Christopher Sharp, Ian Smith Southwest Research Institute

SOUTHWEST RESEARCH INSTITUTE®

POWERTRAIN ENGINEERING

C>SOUTHWEST RESEARCH INSTITUTE swri.org

Evaluating Technologies and Methods to Lower Nitrogen Oxide Emissions from Heavy-Duty Vehicles

Christopher Sharp, Ian Smith Southwest Research Institute

1



Agenda

• Introduction • General Program Details

• CNG Program • Diesel Program

• Question and Answer

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Motivation • Ozone nonattainment areas across the United States

continue to grow – Growth in population – Continued tightening of ozone standard

• 2015 EPA rulemaking changed NAAQS for ozone to 70 ppb

• CARB Inventory shows on-road heavy-duty trucks are ~20% of all NOX emissions

• California requires more reduction in NOX emissions to meet the current NAAQS for ozone and PM

– The current 0.20 g/bhp-hr NOX standard isn’t enough 3



CARB Low NOX Programs at SwRI • Stage 1 – EvaluatingTechnologies and Methods to Lower Nitrogen Oxide

Emissions from Heavy-Duty Vehicles (2014-2017)

– CNG and Diesel – Initial Technology Evaluation – Primary focus on Regulatory Cycles – Focus of today’s presentation...

• Stage 2 – Heavy-Duty Low Load Emission Control (2017-2018)

– Diesel – Expand previous technology evaluation to low-load and urban

operating cycles

• Stage 3 – Further Evaluation and Development of Low NOX Technologies on 2017 (non-Turbocompound) Engine Platform (2017-2018)

– Diesel – Focus on both Low Load (Real world) and Regulatory cycles

4



Program Objectives (Stage 1) • Development target is to demonstrate 90%

reduction from current HD NOX standards – 0.02 g/bhp-hr – Aged parts

• Solution must be technically feasible for production

• Solution must be consistent with path toward meeting future GHG standards

– CO2, CH4, N2O

• Diesel engine and CNG engine

5


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NYNF IANF IAFY NYNF

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Time, s


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120

140

160

180

200

100

80

60

40

20

Test Cycle Selection U.S. Heavy Duty FTP

• Primary Cycles for Program

– US HD FTP – primary focus – WHTC – secondary focus – RMC-SET – required for GHG

assessment – Primary Cycles are calibration focus – CARB Idle

Final NYBCx4 Cycle Note: Normalized torque < 0 indicates closed-throttle motoring torque speed

Example Vocational Cycle - NYBC

• Additional Vocational Cycles

– NYBC, ARB Creep, OCTA

Nor

mal

ized

Torq

ue, %

100

80

60

40

20

0

-

0

20

40

60

80

100

Nor

mal

ized

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d, %

-– Lower load operation (drayage, etc.) -– Demonstration only (no additional -

-0 400 800 1200 1600 2000 2400calibration)

Time, sec

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140

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20

120

140

160

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100

80

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40

20

80

60

40

20

Vocational (Low Load) Cycles Final NYBCx4 Cycle Final Cruise + Creep x 10 Cycle Note: Normalized torque < 0 Note: Normalized torque < 0

indicates closed-throttle motoring indicates closed-throttle motoring torque speed torque speed

100 100

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- 0 - 0 0 400 800 1200 1600 2000 2400 0 400 800 1200 1600 2000 2400 2800 3200

Time, sec

Final OCTA Cycle Note: Normalized torque < 0 indicates closed-throttle motoring torque speed

100

80

60

40

20

0

Time, sec

• NYBC Cycle – Prep cycle + 30min idle + Test Cycle – 6% average power on duty cycle

• Cruise Creep Cycle – Engine Warm up + Test Cycle

100

- 80 – “Cruise” mode is preconditioning – “Creep” mode is 3% average power

• OCTA Cycle - 60

- 40

- 20

- 0 – Prep cycle + Test Cycle (no dwell) 0 400 800 1200 1600 2000

Time, sec – 15% average power

7




Evaluating Technologies and Methods to Lower Nitrogen Oxide Emissions from Heavy-Duty Vehicles:

Natural Gas Engine

Ian Smith,Thomas Briggs and Christopher Sharp Southwest Research Institute

8



NOX Emission Goals: Reduction and Efficiency Two main goals: • Achieve 0.02 g/bhp-hr NOX emissions over the U.S. Heavy-Duty FTP, RMC-

SET and the European WHTC • Minimize the impact to GHG emissions

– Provide the pathway towards meeting Phase 2 GHG standards 0.2

0.18 0.16 0.14 0.12

0.1 0.08 0.06 0.04 0.02

0

CO2 Emissions (g/bhp-hr) Secondary objectives: • Observe the emissions over the CARB extended idle test as well as

3 low-load vocational cycles

NO

X Em

issi

ons

(g/b

hp-h

r)

500 515 530 545 560 575

9

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Test Engine

2014 model year Cummins ISX12-G engine certified to 2010 U.S. Heavy-Duty emissions standards

• 238 kW @ 1800 RPM // 1559 Nm @ 1200 RPM • High-pressure loop, cooled EGR • Stoichiometric – single-point, upstream fueling • Three-way catalyst • Bus application

