Post on 11-Jun-2018
Emissions of Toxic Pollutants from Compressed Natural Gas and Ultra-low
Sulfur Diesel - Fueled Transit Buses
Norman Y. Kado , Robert A. Okamoto , Paul A. Kuzmicky, Reiko Kobayashi , Alberto Ayala , Michael E. Gebel, Paul L. Rieger , Christine Maddox , and Leo Zafonte
Overall Objective
Investigate the regulated and toxic pollutant emissions from heavy-duty vehicles with and without control technologies.
Project Aims
• Investigate toxic emissions for CNG and ULSD-fueled heavy duty diesel vehicles
• Investigate the effect of after-treatment control technologies on emissions
• Investigate the effect of test cycles on emission rates
• Investigate ultrafine PM emissions
Project Notes
• Study is a “snap-shot” of the fleet and not a fleet average
Research Team
• ARB – Research Div, Stationary Source Div., Mobile Source Control Div., Monitoring Laboratory Div. & CAVTC.
• Dept. Environmental Toxicology, UC Davis; Dept. Environmental Engineering, UC Davis.
Contributing:
• South Coast AQMD, UCLA
Experimental Design
Gaseous PM - Toxics VP - Toxics
Chemical
Emissions
Bioassay BioassayChemicalChemical
Vehicle Configurations
CNG w/ OC
CNG no OC
Diesel w/ DPF
Diesel w/ OC
Phase 1b(2002)
Phase 1a(2001)
Configuration
CNG00 CNG01
Vehicles and After-Treatments
CNGOC (1b)Cummins-Westport C-Gas Plus
2001CNG 01
CNGNone (1a & 1b)OC (1b)
DDC-S50G2000CNG 00
ULSDDOC (1a)OC-DPF (1a)
DDC-S501998Diesel
FuelAfter-Treatment(Study)
Engine Make
Model YrVehicle
Catalyzed Diesel Paticulate Filter (DPF) for DDC 50 Diesel (Johnson-Matthey, Inc)
Oxidative Catalyst for CNG DDC S50G Engine
Fuels
• Ultra-Low Sulfur Diesel (ULSD)
• < 15 ppm sulfur
• Compressed Natural Gas (CNG)
• Methane (mole %): > 88%
Measurements Phases 1a & 1b
• Regulated pollutants (TPM, THC/NMHC, NOx, NO2, CO, CO2)
• On-site, VOC-GC analyses c matching off-site analyses
• Elemental/Organic Carbon
• Elements
• PM size-segregated mass (1a only), PM number & size
Toxic Pollutant Measurements
• Polycyclic Aromatic Hydrocarbons (PAHs)
• Carbonyls, BTEX, 1,3 Butadiene
• Bioassay - mutagenicity
Sampling
Ce ntra l Busine ss District (CBD) Cycle
0
5
10
15
20
25
1 30 59 88 117 146 175 204 233 262 291 320 349 378 407 436 465 494 523 552
Tim e (s e conds )
Spee
d (m
ph)
Central Business District Cycle
PM Emissions
0
10
20
30
40
50
D ie s e l (O C ) D ie s e l (D P F ) C N G .0 0 C N G .0 0 (O C ) C N G .0 1 (O C )
Ve hicle Configuration
Em
issi
on
s (m
g/m
ile)
119+/- 7
PM Emissions – CBD
NOx Emissions – CBDN Ox Emissions
0
10
20
30
40
Dies e l (OC ) Dies e l (DP F ) C NG .0 0 C NG .0 0 (OC ) C NG .0 1 (OC )
Ve hicle Configuration
Em
issi
on
s (g
/mile
) Total NOx NO2
CO Emissions - CBD
CO Emissions
0
4
8
12
Diesel (OC) Diesel (DPF) CNG.0 0 CNG.0 0 (OC) CNG.0 1(OC)
Vehicle Configuration
Emis
sion
s (m
g/m
ile)
TARGET PAHS
Particle Assciated PAHsBenzo[ghi]peryleneDibenz[ah]anthraceneIndeno[1,2,3-cd]pryenePeryleneBenzo[a]pyreneBenzo[e]pyreneBenzo[k]fluorantheneBenzo[b]fluorantheneChryseneBenz[a]Anthracene
Semi-Volatile PAHsPyreneFluorantheneMethyl PhenanthreneAnthracenePhenanthreneFluorene
Volatile PAHsDimethyl naphthaleneAcenaphtheneAcenaphthyleneDimethyl naphthaleneBiphenyl1-methyl naphthalene2-methyl naphthaleneNaphthalene
FILTER
�������������������������������������������������������������������
�������������������������������������������������������������������
�������������������������������������������������������������������
�������������������������������������������������������������������
�������������������������������������������������������������������
�������������������������������������������������������������������
�������������������������������������������������������������������
PUF
XAD
Expected PAH phase distribution in ambient and exhaust samples
Polycyclic Aromatic Hydrocarbons
Polycyclic Aromatic Hydrocarbons
PM-PAHs - CBD
0
3
6
9
12
Diesel
(OC)
Diesel
(DPF)
CNG.00a
CNG.00b
CNG.00 (O
C)CNG.01
(OC)
Vehicle Configuration
Emis
sion
s (u
g/m
i) 45
Polycyclic Aromatic Hydrocarbons
SV-PAHs - CBD
0
50
100
150
200
Diesel
(OC)
Diesel
(DPF)
CNG.00a
CNG.00b
CNG.00 (O
C)CNG.01
(OC)
Vehicle Configuration
Emis
