Real-World Characterization of Particulate Matter Emissions from ...
Transcript of Real-World Characterization of Particulate Matter Emissions from ...
CAFEECenter for Alternative Fuels, Engines, and Emissions
Cambridge Particle Workshop
July 3rd, 2015
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CHARACTERIZATION OF PM MASS AND NUMBER EMISSIONS EMITTED BY CURRENT TECHNOLOGY
HEAVY-DUTY ENGINES
REAL-WORLD CHARACTERIZATION OF PARTICULATE MATTER EMISSIONS FROM HEAVY-DUTY TRUCKS
OPERATING IN CALIFORNIA
Arvind Thiruvengadam, Marc Besch, Saroj Pradhan, Daniel Carder
West Virginia University
Mridul Gautam
University of Nevada, Reno
David Quiros, Shaohua Hu, Tao Huai
California Air Resources Board
Adewale Oshinuga, Randall Pasek
South Coast Air Quality Management District
Eon S. Lee, Yifang Zhu
University of California, Los Angeles
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DISCUSSION I - INTRODUCTION
2
• Evaluation of PM emissions from heavy-duty vehicles
powered by Diesel, natural gas or NG/Diesel dual-fueled engines
and,
equipped with advanced after-treatment technology
operated over a variety of real-world driving cycles using a
chassis dynamometer
• Characterization of particle number concentration and
size distributions
• Characterize real-time DPF filtration efficiencies using in-
line particle sensor up/downstream DPF
Effect of regeneration events on DPF filtration efficiency
Restoring rate of high filtration efficiency after regeneration event
=> “soot cake layer” build up
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METHODOLOGY - Test Vehicles
3
Cat Engine/TechnologyTransit
Bus
Refuse
TruckOTR
I Natural Gas Engine with TWC 1 1 3
II HPDI Engine with EGR, DPF at 0.8g NOx 3
III HPDI Engine with EGR, DPF, SCR at 0.2g NOx 1
IV Diesel Engine cert. at 1.2g NOx 1
V Diesel Engine cert. above 0.2g NOx w/o SCR 1 1
VI Diesel Engine cert. at or below 0.2g NOx w/SCR 1 3
Category IVCategory V
Category VI
Category I Category IIICategory II
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METHODOLOGY - PM/PN Sampling System
4
Particle concentrations
and size distributions in
diluted exhaust (CVS)
Gravimetric TPM on
47mm TX40 filter media
(sampling following
recommendations
outlined in 40 CFR 1065)
Total particle number concentrations using double
dilution system with heated first stage and cold
second stage dilution
Gravimetric PM1.0, PM2.5, PM10
47mm TX40 filter media
Parameter 1st Stage 2nd Stage
Diluter TypeEjector Diluter
(AirVac TD110-H)
Ejector Diluter
(AirVac TD110-H)
Dilution Air
Temperature~150°C ~20 - 25°C
Dilution Air
Condition
Dry, HEPA filtered
air
Dry, HEPA filtered
air
Residence Time ~0.6sec Negligible
Dilution Ratio ~7 ~24
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METHODOLOGY - Real-Time PM Sensor
5
• PM detection based on diffusion charging
and escaping current principle
• Flow through device => low maintenance
