2004 deer conference - p2ric
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2004 DEER ConferenceAugust 29 – September 2, 2004
Coronado, California
2004 DEER ConferenceAugust 29 – September 2, 2004
Coronado, California
Aftertreatment Requirements for the Future
• 80 – 90 % NOx reduction• Wide temperature range• Same low PM, HC levels• Limited impact on fuel consumption• Packaging• Competitive cost• Durability of up to
– 1 million miles (Truck)– 10,000 hrs (off-highway)
2004 DEER ConferenceAugust 29 – September 2, 2004
Coronado, California
System Development Process• Understanding of catalyst behavior• Integration: Alignment of catalyst needs and engine
system capabilities• Control system/algorithm development• Catalyst size and cost optimization
– Various engine platforms and ratings– Various engine cycles– Real life application– Durability
2004 DEER ConferenceAugust 29 – September 2, 2004
Coronado, California
System Development Process
i=1Exhaust Gas
Volume
Catalyst Surface
,...),],NO([]NO[ PTxfdtxd=
i=1Exhaust Gas
Volume
Catalyst Surface
,...),],NO([]NO[ PTxfdtxd=
i=1Exhaust Gas
Volume
Catalyst Surface
,...),],NO([]NO[ PTxfdtxd=
Bench Testing
ModelingResearch
Supplier Relationships
Design and Packaging
Catalyst Formulation Development
Engine / Aftertreatment
System Integration
Combustion development
2004 DEER ConferenceAugust 29 – September 2, 2004
Coronado, California
Caterpillar/Xytel MRCSS Catalyst Test BenchMass flow controllers,
switching valves
lean/rich
...
H2OInlet gas mixture
Heat from ovens
TC for closed-loop
temperature control
Gas Cylinders:
NO, NO2, O2, N2, CO2, CO, C3H6,
NH3, H2
Flow rates
NOx adsorber sample
Analyzers
CO2
Dryer NOx
Outlet gas mixture
etc.
2004 DEER ConferenceAugust 29 – September 2, 2004
Coronado, California
Bench Tests: Quantitative Data
NOx Slip vs Time
0
5
10
15
0 20 40 60
time (sec)
NO
x sl
ip (
ppm
)
NO
x Co
nver
sion
NOx Adsorber Catalyst behavior
Temperature (°C)
Catalyst “mapping”
Flow rate 1
Flow rate 2
2004 DEER ConferenceAugust 29 – September 2, 2004
Coronado, California
Aftertreatment Performance Model• Reduce bench data to generalize Catalyst behavior
(“mapped” catalyst)• Can be linked to full engine system model• Couple with transient exhaust-gas emissions data
– Temperatures– SV– Emission levels
• Predict system behavior– Transient emissions– Effect of active control measures– Thermal behavior– Aging/degradation prediction
2004 DEER ConferenceAugust 29 – September 2, 2004
Coronado, California
NOx Adsorber Technology Requirements
• 80 – 90 % NOx reduction• Limited impact on Fuel Consumption• Packaging• Competitive cost
• Main Issue: Durability• Sulfur deactivation• Thermal deactivation• Phosphorus deactivation
2004 DEER ConferenceAugust 29 – September 2, 2004
Coronado, California
Case study: Modeling Phosphorus effect
Long term deterioration from phosphorus deactivation
• Phosphorus (or other ash components) in lube oil can degrade catalyst performance
• Model can be used to predict effects of long-hours Phosphorus accumulation
• Compare transient simulation results with and without Phosphorus deactivation
• Results from APBF study will be used as baseline for simulation
2004 DEER ConferenceAugust 29 – September 2, 2004
Coronado, California
Baseline: APBF heavy duty NOx Adsorber• APBF-DEC program investigated effect of fuels on
aftertreatment durability (2000 hrs)• Modified heavy duty Cummins 15 l engine (2004
emission level)• “Single leg” NOx Adsorber system• NOx adsorber volume: 44 liters• Study performed by NREL and Ricardo Inc, Chicago
Technical Center
NAC1
DOCDOC
DPF
NACDPF
NAC
NOx Sensor
NOx Sensors
2004 DEER ConferenceAugust 29 – September 2, 2004
Coronado, California
Baseline modeling• APBF was not involved in modeling activities by Caterpillar• Phosphorus deactivation was out of scope of APBF program
• Caterpillar used FTP results reported by NREL and Ricardo as input for model
• NOx adsorber model was estimated from reported results of catalyst used by APBF
50556065707580859095
100
0 200 400 600 800 1000
Time [s]
NOx
Trap
ping
[%]
450degC
400degC
350degC
300degC
250degC
2004 DEER ConferenceAugust 29 – September 2, 2004
Coronado, California
Model validation: Hot FTP after 2000 hrs
NOx ConversionMeasured: 95 %Simulated: 94 %
NOx tailpipe: ~ 0.2 g/hphBaseline: Catalyst out measured by Ricardo
Hot FTP after desulfation simulation after 2000 hrs
0.0
200.0
400.0
600.0
800.0
1000.0
1200.0
0.00 5.00 10.00 15.00 20.00Time [minutes]
NO
x [p
pm]
0
10
20
30
40
50
60
70
80
90
100
Con
vers
ion
Effic
ienc
y [%
]
Engine out Catalyst out simulated Conversion simulated
2004 DEER ConferenceAugust 29 – September 2, 2004
Coronado, California
Caterpillar FTP prediction after 10,000 hrs•Simulated Conversion @ 10,000 hrs: 84%
•Catalyst model was modified for Phosphorus effect
Hot FTP after desulfation simulation after 10,000 hrs
0100200300400500600700800900
100011001200
0.00 5.00 10.00 15.00 20.00Time [minutes]
NO
x [p
pm]
0
10
20
30
40
50
60
70
80
90
100
Con
vers
ion
Effic
ienc
y [%
]
Engine out Catalyst out 2000 hrs Catalyst out 10,000 hrsConversion 2000 hrs Conversion 10,000 hrs
2004 DEER ConferenceAugust 29 – September 2, 2004
Coronado, California
Predicted deterioration due to Phosphorus deactivationHot FTP Cycle Results
NOx Adsorber Aging on 15 ppm Fuel
0.0
0.2
0.4
0.6
0.8
1.0
0 2000 4000 6000 8000 10000Age (hours)
NO
x (g
/bhp
-hr)
NOx Mean - Fresh and Pre-Desulfation Desulfation NOx Mean - Post-Desulfation
End of APBF testAfter desulfation
Caterpillar predicted after-desulfation performance
10,000 hrs
APBF measurements(no investigation into Phosphorus)
2004 DEER ConferenceAugust 29 – September 2, 2004
Coronado, California
Conclusion• NOx Adsorber Technology is a promising candidate
for future NOx reduction, BUT…..
• Durability is still a significant challenge• Phosphorus effect should not be neglected, not
easily reversible• Phosphorus can have a significant effect on long
term catalyst performance• More focus needed to understand long-term
performance degradation• Ashless lubricants would be a major benefit to NOx
adsorbers and other aftertreatment devices
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