sion
s (u
g/m
i) 265
Polycyclic Aromatic Hydrocarbons
V-PAHs - CBD
0
50
100
150
200
Diesel
(OC)
Diesel
(DPF)
CNG.00a
CNG.00b
CNG.00 (O
C)CNG.01
(OC)
Vehicle Configuration
Emis
sion
s (u
g/m
i)
405 196
Mutagenic Potency
Specific Activity (Potency) - CBD
0
10
20
30
Diesel
(OC)
Diesel
(DPF)
CNG.00a
CNG.00b
CNG.00 (O
C)CNG.01
(OC)
Vehicle Configuration
Spec
ific
Mut
agen
iAct
ivity
(R
ev/u
g)
Mutagen Emissions - CBD
Mutagen Emissions
0
2
4
6
8
Diesel
(OC)
Diesel
(DPF)
CNG.00a
CNG.00b
CNG.00 (O
C)CNG.01
(OC)
Vehicle Configuration
Emis
sion
s (r
ev/m
i x 1
0 5) PM
SV
HYDROCARBON ANALYSIS
• Tedlar Bag Sampling
• Onsite GC to limit hold time
• SOP # MLD 102/103GC/FID Analysis w/cryo-trappingSpeciation of C2-C12+
• Report:Benzene, Toluene, EthylBenzene, Xylenes (BTEX)and
1,3 Butadiene
• GC/MS Confirmation of BTEX
10 20 30 40 50 60 70
Minute s
-1
0
5
10
15
20
25
30
mVolts
Propane/Propene< 5% of NMHC
Mid Range Chromatogram (T03013; 04/20/01)Diesel fueled bus no trap, CBD cycle
C2 Hydrocarbons< 15% of NMHC
n-Alkanes (C9+)
Toluene
Benzene
5 10 15 20 25 30 35 40
Minute s
0.0
0.5
1.0
1.5
2.0
Volts
Propane/Propene~ 20% of NMHC
Mid Range Chromatogram (T03130; 06/07/01) CNG fueled bus, CBD cycle
C2 Hydrocarbons~ 70% of NMHC
Isopentanen-Butane
TolueneBenzene
25.00 25.25 25.50 25.75 26.00 26.25
Minute s
-2
0
10
20
30
40
50
mVolts
Partial Light End Chromatogram - (04/20/01)CNG fueled bus; CBD cycle
Isopentane
Pentane
1,3 Butadiene
Total BTEX and Benzene Emission (CBD Cycle)(Error bars represent 1 std dev of replicate measurements)
(Tunnel blank value = average of mass emissions/miles per cycle)
0
2
4
6
Tunnel Blank Diesel (OC) Diesel (DPF) CNG.00 CNG.00 (OC) CNG.01 (OC)
Em
iss
ion
Ra
te (
mg
/
Total BTEX
Benzene
1,3 Butadiene Average Emission (CBD Cycle)(Error bars represent 1 std dev of replicate measurements)
(Tunnel blank value = average of mass emissions/miles per cycle)
0
1
2
3
4
5
Tunnel Blank Diesel (OC) Diesel (DPF) CNG.00 CNG.00 (OC) CNG.01 (OC)
Em
issi
on R
ate
(mg/
mi 1,3 Butadiene
1,3 Butadiene was not detected for any vehicle
configuration ortunnel blank except
CNG.00 Without OxiCat
Carbonyl Analysis
• Heated line Sampling
• DNPH Coated Silica Cartridges
• SOP # MLD 104Extraction with AcetonitrileHPLC analysis w/ UV Detection13 Target Compounds
Average Carbonyl Emissions (CBD Driving Cycle)(Error bars for carbonyl sum derived from 1 std dev of replicate runs)
(Tunnel blank value = average of mass emissions/miles per cycle)
0
200
400
600
800
1000
1200
Tunnel Blank Diesel (OC) Diesel (DPF) CNG.00 CNG.00 (OC) CNG.01 (OC)
Em
iss
ion
(m
g/m
Hexanal
m-Tolualdehyde
Valeraldehyde
Crotonaldehdye
Benzaldehyde
Methacrolein
Methyl Ethyl Ketone
Butanal
Propanal
Acetone
Acrolein
Acetaldehyde
Formaldehyde
Both OxiCat and DPF usage show large
reduction in formaldehyde
Summary• DPF reduces PM,, CO, HC, NMHC, EC, OC,
elements• DPF also reduces carbonyls, VOCs, PM-bound
and semivolatile PAHs, and PM-bound andsemivolatile mutagen emissions
• CNG catalyst reduces PM, OC, CO, HC, NMHC, CH4
• CNG catalyst also reduces carbonyls, VOCs, semivolatile PAHs, and PM-bound and semivolatile mutagen emissions
Summary
• NOX from CNG engines approximately 50% lower than NOX from diesel engine
• DPF-equipped bus has NOX emissions that contain 50% NO2
• Although not shown, test cycle differences are seen
• After-treatment durability and deterioration and vehicle maintenance were not evaluated
Acknowledgements
We wish to thank Mindy Salazar, Julia Sandoval, T.S. Yeung, Shiou-mei Huang, Richard Ling, Lyman Dinkins, Norma Castillo, Jack Horrocks, Keshav Sahay, George Gatt, John Karim, Jim Shears, Namita Verma, Wayne McMahon, Mark Fuentes, Bart Croes, Hector Maldonado, Richard Bode, Richard Corey, Linda Smith from the ARB.
Acknowledgements
We also are grateful to: Keith Stiglitz, Fred Gonzalez, and Harvey Porter of CAVTC; Geraldine Navarro, Kelsie Takasaki, Bernice Cheng, Mary Manaloto from UC Davis; Brit Holmen, UConn; Steve Barbosa of the SCAQMD. We also thank: LACMTA, So. Cal Gas Co., BP/ARCO, Detroit Diesel, San Bernardino Rapid Transit. We thank the Air Resources Board and SCAQMD for their support.