Turbochargers at the edge of a new generation – Prof. Dr ...isromac-isimet.univ-lille1.fr/upload_dir/finalpaper/167.finalpaper.pdf · Turbochargers at the edge of a new generation

Technische Universität Berlin FG Verbrennungskraftmaschinen

Turbochargers at the edge of a new generation – a discussion of potentials and limits Prof. Dr.-Ing. Roland Baar

Honolulu, 11.04.2016

2 FG Verbrennungskraftmaschinen

Fuel consumption potentials in a passenger car

example: Diesel car 1.700 kg, Euro6 potential 20% fuel consumption

start-stop and recuperation

downspeeding downsizing

turbocharger- optimizaition

reduction of friction

thermo mana gement

1% 1% 1%

5%

2%

10%

(Quelle: Bosch 2010)

vehicle !  weight !  aerodynamics !  wheel friction powertrain !  gear !  start-Stop !  hybrid engine !  downsizing !  thermodynamics !  friction !  ancillary unit energy management

Potentials and limits of turbochargers | Prof. Dr.-Ing. Roland Baar | 04-2016


Boosting technologies DWL Druckwellenlader / Comprex K Kompressor / Compressor V Strömungsverdichter / Turbo compressor T Turbine / Turbine

K

LLK

M

c) Compressor

V T

LLK

M

d) Turbocharger a) Natural

VOL

SR

M

LLK

M

b) Comprex

DWL



Engine comparison Pass.car Otto Pass.car Diesel Truck Diesel

17,6



Engine comparison - Specific fuel consuption [g/kWh]

Pass.car Otto Pass.car Diesel Truck Diesel



Engine comparison - Lambda [-]




Engine comparison – boost pressure p2/p1 [-]




Engine comparison – exhaust temperature T3 [°C]




a) Passenger car (Gasoline) b) Commercial vehicle (Diesel)

redu

zier

ter T

urbi

nenm

asse

n-st

rom

[kg*

K^0

,5/(s

*bar

)]

0.00.20.40.60.81.01.21.41.61.82.0

totales Turbinendruckverh‰ltnis [-]1.0 1.5 2.0 2.5 3.0 redu

zier

ter T

urbi

nenm

asse

n-

stro

m [k

g*K

^0,5

/(s*b

ar)]

1.01.21.41.61.82.02.22.42.62.83.0

totales Turbinendruckverh‰ltnis [-]1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Totales Turbinendruckverhältnis [-] Totales Turbinendruckverhältnis [-]

WG controll



Turbocharger, HP- & LP-EGR


12 Fachgebiet Verbrennungskraftmaschinen

HP- & LP-EGR

Que

lle: I

AV, H

TT



MK

Z [

kg/s

• K

0.5 /

bar]

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

∏ T,tot/st [-]1 2 3 4

∏ C

,tot

[-]

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

m• C,red [kg/s]0.0 0.1 0.2 0.3 0.4

0.74

Effects of downsizing – map width compressor of basic engine - reference

R6 6,6l – 220 kW- basic singelstage / wastegate / pulse pressure charging GT-Power simulation

Source: Baar (Voith), IQPC 2011, Downsizing & Turbocharging Concepts



∏ C

,tot

[-]

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

m• C,red [kg/s]0.0 0.1 0.2 0.3 0.4

0.74

MK

Z [

kg/s

• K

0.5 /

bar]

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

∏ T,tot/st [-]1 2 3 4

Effects of downsizing – map width compressor of downsized engine

R4 4,5l – 220kW singelstage / VTG („large�) / constant pressure charging - simulation critical surge and speed limit




Low Pressure Turbine

High Pressure Turbine

MK

Z [

kg/s

• K

0.5 /

bar]

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

∏ T,tot/st [-]1 2 3 4

∏ C

,tot

[-]