10

--Cold Sta rt NOx --Hot Start NOx --Speed

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u e 800 QJ 1-""0 600 QJ co

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Time (sec)


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Baseline Emissions: Certification Cycles Looking at the emissions gives insight into areas of improvement

• Cold-start NOX • RMC-SET emissions – NH3 emissions – Catalyst light-off – Slightly rich AFR – Open-loop fueling set-point

• Hot-start NOX emissions – AFR control

Pollutant FTP RMC-SET WHTC NOX, g/bhp-hr 0.115 0.012 0.308 NH3, avg. ppm 75 160 88 CO2, g/bhp-hr 541.8 453.8 505.1

11

NOxg/hr - N0>1 Ave to 1800s. - NH3ppm - C.-.tBcddcgC - Speed RPM

1200 135

"[ CARB Extended Idle 120 1000 ~

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Time !sec)


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Baseline Emissions: Low Load Cycles

The engine was tested over low load cycles to examine performance off-cycle

• Low load vocational cycles representative of the engine’s use in a bus application – CARB Extended Idle – OCTA – NYBC – Cruise-Creep

Tailpipe, g/hp-hr ppm NOX PM NMHC CO CO2 CH4 NH3

NYBC 0.907 0.0009 0.190 1.580 672.4 1.893 11.7 Cruise-Creep 0.070 0.0038 0.157 2.774 612.3 1.596 124.4 OCTA 0.112 0.0024 0.107 2.350 552.8 1.078 91.9

12

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Base

line

Engi

ne

Engine Hardware Improvements

The baseline engine was upgraded with new hardware and engine control unit/calibration to achieve the 0.02 g/bhp-hr NOX emission target

ingle Underfloor TWC (22.4 L)

Close-coupled TWC (9 L) & Underfloor TWC

(20 L)

k CM2180A ECMAftermarket EControls ECU

o CCV System Full CCV System

• Lower PM and gaseous emissions

• Lower oil consumption

Low

NO

X D

emon

stra

tion

Engi

ne

Motivation for CCV System 2012 ISLG FTP NOX

Blowby Emissions (g/bhp-hr)

Cold Start 0.044

Hot Start 0.008

Composite 0.013

13

Air Intake


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Circuit


swri.org

Engine Hardware Improvements

Additional hardware was added to increase the EGR tolerance and transient performance of the engine

• EGR Tolerance – Baseline: Capacitive discharge

ignition coil system – Demonstration: Improved fuel-air-EGR

mixer and higher energy DC ignition coil system

• Additional Improvements – Continuous flow valve (CFV) for fueling – Electronically controlled wastegate – Boost recirculation valve

To Intake Manifold

14

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--Speed --Load

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0 0 200 400 600 800 1000 1200

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Closed Loop Fueling Large focus on keeping the engine within closed loop fueling

itching O2 sensor UEGO Sensor

Base

line

Engi

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Low

NO

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Rev. 2

Closed Loop Timing

Rev 1 Baseline

• Pre- & post- • UEGO sensor located catalyst just downstream of switching O2 turbocharger sensors

• Transport and feedback delay minimized • Accurate measurements of fuel supply,

intake and exhaust volume required

15

Cold - CC Cata lyst

·· ·· · ·· Hot - UF Catalyst 800

700 u :;- 600 (II

~ 500 ~

~ 400 E

: 300

! 200 "' u 100

0

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· · · · ·· · Cold - UF Catalyst

--Baseli ne

100 150 Time (sec}

200

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250 300

- Catalyst Heating Strategy - No Catalyst Heating Strategy 9

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--

Cold Start Improvements

• Catalyst heating strategy – Ignition timing retard after

TDC (up to 15° aTDC) – Slight enrichment – EGR use disabled for first 30

seconds

• Emissions difference – 4x decrease in NOX emissions

with catalyst heating – Slight performance detriment

during ignition timing retard – Once catalyst is up to

temperature, near-zero NOX emissions

16

12%

9"

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~ .¥

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--VECorre ction --Speed --Load

400 600

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400 600

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800 1000


swri.org

Engine Calibration Improvements – Volumetric Efficiency Correction• Volumetric efficiency (VE) correction is used to correct for cylinder wall and

manifold temperature for more accurate transient fueling • Third party ECU adaptive table worked well during hot operation

– Cold operation had incorrect adjustments and took too long to update

• Added long time constant VE correction based on – Engine speed & load history – Coolant temperature

• Long time constant VE correction allows for larger corrections when engine is cold

Cold start FTP Hot start FTP

17

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--Demonstration Cold Start --Demonstration Hot Start --- - Baseline Cold Start

---- Baseline Hot Start --Speed

6

4

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0

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2000

1500

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1000 1200

500

400

300

200

100

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--Demonstration Ammonia --Baseline Ammonia --Speed

~-------------------------------~ 2500

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+------r------..-----------'----------ti---+ 1500

+---t--------------------------~t---+ 1000 E +----------------------------------+ 500 _g:

-0 QJ QJ C. V,

QJ C ·.,, C w

2400 2800 3200 3600

Time(sec)

