f. bozza m.c. cameretti a. senatore r. tuccillo dipartimento di ingegneria meccanica per...
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F. Bozza M.C. Cameretti
A. Senatore R. Tuccillo
Dipartimento di Ingegneria Meccanica
per l’Energetica (D.I.M.E.)
Università di Napoli “Federico II”
Naples, Italy
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Engine TurboDieselFIAT 154 D1.000
Total Displacement andCompression Ratio
1929 cm3
19.5
Fuelling Direct Mech. Injection
Characteristics EGR, Electronic Control
Bore x Stroke 82.6 mm x 90.0 mm
Turbocharger Intercooled compressionVariable Nozzle Turbine
Engine Specifications
Tuccillo et al., SAE p. 932459, Jrl. of Engines -Vol.102, 1993 Bozza et al., Jrl. of POLISH CIMAC, Vol. 2, n. 1, 1996 Bozza et al., SAE p. 970057, SAE SP1255
Author’s background:
The behavior of a light-duty Turbocharged Diesel Engine is analyzed by means of:
Experimental activities Numerical simulation
C4 C3 C2 C1
CT
IC
EGR
ExhaustAir
A1
A2 A4 A6A3 A5 A7
E6E4E2
E3 E5
E7
E1 E8
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 2 of 25
To improve the understanding of unsteady engine operation by looking at in-cylinder details and to the whole system behavior
A fully theoretical prediction of EGR influence on both engine performance and NOx emissions
An integrated computational procedure: A Flow Model (1D TVD approach) A Combustion Model (KIVA II code)
allows the desired characterization of the Turbocharged engine operation
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 3 of 25
A first characterization of the tested engine through the acquisition of:
Time-average and instantaneous data Performance and emission parameters
In-cylinder multidimensional analysis: Improved KIVA II code normal and EGR operation different Load conditions
Whole system simulation with EGR : 1D Flow Model in external ducts Turbocharger equilibrium computation
In-cylinder analysis is then improved at the updated operating conditions
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 4 of 25
Experimental Equipment
Experimental tests were carried out at constant speed operation (3000 rpm)
Both time-averaged and instantaneous data are acquired:
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 5 of 25
Equivalence Ratio
Torque
Power
Spec. Fuel Cons.
CO2
O2
CO
NOx
Exhaust Gas composition analysis
Performance Data
Equivalence Ratio Equivalence Ratio
3000 rpm
[kW
]
O2 [
g/kW
h]
g/kW
h[N
m]
CO
2 [g/
kWh]
NO
X [
g/kW
h]
CO
[g/
kWh]
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 6 of 25
Exhaust
Cylinder
Intake Plenum
Intake Duct
Eq.Ratio 0.31Load 34%
(a)
Injection pressure
Needle Lift
Eq.Ratio 0.31Load 34%
(d)
Pre
ssur
e, b
ar
Crank Angle, deg
Pre
ssur
e, b
ar
Crank Angle, deg
Lif
t [%
]
Equivalence Ratio 0.31 - 34% Load
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 7 of 25
Equivalence Ratio 0.45 - 65% LoadP
ress
ure,
bar
Crank Angle, deg
Pre
ssur
e, b
ar
Crank Angle, deg
Exhaust
Cylinder
Intake Plenum
Intake Duct
Eq.Ratio 0.45Load 65%
(b)
Injection pressure
Needle Lift
Eq.Ratio 0.45Load 65%
(e)L
ift [
%]
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 8 of 25
Pre
ssur
e, b
ar
Crank Angle, deg
Pre
ssur
e, b
ar
Crank Angle, deg
Exhaust
Cylinder
Intake Plenum
Intake Duct
Eq.Ratio 0.63Full Load
(c)
Injection pressure
Needle Lift
Eq.Ratio 0.63Full Load
(f)L
ift [
%]
Equivalence Ratio 0.63 - Full Load
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 9 of 25
fDinj
pCV
2
Ninjff AVm
inj
dmm ff )(
maxmax
L
LDD z
zCC
A velocity profile is computed employing experimental data on Needle Lift and Injection Pressure:
Improvements in multidimensional calculations were obtained on:
Fuel injection process simulation Ignition delay calculation Thermal NO formation kinetics
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 10 of 25
Full Load
81%
65%
44%
34%
24%
Exp. LevelsTheor. profiles
Full Load81%65%44%34%24%
Crank Angle, deg
Crank Angle, deg
Inje
cted
Fue
l Vel
ocit
y, m
/sIn
ject
ed F
uel M
ass,
g
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 11 of 25
Tp
TRE
pA Anid
5473exp 0405.0exp 757.0
The correlation of Stringer et al. holds in a pressure and temperature range close to that of the tested Turbocharged engine:
The original algorithm of solution was replaced by the sequential solution of the extended Zel’dovich kinetics equations:
)/23650exp(100.2
101.4 )3
)/19500exp(105.1
)/3150exp(104.6 )2
106.1
)/38000exp(106.7 )1
143
133
92
92
2
131
131
2
Tk
kHNOOHN
TTk
TTkONOON
k
TkNNONO
b
f
b
f
b
f
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 12 of 25
)7, ... ,1 = (
3
1
7
1
7
1
~~ ,,i
k jjfb
jjfk
i jkbjkf xkxkdtdx
)~()1()( ~ ttxtxx jjj
A predictor-corrector method was employed with an automatic reduction of the time step:
A constant temperature test demonstrates the absence of fluctuations up to the NO equilibrium level:
1 E -8 1 E -7 1 E -6 1 E -5 1 E -4 1 E -3 1 E -2 0 .1 1
3
3
3
3
3
1
1 0
10 0
1 00 0
1 00 0 0
1500 K
17502000225025002750
ChemicalEquilibrium
Time, s
[NO]p.p.m.
