30 40 50 60 70 200 400 600 800 1000 1200 1400 1600 1800 Time (s) Speed (km/h)

Orange County Bus cycle

10 20 30 40 50 60 70 500 1000 1500 2000 Time (s) Speed (km/h)

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NOx vs. PM FOR TOTAL BUS MATRIX

NOx and PM emissions over the Braunschweig city bus -cycle

5 10 15 20 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

PM g/km NOx g/km

Diesel Euro 1 Diesel Euro 2 Diesel Euro 3 Diesel + CRT Euro 2 & 3 CNG Euro2 CNG Euro3 CNG EEV Euro limits (by factor 1.8)

Euro 1 Euro 2 Euro 3 Euro 4 Euro 5 / EEV

Brands A&B Brand B Brand A Brand A Brand A Brand C Brand C Brand A Brand C Brand B Brands D&E

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NOx TREND

NOx emissions vs. Euro-levels in Braunschweig city bus -cycle

5 10 15 20 25

Euro emission level g/km Diesel Diesel + CRT CNG CNG EEV LB CNG EEV LM CNG EEV SM Euro limits (by factor 1.8)

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PM TREND

PM emissions vs. Euro-levels in Braunschweig city bus -cycle

0.0 0.1 0.2 0.3 0.4 0.5 0.6

Euro emission level g/km Diesel Diesel + CRT CNG CNG EEV LB CNG EEV LM CNG EEV SM Euro limits (by factor 1.8)

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PARTICLE NUMBERS

Particle size distribution over Br and Or test (ELPI)

1.E+09 1.E+10 1.E+11 1.E+12 1.E+13 1.E+14 1.E+15 1.E+16 0.01 0.10 1.00 10.00

Aerodynamic Dp [µm]

dN/dlogDp [#/test]

DI Euro III - Br DI Euro III - Or DI Euro III OC - Br DI Euro III OC - Or DI Euro III CRT - Br DI Euro III CRT - Or CNG Euro III OC - Br CNG Euro III OC - Or CNG1 EEV OC - Br CNG1 EEV OC rep. - Br CNG1 EEV OC - Or CNG2 EEV TW/OC - Br CNG2 EEV TW/OC - Or CNG EEV SM TW - Br

DIESEL, DIESEL + OC DIESEL + CRT CNG SM CNG

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DIESEL CRT vs LEAN-MIX CNG

Items evaluated: Carcinogenic PAHs NMHC NOx NO2 (tailpipe) CO2 Ames mutagenicity Formaldehyde (FA) Particle mass (PM) Particle numbers (PM#)

Relative emissions, worst result = 100% Brauschweig cycle

0 % 50 % 100 % PAH car. FA Ames NO2 NOx CO2 PM PM# NMHC

Euro 3 Diesel

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VTT PROCESSES VTT TECHNICAL RESEARCH CENTRE OF FINLAND

Captive Fleets 14.1.2005

DIESEL CRT vs LEAN-MIX CNG

Items evaluated: Carcinogenic PAHs NMHC NOx NO2 (tailpipe) CO2 Ames mutagenicity Formaldehyde (FA) Particle mass (PM) Particle numbers (PM#)

Relative emissions, worst result = 100% Brauschweig cycle

0 % 50 % 100 % PAH car. FA Ames NO2 NOx CO2 PM PM# NMHC

Euro 3 Diesel Euro 3 Diesel +CRT

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VTT PROCESSES VTT TECHNICAL RESEARCH CENTRE OF FINLAND

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DIESEL CRT vs LEAN-MIX CNG

Items evaluated: Carcinogenic PAHs NMHC NOx NO2 (tailpipe) CO2 Ames mutagenicity Formaldehyde (FA) Particle mass (PM) Particle numbers (PM#)

Relative emissions, worst result = 100% Brauschweig cycle

0 % 50 % 100 % PAH car. FA Ames NO2 NOx CO2 PM PM# NMHC

Euro 3 Diesel Euro 3 Diesel +CRT CNG EEV LM

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CONCLUSIONS

On average, CNG delivers better emission performance than CRT equipped diesel Exhaust from advanced CNG vehicles was found less toxic than exhaust from CRT diesel Total numbers of particles and nanoparticles with CNG are similar to CRT diesel How will new diesel technology perform?