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All content in this area was uploaded by Marco Moser on Jun 27, 2022
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Content uploaded by Marco Moser
Author content
All content in this area was uploaded by Marco Moser on Jun 16, 2022
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DOC Ageing and Diagnosis
w/o DPF Regeneration
March 1, 2022
Marco Moser, IAV -Berlin
Motivation
Tasks of the Diesel Oxidation Catalyst
IAV 03.2022 -IAV Marco Moser -DOC Ageing and Diagnosis w/o DPF Regeneration2
DOC
HC
CO H2O
CO2
NO NO2
O2
Engine
Exhaust
Treatment
Storage:
HC, NOX, O2, H2O
Heat
NO2/NO ratio
O2
standard approach for DOC OBD: exothermic in DPF regeneration mode (every ~1000km)
future legislation with less selectivity for monitoring? continuous monitoring available?
NO
N2O
Heat Heat
Content
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DOC Monitoring
Usable Effects
DPF Regeneration
Accuracy Improvements: Sensors and Models
Frequency and Spreading of OBD
DOC Ageing
Real World Effects
Ageing Procedures
DOC Monitoring
IAV 03.2022 -IAV Marco Moser -DOC Ageing and Diagnosis w/o DPF Regeneration5
DOC Monitoring
Usable Effects
Storage: HC, NOX, O2, H2O
•not measurable with current sensors
•sensor concept: Radio Frequency
antenna (not ready for production)
NO2/NO ratio
•effect in SCR conversion
•Feed gas conversion drop NOX
sensors not ready
•SCR overfill extreme long-term
effect / side effects
O2in/out ratio
•Normal operation effect in sensors negligible
•DPF Regeneration up to 2% oxygen drop
Heat
•exothermic measurable with temperature sensors
•heat balance depending on sensors and models
•Different operation modes with different HC/CO
load exothermic
•DPF Regeneration: simple because of high
exothermic
exothermic monitoring approach sensible
DOC Monitoring
Diesel Oxidation Catalyst -Setup
IAV 03.2022 -IAV Marco Moser -DOC Ageing and Diagnosis w/o DPF Regeneration6
HC
CH2O
CO
Engine DOC
CH4TT
Conversion
HC,CO,CH4,CH2O
Diagnostics
O2from NOXsensors … not directly at DOC
DOC monitoring with temperature sensors obvious
CH4
HC
CO
CH2O
HC injector?
Heating disc?
Burner?
O2O2
Models
DOC Monitoring
DPF Regeneration –Common OBD Approach
IAV 03.2022 -IAV Marco Moser -DOC Ageing and Diagnosis w/o DPF Regeneration7
DOC
TT
simple overall
HC conversion
model
DPF regen in focus high exothermic to compensate cumulative inaccuracies
simple overall
Engine HC
model
complex mechanisms
specific to the carbon
components normally not
mapped
sensor tolerances normally
not fully compensated
accumulation of error
conversion model based on engine out inaccuracies
=
DOC Monitoring
Accuracy Improvement: Sensors
IAV 03.2022 -IAV Marco Moser -DOC Ageing and Diagnosis w/o DPF Regeneration8
compensation of sensor tolerances helps to improve efficiency calculation
Temperature sensors:
tolerances lead to miscalculation
must-have: identical sensors (relative
to each other)
Temperature
time
Temperature
time
offset
gain
adapted
sensors
=
enables diagnosis outside DPF
regeneration
T upstream
T downstream
T upstream
T downstream
DOC Monitoring
Accuracy Improvement: DOC Conversion
IAV 03.2022 -IAV Marco Moser -DOC Ageing and Diagnosis w/o DPF Regeneration9
Physico-chemical
Machine Learning
high class modelling leads to high accuracy in exothermic prediction
DOC Conversion:Raw Emissions:
C3H6, C3H8, CO, CH4, CH2O
C3H6C3H8CH4
DOC Temperature
DOC Conversion
CO
C species
=
options
enables continuous
monitoring
Machine Learning approaches
with high accuracy
Modelling of different carbon species
DOC Monitoring
Low Dimensional Conversion Model for DOC
IAV 03.2022 -IAV Marco Moser -DOC Ageing and Diagnosis w/o DPF Regeneration10
high class DOC conversion models available
_
_
=
Reaktionen
,
,,
,
DOC
Arrhenius approach
Meas.
time
time
HC [-] (normalized)HC [-] (normalized)
HC DOC downstream
Meas.
