Evaluation and Demonstration of Ultra Evaluation and Demonstration of Ultra Low NOX Technologies for an On-
Highway Diesel EngineARB Low NOX Demonstration Stage 1ARB Low NOX Demonstration Stage 1
Christopher A. Sharp, SwRICynthia C. Webb, Low Emission Technology Solutions
Dr Cary Henry Gary Neely Jayant Sarlashkar Sankar Rengarajan SwRIDr. Cary Henry, Gary Neely, Jayant Sarlashkar, Sankar Rengarajan, SwRIDr. Seungju Yoon, California Air Resources Board
Vienna Motor SymposiumAdvance Science. Applied TechnologyApril 28, 2017
1
Program Objectives
• Development target is to demonstrate 90% reduction from current HD NOX standards
• 0 02 g/bhp-hr0.02 g/bhp hr• Aged parts
• Solution must be technically feasible for production
• Solution must be consistent with path toward • Solution must be consistent with path toward meeting future GHG standards
• CO2, CH4, N2O
• Diesel engine and CNG engine• This presentation focuses only on the Diesel engine• This presentation focuses only on the Diesel engine
2
Test Cycle Selection
P i C l f PU.S. Heavy Duty FTP
• Primary Cycles for Program• US HD FTP – primary focus
• WHTC – secondary focusy
• RMC-SET – required for GHG assessment
P i C l lib ti f• Primary Cycles are calibration focus
• CARB Idle
200100
Final NYBCx4 Cycletorque speed
Note: Normalized torque < 0 indicates closed‐throttle motoring
Example Vocational Cycle ‐ NYBC
• Additional Vocational Cycles• NYBC, ARB Creep, OCTA
L l d i (d )100
120
140
160
180
0
20
40
60
80
%
Normalize
d Torque
, %
• Lower load operation (drayage, etc.)
• Demonstration only (no additional calibration) 0
20
40
60
80
‐100
‐80
‐60
‐40
‐20
0 400 800 1200 1600 2000 2400
Normalize
d Spee
d,
Time, sec
3
,
Program Engine – 2014 Volvo MD13TC Euro VI• A diesel engine with cooled EGR, Tailpipe NOx g/hp hrA diesel engine with cooled EGR,
DPF and SCR• 361kw @ 1477 rpm
• 3050 Nm @ 1050 rpm
FTP RMCAverage 0.14 0.084SD 0.012 0.0093
Tailpipe NOx, g/hp‐hr
• 3050 Nm @ 1050 rpm
• Representative of OEM’s planned U.S. direction for future GHG t d d T t i
Engine‐out NOX ~ 3 g/hp‐hr
COV 8.5% 11%SD % Std 5.9% 4.6%
standards on Tractor engines• Incorporates waste heat recovery –
mechanical turbo-compound (TC)
No tailpipe NH3Tailpipe N2O ~ 0.05 g/hp‐hr
600
MD13TC Baseline 2017 GHG Standards
547
458
555
460
0
100
200
300
400
500
600
CO2, g/hp‐hr
4
0Vocational (FTP) Tractor (SET)
Program Engine - Challenges
400
450
500
2011 MD13 VGT 2014 MD13TC
250
300
350
400
empe
ratu
re, °
C
100
150
200
Exha
ust T
e
0
50
0 200 400 600 800 1000 1200
Time, sec
T b d i h 50°C l i l ld l• Turbocompound engine exhaust 50°C lower in early cold cycle• Mechanical turbocompound system allowed no method to bypass• MD13TC Platform was likely closer to a worst-case situation for ultra-low NOX
5
Diesel Engine Calibration Approach – Cold-Start
Increased Temperatures
• Modify existing engine calibration during cold-start warm-up• help AT light-off and reduce engine-out NOx until that time
Decreased EO NOX
• EGR modifications, multiple injections, intake throttling, elevated idle speed
• Release controls to baseline calibration after AT system light-off• maintain fuel economy and GHGy
• Minimal modifications during warmed-up operation6
Diesel Aftertreatment Technology Options
Traditional Approach Advanced Approach
Examined 33 out of 500 possible configurations of Examined 33 out of 500 possible configurations of component and heat addition options component and heat addition options
7
Catalyst Aging Approaches• Development Aged (hydrothermal only, oven p g ( y y,
aging permitted)• All parts for technology screening and development
P j d f FUL f A i R i b li i • Projected from FUL of Active Regeneration on baseline engine data
• Advanced Systems – 100 hours at 650°C
