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