Urea SCR Durability Assessment for Tier 2 Light-Duty Truck

2008 DEER Conference

Ed Badillo, Geoffrey Brohl, Giovanni Cavataio, Douglas Dobson, Gang Guo, Yinyan

Huang,

Christine Lambert, James Warner, Scott Williams

Ford Research and Innovation Center

August 2008 2

Program Objectives•

Develop Tier 2/LEV II Urea SCR/DPF systems

for

chassis-certified, light-duty diesel trucks

•

Calibration

of surrogate EU3 2.7L European LR3 diesel vehicles for US test cycles (FTP-75 and US06)

•

Mileage accumulation

up to 50,000 miles with periodic emission measurements

Objectives/Deliverables

50k mi Standards 120k mi Standards

[g/mi] NOx PM CO NMOG HCHO NOx PM CO NMOG HCHO

Tier 2 Bin 5 0.05 --- 3.4 0.075 0.015 0.07 0.01 4.2 0.09 0.018

LEV II, ULEV 0.05 --- 1.7 0.04 0.008 0.07 0.01 2.1 0.055 0.011

Tier 2 Bin 2 --- --- --- --- --- 0.02 0.01 2.1 0.01 0.004

LEV II, SULEV --- --- --- --- --- 0.02 0.01 1.0 0.01 0.004

August 2008 3

General Aftertreatment Layout

Exhaust System Configurations

DO

C

SCR cDPFMixerurea

Turbo

DO

C

SCR cDPFMixerurea

Turbo

DO

C

SCRFMixerurea

Turbo

Advantages:• reduced cost• reduced complexity

All substrates are cordierite.

SCRF is combination of SCR on to DPF substrate

August 2008 4

DOC-SCR-CDPF System at 48k mi

0.072 0.023 0.2427 0.068 0.0460.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

THC NMHC CO NOX NOX

gram

s/m

ile

Weighted Total

Tier 2 - Bin 5 Standards, 50k

3.4

0.31FG Projection

August 2008 5

DOC-SCRF System at 46k mi

0.067 0.026 0.2725 0.100 0.0630.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

THC NMHC CO NOX NOX

gram

s/m

ile

Weighted Total

Tier 2 - Bin 5 Standards, 50k

3.4

0.31FG Projection

August 2008 6

NMHC Results SummaryNMHC Efficiency

System Supplier Type 4k 20-25k 40-50k

1 A DOC-SCR-CDPF 99.0% 99.1% 98.7%

2 B DOC-SCR-CDPF 99.4% 99.1% 98.1%

3 B DOC-SCRF 99.4% 98.9% --

4 A DOC-SCRF 99.1% 98.9% 98.2%

Note: Highest TP NMHC value for EU4 LR3 was ~0.03 g/mile on FTP (std 0.075)

Emission Summary

August 2008 7

CO Results Summary

Note: Highest TP CO value for EU4 LR3 was 0.27 g/mile on FTP (std 3.4)

Emission Summary

CO EfficiencySystem Supplier Type 4k 20-25k 40-50k

1 A DOC-SCR-CDPF 98.4% 98.5% 96.4%

2 B DOC-SCR-CDPF 98.0% 97.1% 95.2%

3 B DOC-SCRF 98.5% 98.4% --

4 A DOC-SCRF 97.7% 96.4% 95.8%

August 2008 8

NOx

Results Summary

•

Lower 4K NOx

efficiency of combined systems is attributed to washcoating

on SCRF bricks @ only 60% of WCL on flow-

through bricks.•

Best 50k emissions from EU4 vehicle was 0.057 g/mi.

Emission Summary

NOx

EfficiencySystem Supplier Type 4k 20-25k 40-50k

1 A DOC-SCR-CDPF 91% 90% 87%

2 B DOC-SCR-CDPF 87% 86% 85%

3 B DOC-SCRF 78% 73% --

4 A DOC-SCRF 88% 84% 80%

August 2008 9

PM Results SummaryEmission Summary

Filtration EfficiencySystem Supplier Type 4k 20-25k 40-50k

1 A DOC-SCR-CDPF 99.7% 99.4% 34%

2 B DOC-SCR-CDPF 99.4% N/A 74%

3 B DOC-SCRF 99.7% 91% --

4 A DOC-SCRF 99.8% N/A 55%

•

Due to aggressive filter regeneration, some loss in filtration efficiency was experienced for both CDPF and SCRF systems

August 2008 10

DPF Development Issues•

LR3 fleet was launched with soot loading targets based on lower (~52%) porosity substrates.–

MSL (maximum soot load) = up to 6.0 g/L.

•

EU3 vehicles required aggressive EGR to meet PM targets.–

Regeneration interval was roughly 350-400 miles.

DPF Control

August 2008 11

System 1 CDPF at 48k mi

Outlet

Filtration Efficiency: 74%

DPF Control

Outlet

System 4 SCRF at 46k mi

Filter Post Mortem Results

Filtration Efficiency: 55%

August 2008 12

0

200

400

600

800

1000

1200

55000 60000 65000 70000 75000 80000 85000Time (s)

Tem

pera

ture

(oC

)

0

1

2

3

4

5

6

7

8

DPF

Reg

en

urd_t_postturbourd_t_pre_scrurd_t_post_scrT_post_dpfDPLD_ENA_RGN_CLC_PFRestriction #

System 4 SCRF at 46k miTemperature profile on-road during regeneration

High temperature event

Regeneration triggers

DPF Control

August 2008 13

System 4 SCRF at 46k miDPF Control

-20

0

20

40

60

80

100

150 250 350 450 550 650

Temperature (°C)

NO

x co

nver

sion

(%)

Degreened

HTA800°C50hr

2" from Inlet

4" from Inlet

1" from Outlet

Outlet

inlet/middle

outlet

1”

from outlet

Flow Reactor30k h-1

Majority of SCRF remained active for high NOx

conversion

August 2008 14

50k mi Aging Correlation

•

On-Road 50k mi samples show similar FTP conversion performance as oven-aged 50k equivalent samples.

75%

80%

85%

90%

95%

100%

NMHC CO NOx

Con

vers

ion

Eff

icie

nc

DOC+SCR - Road DOC+SCR - Oven

August 2008 15

Potential for T2B2 Diesel Advanced SCR Concept on LR3 surrogate vehicle

70%

75%

80%

85%

90%

95%

100%

0.2 0.3 0.4 0.5 0.6 0.7FTP-75 Engine-out NOx (g/mi)

FTP-

75 N

Ox

Con

v (%

)

4k

50k

120k

Achieve Tier 2 Bin 5

Potential Target Tier 2 Bin 2

lower engine-outhigher conversion

•

Catalysts were oven-aged to simulate 4k, 50k and 120k mi.

•

Engine-out NOx

was lowered during the course of the testing.

•

Results do not include the DPF regeneration penalty for final emission certification.

August 2008 16

Conclusions•

DOC-SCR-CDPF systems were Tier 2 capable with little deterioration over 50k mi except for PM

•

Robust filter regeneration critical for cordierite

•

SCRF retained high NOx

conversion despite loss in filtration efficiency

•

SCRF systems require additional development to achieve full useful life (120,000 mile) T2B5 emissions