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LABORATORY OF APPLIED THERMODYNAMICS
ARISTOTLE UNIVERSITY THESSALONIKI
SCHOOL OF ENGINEERING
DEPT. OF MECHANICAL ENGINEERING
1
LAT
Technical Support for
the Development of
WLTP Phase 2 and RDE
Part A: Revision of the Durability
procedure
DTF Teleconference16 May 2018
Overview
➢ Part A: Revision of the Durability procedure
Revision of the durability verification procedure of pollution control devices (Type 5 or Type V test)
• Literature review of ageing mechanisms of After-Treatment Systems (ATS)
• Experimental campaign: temperature distribution along the exhaust line of the vehicle, as well
as inside the ATS devices
• Modelling of temperature distribution
• Proposals for the revision
o Current procedure
o Proposals for revised procedure
• 1st step: Focus on the revision of technical issues
• 2nd step: Revision of procedural issues
2
Current Procedure
➢ Type V test: Durability of Pollution Control Devices
Options
1. Whole vehicle durability
o 160,000km on test track, road, chassis dynamometer
2. Bench ageing durability
o Test of ATS durability on a bench
o Standard Bench Cycle (SBC) for SI engines
o Standard Diesel Bench Cycle (SDBC) for CI engines
3. Application of Assigned Deterioration Factors (ADF)
3
Source: Regulation No. 83, Revision 4, 26 April 2011
Current Procedure – Option 1
➢ Type V test: Durability of Pollution Control Devices
Option 1 : Whole vehicle durability
✓ 160,000km on test track, road, chassis dynamometer
I. 1st alternative: Repetitive operating cycle
o 11 cycles
o 6km/cycle
o Different maximum speed of each cycle
o Dyno load setting at 80km/h
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Current Procedure – Option 1
➢ Type V test: Durability of Pollution Control Devices
Option 1 : Whole vehicle durability
✓ 160,000km on test track, road, chassis dynamometer
II. 2nd alternative: Standard Road Cycle – SRC
o 7 laps
o ~6km/lap
o Dyno load setting at 80km/h
o Gear shifting strategy not defined
o Necessary to include gear strategy
5
0
20
40
60
80
100
120
140
0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200
Vel
oci
ty [
km/h
]
Time [s]
Gear Shift Strategy Equiv. AT [h]
5 gears 1247.7
6 gears, 6th above 100km/h 1529.6 (=100%)
JRC with corrections 1769.4 (=116%)
Free gear shifting 2051.4 (=134%)
JRC w/o corrections 1970.9 (=129%)
Current Procedure – Option 2
➢ Type V test: Durability of Pollution Control Devices
Option 2: Bench ageing durability✓ Test of ATS durability on a bench
➢ SI Engines: Standard Bench Cycle (SBC)
o Ageing bench with an engine as the source of exhaust gas
o Run SBC for the BAT
• R – catalyst thermal reactivity
• Tr – effective reference temperature
• A – to consider other ageing than thermal
o Tr is determined following a specific
procedure
o R and A values under revision
6
r bin
R RT Ti i
e bint t e
−
=
1
nie
i
BAT A t=
=
Current Procedure – Option 2
➢ Type V test: Durability of Pollution Control Devices
Option 2: Bench ageing durability✓ Test of ATS durability on a bench
➢ SI Engines: Standard Bench Cycle (SBC)
o Analysis of the BAT equation
• R – catalyst thermal reactivity
• Tr – effective reference temperature
• A – to consider other ageing than thermal
7
r bin
R RT Ti i
e bint t e
−
=
1
nie
i
BAT A t=
=
➢ Reaction speed (Arrhenius)
• C – concentration• Ea – activation energy of the reaction• Ru – 8.314 kJ/kmol/K• AArrh – pre-exponential factor
➢ Conversion ratio
➢ Considering a starting point at t=0 the time Δt needed to achieve a
conversion ratio CR at a given temperature 𝑇𝑏𝑖𝑛𝑖 will be 𝑡𝑏𝑖𝑛
𝑖 .
• R=Ea/Ru – catalyst thermal reactivity
➢ Considering a starting point at t=0 the time Δt needed to achieve a
conversion ratio CR at a reference temperature Tr will be 𝑡e𝑖 .
o R depends on the activation energy of each reaction
Arrh
d[C]A [C]
dt
a
u
E
R Te−
=
d[C] [C]
[C] [C]CR
= =
ArrhAi
bin
R
T
ibin
CRe
t
−
=
ArrhA r
R
T
ie
CRe
t
−
=
Arrh
Arrh
A
A
ibin i
r bin
r
RR RTiT Ti ibin
e binR
Tie
CR
t et t e
CRet
− −
−
→ =
=
Current Procedure – Option 2
➢ Type V test: Durability of Pollution Control Devices
Option 2: Bench ageing durability✓ Test of ATS durability on a bench
➢ SI Engines: Standard Bench Cycle (SBC)
o Revision of R (catalyst thermal reactivity values) values
• R=Ea/Ru – catalyst thermal reactivity
o ATS to be applied: TWC
o Value given in regulation: 17,500 → Corresponds to Eact=145 kJ/mol
o A=1.1
o Additional reactions to be considered (?)