• Represented about 75% FUL compared to Final Aging protocol
• Final Aged (on engine)• For final demonstration – final down-selected parts only• For final demonstration – final down-selected parts only
• Protocol developed based on final Active Regeneration Frequency (which was 1.7%)
• Based on SwRI DAAAC protocol
• 1000-hour planned duration
• 100% of FUL hydrothermal exposure• 25% of FUL chemical exposure
8
FUL = Full Useful LifeDAAAC = Diesel Aftertreatment Accelerated Aging Cycles
Aftertreatment Screening Approach – Hot Gas Transient Reactor (HGTR®)
• HGTR® allows simulation of transient exhaust for • HGTR® allows simulation of transient exhaust for evaluation of full-size parts
• Rapid screening of different aftertreatment configurations
• Highly repeatable aftertreatment inlet conditions• closed loop control on Temperature, Flow, NOX,
water, O2
M difi ti f i l t diti t t t t ti l • Modification of inlet conditions to test potential engine scenarios
9
Screening Test Results for Diesel Aftertreatment System ConfigurationsAftertreatment System Configurations
Multiple potential pathwaysMultiple potential pathways to achieveto achieve NONOXX emissions belowemissions below
10
Multiple potential pathways Multiple potential pathways to achieve to achieve NONOXX emissions below emissions below 0.02 g/bhp0.02 g/bhp‐‐hrhr
Technology Screening Results – NOXPotential and GHG Impactp
Advanced Approaches can reach lower NOAdvanced Approaches can reach lower NOXX at a given GHGat a given GHG
11
Advanced Approaches can reach lower NOAdvanced Approaches can reach lower NOXX at a given GHG at a given GHG impact (depending on impact on Regeneration)impact (depending on impact on Regeneration)
On-Engine Evaluation of Final Technologies
1
Additional
• 0.025 to 0.030 g/hp‐hr with 2kw EHC (HD1)• 0.022 to 0.025 g/hp‐hr with 6kw EHC
• 0.022 to 0.025 g/hp‐hr with 3” zeolite LO‐SCR and 3.5kW HD1Exhaust from
Manifold
2
4PN
A
SC
R
AS
CSCRF
DEF
+V
LO-
SC
R
NH3
• 0.022 to 0.025 g/hp‐hr with 1kw HD2 and 3” zeolite LO‐SCR
• (note evaluation with gaseous NH3 at LO‐SCR in and DEF/HD1 at SCRF in
• 0 012 /h h ith 10k i i b3
• Not evaluated due to insufficient heat potential for 0 02 or below
• 0.012 g/hp‐hr with 10kw mini‐burner
Selected for the final demonstration
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potential for 0.02 or below
Final ARB Low NOX Configuration
• All catalysts are coated on 13” diameter substrates• SCRF is 13” X 12” on high porosity filter substrate• Remaining catalysts are 13” X 6” on “thin wall low thermal mass • Remaining catalysts are 13 X 6 on thin wall, low thermal mass
substrates”• All sensors shown are production-type
/NOX Levels with Development Aged Parts, g/hp‐hr
Cold‐FTP Hot‐FTP Composite RMC‐SET
Engine‐Out 2.8 3.0 3.0 2.1
il i
13
Tailpipe 0.06 0.008 0.016 0.015
Model-Based SCR Controller with Mid-Bed NH3
Sensor Feedback TIn TIn
SCR Model CellThermal
SCR Model CellThermal TIn
SCR Model CellThermal TIn
ṁexh
NOX
NO2/NOX
NH3
ṁexh
NOX
NO2/NOX
NH3
Thermal Model
Kinetic Model
Twall
Thermal Model
Kinetic Model
Twall
ṁexh
NOX
NO2/NOX
NH3
Thermal Model
Kinetic Model
Twall
ṁexh
NOX
NO2/NOX
NH3
θ1 θ2 θ3
• Separate coverage observer models for SCR and SCRF• Primary calibration parameters are controller gains and coverage targets
• Same calibration used for FTP RMC SET CARB Idle vocational cycles• Same calibration used for FTP, RMC-SET, CARB Idle, vocational cycles• Slightly modified coverage targets for WHTC
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Final Aging Protocol 2009 Cummins ISX 625 2009 Cummins ISX
mule engine (DAAAC modified) 4-hour duration525
550575600625
] tion
Mod
e
30 g/hr Soot RateExhaust Flow = 975 kg/hr
Ope
ratio
n /
oval M
ode
4 hour duration Regeneration is via