• Constant dilution air pressure leading to
constant sample inlet flow => constant
internal dilution ratio
• Sensor shows proportional response to
particle surface area
Pre DPF Sampling Location
• Sample extraction via 3ft heated line (@200°C)
• Internal DR ≈ 2.9 @ 22psi dil. pressure
• Sensor heated to 200°C
Post After-treatment Sampling Location
• Directly mounted to exhaust stack
• Internal DR ≈ 3.06 @ 22psi dil. pressure
• Sensor heated to 200°C
Sample ProbePPS
DO
C
DPF
EGR PPSPre-DPF
SCR
Urea Injection
PPSPost-aftertreatment
To CVS
Diesel fueled
DO
C
DPF
EGR PPSPre-DPF PPSPost-aftertreatment
To CVS
Diesel fueled
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METHODOLOGY - Test CyclesVehicle
Vocation
HD-
UDDS
SCAQMD Refuse
Truck Cycle
OCTA
Cycle
Double-length
CBD Cycle
Drayage Port Cycles
i) Neardock, ii) Local, iii) Regional
Refuse Truck X X
Transit Bus X X X
OTR X X
0
20
40
60Neardock Cycle
0
20
40
60Local Cycle
Vehic
le S
peed [m
ph]
0 500 1000 1500 2000 2500 3000 3500 4000 45000
20
40
60Regional Cycle
Time [sec]
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RESULTS - TPM, NG Vehicles (Cat I)
0
5
10
15
20
25
30
35U
DD
S
Loca
l
Reg
ion
al
Nea
r-D
ock
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
UD
DS
AQ
MD
RT
Cyc
le
AQ
MD
RC
Cyc
le
UD
DS
OC
TA
2 x
CB
D
OTR 1 (low mileage) OTR 2 (medium mileage) OTR 3 (medium mileage) Refuse Truck Transit Bus
TP
M E
mis
sio
n R
ate
s [m
g/m
ile]
dsPM dsPM Bgcorr
(116,232 mi)(21,465 mi)(63,256 mi)(45,563 mi)(192 mi)
• Increased TPM emissions for refuse truck and transit bus possibly due to increased oil
consumption
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RESULTS - TPM, Dual-Fuel Vehicles
(Cat II & III)
0
5
10
15
20
25
30
35
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Cat II - OTR 1 Cat II - OTR 2 Cat II - OTR 3 Cat III - OTR
TP
M E
mis
sio
n R
ate
s [m
g/m
ile]
dsPM dsPM Bgcorr
(45,621 mi)(45,621 mi)(368,080 mi)(196,562 mi)
Local immediately
followed UDDS
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RESULTS - TPM, Diesel Vehicles
(Cat IV & V & VI)
0
5
10
15
20
25
30
35
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
UD
DS
AQ
MD
RT
Cyc
le
AQ
MD
RC
Cyc
le
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
UD
DS
AQ
MD
RT
Cyc
le
AQ
MD
RC
Cyc
le
IV - OTR w/ DPF V - OTR w/o SCR V - Refuse Truckw/o SCR
VI - OTR 1 w/ SCR VI - OTR 2 w/ SCR VI - Refuse Truckw/ SCR
TP
M E
mis
sio
n R
ate
s [m
g/m
ile]
dsPM dsPM Bgcorr
(178,564 mi)(36,982 mi)(10,014 mi)(67,373 mi)(80,412 mi) (14,269 mi)
2009 post-2010
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0
5
10
15
20
25
30
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
UD
DS
AQ
MD
RT
Cyc
le
AQ
MD
RC
Cyc
le
Bck
gnd
UD
DS
OC
TA
2 x
CB
D
Bck
gnd
OTR 1 (low mileage) OTR 2 (medium mileage) OTR 3 (medium mileage) Refuse Truck Transit Bus
Em
issio
ns R
ate
s [m
g/m
ile],
Bckg
nd
[m
g/h
]
PM1.0 PM2.5 PM10
RESULTS - PM1, 2.5, 10, NG Vehicles (Cat I)
