cmcl innovations
the application of our software tools
application areas
fuels
biofuels
natural gas
advanced gasoline / diesel
emissions
CO, uHC, CO2, NOx
soot mass
soot size / mass distributions
conventional combustion
SI mode
CI mode
advanced combustion
multiple direct injection
low temperature combustion
HCCI
SI “downspeeding” / knock
products
srm suite
automated model development
turbulent combustion – CFD
how srm suite works
CI mode
SI mode
software coupling
3D CFD
1D cycle modelling
diesel combustion modelling challenges
heat transfer
compression/expansion
mixture preparation/injection
combustion
premixed
premixed/mixing controlled
mixing controlled
emissions
compression/expansion
diesel combustion: compression
key processes
compression
heat transfer
mass loss/blow-by
mixture preparation
diesel combustion: mixture preparation
key processes
port injection
multiple direct injection
charge cooling
temperature stratification
mixture stratification
-30 CAD aTDC -10 CAD aTDC 0 CAD aTDC 10 CAD aTDC
20 CAD aTDC
30 CAD aTDC
(no combustion)
combustion
diesel combustion: pilot ignition
key processes
mixture preparation
chemical kinetics
TDC
diesel combustion: premixed/mixing controlled
10 deg aTDC
20 deg aTDC 30 deg aTDC
key processes
turbulent mixing
chemical kinetics / emissions formation
diesel combustion: mixing controlled
30 deg aTDC
50 deg aTDC
key processes
turbulent mixing
emissions formation
emissions
diesel combustion: emissions
10 deg aTDC
soot
NOx
CO/uHCs
where do the emissions come from?
on-going chemical kinetics
exhaust emissions
• regulated
• non-regulated
• particulates
spark ignition combustion mode
spark ignited combustion modelling challenges
heat transfer
compression/expansion
mixture preparation/injection
combustion
flame propagation
knock (pre-ignition)
emissions
mixture preparation
mixture preparation
key processes
port injection
multiple direct injection
charge cooling
temperature stratification
mixture stratification
-30 CAD aTDC -10 CAD aTDC 0 CAD aTDC 10 CAD aTDC
20 CAD aTDC
30 CAD aTDC
(no combustion)
combustion
ENTRAINED
BURNED
UNBURNED
SI modelling approach
SI combustion: flame propagation
key processes
mixture preparation
ignition
chemical kinetics
-20 CAD aTDC 0 CAD aTDC
10 CAD aTDC
SI combustion: knock
key processes
chemical kinetics
20 CAD aTDC 25 CAD aTDC
emissions
SI combustion: emissions
10 deg aTDC (diesel)
soot
NOx
CO/uHCs
where do the emissions come from?
chemical kinetics – on-going computations
gas phase emissions
• regulated
• non-regulated
particulates
advanced combustion mode
multiple direct injection
gasoline – fuel for advanced diesel engine ?
A 0.537 litre single cylinder diesel engine with a compression ratio of 15.8:1 operated using an 84 RON gasoline fuel.
Bosch injectors were adopted with seven holes of 0.13mm diameter. Single injection SOI =-11.2 CAD aTDC, Triple injections a) 25% SOI @ -180 CAD aTDC, b) 15% @ - 76 CAD aTDC and main @ -7 CAD aTDC.
multiple injection strategies
dp/dt [bar/CAD] burn duration [CAD]
NOx emissions [-]CO emissions [-]uHCs emissions [-]
~12 bar IMEP
advanced diesel combustion
JSAE 20077195
JSAE 20077195
Optimal second injection
Euro V, NOx = 2000 mg/kWh
Euro V = 0.46 g/kWh
Multiple steady state operating points
Scania turbocharged truck engine
emissions: uHCs and NOx
emissions: system level soot model
THE CHALLENGE
Predict soot emissions from typical diesel engine
THE SOLUTION
Optimise “Soot system level model” parameters from diesel engine DOE database
Use optimised parameters for predicting results
system level soot model – a fast solution for soot mass predictions
emissions: system level soot model
0
0.04
0.08
0.12
0.16
0.2
1 2 3 4 5 6 7 8 9 10
Operating Point
Soo
t con
cent
ratio
n [g
/kW
-hr]
ExperimentModel example of model performance
emissions: detailed soot model
Experiment Simulation
aggregate size distribution evolution
detailed soot size distribution: role of EGR
software coupling: 3D CFD codes
NO (ppm) CO (ppm) uHC (ppm) CO/CO2
Experiment 54.9 2673.0 190.0 0.21
CFD-SRM 65.5 2722.0 376.0 0.32
CFD 0.7 5225.0 2772.0 0.26
software coupling: 3D CFD codes
NOx [ppm]
CO [ppm]
uHC [ppm]
Open bowl 66 2720 376
Re-entry bowl 6 2480 580
Vertical side wall bowl
35 2450 482
KIVA-srm suite coupling
KIVA- 1 month, KIVA/srm suite – 8 hours + 1 hour
software coupling: 3D CFD codes
CO
HC
SI engine applications
GDI SI
Cycle to cycle variation (CCV) in SI engine.
srm suite: multi-cycle simulation
• srm suite coupled with GT-Power for multi-cycle simulation.
• 40 simulated and 200 experimental cycles.
• NOx emissions:
- 496 ppm simulation- 528 ppm experiment
SI “knocking” combustion
SI combustion: “downspeeding”
Intake pressure 2.2 bar, 1000rpm
retarded ignition
some cycles pre-ignited
oil-ignition was simulated
SI emissions
Soot in DISI operation
Optimisation of injection strategy
λ = 1.0EOI = -50 CAD ATDCSpark = -30 CAD ATDC
Late injection produces stratified mixture.