4000 4400 4800



Improved Calibration & Hardware Results: FTP & RMC-SET

• Demonstration cold start emissions equivalent to baseline hot start

• Near zero NOx emissions over the RMC-SET

• Significantly lower NH3 emissions

18

1.2 .------------Low Control Temp+ 90 deg C

~ 0.8

.. i 0.6

2' UJ 04

- EC lambda

- 2ndAir - CatBed

Low Control Temp

0.2

0 -----,.----.----------~-.-------+ 0 10 20 30 40 50 60

Time seconds



CNG Catalyst Final Aging Field Cycle - OCTA Standard Bench Cycle

Exhaust T degC CC TC1 bed degC CC TC2 bed degC CC TC3 (rear gas) degC

CC TC4 (front gas) degC UF TC5 (rear gas) degC UF TC6 bed degC Aftertreatment Out T degC (Accelerated Aging) 650

965°C 600

550

Average ~ 550°C – 600°C

1900 2100 2300 2500 2700 2900 3100 3300 3500 3700 3900

500

875°C 450

400

Cycle is 13 miles of driving FUL = 137 hours FUL = 435,000 miles

FUL = Full Useful Life

• OCTA bus cycle used for field duty cycle • Standard Bench Cycle for 3-way catalyst aging

– Low Control Temp = 875°C – Exotherm peak (LCT + 90°C) = 965°C – This results in “reference” temperature = 900°C based on an actual cycle run

• 137 hours on SBC = 435,000 miles (includes factor of 1.2 for oil poisoning) – Performed using natural gas fired FOCAS® burner stand

19



CARB Demonstration

Testing performed over the span of a couple weeks • US certification cycles

– 5 repeats of cold + 3 hot FTP & RMC-SET – CARB extended idle (optional certification cycle)

• Non-US certification cycles – 3 repeats of cold + 3 hot WHTCs

• Low load vocational – 3 repeats of NYBC, OCTA, and Cruise-Creep

• Testing performed in compliance with 40 CFR 1065 • Raw and dilute emissions measurements to verify low emissions levels

– Both raw and dilute measurements required two different gas calibration ranges for cold and hot start

» Ex. 250 ppm NOX range for cold-start and 25 ppm NOX range for hot-start

20

0.1 '-..c

I

a. ::E 0.08 ......... 0.0 Vl'

§ 0.06 Vl Vl

E LU 0.04

X

0 z

0.02

0

■ Day 1 ■ Day 2 ■ Day 3 ■ Day 4 ■ Day 5

Co ld Hot 1 Hot 2 Hot 3 Composite RMC-SET



NOX Emissions: FTP, RMC-SET & WHTC

Certification cycles were the primary focus for calibration efforts

NOX Emissions Comparison, g/bhp-hr FTP

RMC-SET WHTC

Cold Hot Composite Cold Hot Composite Baseline 0.247 0.093 0.115 0.012 0.310 0.308 0.308

Low NOX Engine 0.065 0.001 0.010 0.001 0.043 0.006 0.011 Reduction 74% 99% 91% 92% 86% 98% 96%

21


■ 2014 CO2 Std. ■ 2017 CO2 Standard ■ CO2 ■ CO2+ 25xCH4 >.l

700

650

600

~ 550 c.. .s:: .-e_ 500 ~ ON 450 u

400

350

300

1

0.9

0.8

0.7

Vocational (FTP) Tractor (SET)

■ CH4 Std ■ CH4

0.92

~ 0.6 +----------------------, a. ~ 0.5

'tio 0.4 +----------------------,

a" 0.3

0.2

0.1

0



swri.org

Other Emissions: FTP, RMC-SET & WHTC

GHG emissions and ammonia were of interest

Other Emissions Comparison Pollutant FTP RMC-SET WHTC

Baseline CH4, g/bhp-hr 0.96 1.20 1.54 NH3, avg. ppm 76 162 100 CO2, g/bhp-hr 542 454 510 CH4, g/bhp-hr 0.15 0.92 0.10

Low NOX Engine NH3, avg. ppm 52 37 44 CO2, g/bhp-hr 547 445 513 CH4, g/bhp-hr 84% 23% 94%

Reduction NH3, avg. ppm 32% 77% 56% CO2, g/bhp-hr -0.9% 2.0% -0.6%

22

tio ox z (1/ :,, ·;:

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4

3

2

1

0

--Demonstration NOx --Baseline NOx --Speed

2000

lSOO

1000 E a.

>------------------------+ 500 ~

" (1/ (1/

a. II\ (1/ C:

·a:o C:

UJ

1910 2410 2~10 Time {sec)

3410

tio ox z (1/ :,, ·;:

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--Demonstration NOx --Baseli ne NOx --Speed

2000

1500

1000 E a.

500 ~

" (1/

20

15

10

5

0

~

~ __.,.-r-

~

0 (1/

a. II\ (1/ C:

·a:o C:

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4200 4700 5200 5700 6200 Time (sec)


swri.org

Low LoadVocational Cycles

Near zero NOX emissions with no GHG/fuel penalty over low load cycles

OCTA Tailpipe Emissions, g/bhp-hr

NYBC Tailpipe Emissions, g/bhp-hr

NOX CO2 CH4 NOX CO2 CH4

Baseline 0.112 552.8 1.078 0.907 672.4 1.893 Low NOX Engine 0.000 552.3 0.039 0.002 667.1 0.421

Reduction 99.7% 0% 96% 99.8% 1% 78%

OCTA NYBC

23

:§ 0 z QI

-~ "' :i E E ::;i u

--Demonstrat ion NOx --Baseli ne NOx --Speed

2000

1500

1000 E i-----------------------1- 500 ~

4

3

2

1

0 1910 2410 2910

Time {sec) 3410

0

"O QI QI a.