10
PM10
79.9g/h
(116,232 mi)(21,465 mi)(63,256 mi)(45,563 mi)(192 mi)
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0
20
40
60
80
100
120
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
Cat II - OTR 1 Cat II - OTR 2 Cat II - OTR 3 Cat III - OTR
Em
issio
ns R
ate
s [m
g/m
ile],
Bckgnd [m
g/h
]
PM1.0 PM2.5 PM10
11
RESULTS - PM1, 2.5, 10, Dual-Fuel Vehicles
(Cat II & III)
(45,621 mi)(45,621 mi)(368,080 mi)(196,562 mi)
1.E+04
1.E+05
1.E+06
1.E+07
1.E+08
1 10 100 1000
Cat II - OTR 1 Cat II - OTR 1 Cat II - OTR 2 Cat II - OTR 2
UDDS
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0
20
40
60
80
100
120
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
UD
DS
AQ
MD
RT
Cyc
le
AQ
MD
RC
Cyc
le
Bck
gnd
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
UD
DS
AQ
MD
RT
Cyc
le
AQ
MD
RC
Cyc
le
Bck
gnd
IV - OTR w/ DPF V - OTR w/o SCR V - Refuse Truckw/o SCR
VI - OTR 1 w/ SCR VI - OTR 2 w/ SCR VI - Refuse Truck w/SCR
Em
issio
ns R
ate
s [m
g/m
ile],
Bckg
nd
[m
g/h
]
PM1.0 PM2.5 PM10
RESULTS - PM1, 2.5, 10, Diesel Vehicles
(Cat IV & V & VI)
Regeneration Event
• Increase in size selective PM due to regeneration for Cat IV OTR (2009) and refuse truck
w/o SCR after-treatment system
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0
5
10
15
20
25
30
35
40
45
50
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
IV - MY 2009 Diesel w/ DPF VII - MY 2011 Diesel w/o SCR VIII - MY 2011 Diesel w/ SCR
Em
issio
ns R
ate
s [m
g/m
ile],
Bckgn
d [m
g/m
in]
TEC
TOC
0
10
20
30
40
50
60
70
80
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
MY 2009 Vehicle 1 MY 2009 Vehicle 2 MY 2009 Vehicle 3 MY 2011 Vehicle 4
Em
issio
ns R
ate
s [m
g/m
ile],
Bckgn
d [m
g/m
in]
TEC
TOC
0
2
4
6
8
10
12
14
16
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
UD
DS
Loca
l
Reg
ion
al
Nea
r-D
ock
Bck
gnd
Vehicle 1 Vehicle 2 Vehicle 3
Em
issio
ns R
ate
s [m
g/m
ile],
Bckgn
d [m
g/m
in]
TEC
TOC
0
2
4
6
8
10
12
14
16
18
20
UDDS AQMDRefuse
Truck Cycle
AQMDRefuse
CompactionCycle
Bckgnd UDDS AQMDRefuse
Truck Cycle
AQMDRefuse
CompactionCycle
Bckgnd
VII - MY 2011 Refuse Truck w/o SCR VIII - MY 2011 Refuse Truck w/ SCR
Em
issio
ns R
ate
s [m
g/m
ile],
Bckgn
d [m
g/m
in]
TEC
TOC
RESULTS - EC/OC Analysis
Cat I, NG VehiclesCat V & VI, Diesel
Cat IV & V & VI, Diesel Cat II & III, Dual-fuel
OTR 1 OTR 2 OTR 3 Cat V Cat VI
Cat VICat VCat IV
OTR 1 with lowest mileage (192 mi)
=> peak catalytic activity not yet
reached (ageing needed)
DPF regeneration event
DPF regeneration event
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101
102
104
105
106
107
108
109
Inte
gra
ted C
oncentr
atio
n d
N/d
log(D
p)
[#/c
m3]
Diameter (Dp) [nm]
Dp [
nm
]
0 100 200 300 400 500 600 700 800 900 1000 11005.6
10
24
42
87
178
365
560
0 0.5 1 1.5 2 2.5 3 3.5
x 106
0 100 200 300 400 500 600 700 800 900 1000 11000
1
2
3
4
5
6
7x 10
5
Tot
Conc.
[#/c
m3]
0 100 200 300 400 500 600 700 800 900 1000 11000
100
200
300
400
Exh.