Fuel rich regions close to spark gap.
Soot in DISI operation
12.6 CAD ATDC 32.6 CAD ATDC2.6 CAD ATDC
detailed soot size distribution
experiment simulation
SI-CAI-SI transients: mode switching
tabulation - RT
• Problem: Computational expense (1-2 hrs per cycle)
• Studies of transient engine operation, control, DOE, and optimization involve simulations over many cycles
• Solution: Storage/retrieval
real-time (RT) transient simulation
• Incorporate tabulation as external cylinder model into GT-Power
• Collaboration with M. Sjöberg, J. Dec
• GT-Power engine map, with sensors and controller:
control application: fuel blending
Load transients - RT
• … ignition timing (CA50) is held at a given set point.
• Imposed equivalence ratio profile
• PID controller changes fuel composition (octane number) such that…
transient RT: emissions
misfire cycle
• maximum pressure rise rates,
• Since SRM accounts for inhomogeneities, turbulent mixing, and detailed chemical kinetics, can look at…
• and emissions (e.g.)
ENTRAINED
BURNED
UNBURNED
SI modelling approach
chemical kinetics and fuel modelling
chemical kinetics and fuel modelling
“The implementation of detailed chemical kinetics is critical inexpanding the predictive capabilities of reactive flow modelling”
chemical fuel models
practical fuel modelling
emissions chemistry and validation
fuel models in srm suite: applications
chemical fuel models
complexity of chemical kinetics
Law et al.
conventional and futuristic fuels
we have chemical fuel models for
Surrogate chemical kinetic models can be generated based on the Research Octane Number (RON)
and Motor Octane Numbers (MON) of the desired fuel
Detailed fuel models of conventional practical fuels such as gasoline and diesel
Reference fuels such as iso-octane, n-heptane, toluene, n-decane
Hydrogen, CNG, ethanol, methanol, bio-diesel
Future fuels and blended fuels such as dieseline, M85 and E85.
Conventional mechanism development for hydrocarbons and inorganic chemistry such as titania,
iron and silver chemistry.
biofuels
practical fuel modelling
practical fuel modelling
Conventional fuels
(a) Research Octane Number (RON)
(b) Octane "Sensitivity" (RON – MON)
Tri-component surrogate fuels increase the robustness of practical fuel modelling as fuel sensitivity can also be simulated
fuel blends practical gasoline ethanol/gasoline blending biofuels & future fuels
practical fuel modelling: validation
validation of tri-component surrogate blends
range of enginesoperating points
detailed modelling of practical fuels
98.5RON/88MON gasolineGasoline/ethanol blends
0
20
40
60
80
100
-40 -20 0 20 40Crank Angle [deg. ]
Pres
sure
[bar
]
Case 711 - Experiment (Surr. B)
Case 711 - Model (Surr. B) - 100pt
Case 710 - Experiment (Surr. A)
Case 710 - Model (Surr. A) - 100pt
practical fuel modelling: application
(a) Turbocharged (with intercooling) limit
(b) Naturally aspirated limit
Simulation of HCCI peak operating limit using SRM for fuel with/without octane sensitivity
emissions chemistry and validation
soot precursors and validation
soot chemistry includes a variety of unsaturated HCs and PAHs
interaction of soot chemistry with the gas phase chemistry
validation carried out in fuel-rich flame and engine experiments
C10H8
0.0E+0
3.0E-2
6.0E-2
9.0E-2
0 0.3 0.6 0.9 1.2
C10H7
0.0E+0
2.0E-5
4.0E-5
6.0E-5
8.0E-5
0 0.4 0.8 1.2 1.6
Na-Na
0.0E+0
4.0E-6
8.0E-6
1.2E-5
1.6E-5
0 0.5 1 1.5
Perylene
0.0E+0
5.0E-7
1.0E-6
1.5E-6
2.0E-6
2.5E-6
0 0.5 1 1.5
Benzo(ghi)Perylene
0.0E+0
2.0E-6
4.0E-6
6.0E-6
0 0.5 1 1.5
Coronene
0.0E+0
2.0E-6
4.0E-6
6.0E-6
8.0E-6
1.0E-5
0 0.5 1 1.5
Mol
e F
ract
ion
Height Above Burner (cm)
Armchair ring growth
Free edge growth
5-member ring addition
5-member ring desorption
5-member ring free edge desorption
5-member ring conversion at AC
6- to 5-member ring conversion
6-member ring desorption
Oxidation steps: rates from quantum chemistry
PAH reaction steps
electronic energy
geometry optimisation
rotational constants
vibrational frequencies
temperature variation of Cp, H, and S
transition state theory
)/exp()( TkEQQ
Q
h
TkTk bact
BA
TSTb
quantum calculations to reaction rates
fuel models in srm suite: applications
chemical model: 208 species, 1002 reversible reactions
Soot composition and size distribution
recirculated aggregates
fuel reformed hydrogen gas
HRG added to gasoline
DEE/EtOH blending
Point with optimal HC emissions recommended to test cell engineers
CNG with EGR
2 106
3 106
4 106
5 106
6 106
-30 -20 -10 0 10 20 30
ModelExptl.
p [
Pa
]
CAD
1.5 106
2 106
2.5 106
3 106
3.5 106
4 106
4.5 106
5 106
-30 -20 -10 0 10 20 30
Model
Exptl.
p [
Pa]
CAD
Cooled eEGR [27-51%]Volvo TD 100-series diesel engineFuel: CNG
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