V'I QI C: ·;;;, C:

uJ


800

E 1:l: 600

£ z 400

200

0

1910

--Demonstra tion NH3 --Baseline NH3 --Speed

2410 2910 Time {sec)

3410

2000

1500

1000 -E

500 e-"O QI QI a.

V'I QI C:

·;;;, C:

uJ


swri.org

OCTA Demonstration Results Much improved air-fuel ratio control during heavily transient operation

• OCTA – Zero tailpipe NOX emissions – Significantly reduced methane and

NMHC emissions – No impact to CO2

OCTA Tailpipe Emissions, g/bhp-hr ppm NOX PM NMHC CO CO2 CH4 NH3

Baseline 0.112 0.0024 0.107 2.350 552.8 1.078 91.9 Low NOX Engine 0.000 0.0010 0.000 1.256 552.3 0.039 47.3

Reduction 99.7% 60% 100% 47% 0% 96% 49%

24

--NOxg/hr --Speed --cccatalyst --UFCatalyst

--------------------- 1200

... .i::.

~ 1

0 0.8 z 0.6

0.4

0.2

0

1200 2000 2800 3600 Time (sec)

4400

""O C:

"' 1000 u

800

400

200

QI)

!E ., Cl. ...... ::, -~ -g ., ., Cl. Cl. E Vl

~ -~ ""O QI) ., C: a, u.o .... "' > "iii ;. u

--Demonstration NH3 ppm --Baseline NH3 ppm --Speed

400 E Cl.

.!:: 300 £ z

200

100

0 1200 2000 2800 3600 4400

Time (sec)

1200

900

600 E 300 e-0

""O ., ., Cl. V, ., C: '00 C: u.o



swri.org

Low Load CARB Extended Idle

• CARB Extended Idle – Catalyst temperature stays above

400°C – Zero NOX emissions – Decreased NH3 for elevated idle

compared to baseline » Operating closer to

stoichiometric » NH3 emissions trending down

over time

25

.... ..,

I I

I I

I II

.... ~ ..., ..c--- •



Conclusions This engine and calibration met the 0.02 g/bhp-hr NOX emission target with Full Useful Life aged catalysts

0.2 0.18 0.16 • Required: 0.14

– Close-coupled and underfloor TWC 0.12 0.1

– Rapid catalyst heating strategy 0.08 0.06

– Improved AFR control 0.04

– Improved EGR tolerance 0.02 0

500 515 530 545 560 575

2014 CO2 2010 NOX

2027 CO2 90% lower NOX

» New hardware CO2 Emissions (g/bhp-hr)

NO

X Em

issi

ons (

g/bh

p-hr

)

NOX Emissions Comparison, g/bhp-hr FTP

RMC-SET WHTC

Cold Hot Composite Cold Hot Composite Baseline 0.247 0.093 0.115 0.012 0.310 0.308 0.308

Low NOX Engine 0.065 0.001 0.010 0.001 0.043 0.006 0.011 Reduction 74% 99% 91% 92% 86% 98% 96%

26

California Environmental Protection Agency

9 Air Resources Board

EControls. by El{OVATION CONTROLS



Natural Gas Engine Acknowledgements

James Chiu

California Air Resources Board

EControls

27




Evaluating Technologies and Methods to Lower Nitrogen Oxide Emissions from

Heavy-Duty Vehicles: Diesel Engine

Christopher A. Sharp, SwRI Cynthia C.Webb, Low Emission Technology Solutions

Dr. Cary Henry, Gary Neely, Jayant Sarlashkar, Sankar Rengarajan, SwRI Dr. SeungjuYoon, California Air Resources Board

CARB Research Seminar June 15, 2017

31

0.80 0.71

0.70

0.60 ~

.c c. 0.50 .c

■ Day l --~0.40 ■ Day2 ><

~ 0.30 ■ Day3 "' 0 .14 a,

0.20 0 .047 0.084 • •

0.10

0.00 Cold Ho t Composite RMC-SET



Program Engine – 2014 Volvo MD13TC EuroVI • A diesel engine with cooled EGR,

DPF and SCR – 361kw @ 1477 rpm – 3050 Nm @ 1050 rpm

• Representative of OEM’s planned

Tailpipe NOx, g/hp-hr FTP RMC

Average 0.14 0.084 SD 0.012 0.0093 COV 8.5% 11% SD % Std 5.9% 4.6%

U.S. direction for future GHG Engine-out NOX ~ 3 g/hp-hr standards on Tractor engines No tailpipe NH3

• Incorporates waste heat recovery – Tailpipe N2O ~ 0.05 g/hp-hr mechanical turbo-compound (TC)