Tem
pera
ture
s [C
]
Time [sec]
Post SCR
PPS Sample Plane
RESULTS - Particle Size Distribution
• Particle size distribution measured in CVS
(no dilution, no correction for CVS dilution)
• Cat VI Vehicle with SCR operated over
UDDS
• Large release of 17.8nm (CMD) particles
starting at ~650sec
No DPF regeneration event => supported
by Pegasor and CPC measurement in raw
exhaust
• Removing data between ~650 to 840sec
leads to an order of magnitude reduction in
17.8nm particles
1.87x108 vs. 1.58x107
=> UDDS
Dp [nm
]
0 100 200 300 400 500 600 700 800 900 1000 11005.6
10
24
42
87
178
365560
0 0.5 1 1.5 2 2.5 3 3.5
x 106
0 100 200 300 400 500 600 700 800 900 1000 11000
1
2
3
4
5
6
7x 10
5
Tot C
onc. [#
/cm
3]
0 100 200 300 400 500 600 700 800 900 1000 11000
100
200
300
400
Exh. T
em
pera
ture
s [C
]
Time [sec]
Post SCR
PPS Sample Plane
Pre DPF
200C
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RESULTS - Particle Size Distribution UDDS
101
102
104
105
106
107
108
109
Inte
gra
ted C
oncentr
atio
n d
N/d
log(D
p)
[#/c
m3]
Diameter (Dp) [nm]
Cat VI - OTR 1 w/ SCR (UDDS)
101
102
104
105
106
107
108
109
Inte
gra
ted C
oncentr
atio
n d
N/d
log(D
p)
[#/c
m3]
Diameter (Dp) [nm]
Cat VI - OTR 2 w/ SCR (UDDS)
101
102
104
105
106
107
108
109
Inte
gra
ted C
oncentr
atio
n d
N/d
log(D
p)
[#/c
m3]
Diameter (Dp) [nm]
Cat V - OTR w/o SCR (UDDS)
101
102
104
105
106
107
108
109
Inte
gra
ted C
oncentr
atio
n d
N/d
log(D
p)
[#/c
m3]
Diameter (Dp) [nm]
Cat V - Refuse Truck w/o SCR (UDDS)
101
102
104
105
106
107
108
109
1010
1011
Inte
gra
ted C
oncentr
atio
n d
N/d
log(D
p)
[#/c
m3]
Diameter (Dp) [nm]
Cat VI - Refuse Truck w/ SCR (UDDS)
101
102
104
105
106
107
108
109
1010
1011
Inte
gra
ted C
oncentr
atio
n d
N/d
log(D
p)
[#/c
m3]
Diameter (Dp) [nm]
Cat IV - OTR w/ DPF (UDDS)
Regeneration
Increase in 17.8nm particles not due to DPF
regeneration => low raw concentrations
Increase in 9.31nm particles not due to DPF
regeneration => low raw concentrations
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0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2x 10
6
Time [sec]
CP
C P
art
icle
Concentr
ation [
#/c
m3]
0 200 400 600 800 10000
2
4
6
8
10
12
14
16
18
20
PP
S p
ost-
aft
ert
reatm
ent
Sig
nal [m
v]
Axle-Work-specific PN [#/kW-hr] 6.22 E+13 2.16 E+13
Distance-specific PN [#/km] 9.92 E+13 3.44 E+13
DPF Filtration Efficiency [%] 99.0 99.59
Dilution
corrected with
DR ≈ 160
Re
d
Blu
e
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2x 10
6
Time [sec]C
PC
Part
icle
Concentr
ation [
#/c
m3]
0 200 400 600 800 10000
2
4
6
8
10
12
14
16
18
20
PP
S p
ost-
aft
ert
reatm
ent
Sig
nal [m
v]
Re
d
Blu
e
Dilution
corrected with
DR ≈ 160
With DPF Regeneration Event Without DPF Regeneration Event
• Three-fold increase in PN during cycle with regeneration event
Total engine-out PN levels increase by ~25%
W/ Regen. W/O Regen.