in-exhaust injection upstream of PNA400
425450475500
Tempe
rature [°C]
Activ
e Re
gene
rat
Mod
e
ssive Oxidatio
n /
Ash Ac
cumulation
High
Temp
HC‐Rem
o
upstream of PNA Final duration was
847 hours 100% FUL thermal 275
300325350375400
SCRF
Inlet Te
PaSoot & A
Low Temperature Soot & Ash 100% FUL thermal exposure
23% FUL chemical exposure200
225250275
0 1000 2000 3000 4000 5000 6000 7000 8000 9000
Ti [ ]
Low Temperature Soot & AshAccumulation Mode
• This is based on regeneration frequency of ~ 1.7% (near x2 from base engine)• resulted in 194 hours of regeneration for FUL thermal equivalent
Time [s]
• this is more than 300 Active Regeneration events
15
Final Aging - Issues• Early PNA face coking – resolved by adjusting cycle but resulted in large HC buildup
h h d b b k d ffthat had to be baked off• Regeneration process had to be adjusted to insure complete soot cleaning – some
early localized exotherms possible
PNA C i f il t 710 h PNA t f il d• PNA Canning failure at 710 hours – PNA mat failed• Large buildup of HC and soot on PNA – had to be recovered
• Ingestion of mat into SCRF (mal-distribution and local exotherms ?) – had to be mechanically removed without disturbing deep ash
PNA SCRF Inlet SCRF ChannelsAbnormal M t/A h
N l
Mat/Ash
Normal Ash Load
16
Final Tailpipe NOX Results0.20
0.71
0.14
0
4 0.11
5
0.11
0.120.140.160.18
g/hp
‐hr
0.04
7
0.08
4
0.03
5 08 10
0.06
08 .016
.015
.019
021 0.03
4
0.03
8
0.03
6
0 040.060.080.10
Tailpipe NO X,
Baseline
Degreened
Devel‐Aged0
0.00
5
0.00
0.010.0 0 0 0.0.0
0.000.020.04T g
Final‐Aged
Aftertreatment NOX Conversion Efficiency, %Aftertreatment NOX Conversion Efficiency, %
Test ConfigFTP Transient
RMC‐SET WHTCCold Hot Composite
Devel Aged 98% 99.7% 99.5% 99.3% 99.4%
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Final Aged 96% 99.3% 98.8% 98.2% 98.8%
Cold-FTP Final Aged versus Development AgedPNA Performance
300
350
3.0
4.0
Devel Aged‐Final Controls Final Aged Inlet Temp
SCRF Light‐Off
Full SCR Conversion 0‐200 secs, % Full Cycle,
NOX reduction across system components
200
250
1.0
2.0
Temp, degC
d NOx, grams
NOX conv % NOX conv
Devel Aged
Final Aged
Devel Aged
Final Aged
PNA 44% 27% 10% 5%
50
100
150
‐1.0
0.0 PNA Inlet
PNA Stored PNA 44% 27% ‐10% ‐5%
SCRF 64% 28% 90% 84%
SCR‐SCR/ASC
10% 13% 80% 80%
0
50
‐2.00 100 200 300 400 500 600 700
Time, sec
SCR/ASC
• Cold‐start performance change is primarily due to loss of NOX storage capacity on PNA• more NOX reaches SCRF before it reaches light‐off temperature,
18
downstream SCR still too cold to help
Hot-FTP Final Aged versus Development AgedSCRF Performance
300
350
400
Devel Aged‐Final Controls Final Aged
Final Controls = 90%, 0.30 g/hp‐hrFinal Aged = 87%, 0.40 g/hp‐hr
35 0
40.0
45.0
50.0
Devel Aged Final Controls Final Aged
Final Controls = 99.7%, 0.009 g/hp‐hrFinal Aged = 99.3%, 0.020 g/hp‐hr
TailpipeSCRF‐Out
150
200
250
SCRF
‐Out NOx, g/hr
15 0
20.0
25.0
30.0
35.0
Tailpipe NOx, g/hr
0
50
100
0 200 400 600 800 1000 12000.0
5.0
10.0
15.0
0 200 400 600 800 1000 1200
• Hot-start performance change appears to be due primarily to change in SCRF performance
• lower NH storage capacity
Time, sec Time, sec
• lower NH3 storage capacity• higher tendency towards ammonia oxidation
• Early cycle tailpipe performance still maintained but later there is more NH release to downstream catalystmore NH3 release to downstream catalyst
• small increase in late cycle NO generation due to larger amount of NH3 to be oxidized
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Final GHG ResultsCycle Measured CO2 and N2O Emissionsy 2 2
Overall CO2 / Fuel Consumption Impact • WHTC very similar to FTP• Slight increase for Final Aged (about
0.3%) due to backpressure and slightly higher MB fueling to reach temperature thresholds
