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1
Ionic and Organic Species in PM
Emissions from Advanced Technology
Heavy-Duty Diesel Vehicles
Alberto Ayala, Shaohua Hu, Jorn Herner, M.-C. Oliver Chang, William Robertson, John Collins, Tao Huai,
and Paul Rieger
California Air Resources BoardOctober 23, 2008
27th AAAR Annual ConferenceOct 20-24, 2008, Orlando, Florida, USA
Courtesy of D. Su, Fritz-Haber Institute
2
Acknowledgements:
2005-01-3800
CO-Investigators: CARB’s Monitoring and Laboratory Division, CARB’s Mobile Source Control Division, University of Southern California, UC Davis, U of Wisc.
Co-Sponsors:
In Kind Contributors:
3
NOX and PM Retrofits Investigated 1
Heavy-Duty Vehicles
Diesel Particle Filter
NOX Catalyst+ +
Catalyzed Filter
DOC
UncatalyzedFilter
UncatalyzedFilter
DOC
Catalyzed Filter
Urea
OxidCat
VanadiumSCR
1. Herner et al. 2007. Towards 2010 NOx and PM emission Levels: Overview of CARB's Investigation of Advanced Heavy-duty On-road Vehicle Retrofits and Other Technologies. 26th AAAR Annual Conference, September 24-28, 2007, Reno, NV
Baseline vehicle = no retrofit
Urea
OxidCat
Zeolite SCR
• One vehicle tested with DPF + SCR
• DPF + SCR is of special interest as it represents most advanced technology for meeting 2010 standards
• SCRT® systems used in this project are development prototypes not commercial units
4
Particle filter is game-changing technology. It ach ieves significant PM emission reductions from diesel engi nes
PM Mass Emissions [mg/mi]
Veh#1, Baseline
Veh#1, CRT
Veh#1, V-SCRT
Veh#1, Z-SCRT
Veh#2, DPX
Veh#3, Horizo
n
Veh#4, CCRT
mg/
mi
-5
0
5
10
15
20
25
30
150300450600750
Cruise at 50mphUDDS
Not
Mea
sure
d
PM retrofits yield greater than 90% reduction in PM emissions
Baseline Diesel Sample DPF+SCR SampleAgglomerates Clean as Blank
SEM images courtesy of D. Su, Fritz-Haber Institute
5
Experimental Setup @ CARB’s Emissions Lab
Exhaust from Testing Vehicles
Dilution Air
Filters
(+ vapor traps)
PM, PAHS,Nitro-PAHs,Ions, Trace elements,EC/OC,
Mutagenicity
NanoMOUDI
PM, organics and Ions
HiVolSampler
Organics, Ions, Redox
activity
ThermaldenudedSample
Metals, Ions, Redoxactivity, CPC
Cartridges
Carbonyls
Particle Characterization
EEPS, DMS, multiple CPCs,
PAS, EAD
FTIRN2O, NH3
BagsGases, VOCs
Sioutas Impactor @
V2O5
CVS TunnelQ=2600 or 1600 cfm
Sample Types Filter MediaFlow RateRange (lpm) Method Instrument
organic and elemental carbon Quartz fiber 38-40
IMPROVE_A, DRI Model 2001
Ionic species PTFE filter 40-45 IC Dionex
PAH TX60 75-80 GC-MSASE-
GC/MS
6
• EC (i.e., diesel soot) is not dominant emission. Mo re OC than EC
• All retrofits yield significant reductions of EC an d OC
• Elevated sulfate and ammonium are observed for retr ofits that also exhibit high particle nucleation
T ra n s ie n t U D D S
Io n s
Nitrate
Sulfate
Sodium
Am monium
PotassiumOC EC
mg/
mile
0 .0 1
0 .1
1
1 0
1 0 0
1 0 0 0
1 0 0 0 0
B a se lin eC R TV -S C R TZ -S C R TD P XH o rizo nC C R T
Z-SCRT shows comparable sulfate and ammonium as baseline
Reduction
Bel
ow d
etec
tion
Bel
ow d
etec
tion
Bel
ow d
etec
tion
Bel
ow d
etec
tion
Ions and Carbon Emissions
7
Relative Fraction of Ions and Carbon Emissions
• EC/OC about equal fractions of PM emissions for bas eline vehicle
• Sulfate is dominant for most retrofits during cruis e operation. 40-50% of PM is sulfate for retrofits with significant nucleation events (e .g. CRT, SCRTs and DPX)
• OC dominates PM emissions from most retrofits when vehicle operates over transient cycle
0%
25%
50%
75%
