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

12

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

14

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%

17

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

19

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 

20

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

21

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

23

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– chris.sharp@swri.org

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