1.0

1.5

2.0

2.5

3.0

3.5

4.0

m• C,red [kg/s]0.0 0.1 0.2 0.3 0.4

0.770.73

Low Pressure Compressor

High Pressure Compressor

Effects of downsizing – map width compressor downsized engine

R4 4,5l – 220kW twostage / 1 wastegate / constant pressure charging – simulation reduced load



twostage


Specific load

fuel: 269 kW

engine out: 100kW 37%

ambient heat: 92kW 34%

turbine: 16kW 6%

rest exhaust: 61kW 23%

Pcompressor

Pengine

1

7

14 kW

100 kW = =

nTC

nengine

45

1

180000 min-1

4000 min-1 = =

mTC

mengine

1

21

8 kg

170 kg = =

Power/mass-ratio: engine: 0,59 kW/kg TC: 1,75 kW/kg

x 3



Specific load

Que

lle: I

CS

I

turbine power 25000 W

tip speed 580 m/s = 2088 km/h

Centrifugal force at turbine blade appr. 19000 N

Molecular residence time < 2ms

~130 mm



Market development



!  exploded market

!  increased number of suppliers

!  maximum number of variants due to power an package demands

!  high specific load

!  difference in applications

!  meaning for engine themodynamics

!  quality demands

world market

0"

10"

20"

30"

40"

50"

60"

70"

1940" 1960" 1980" 2000" 2020"

0,01"

0,1"

1"

10"

100"

1940" 1960" 1980" 2000" 2020"

Ein

heite

n [M

io. T

C/ a

]

Market development



1989 Start TDI

2000 10 Mio / a wolrd production

1999 Inhouse VW (til 2004) J/V Daimler IHI (til2013)

2005 Start Bosch, Mahle, Continental

2002 Competence team BMW

1998 Competence team Daimler

2011 Competence team VW

2012 SOP BoschMahle, Continental

Competence development

1982 Inhouse Toyota (70%)

1978 1. Diesel-car with TC (Mercedes 300 SD)

196x 1. Otto-car with TC (USA)

bis 2000 Market dominance Garrett (HTT), KKK (BWTS)

ab 2000 Intensification IHI, MHI

OE

M-a

ctiv

ities

TIE

R1-

activ

ities



Market development Market share 2007 world 17 Mio.

HTT: Honeywell Turbo Technology BWTS: BorgWarner Turbosystems ICSI: IHI Chargingsystems International MHI Mitsibishi Heavy Industries CTT: Cummins Turbo Technologies BMTS:Bosch Mahle TurboSystems Continental

HTT"36%"

BWTS"32%"

MHI"13%"

ICSI"10%"

CTT"7%"

HTT""30%"

BWTS""24%"

MHI""14%"

ICSI"12%"

CTT""7%"

BMTS"5%"

Con89nental"4%"

Sons8ge"4%"

Market share2015 world 50 Mio.


22 Department of Internal Combustion Engines 22 Potentials and limits of turbochargers | Prof. Dr.-Ing. Roland Baar | 04-2016

Comparison of advanced technologies


Solutions Turbocharger technologies


0

200

400

600

800

1000

1200

0 500 1000 1500

GMR235 713C MAR247 Titanaluminid

redu

zier

ter T

urbi

nenm

asse

n-st

rom

[kg*

K^0

,5/(s

*bar

)]

0.00.20.40.60.81.01.21.41.61.82.0

totales Turbinendruckverh‰ltnis [-]1.0 1.5 2.0 2.5 3.0 re

duzi

erte

r Tur

bine

nmas

sen-

st

rom

[kg*

K^0

,5/(s

*bar

)]

1.01.21.41.61.82.02.22.42.62.83.0

totales Turbinendruckverh‰ltnis [-]1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

V T

V T

Turbolader (Hochdruck-

stufe) mit Regelklappe

Turbolader (Niederdruck-

stufe)

Ball bearing Titanium-Aluminide

Mixedflow- axial-turbine

E-Turbo WG

twostage VTG

sour

ces:

Dai

mle

r, H

TT, V

aleo

Mass production Specific applications Future potential

Efficiency and transient response


Transient response Different measure

measures to improve transient response with similar effectiveness !  different level of availability !  other effects (efficiency) !  unclear interaction

electric ball titanium- axial booster bearing aluminide TW TW –

0

200

400

600

800

1000

1200

0 500 1000 1500



Advanced development tools needed !  Heat transfer (turbocharger) !  Friction losses (turbocharger)

!  Cycle simulation (engine process) !  Energy management (engine process)


Electrically assisted turbocharger

Characteristics •  integrated motor-generator •  external power electronics •  cooling with oil and/or

water •  eventually cooling with

compressor air

pros and cons +  transient boost +  package (only small

increase of turbo size) +  cold start emissions +  energy recovery -  2-3 kW electric power -  temperature sensible -  surge of compressor -  only transient operation

