F. Bozza M.C. Cameretti A. Senatore R. Tuccillo Dipartimento di Ingegneria Meccanica per...

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


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


ICE97


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


ICE97


Experimental Equipment

Experimental tests were carried out at constant speed operation (3000 rpm)

Both time-averaged and instantaneous data are acquired:


ICE97


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]


ICE97


Exhaust

Cylinder

Intake Plenum

Intake Duct

Eq.Ratio 0.31Load 34%

(a)

Injection pressure

Needle Lift


(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


ICE97


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


(b)

Injection pressure

Needle Lift


(e)L

ift [

%]


ICE97


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


ICE97


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


ICE97


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


ICE97


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


ICE97


)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.


ICE97


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


ICE97


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.


ICE97


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


ICE97


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

.


ICE97


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

.


ICE97


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


ICE97


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


ICE97


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 )(


ICE97


• 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


ICE97


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


ICE97


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


ICE97


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


ICE97


Date post:	31-Mar-2015
Category:	Documents
Upload:	prince-howett
View:	212 times
Download:	0 times

F. Bozza M.C. Cameretti A. Senatore R. Tuccillo Dipartimento di Ingegneria Meccanica per...

Documents