• CO2 impact on FTP driven by low temperat res from t rbocompo ndtemperatures from turbocompound
• different GHG approach would require less thermal management
• Impact could be reduced via better
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ppackaging and integration
Example Vocational Cycle – NYBCx4 – Final Aged Parts
1000
2000
1000
1200
Spee
d
EO NOx TP NOx DOC In T DPF Out T Aftertreatment Out T Speed
1000
2000
800
900
1000
Spee
d, rp
m
C
EO NOx TP NOx PNA In T SCRF In T SCR In T Speed
‐2000
‐1000
0
400
600
800
r‐Temp, degC
‐2000
‐1000
0
400
500
600
700
Ox, g/h ‐o
r‐Temp, degC
‐4000
‐3000
000
0
200
400
0 500 1000 1500 2000 2500 3000 3500 4000
NOx, g/hr ‐or
‐4000
‐3000
000
0
100
200
300
0 500 1000 1500 2000 2500 3000 3500 4000
NO
EO, g/hp‐
TP, g/hp‐ NOx Conversion,
%Fuel Rate, kg/hr
Baseline Engine Ultra‐Low NOX Engine• Duty cycle is average 6% of
maximum engine power (not
Time, sec Time, sec
hr hr % kg/hr
Baseline 6.1 2.3 62 % 5.3
ULN Engine 3.9 0.38 90% 5.3
maximum engine power (not including idle segment)• test cycle starts after the idle• precondition before idle with
% Change ‐35% ‐84% n/a None
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psame cycle
Summary (1)• Multiple technology approaches to reach ultra low • Multiple technology approaches to reach ultra-low
NOX levels• appropriate choice depends on engine and GHG approach
• Final system was able to achieve 98.8% conversion efficiency on composite FTP / WTHC fully agedy p y g
• this is despite Final aging AT failure issues and a very difficult low temperature test engine
• For this turbocompound engine, 0.02 g/hp-hr was very challenging
• Development aged parts < 0.02 g/hp-hrp g p g p• Final aged parts > 0.02 g/hp-hr• system complexity and GHG impact higher due to very low
temperaturestemperatures
22
Summary (2)
• Questions still open regarding durability• Final aging issues make it difficult to assess system
degradationdegradation
• NOX performance gap between regulatory and vocational cycles is smaller with ULN engine than baseline engine
• this is driven to some degree by calibration approachg y pp
• Significant potential for low NOX levels on vocational d fi ld land field cycles
• BUT more work needs to be done to examine potential NOX reduction and GHG impact
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Next Steps• Stage 1b – Aging and Testing of another set of Stage 1 parts Stage 1b Aging and Testing of another set of Stage 1 parts
(planned)• answer durability questions with an undisturbed aging process
• provide more representative parts for Stage 2 provide more representative parts for Stage 2
• Stage 2 – Low Load NOX Control using Stage 1 engine (In Progress)
• Develop Low Load duty cycle profiles from vehicle data
• Develop low load calibrations/approaches for the Stage 1 engine
• Examine different “load” metrics for low load cyclesyo torque, fueling, CO2, mass-over-time
• Stage 3 – Low NOX Development and Demonstration on a non-turbocompound engine (Planned)turbocompound engine (Planned)
• Engine platform more representative of mainstream approach to GHG regulations
C bi i f b h l d l l d l• Combination of both regulatory and low-load cycles
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Acknowledgements
• California Air Resources Board• Program PartnersProgram Partners
• Volvo• Manufacturers of Emission Controls
A (MECA)Association (MECA)• MECA member companies who have provided emission control hardware
• Program Advisory Group membersg y p
25
More Information
California ARB website– http://www.arb.ca.gov/research/veh-
i i /l /l hemissions/low-nox/low-nox.htm
S RI C t tSwRI Contact– Christopher Sharp
+1 210 522 2661– +1 210-522-2661– [email protected]
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