V T

LLK

M

E-Motor

source: ICSI



Electric booster plus turbocharger

V T

LLK B

ypas

s

E-Motor

V

source: Valeo

Characteristics •  separate component •  two compressors in series •  integrated power

electronics •  cooling with oil and/or

water •  turbocharger without

change

pros and cons +  transient boost +  package (freedom of

placement) +  cold start emissions +  energy recovery -  2-3 kW electric power -  temperature sensible -  additional bypass -  only transient operation



Electric booster Transient response

2.0l 110kW Diesel engine EU5 load step at 1250 1/min GT-Power-simulation Phase I !  torque increase similar to

naturally aspirated engine

Phase II !  influence of boosting

with / without electric booster in series setup

!  time improvement to Mmax: 1,5 s

!  influence reduced with increasing speed

1,0

1,2

1,4

1,6

1,8

2,0

2,2

2,4

2,6

2,8

3,0

0

50

100

150

200

250

300

0,0 1,0 2,0 3,0 4,0 5,0 6,0 7,0 8,0 9,0 10,0

Lade

druc

k [b

ar]

Dre

hmom

ent [

Nm

]

Zeit [s]

I II !

troque

boost pressure

Electric booster

off on

1,4s

torq

ue

boos

t pre

ssur

e

time Potentials and limits of turbochargers | Prof. Dr.-Ing. Roland Baar | 04-2016


Electric booster Component testing


Impe

ller s

peed

[rpm

]

0

20000

40000

60000

80000

100000

time [s]0 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00

Current supply [A] Impeller speed [rpm] compressor pressure ratio [-]

nstart= 10.000 min-1

nend= 67.000 min-1

Πstart= 1.0Πend= 1.2

Current supply [A] Impeller speed [rpm] compressor pressure ratio [-]

nend= 80.000 min-1

Πend= 1.3

Current supplystart= 0,977 A Cur

rent

sup

ply

[A]

0

50

100

150

200

250

0.30 0.5

1.2

1.3


Electric booster Potential assessment


!  Development since 15 years, still no mass product, announced SOP at AUDI in 2016

!  Competence mainly electrics / electronics !  Problem of availability of electric energy !  Voltage drop may be risks for ECU supply !  CO2 effect combined only in strong downsizing /

downspeeding concepts for transient compensation

!  Very diverse opinions about mass production !  Will probably remain niche product (e.g. high specific engine

power)


Ballbearing

Materials: !  High temperatur resistent, coated

steel !  Ceramic (balls)

Sou

rce:

Dai

mle

r

!  First SOP at Daimler in 2010 6-Cylinder Diesel engine

!  SOP at BMW in 2014 !  Audi rejected SOP after 2

postponements in 2011


31 FG Verbrennungskraftmaschinen 31

Motivation –  less friction losses –  better efficiency –  better transient response

Challenges !  max speed !  durability !  acoustics (especially in cold

conditions)

Potentials (as of TC supplier) !  TC efficiency: +5% !  time to 90% torque: 60% !  boost pressure at 1500 rpm:

+130mbar

Source: BMTS

Ballbearing



Ballbearing Potential for transient response

Sou

rce:

Hon

eyw

ell /

IAV



full floating bearing ball bearing

-10�C

+80�C

engine test bench idle to full load variation of oil temp. frequency analysis of vibration signal

Ballbearing



Ballbearing Potential assessment


!  Development since more 25 years, first series applications in passenger cars

!  Different problems, mainly acoustics and costs !  Few suppliers !  Potential for CO2 reduction and transient response in all

turbochargers if successfully realized


VTG in gasoline applications

Porsche 911 Turbo 3,6l 353 kW 620/(680) Nm (Boxer-engine)

0 1000 2000 3000 4000 5000 6000 7000

400

500

600

700

200

250

300

350

torq

ue [N

m]

pow

er [k

W]

speed [1/min]

Overboost

Chalenges !  Exhaust temperature !  Costs

sour

ce; P

orsc

he



VTG in gasoline engines Potential assessment


!  Development since more 25 years, first series applications in passenger cars

!  Effects on controllability, accuracy, lambda control, ... !  Different problems, mainly durability, reliability and costs !  Chance through water cooling (instead of fuel enrichment) !  Potential for CO2 reduction, emissions reduction and

transient response in all turbochargers if successfully realized


Titanaluminid for the turbine wheel

0

200

400

600

800

1000

1200

0 500 1000 1500


tens

ile s

treng

th R

m in

MP

a

temperatur in °C

Potential !  lower inertia !  eventually higher may

speed Challenges •  industrial availably •  raw material price •  material specific design •  unknown LCF und HCF •  welding of shaft an wheel •  machining