RESULTS - Diesel, DPF (1.2g/bhp-hr NOx) UDDS
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1.E+00
1.E+02
1.E+04
1.E+06
1.E+08
1.E+10
1.E+12
1.E+14
I II III IV V VI
bsPN [#/kW-hr]
dsPN [#/km]
I Diesel, SCR/DPF (< 0.2g/bhp-hr NOx)II Diesel, DPF/heavy EGR (> 0.2g/bhp-hr NOx)
III Diesel, DPF (1.2g/bhp-hr NOx) => no regenIV Diesel, DPF (1.2g/bhp-hr NOx) => with regen
V CNG/Diesel, HPDI 3rd gen/DPF (0.8g/bhp-hr NOx)VI CNG/Diesel, HPDI 4th gen/DPF-SCR (< 0.2g/bhp-hr NOx)
98.4%
98.6%
98.8%
99.0%
99.2%
99.4%
99.6%
99.8%
100.0%
I II III IV V VI
Tota
l D
PF
Filt
ration E
ffic
iency [%
]
with regeneration
event
• Filtration efficiencies calculated using PPS
measurements up/downstream
aftertreatment system
• For DPF/SCR equipped vehicles => filtration
efficiency corresponds to overall
aftertreatment particle removal efficiency
=> [kW-
hr]
represent
s axle
work
RESULTS - Total PN Comparison
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0 200 400 600 800 1000 12000
200
400
600
800
1000
1200
1400
1600
1800
2000
Time [sec]
PP
S S
ignal [m
V]
I - Diesel, SCR/DPF (< 0.2g/bhp-hr NOx)
VI - CNG/Diesel, HPDI 4th gen/DPF-SCR (< 0.2g/bhp-hr NOx)
• Reduced engine-out particle number concentrations for dual-fueled vs. diesel-only
fueled engine during acceleration and high load modes
• Increased engine-out PN during idle portions for dual-fueled engine
RESULTS - Engine-out PN, Diesel vs. Dual-fueled
Engine
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• Real-world emissions from heavy-duty vehicles are of importance
• Operation of SCR (identifying operations leading to higher NOx
emissions)
• DPF filtration efficiencies (Operations that could lead to higher solid
particle emissions)
• In addition to in-use conformity testing using PEMS instrumentation, the
use of a transportable laboratory-grade CVS system offers better
accuracy and versatility in integrating measurement instrumentation
• Regulated pollutants(laboratory grade and PEMS)
• Unregulated pollutants (FTIR)
• PM speciation (EEPS, PMP sampling, soot sensor, etc.)
• European RDE proposal also voices the need for monitoring vehicle
emissions beyond just certification cycles, in particular urban operation.
DISCUSSION II - INTRODUCTION
19
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Day 2: 146 mi
Port of LB/LA Route
Congested Hwy
+ Creep Simulation
Day 1: 437 mi
Central Valley Via
I-5
Open Hwy +
GrapevineDay 5: 439 mi
Central Valley
Via SR-99
Open Hwy +
Grapevine
Day 3: 150 mi
OC Delivery
Congested Hwy +
Suburban Arterial
Day 4: 521 mi
Needles/Blythe
Open Hwy +
Cajon Pass
20
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• Three dilution setups were used
• Mini-Dilution Setup: Ejector-type dilution of raw exhaust (HEPA filtered dry pressurized
air at 25 DegC)
• CVS dilution with HEPA filtered ambient air
• Thermodilution using rotating disk dilutor and TSI Thermodilution (Model 379020A) and
Conditioning system (PMP compliant-Model 379030)
METHODOLOGY - Sampling System
21
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Vehicle Engine Model After Treatment
System
Vehicle 1 (MY 2008) Cummins ISX 525 DPF only
Vehicle 2 (MY 2013) Cummins ISX 15/450 DPF and SCR
Vehicle 3 (MY 2013) Cummins ISX 12G
(Natural gas)
Three-way catalyst
Vehicle 4 (MY 2014) Detroit Diesel DDC15 DPF and SCR
• Vehicle 5 (Volvo D13 with DPF and SCR) and Vehicle 6 (Navistar N13
with DPF and SCR) to be tested.
METHODOLOGY - Test Vehicles
22
CAFEECenter for Alternative Fuels, Engines, and Emissions
Cambridge Particle Workshop
July 3rd, 2015
Cambridge, UK
KEY QUESTIONS OR
HYPOTHESESQuestion 1: Does the activity of SCR result in any new
particle formation?
Question 2: How effective are DPFs during real-world
operation?
Hypothesis 1: Idle and low load operation of natural gas
engines produces higher PM emissions. Such PM emissions
are dominated by lubrication oil derivatives.
Hypothesis 2: No significant differences in PM emissions are
observed between different engine manufacturer platforms.