CO2,

g/h

p-hr

MD13TC Baseline 2017 GHG Standards

600

500

400

300

200

100

0

547

458

555

460


32

Program Engine - Challenges 2011 MD13 VGT 2014 MD13TC

Exha

ust T

empe

ratu

re, °

C

500

450

400

350

300

250

200

150

100

50

0 0 200 400 600 800 1000 1200

Time, sec

• 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



33

200 I-

New Calibration

Baseline Calibration

0 -t----.------.------1------.----~-----l

0 200 400 600 800 1000 1200


Lower NOx t han baseline w hen AT is

1 1600

1400

~ 1200 ~

cold Different base engine c_a_l _ __,

" 1000 0 2 800 J!l ..2 600 i5

400

200

0 .m•~~~±~ 0 200 400 600 800 1000 1200

90 ~ ----------1-------------80 4---

70 :§ 60

" 0 so -t--------1'-- +-----.,,.,.------_j 2 E 40 a 30 t-------+ --+:..~ 'F------==-- New

20 Calibration 10

0 0 200 400 600 800 1000 1200


swri.org

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 – EGR modifications, multiple injections, intake throttling, elevated idle speed

• Release controls to baseline calibration after AT system light-off – Maintain fuel economy and GHG

• Minimal modifications during warmed-up operation

Decreased EO NOX

34

•Burner •EHC

•DEF

•NH3 injection •Heated Dosing

Heat Addition Options

Component Options

•Burner

•E HC

•Fuel Dosing

•DOC

•PNA

•Compact M ixing

•NH3 injection •Heated Dosing

•SCR

•ASC

•Blank

Examined 33 out of 500 possible configurations of component and heat addition options



Diesel Aftertreatment Technology Options

Traditional Approach Advanced Approach

Examined 33 out of 500 possible configurations of component and heat addition options

35



Catalyst Aging Approaches • Development Aged (hydrothermal only, oven

aging permitted) – All parts for technology screening and development – 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 – 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

FUL = Full Useful Life DAAAC = Diesel Aftertreatment Accelerated Aging Cycles

36

Cold Collbrarlon Low T~mp,:1011111: Enabl~t O. H T

... ~ ( ,..

ce: o.u 1111 ,i ~ 0.1 &I

15 Q.

l§ o.oa

Acronym

DOC

SatT-

0 DEf Only Heated D0s1n1

H3

1111plemcntal Cnrrgy

• ' fflf ..,.,.,.,

•

• Burner EHC

rac:11 ion I App 0&c:hos

• •

0

H I I I

Multiple potential pathways to achieve NOx emissions below 0.02 g/bhp-hr



ScreeningTest Results for Diesel Aftertreatment System Configurations

37

Multiple potential pathways to achieve NOX emissions below 0.02 g/bhp-hr

0.16

~ 0.14 ,', C.

~ 0.12 1>Q

~ 0.1 z -~ 0.08 Ill 0 C. E 0.06 0 u

"ia 0.04 <J C GI 0 0.02 C.

0

--. --

--

-

-"" u B <I)

' u <I)

<C

-----0:

~ + 0: u <I)

+ u.. w 0 + u.. n. 0 + u 0 0

Traditional Approach

--" "••• . --

------

0 0

rl -"" u u u 0

-"" ti, u 0

~ ti, ~ u 0: <I) u <C "'

-----+ 0: 0:

~ u <I) + + 0:

u u.. w <I) 0 + + u.. u.. w n. 0 0 + + u..

n. u 0 0 + 0 u + 0 a:, 0 ~

-·o. ___ o

···-

rl u u

~ ~ 0: u <I)

+ 0: u "' + u.. w 0 + u.. n. 0 + u 0 0 + a:,

~

u <I)

<C

~ + 0:

~ + rl 0 I + u.. n. 0

0 0 0

·· ...

-

·-o

~ ~ 0:

l7: + 5 <I)

+ u.. w 0 + u.. n. 0 + u 0 0 + a:,

~

ci

~ 1 u.. 0: u <I)

+ 0: u "' + rl 0

l u.. n. 0 + u 0 0 + 0: u <I)

g +

((')

I z

Potent ial Composite NOX

:

0

u <I)

~

~ + rl 0 I + u I w + u.. n. 0 + u 0 0

Advanced Technology Approacn

n • (J_

u ------v

~ <C

~ + u.. 0: u <I)

+

~ + u.. w 0 + u 0 0 + a:,

~

~ ~ 0: u <I)

+ u.. 0: u "' + u.. w 0 + u 0 0 + a:,

~

0

n- -----8 __

u <I)

~ 0:

l7: + 5 <I)

+ u..

~ + rl 0 I + u 0 0

u <I)

~

~ + u.. 0: u <I)

+ u.. w 0 + <C z n.

---

u

~ ~

~ + u.. 0:

~ + u.. w 0 + ((')

I z + <C z n.

······

0

u <I)

~

~ + u.. 0:

~ + rl 0 I + <C z n.

-----

0

v -

u <I)

<C

~ + u.. 0: u <I)

+ rl 0 I + N <C z n.