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 13 of 25
A relevant increase of computational time!
Full Load81%65%44%34%
Full Load81%65%44%34%
Crank Angle, deg
Crank Angle, deg
Pre
ssur
e, b
arT
empe
ratu
re, K
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 14 of 25
Normal Operation(No EGR)
Full Load81%65%44%34%
Full Load81%65%44%34%
Crank Angle, deg
Crank Angle, deg
Fue
l Bur
ned
Fra
ctio
n[N
O],
p.p
.m.
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 15 of 25
Full Load
No EGR
7% EGR
12% EGR
Full Load
No EGR
7% EGR
12% EGR
Crank Angle, deg
Crank Angle, deg
Pre
ssur
e, b
arT
empe
ratu
re, K
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 16 of 25
Full Load No EGR
7% EGR
12% EGR
Full Load
No EGR
7% EGR
12% EGR
Crank Angle, deg
Crank Angle, deg
Fue
l Bur
ning
Rat
e, 1
/deg
[NO
], p
.p.m
.
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 17 of 25
81% Load
No EGR
7% EGR
81% Load
No EGR
7% EGR
Crank Angle, deg
Crank Angle, deg
Fue
l Bur
ning
Rat
e, 1
/deg
[NO
], p
.p.m
.
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 18 of 25
0
10 00
20 00
30 00
40 00
50 00
60 00
NO EGR
12% EGR
7% EGR
NO Levelsp.p.m.
Full Load
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 19 of 25
10° aTDC
Initial conditions at IVC exert a great influence on start of combustion, burning rate profile and emission characteristics
Moreover, the EGR amount is itself unknown!
The interaction between the in-cylinder processes, external flows and turbocharger operation imposes to analyze the system as a whole
Variations at IVC are induced by EGR as a consequence of different engine and turbocharger matching conditions
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 20 of 25
An integrated data exchange procedure between a 1D Model and KIVA code has been developed:
Initial P,T,m,EGR at IVC KIVA
Theor.Heat Release
1D Flow
Updated Conditions at IVC
?
ConvergedConverged
Theoretical ROHR and wall heat transfer are derived from KIVA calculation:
dt
dhm
d
dhm
dt
d
d
dmLHV
ns
s
oss
of
injf
cmbf
1
)()(
dATThQ wcw )(
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 21 of 25
• 2nd Order, Finite Volume upwind scheme• Total Variation Diminishing (TVD) Technique
ICE97
C4 C3 C2 C1
CT
IC
EGR
ExhaustAir
A1
A2 A4 A6A3 A5 A7
E6E4E2
E3 E5
E7
E1 E8
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 22 of 25
Scalar transport eqs. of residual, xr, and fuel, xf , gas fractions for the evaluation of a correct gas composition with EGR active
Full Load
Original InitialConditionsUpdated InitialConditions
No EGR
12% EGR
12% EGR
Crank Angle, deg
Pre
ssur
e, b
arT
empe
ratu
re, K
NORMAL
OPERATION
EGRACTIVE
Turboch. Speed, rpm 124000 114500Boost pressure ratio 1.77 1.67Air flow rate, kg/h 266.8 215.4Cyl. Temp. at IVC, K 417.6 447.4Cyl. Press. at IVC, bar 2.42 2.32Residual Fraction, % 4.56 15.0Air / Fuel Ratio 21.9 17.7
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 23 of 25
Crank Angle, deg
Crank Angle, deg
Crank Angle, deg
Fue
l Bur
ning
Rat
e, 1
/deg
[NO
], p
.p.m
.
Full Load
Original InitialConditionsUpdated InitialConditions
No EGR
12% EGR
12% EGR
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 24 of 25
Main results found:
Future work:assessment of the methodology and improvement of 1D e 3D models for a more direct comparison with experimental data.
The integrated computational procedure between: A Flow Model (1D TVD approach) A Combustion Model (KIVA II code)
together with experimental data, allows to fully characterize the Turbocharged engine under EGR operation.
Appropriate initial conditions are of fundamental importance for realistic evaluations of in-cylinder phenomena
33rdrd International Conference : Experiments and Modeling International Conference : Experiments and ModelingConsiglio Nazionale delle Ricerche Consiglio Nazionale delle Ricerche Istituto MotoriIstituto Motori
ICE97
Bozza F., et al., DIME, University of Naples, ITALYA Flow and Combustion Model for NOX …, p. 25 of 25