NO2DOC downstream
Meas.
time
NO2[-] (normalized)
DOC Monitoring
Diagnostics: Frequency and Spreading
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approaching legislative changes may lead to need of statistical approaches
•wish for higher diagnosis frequency
•legislation which allows fewer efficiency drop
Diagnosis result frequency
DOC efficiency
01
state of the art:
-high selectivity
-BUT: diagnostic failure leads
to waiting till next regeneration
expansion of diagnostic area:
-high frequency
-BUT: possible selectivity drop
statistical post-processing
Diagnosis result frequency
DOC efficiency
01
DOC Monitoring
Statistical Post-Processing
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statistical post-processing leads to stable ageing detection
Statistical spreading statistic filters: EWMA, median, mean
Ageing detection
filters faster than ageing
Sudden Error
filter fast enough?
DOC Ageing Effects and Procedures
DOC Ageing Procedures
Real Life Effects
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14
There are several states of DOC operation to consider when determining aging effects.
cold start, light off, light out, dpf regeneration, different space velocities
important: May differ with different DOCs and exhaust setups
DOC efficiency
DOC surface temperature [°C]
0600
1
new DOC
aged DOC
DOC efficiency
DOC surface temperature [°C]
0600
1new DOC
aged DOC
warming regeneration
cold start
higher space
velocity
DOC Ageing Procedures
Chemical Analysis
IAV 03.2022 -IAV Marco Moser -DOC Ageing and Diagnosis w/o DPF Regeneration
15
front rear
poison mg/kg
Poisons -real aged DOC
Phosphorus Potassium Sulfur Calcium Zinc
phosphor known as a big player (literature / confirmed by analysis) selected for synthetic aging procedure
no change in precious metals quantity but dispersion occurs affects the conversion
0
20
40
60
80
100
precious metal [%]
Precious metals –fresh vs. real aged
Pt (fresh) Pt (real aged) Pd (fresh) Pd (real aged)
•searching for poisons and precious metals degeneration in real aged DOCs
DOC Ageing Procedures
Chemical Poisoning
IAV 03.2022 -IAV Marco Moser -DOC Ageing and Diagnosis w/o DPF Regeneration
16
proven process for targeted poisoning
DOC
Extract drill core
or whole DOC
Soak in solution
that contains
selected poison(s)
Drying and
calcination
poisoned
sample for
testing
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•hydrothermal aging conditions (temperature, duration) rebuild real aged catalyst
DOC Ageing Procedures
Heat Treatment
DOC efficiency
DOC surface temperature [°C]
0600
1
1. Poisoning
because of poisoning lower temperatures sufficient for ageing more realistic
−C3H6
−C3H8
−NO2/NOX
2. Heat
DOC efficiency
DOC surface temperature [°C]
0600
1
IAV 03.2022 -IAV Marco Moser -DOC Ageing and Diagnosis w/o DPF Regeneration
18
Continuous DOC Monitoring is possible, if:
Raw emission models high quality
DOC conversion models high quality
Temperature sensors high accuracy
Specific Ageing of DOC to real life behavior is possible
DOC Ageing Procedures
Summary
Treatment for unresolved effects (dynamics, operation areas, zones):
Variation of poison quantities
Combination of poisons
Zoning (sintering, clogging, molecular destruction)
Interactions between poisoning and heat
OBD
OBM
Control
Contact
Marco Moser
IAV GmbH
Carnotstr.1, 10587 Berlin
www.iav.com