100%V
eh#1
, Bas
elin
e
Veh
#1, C
RT
Veh
#1, V
-SC
RT
Veh
#1, Z
-SC
RT
Veh
#2, D
PX
Veh
#3, H
oriz
on
Veh
#4, C
CR
T
Veh
#1, B
asel
ine
Veh
#1, C
RT
Veh
#1, V
-SC
RT
Veh
#1, Z
-SC
RT
Veh
#2, D
PX
Veh
#3, H
oriz
on
Veh
#4, C
CR
T
EC
OC
Potassium
Ammonium
Sodium
Sulfate
Nitrate
Cruise at 50mph UDDS
not
mea
sure
d
8
Charging Balance (Anions/Cations)
Transient-UDDS
Veh#1
, Bas
eline
Veh#1
, CRT
Veh#1
, V-S
CRTVeh
#1, Z
-SCRT
Veh#2
, DPX
Veh#3
, Hor
izon
Veh#4
, CCRT
Ani
on/C
atio
n
0
1
2
3
4
5
6
SulfateBi-sulfate
Cat
ions
=0
a. Anions: sulfate and nitrateb. Cations: ammonium, potassium and sodium
– Particles from some retrofits (e.g., CRT & Horizon) are more acidic (anions/cations > 1)
– Suspect formation of nitric acid and sulfuric acid
– Transient cycle increases acidity
– Emissions from baseline and other retrofits appear to be neutralized
9
Preliminary Results - Particle Phase PAHs 2
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
Total PAH vapor phasePAH
SemiVol-PAH P-bound-PAH
Em
issi
on r
ate
in u
g/ho
ur
Baseline/1000 V-SCRT Zeo-SCRTCRT Englehart DPX HybridHorizon
UDDSUDDS
2. Chang et al. 2008. Air Toxic Emissions from HD Diesel Vehicles Equipped with NOx and PM Retrofits. 18th CRC On-Road Emissions Workshop, March 31 - April 2, 2008, San Diego, CA
Baseline divided by
1000
10
IDLE
1,3
Butad
iene
Benze
ne
Toluen
e Eth
ylben
zene
m,p
-xyle
ne
styre
ne
o-xy
lene
mg/
hr
1
10
100
1000
UDDS
1,3
Butad
iene
Benze
ne
Toluen
e Eth
ylben
zene
m,p
-xyle
ne
styre
ne
o-xy
lene
mg/
mile
1e-5
1e-4
1e-3
1e-2
1e-1
1e+0
1e+1
1e+2
BaselineCRTV-SCRTZ-SCRTDPXHorizonCCRT
Not
Mea
sure
d
Not
Mea
sure
d
Not
Mea
sure
d
Not
Mea
sure
d
Not
Mea
sure
d
Not
Mea
sure
d
Not
Mea
sure
d
Not
Mea
sure
d
Not
Mea
sure
d
Not
Mea
sure
d
Air Toxics (Benzene, Toluene, Ethylbenzene and Xylen e )
Cruise and UDDS Cycles
• Greater than 70% reduction of BTEX by all retrofits
• For some emissions are below background
a. No measurements for CRT and CCRT during idle operationb. Values not displayed are below the levels of filtered ambient air
Idling• Greater than 70% reduction of
BTEX by most aftertreatmentdevices
• But, increased levels of Benzene observed from DPF+SCR retrofits
11
Final Remarks• Well-functioning retrofits are performing as designed. They reduce emissions
significantly (EC/OC, PAHs, BTEX).
• No surprises. Just a few remaining questions.
• Some retrofits are prototypes. So there is room for optimization in production-ready systems
• Chemical composition of PM emissions is altered by retrofits
• Elevated sulfate and ammonium correspond to retrofits that also exhibit high particle nucleation
• Study presents significant challenges for analytical analysis due to very low mass emissions from retrofit-equipped vehicles
• Future work:– Complete analysis/publication of results for heavy-duty vehicles– Study passenger cars fueled by diesel, E85, CNG, gasoline, biodiesel
12
See Also at AAAR08: • 8D.5 Wednesday 4:15pm: Novel Approaches for Speciation of Platinum and Vanadium in Mobile
Source Emissions.
• 9A.1 Thursday 9:20 am: Chemical Speciation of PM Emissions from Heavy-Duty Diesel Vehicles Equipped with DPF and SCR Retrofits.
• 9A.26 Thursday 9:20 am: Elements Emitted from Advanced Technology Heavy Duty Diesel Vehicles.
• 10A.3 Thursday 11:15am:Toxicity of Particulate Matter from Heavy-Duty Vehicles Retrofitted with Emission Control Technologies.
THANK YOU
Questions?
More about vehicle emissions research program by CARB:
http://www.arb.ca.gov/research/veh-emissions/veh-emissions.htm