-· O Potent ial Composite Fuel Penalty

0

-u <I)

~

~ + u.. 0:

~ + .-i 0 I + <C z n.

Alterna te Approaches

_n 0

0 -------o

~ ~ 0: u <I)

+ u.. 0:

~ + rl 0 I + <C it +

~ 0 ...J + ((')

I z

u <I)

<C

~ + u.. 0: u <I)

+ u.. w 0 + a:,

~ + <C z n.

2.0% ~

i "ia

1.5% C GI C.

"ii ::,

u.. GI ~

1.0% Ill 0 C. E 0 u

0.5% ] C GI

0 C.

0.0%

Advanced Approaches can reach lower NOx at a given GHG • act (depending on impact on Rege



Technology Screening Results – NOX Potential and GHG Impact

38

Advanced Approaches can reach lower NOX at a given GHG impact (depending on impact on Regeneration)

cc z A.


ct: z Q.

W SCRF

ICIP Ill: u Cl)


swri.org

On-Engine Evaluation of FinalTechnologies

1

Additional

• 0.025 to 0.030 g/hp-hr with 2kw EHC (HD1) • 0.022 to 0.025 g/hp-hr with 3” zeolite LO-SCR • 0.022 to 0.025 g/hp-hr with 6kw EHC Exhaust from and 3.5kW HD1

2

3

4 • 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)

• 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

DEF

+V

Manifold

LO-

SC

R

PN

A

SC

R

AS

C

SCRF

NH3

39

IEO IN Ox IPINA--Out IN Ox .........,._ ........, M IB

C I . · ...,_....,,,,,.,,

z a.

131L

261L


IM ~d-lBed IN H3

IC u fl)

131L 13,IL

TIP IN(lx

I = Te1m1p Sensor


swri.org

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

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

Tailpipe 0.06 0.008 0.016 0.015

40

Final ARB Low NOX Aftertreatment Configuration

MB

PNA

Multi-bed SCRF-SCR

Doser/Mixer

PNA Downpipe (equivalent to truck configuration)

Final configuration components were insulated (shown here without)



• Modular components used in order to support the screening process • Downpipe equivalent to underfloor mounting based on actual vehicle

configuration (no close coupling)

41

Low NOX AT Configuration Details Final configuration components were

MB

Mixer

SCRF

SCR

SCR/ASC NH3 Sensor

insulated (shown here without)

DEF Nozzle



• Production air-assist DEF dosing system was retained (Albonair) • All aftertreatment sensors are production type

– Latest generation NOX sensors – Production thermocouple type temp sensors (CAN) – Production NH3 sensor

• Thermal packaging of dosing/mixing section could be improved to reduce heat input

42

0 erating NH3

conditions Coverage

Target SCRT0

UREA model Urea INJECTOR

injection

Engine-out control ler SCR SCR NOx

NH3

N02/N0x Coverage NH3 SENSOR

model Observer Closed-loop

control ler Exhaust flow

NH3 slip model



Cell Cell Cell

Model-Based SCR Controller with Mid-Bed NH3

TIn

SCR Model

Thermal Model

Kinetic Model

Twall

TIn

SCR Model

Thermal Model

Kinetic Model

Twall

TIn TInSensor Feedback ṁexh ṁexh ṁexh ṁexh

NOX NOX NOX NOX

NH3 NH3 NH3 NH3

NO2/ NO2/ NO2/ NO2/ NOX NOX NOX NOX

θ1 θ2 θ3

SCR Model

Thermal Model

Kinetic Model

Twall

• 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 – Slightly modified coverage targets for WHTC

43

- EO NOx - PNA-Out NOx - Tailpipe NOx - SCRF Out NOx

-PNAOutt - SCRF Inlet T - SCRF Out T ASC Out T

1200

1000

800 200 u b0 41

E "Cl

OJ C. C.

.. 600 150 ::::,

x .. Ill

0 .. z 41

C. E

400 100 ~

200

0

0 50 100 150 200 250 300 350 400 450

Time, sec



Cold-FTP NOX and Temperature – 0-450 seconds – Final System, Devel Aged Parts

• PNA function most important during first 90 seconds of cold-start

• Thermal management active until ~ 375 secs

– Mini-burner, engine calibration, elevated idle

• SCRF light off at 125 secs – Full SCR conversion

by 220 secs

• Development Aged parts – Cold-FTP result = 0.06 g/hp-hr

44



Hot-FTP Thermal Management – Final System, Devel Aged Parts

PNA In SCRF In SCRF In-with TM PNA In SCRF Out SCRF Out-with TM SCRF Inlet T 350 SCRF Outlet T 350

Tem

pera

ture

, deg

C 300 300

Tem

pera

ture

, deg

C

250 250 200 200 150 150 100 With TM ~ 0.008 g/hp-hr

50 100

50 0 0

0 300 600 900 1200 0 300 600 900 1200 Time, sec Time, sec

• These idle segments from the engine result in a small drop in SCRF and SCR catalyst temperature (down to 175C with no intervention)

– Small “cool wave” passes through the catalysts and requires some intervention – This makes a difference between hot-starts < 0.01 g/hp-hr and > 0.015 g/hp-hr