23
CAFEECenter for Alternative Fuels, Engines, and Emissions
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24
0 1000 2000 3000 4000 5000 6000 7000 80000
20
40
60
80
Vehicle Speed [mph]
0 1000 2000 3000 4000 5000 6000 7000 80000
0.1
0.2
0.3
0 1000 2000 3000 4000 5000 6000 7000 80000
2
4
6NOx [g/s]
NH3 [ppm]
0 1000 2000 3000 4000 5000 6000 7000 8000
200
400
600
avg SCR Temp [degC]
avg DPF Temp [degC]
0 1000 2000 3000 4000 5000 6000 7000 800010
7
109
1011
1013
Time [sec]
PM # Mini-dilution [#/sec]
PM # CVS-dilution [#/sec]
PM # Thermo-dilution [#/sec]
Periodic SCR
activity and
increased PN
count
Observed particles
are believed to be
liquid in nature and
magnitude is
lowered upon heat
treatment of
sample
RESULTS: Question 1
SCR Activity and Particle Formation
CAFEECenter for Alternative Fuels, Engines, and Emissions
Cambridge Particle Workshop
July 3rd, 2015
Cambridge, UK
Question 1 Cont’d
25
*Impact of Selective Catalytic Reduction on Exhaust Particle Formation over Excess Ammonia Events,
Environ. Science and Tech, 2014, 48, 11527−11534
Accumulation mode particles
coinciding with SCR activity
• Further questions: Ammonium nitrate? Ammonium sulfate
or ammonium chloride????????
• Aggressive urea dosing could increase the particle count
Vehicle 2: DPF-SCR
Vehicle 4: DPF-SCR
=> Results derived from extended highway operation
Thermodilution (PMP)
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26
• For measurements from the CVS no significant differences are observed in PM emissions between
different power levels
• In the case of thermodilution of sample
Close to an order of magnitude higher PN count for power levels between idle and 20% load in
comparison to higher load operation
• Previous studies on chassis dynamometer have indicated possible inorganic nucleation mode particles
derived from lube oil.
• Presence of nucleation mode particles after evaporator stage of thermodilutor indicates the possible
presence of solid particles (lube oil ash, re-nucleated lube oil additives)
< 10 nm particles
RESULTS: Hypothesis 1
Natural Gas Engine PM vs. Engine Load
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• Distance-specific PN count are
well below the to EU-PN
regulation of 6 X 1011 #/km
• Higher PN count with
thermodilutor sampling with a
2.5 nm cut-point CPC,
indicates particles below 23 nm
exists even after thermal
conditioning
• Differences in after-treatment
design and urea dosing
strategy between vehicles 2
and 4 do not seem to influence
the PN count significantly
• In the case of natural gas
engines the PMP measurement
might be ignoring the inorganic
particles below 23 nmVehicle 2 was equipped with a conventional DPF and SCR while Vehicle 4 was
equipped with an integrated DPF and SCR design with an Ammonia Oxi. Catalyst
Above chart represents PN count for hill climb route
RESULTS: Hypothesis 2
Differences in PM Emissions Between Engine Platforms
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• Close to 100% filtration
efficiency during all
operating conditions
• Above chart shows
filtration efficiency for hill
climb route with maximum
gravimetric filter loading
• No regeneration events
observed during the 1700
mi test campaign on each
vehicle
ON A SEPARATE NOTE
Need of the hour: Robust OBD strategy to detect DPF failures (tailpipe
sensors????)DPF failures caused as a cascading effect originating from a engine durability issues-
EGR related issues invariably result in DPF failures undetected by engine
0 1 2 3 4 5 660
70
80
90
100
110
Time [sec]
DPF Efficiency [%]
RESULTS: Question 2
Real-World DPF Efficiency
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• Measuring particulate matter emissions from Diesel, natural gas, and
NG/Diesel dual-fueled engines equipped different after-treatment system
configurations.
• NG fueled engines showed lowest overall gravimetric TPM emissions
Increased TPM emissions observed for NG engines; i) with high mileage
(transit bus) and; ii) aggressive operation => frequent accel./decel. (refuse
hauler)
Due to increased oil consumption leading to ash particle formation
• DPF regeneration events increase TPM emissions
• PM1,2.5,10 emissions results show large variability in filter weights => low signal-
to-noise ratio
• PM for all engine technologies, fuels and after-treatment packages are
predominantly of organic nature (OC). EC is negligible for all engines unless
during DPF regeneration events that show a slight increase in EC.
