2. application areas
fuels conventional combustion products
srm suite
biofuels SI mode
automated model development
natural gas CI mode
turbulent combustion – CFD
advanced gasoline / diesel
how srm suite works
emissions advanced combustion CI mode
CO, uHC, CO2, NOx multiple direct injection SI mode
soot mass low temperature combustion
soot size / mass distributions HCCI software coupling
SI “downspeeding” / knock 3D CFD
1D cycle modelling
13. diesel combustion: emissions
where do the emissions
come from?
soot
on-going chemical kinetics
exhaust emissions
•regulated
•non-regulated
NOx
CO/uHCs •particulates
10 deg aTDC
23. SI combustion: emissions
where do the emissions
come from?
soot
chemical kinetics – on-going
computations
gas phase emissions
•regulated
•non-regulated
NOx
CO/uHCs particulates
10 deg aTDC (diesel)
25. 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.
29. emissions: uHCs and NOx
Euro V, NOx = 2000 mg/kWh
Multiple steady state operating points
Euro V = 0.46 g/kWh
Scania turbocharged truck engine
30. emissions: system level soot model
system level soot model
– a fast solution for soot mass predictions
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
31. emissions: system level soot model
0.2
Experiment
Model
example of model performance
0.16
Soot concentration [g/kW-hr]
0.12
0.08
0.04
0
1 2 3 4 5 6 7 8 9 10
Operating Point
49. real-time (RT) transient simulation
• Collaboration with
M. Sjöberg, J. Dec
• Studies of transient engine
operation, control, DOE, and
optimization involve simulations
over many cycles
• Problem: Computational
expense (1-2 hrs per cycle)
• Solution: Storage/retrieval
• Incorporate tabulation as
external cylinder model into
GT-Power
51. Load transients - RT
• Imposed equivalence
ratio profile
• PID controller changes
fuel composition
(octane number) such
that…
• … ignition timing
(CA50) is held at a
given set point.
52. transient RT: emissions
• Since SRM accounts for
inhomogeneities, turbulent
mixing, and detailed
chemical kinetics, can look
at…
• maximum pressure rise
rates,
• and emissions (e.g.)
misfire cycle
55. chemical kinetics and fuel modelling
“The implementation of detailed chemical kinetics is critical in
expanding the predictive capabilities of reactive flow modelling”
chemical fuel models
practical fuel modelling
emissions chemistry and validation
fuel models in srm suite: applications
58. 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
biofuels
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.
60. practical fuel modelling
(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
Conventional fuels
fuel blends
practical gasoline
ethanol/gasoline blending
biofuels & future fuels
61. practical fuel modelling: validation
Case 711 - Experiment (Surr. B) 100
Case 711 - Model (Surr. B) - 100pt
Case 710 - Experiment (Surr. A)
80
Case 710 - Model (Surr. A) - 100pt
Pressure [bar]
60
40
20
0
-40 -20 0 20 40
Crank Angle [deg. ]
validation of tri-component surrogate blends detailed modelling of practical fuels
range of engines 98.5RON/88MON gasoline
operating points Gasoline/ethanol blends
62. practical fuel modelling: application
Simulation of HCCI peak operating limit using SRM for fuel with/without octane sensitivity
64. soot precursors and validation
C10H8 C10H7 Na-Na
9.0E-2 8.0E-5 1.6E-5
6.0E-5 1.2E-5
6.0E-2
4.0E-5 8.0E-6
3.0E-2
2.0E-5 4.0E-6
Mole Fraction
0.0E+0 0.0E+0 0.0E+0
0 0.3 0.6 0.9 1.2 0 0.4 0.8 1.2 1.6 0 0.5 1 1.5
Perylene Benzo(ghi)Perylene Coronene
2.5E-6 6.0E-6 1.0E-5
2.0E-6 8.0E-6
4.0E-6
1.5E-6 6.0E-6
1.0E-6 4.0E-6
2.0E-6
5.0E-7 2.0E-6
0.0E+0 0.0E+0 0.0E+0
0 0.5 1 1.5 0 0.5 1 1.5 0 0.5 1 1.5
Height Above Burner (cm)
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
65. PAH reaction steps
Armchair ring growth 5-member ring desorption 6-member ring desorption
Free edge growth 5-member ring conversion at AC
5-member ring addition 6- to 5-member ring conversion
5-member ring free edge desorption
Oxidation steps: rates from
quantum chemistry
66. quantum calculations to reaction rates
electronic energy
geometry optimisation
rotational constants
vibrational frequencies
temperature variation of Cp, H, and S
transition state theory
kbT QTST
k (T ) exp( Eact / kbT )
h QAQB