• Engine calibration changes at idle made to help minimize, but engine alone was not enough • Small amount of thermal management from the mini-burner was used as a countermeasure

45

625

Final Aging Protocol

Time [s] Ac

tive

Rege

nera

tion

Mod

e

Pass

ive

Oxi

datio

n /

Soot

& A

sh A

ccum

ulat

ion

Mod

e

Low Temperature Soot & Ash Accumulation Mode

30 g/hr Soot Rate Exhaust Flow = 975 kg/hr

High

Tem

p O

pera

tion

/ HC

-Rem

oval

Mod

e



0 1000 2000 3000 4000 5000 6000 7000 8000 9000

2009 Cummins ISX 600 575 550 525

mule engine (DAAAC modified) 4-hour duration

500 475 450 425 400 375 350

Regeneration is via in-exhaust injection upstream of PNA Final duration was

325 847 hours 300 275 250

100% FUL thermal exposure

225 23% FUL chemical 200 exposure

• This is based on regeneration frequency of ~ 1.7% (near x2 from base engine) – Resulted in 194 hours of regeneration for FUL thermal equivalent – This is more than 300 Active Regeneration events

SCRF

Inle

t Tem

pera

ture

[°C]

46

Final Aging - Issues • Early PNA face coking – resolved by adjusting cycle but resulted in large HC buildup

that had to be baked off • Regeneration process had to be adjusted to insure complete soot cleaning – some

early localized exotherms possible

• Mechanical Canning failure on PNA 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 Channels

Normal Ash Load

Abnormal Mat/Ash



47


■

■

■

■

swri.org

Final Tailpipe NOX Results

0.71

0.04

7

0.14

0

0.08

4

0.11

5

0.03

0.00

5

0.00

8

0.01

0

0.06

0.00

8

0.01

6

0.01

5

0.01

9

0.11

0.02

1 0.03

4

0.03

8

0.03

6

0.00

0.05

0.10

0.15

0.20

Tailp

ipe

NO X

, g/h

p-hr

Baseline Degreened Devel-Aged Final-Aged

48

Aftertreatment NOX Conversion Efficiency, %

Test Config FTP Transient

RMC-SET WHTC Cold Hot Composite

Baseline 75% 98.5% 95% 97% 97%

Devel Aged 98% 99.7% 99.5% 99.3% 99.4%

Final Aged 96% 99.3% 98.8% 98.2% 98.8%

Note: IRAF calculation for NOX would add adjustment of + 0.004 g/hp-hr to Final Aged results with Low NOX Engine (+0.003 g/hp-hr for Devel Aged and Degreened).

' I ,.,,. .. ' I II " ·~ A f I I . , ... I '1• I I

I I I I I I I I I ,, I ,, ,,



Cold-FTP Final Aged vs Devel Aged PNA Performance

0

50

100

150

200

250

300

350

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

0 100 200 300 400 500 600 700

PNA

Inle

t Tem

p, d

egC

PNA

Stor

ed N

Ox,

gra

ms

Time, sec

Devel Aged-Final Controls Final Aged Inlet Temp

SCRF Light-Off

Full SCR Conversion

NOX reduction across system components

0-200 secs, % NOX conv

Full Cycle, % NOX conv

Devel Aged

Final Aged

Devel Aged

Final Aged

PNA 44% 27% -10% -5%

SCRF 64% 28% 90% 84%

SCR- 10% 13% 80% 80% 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,

downstream SCR still too cold to help

49

~

' I ~ ' 1 fl1I ' -

l I

j L fDJ & L A I l



350

300

Hot-FTP Final Aged vs Devel Aged SCRF Performance

Devel Aged-Final Controls Final Aged Devel Aged Final Controls Final Aged

400 50.0

Final Controls = 90%, 0.30 g/hp-hr 45.0 Final Aged = 87%, 0.40 g/hp-hr

Tailp

ipe

NO

x, g

/hr

SCRF-Out

0 200 400 600 800 1000 1200

Tailpipe Final Controls = 99.7%, 0.009 g/hp-hr 40.0 Final Aged = 99.3%, 0.020 g/hp-hr

35.0

SCRF

-Out

NO

x, g

/hr

250

200

150

100

50

0

30.0

25.0

20.0

0 200 400 600 800 1000 1200

15.0

10.0

5.0

0.0

Time, sec Time, sec

• Hot-start performance change due primarily to change in SCRF performance – Lower NH3 storage capacity, higher tendency towards ammonia oxidation – More demand on downstream SCR catalyst

• Early cycle tailpipe performance still maintained but later there is more NH3 release to downstream catalyst

– Small increase in late cycle NO generation due to larger amount of NH3 to be oxidized

50

Poll utant FTP W HTC

Engine Cold

RM C-SET Composite Hot Composite

Baseline CO2, g/hp-hr 574 543 547 458 485 N2O, g/hp-hr 0.024 0 .047 0.044 0.05 0.06