• Oxidation of NH3 – possible only on O2 presence, competitive reactions with CO, HC oxidation, selectivity of O2
reactions in case of higher CO, HC concentrations
• NH3 is produced in the TWC in rich conditions, lower concentration of CO, HC → importance of this set of reactions ?
• Oxidation of NH3 – activation energy up to 178 kJ/mol → thermal reactivity: 21,410 K
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TWC
Reaction Activation Energy Range [kJ/mol] Catalyst thermal reactivity [K]
CO oxidation 70 – 110 8,420 – 13,230
HC oxidation 85 – 130 10,223 – 15,636
NOx reduction 25 – 130 3,007 – 15,636
Current Procedure – Option 2
➢ Sensitivity of Ageing Time (AT) on Catalyst Thermal Reactivity (R)
• Tr=400⁰C
• ΔR=R/R0
• ΔAT=AT/AT0
• R0=18,050
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0
200
400
600
800
1000
1200
1400
1600
1800
2000
0
20
40
60
80
100
120
140
160
180
0 50 100 150 200 250 300 350 400 450 500 550 600 650 700
Fre
qu
en
cy
Temperature - inlet ATS
ATS inlet Frequency
Cumulative [s]
y = 0.9701x3 - 0.9475x2 + 0.4161x + 0.5506R² = 0.9997
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
AT/A
T 0
R/R0
Sensitivity of AT on R
0 0
,0
r bin
R RT Ti i
e bint t e
−
=
r bin
R RT Ti i
e bint t e
−
= ( )( )
Δ
Δ 1
,0
R
R
ie
ibin
ie
tt
t−
=
ΔR ΔAT
0.4 0.640.6 0.650.8 0.77
0.9 0.871.0 1.00
1.1 1.161.2 1.361.4 1.92
1.6 2.77
Current Procedure – Option 2
➢ Selection of the R value for each ATS
o High R value, i.e. high activation energy → insensitive reaction, low reaction rate (from Arrhenius eq.)
o Low R value, i.e. low activation energy → sensitive reaction, high reaction rate (from Arrhenius eq.)
➢ Selection criteria
o Most sensitive (to temperature) reaction, i.e. the one with the lowest activation energy
o Most insensitive (to temperature) reaction, i.e. the one with the highest activation energy
o Other?
✓ According to the regulation, the lowest R value (worst case) is used for the BAT equation
Reg. 83, Annex 9, App. 1, 4.1.7: Compare the R-factor determined separately for each exhaust constituent.
Use the lowest R-factor (worst case) for the BAT equation.
10
Current Procedure – Option 2
➢ Type V test: Durability of Pollution Control Devices
Option 2: Bench ageing durability✓ Test of ATS durability on a bench
➢ CI Engines: Standard Diesel Bench Cycle (SDBC)
o Revision of R (catalyst thermal reactivity values) values
• R=Ea/Ru – catalyst thermal reactivity
o ATS to be applied: DOC
o Oxidation of SOF adsorbed on soot (C) – oxidation of solid C particles requires higher temperature
o Value proposed in (Heavy Duty Vehicle) HDV regulation: 18,050 → Corresponds to Eact=150 kJ/mol
o Proposal for the A factor
• DOC: 1.1 – similar operation to TWC
• cDPF: 1.1 – sharing the same with DOC, since the catalytic coating is similar
11
DOC
Reaction Activation Energy Range [kJ/mol] Catalyst thermal reactivity [K]
CO oxidation 100 -110 12,028 – 13,230
HC oxidation 80 – 130 9,622 – 15,636
NO oxidation 35 – 40 4,210 – 4,811
Current Procedure – Option 2
➢ Type V test: Durability of Pollution Control Devices
Option 2: Bench ageing durability✓ Test of ATS durability on a bench
➢ CI Engines: Standard Diesel Bench Cycle (SDBC)
o Revision of R (catalyst thermal reactivity values) values
• R=Ea/Ru – catalyst thermal reactivity
o ATS to be applied: SCR
o Values proposed in HDV regulation
• Cu-Z: 11,550 → Eact=96 kJ/mol
• Fe-Z: 5,175 → Eact=43 kJ/mol
• V: 5,175 → Eact=43 kJ/mol
o Proposal for the A factor
• Cu-Z:
• Fe-Z:
• V:
12
Cu-SCR
Reaction Activation Energy Range [kJ/mol] Catalyst thermal reactivity [K]
Standard SCR 45 – 65 5,413 – 7,818
Fast SCR 30 – 50 3,608 – 6,014
NO2 SCR 40 – 65 4,811 – 7,818
Fe-SCR
Reaction Activation Energy Range [kJ/mol] Catalyst thermal reactivity [K]
Standard SCR 65 7.818
Fast SCR 50 6,014
NO2 SCR 30 3,608
TiV-SCR
Reaction Activation Energy Range [kJ/mol] Catalyst thermal reactivity [K]
Standard SCR 70 8,420
Fast SCR 95 11,427
NO2 SCR 95 11,427
Current Procedure – Option 2
➢ Type V test: Durability of Pollution Control Devices
Option 2: Bench ageing durability✓ Test of ATS durability on a bench
➢ CI Engines: Standard Diesel Bench Cycle (SDBC)
o Revision of R (catalyst thermal reactivity values) values
• R=Ea/Ru – catalyst thermal reactivity
o ATS to be applied: LNT
o Value proposed in HDV regulation: 18,050 → Corresponds to Eact=150 kJ/mol
o Oxidation action of LNT to be considered (?)