• Particle size distributions and number concentrations measured in CVS were
found to be dependent on engine technology
DISCUSSION I - CONCLUSION
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1. SCR activity results in particles both in nucleation (e.g. sulfates) and
accumulation mode particles
2. Composition and the environmental impact (if any) from these accumulation
mode particles is worth investigating
3. Solid particles in the nucleation mode are observed in exhaust of natural
gas vehicles
a) Data from this study suggests that lubrication oil contribution is
prevalent even in engines with less miles
b) Engine component ageing could potentially increase the PN count from
natural gas engines
4. No significant differences in PM emissions (both mass and number) were
observed between different engine manufacturers
1. It would be interesting to observe the impact of optional regulation such
as ARB 0.02 g/bhp-hr Nox standard on PM emissions
5. OBD related development of PM sensors or fault detection algorithms are
the need of the hour to monitor DPF efficiency
DISCUSSION II - CONCLUSION
CAFEECenter for Alternative Fuels, Engines, and Emissions
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OUTLOOK - Effects of Dilution Conditions on Particulate Matter Emitted from HD Engines: In-Plume, Windtunnel and
In-Laboratory Measurements
SCRDPF
Engine
Tpre-DPF
Ppre-DPF
Part ial-Flow System
Dry, Ambient
Temperature,
Compressed
HEPA Filtered Air
Supply
ECU Data
via J1939
Horiba OBS-2200
+
Horiba OBS-TRPM
Tpost-SCR
Pitot-tube
flowmeter
Ppost-SCR
TSI
EEPSMFC
TSI
EEPS
TEM Grid
Holder
Probe
FTIR
Analyzer
Adjustable
Probe Holder
Solenoid
Valves
Manifold
• Assess the likelihood of reproducing real-world PM size distributions collected from the
exhaust plume, by using two methodologies: CVS and Partial-Flow sampling
Differences in dilution rates occurring in dispersing plume => enhancement/suppression
of nucleation
• Compare PM development in real-world exhaust plume vs. full-scale windtunnel vs. full-flow
CVS vs. partial flow sampling
• Compare PM morphology and composition via TEM/EDX analysis of PM samples obtained
through plume and laboratory sampling
CAFEECenter for Alternative Fuels, Engines, and Emissions
Cambridge Particle Workshop
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• Provide spatial and temporal coverage of ambient air PM pollution measurement through a network of mobile low-cost sensors
• Monitor real-time tailpipe PM/PN emissions rates from heavy-duty vehicles
• Neural Network learning algorithms to be used as an advanced engine fault diagnosis and high emissions alert (Sensor Failure Detection and Accommodation) Monitoring real-time DPF filtration efficiency
AirCom Mobile
Sensor Platforms
Community Data
Usage and Interface
App
Mobile Application
Web-interface
Community Organizations
AirCom Data QA/QC, Processing and Storage
Sensor
Models
Pollutant
Gradient Map
Modeling
Stationary Air
Monitoring Data
CO2
CO NO2
O3
PM2.5
Concentration
Calculation
Drift
CorrectionQA/QC
OUTLOOK - Increase in special resolution of PM data via mobile, miniaturized measurement platforms
115ft
CAFEECenter for Alternative Fuels, Engines, and Emissions
Cambridge Particle Workshop
July 3rd, 2015
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33
THANK YOU FOR YOUR ATTENTION
Arvind Thiruvengadam - [email protected]
Marc C. Besch - [email protected]
Saroj Pradhan – [email protected]
Daniel K. Carder - [email protected]
Mridul Gautam - [email protected]
CAFEE Center for Alternative Fuels,
Engines and Emissions
ACKNOWLEDGEMENT
• ARB and SCAQMD for funding the study
• Don Chernich, Mark Burnitzki, Wayne Sobeiralski, Robert Ianni from ARB
Depot Park facility for their support and providing instrumentation
• Eon S. Lee, Yifang Zhu from UCLA for providing PM instrumentation