Devel Aged CO2, g/hp-hr 600 547 555 462 491

Low NOx N2O, g/hp-hr 0.075 0 .087 0.085 0.033 0.085

Engine Fina l Aged

CO2, g/hp-h r 604 549 558 464 494 N2O, g/h p-hr 0.101 0 .108 0.107 0.055 0.086

BSCO2, g/hp-hr

Cold Hot Composite RMC

Baseline Engine 574.2 542.6 547.4 457.7

Final ULN Config 604.4 548.8 558.2 463.6

% change 5.3% 1.1% 2.0% 1.3%

M ini-burner air 0.4% 0.2% 0.2%

Increased SCRF Regenerat ion 0.3% 0.3%

Total FTP CO2 Impact 2.5% 1.6%



Final GHG Results Cycle Measured CO2 and N2O Emissions

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 temperatures from turbocompound

– Different GHG approach would require less thermal management

• Impact could be reduced via better packaging and integration

51

500

450

400 u b,O

" -a_ 350 I:! :,

i! 300 8. E ~ 250

.:. 'i' 200 ..

.c:

---b,O 150 a' z

100

50

0

- EO NOx - TP NOx - DOC In T - SCR In T - AT Out T - Sp.eed

2000

1000

. 0

1200 1600 2000 2400 2800 3200 3600 4000 4400 4800

Time, sec

E ~

-u'

" 8. U'l


- EONOx - TPNOx - PNAlnT - SCRFlnT - SCRln T - AT Out T - Speed

500 2000

450

1000 u 400 b,O 01

-.;, 01' 350

. 0 ] ~ 01 C. E {!

' 9 ..c ..... b,O ~-z

300

250

200

150

100

50

0

1200 1600 2000 2400 2800 3200 3600 4000 4400 4,800

TTme,sec


swri.org

E ~ -a 01 OI C. ell

CARB Idle Test Result – Final Aged Parts

Baseline Engine Ultra-Low NOX Engine Low Idle (550 rpm) PTO Idle (1100 rpm)

TP NOX, g/hr

Avg Fuel Rate, kg/hr

TP NOX, g/hr

Avg Fuel Rate, kg/hr

Baseline 11.7 1.18 52.7 3.16

ULN 0.2 1.00 14.6 3.21 Engine

• Low Idle – 98% reduction • PTO Idle – 72% reduction • Partially engine-out changes,

mostly improved AT performance • Thermal management needed for

PTO idle segment

52

- -



4000

3000

2000

1000

4000

3000

2000

1000

Example Vocational Cycle – NYBCx4

-

-

-

-

0

1000

2000

0

200

400

600

800

1000

1200

0 500 1000 1500 2000 2500 3000 3500 4000

Spee

d

NO

x, g

/hr -

or-T

emp,

deg

C

Time, sec

EO NOx TP NOx DOC In T DPF Out T Aftertreatment Out T Speed

-

-

-

-

0

1000

2000

0

100

200

300

400

500

600

700

800

900

1000

0 500 1000 1500 2000 2500 3000 3500 4000

Spee

d, rp

m

NO

x, g

/h -o

r-Te

mp,

deg

C

Time, sec

EO NOx TP NOx PNA In T SCRF In T SCR In T Speed

Baseline Engine Ultra-Low NOX Engine (Final Aged Parts) EO,

g/hp hr

TP, g/hp

hr

NOx Conversion, %

Fuel Rate, kg/hr

Baseline 6.1 2.3 62 % 5.3

• Duty cycle is average 6% of maximum engine power (not including idle segment)

– Test cycle starts after the idle ULN Engine 3.9 0.38 90% 5.3

– Precondition before idle with % Change -35% -84% n/a None same cycle

53



Summary (1) • Multiple technology approaches to reach ultra-low

NOX levels – Appropriate choice depends on engine and GHG approach

• Final system was able to achieve 99% conversion efficiency on composite FTP / WHTC fully aged

– 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-hr – Final aged parts > 0.02 g/hp-hr – System complexity and GHG impact higher due to very

low temperatures

54



Summary (2)

• Questions still open regarding durability – Final aging issues make it difficult to assess system

degradation

• NOX performance gap between regulatory and vocational cycles is smaller with ULN engine than baseline engine

– This is driven to some degree by calibration approach

• Significant potential for low NOX levels on vocational and field cycles

– More work is being done to examine potential NOX reduction and GHG impact

55



Next Steps • Stage 1b – Aging andTesting of another set of Stage 1 parts

(Planned) – Answer durability questions with an undisturbed aging process – 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 cycles

• Torque, fueling, CO2, mass-over-time

• Stage 3 – Low NOX Development and Demonstration on a non-turbocompound engine (Planned)

– Engine platform more representative of mainstream approach to GHG regulations

– Combination of both regulatory and low-load cycles

56



Acknowledgements

• California Air Resources Board • Program Partners

– Volvo – Manufacturers of Emission Controls

Association (MECA) • MECA member companies who have provided emission control hardware

• Program Advisory Group members

57



More Information

• California ARB website – http://www.arb.ca.gov/research/veh-

emissions/low-nox/low-nox.htm

• SwRI Contact – Christopher Sharp – +1 210-522-2661 – [email protected]

58

http://www.arb.ca.gov/research/veh-emissions/low-nox/low-nox.htm

mailto:[email protected]

Documents

Christopher Sharp, Ian Smith Southwest Research Institute