o Proposal for the A factor
• LNT: Currently analyzing additional literature to separate thermal ageing and chemical poisoning effects on
quantitative manner
13
LNT
Reaction Activation Energy Range [kJ/mol] Catalyst thermal reactivity [K]
NOx reduction 25 – 90 3,007 – 10,825
Current Procedure – Option 2
➢ Type V test: Durability of Pollution Control Devices
Option 2: Bench ageing durability✓ Test of ATS durability on a bench
➢ CI Engines: Standard Diesel Bench Cycle (SDBC)
o Revision of R (catalyst thermal reactivity values) values
• R=Ea/Ru – catalyst thermal reactivity
o ATS to be applied: ASC
o Not considered in any regulation
o Very important for diesel engines
o ASC already installed in a number of vehicles, either as a separate device or at the last part of SCR
o ASC stores NH3, apart from oxidizing it
o Proposal for the A factor
• ASC: Available literature/data/information ?
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ASC
Reaction Activation Energy Range [kJ/mol] Catalyst thermal reactivity [K]
NH3 oxidation
on PGM80 – 110 9,622 – 13,230
Current Procedure – Option 2
➢ Type V test: Durability of Pollution Control Devices
Option 2: Bench ageing durability✓ Test of ATS durability on a bench
➢ Considerations on the approach of combined systems
o Gasoline engines (indicative ATS layouts)
• TWC
• TWC + GPF
• TWC + LNT
• TWC + pSCR (p=passive)
• TWC + aSCR (a=active) + ASC
➢ Proposed options
o Option 1: Apply a global R, calculate global ageing time (AT)
o Option 2: Apply individual R and calculate individual AT for each after-treatment device
✓ The combination, the position and the order of the ATS vary significantly
✓ Since temperature (as well as concentrations of the various constituents in the exhaust gas) varies along the exhaust, e.g. great temperature difference between a close-coupled device and an underfloor one, Option 2 is more suitable for ATS consisted of various after-treatment devices.
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o Diesel engines (indicative ATS layouts)
• DOC + DPF + SCR
• DOC + DPF + SCR + ASC
• DOC + DPF + LNT
• DOC + DPF + SCR + LNT
• LNT + LNT + DPF
Current Procedure
➢ Type V test: Durability of Pollution Control Devices
Option 3: Assigned Detarioration Factors
3. Application of Assigned Deterioration Factors (ADF)
• The most preferred option by car manufacturers
• Important in order to comply with durability requirements at the Type Approval (TA) step and for all vehicles
16
Sources:1. Regulation 692/2008, 18
July 20082. Durability demonstration
procedures of emission control devices for Euro 6 vehicles, JRC, 2014
Source: Regulation No. 83, Revision 4, 26 April 2011
Current Procedure
➢ Type V test: Durability of Pollution Control Devices
Option 3: Assigned Detarioration Factors
3. Application of Assigned Deterioration Factors (ADF)
• However, application of DF may not ensure full compliance with the durability requirements, as it does
not incorporate the actual degradation rate
• Case A: High initial conversion efficiency with different cases of degradation rate – possibility of
noncompliance with durability requirements
• Case B: Low initial conversion efficiency, but final compliance with durability requirements
• Should the procedure to determine ADF be discussed?
17
Source: Durability demonstration procedures of emission control devices for Euro 6 vehicles, JRC, 2014
Sources
➢ Part A: Revision of the Durability procedure
Sources used
1. Regulation 83, Revision 4, 26 April 2011
2. Regulation 692/2008, 18 July 2008
3. Relevant procedure for the Heavy Duty vehicles – Regulation 2016/1718, 20 September 2016
4. A relevant report from JRC – Durability demonstration procedures of emission control devices for Euro 6 vehicles, JRC, 2014
5. Open literature
6. Any information/data from the experimental campaign that can provide input
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Contact
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Thank you for your attention
Athanasios (Thanasis) Dimaratos
+30 2310 996521
http://lat.eng.auth.gr