Titanaluminid for the turbine wheel Potential assessment


!  New alloy, first series applications in gasturbines and passenger cars; recent failure in passenger car mass production

!  Effects on inertia !  Unclear long-term behaviour (e.g. oxidation) !  Different problems, mainly machining, welding and costs !  Potential for transient response only


Axial turbine

Potential !  better matching with

compressor (efficiency) !  lower interia (transient

respone) Challenges •  reduced turbine power •  thrust load on bearing

increased •  little advantage (see above) •  more complex casting •  VTG more complex

Radial turbine Mixed flow turbine Axial turbine

sour

ce; H

oney

wel

l



Axial turbine Potential assessment


!  State of the art technology in gasturbines !  Effects on inertia !  Different problems, little advantage !  Potential for transient response only


Variable compressor

Potential !  extend surge line / map

width !  apply operation to areas of

good compressor efficiency Challenges •  complexity •  limited use

sour

ce; I

AV /

VW



Variable compressor Potential assessment


!  Development since 10 years, still research !  Effects on compressor map width, eventually transient

response !  Different problems, little advantage !  Potential only in niche product (e.g. high specific engine

power)


Passenger cars Turbocharger demands & technologies


level of relevanz WG VTG two-stage

e-turbo

ball bear.

TiAl axial turb.

var. compr

efficiency

boost pressure

operation range

transient response

controllability

durability

noise


Engine process simulation

FG Verbrennungskraftmaschinen Potentials and limits of turbochargers | Prof. Dr.-Ing. Roland Baar | 04-2016

Hybrid powertrain

clutch gear differential

Driving profile (vSoll))

Pedals

VM

Wheel Vehicle

Pedal position comparing vIst / vSoll

Vehicle data - mFzg - cW • A - etc. vIst

Pedal position

nAntr MAntr

vIst

Gear selection

nM

EM Powertrain

nM Md

nM Md + MEM

Battery Pel

Powertrain manager

Driver incl. gear change

strategies

FG Verbrennungskraftmaschinen Potentials and limits of turbochargers | Prof. Dr.-Ing. Roland Baar | 04-2016

mLΔhV .

mAΔhT .

Hybrid powertrain Extension of degree of freedom of supercharging

clutch / gear / differential

VM

nAntr MAntr

Gear selection

EM Powertrain

nM Md

nM Md + MEM

Battery Pel

Boosting system (incl. compound)

Pel

Pmech

56 FG Verbrennungskraftmaschinen Potentials and limits of turbochargers | Prof. Dr.-Ing. Roland Baar | 04-2016

Heat-up performance RDE time scale

Turbulence 0,0000005 s

Blade passing 0,00005 s

Engine pulsation 0,005 s

Load step 5 s

Cycle 5000 s

time scale issue ▶  models and

simplification necessary


Cycle analysis NEDC G

esch

win

digk

eit [

km/h

]

0

20

40

60

80

100

120

140

Zeit [s]0 200 400 600 800 1000 1200

Geschwindigkeit NEDC Beschleunigungsbereich Bereich konstanter Fahrt Bremsbereich Stillstandsbereich Restlicher Bereich


Comparison WLTC / NEDC

WLTC NEDC

Duration 1800 s 1180 s Ø speed 46,5 km/h 33,6 km/h Max. acceleration 1,7 m/s² 1,0 m/s² Max. deceleration -1,5 m/s² -1,4 m/s² Standstill 231 s 267 s Number of accelerations 32 (381 s) 31 (278 s) Number of decelerations 46 (622 s) 18 (204 s) Number of stationary operations 44 (350 s) 24 (431 s) Rest 216 s 15 s


Cycle simplification Definition of representative load change collective

stationary

transient

Examine / develop possibilities in simulation

Definition of criteria for delimitation stationary / transient operation

Model assumptions: stationary operation

Reality: Quasi-stationary operation

Consumption (CO2), emissions (measurable variables (PST))

vs.

NEFZ

RDE

X

Transientfactor

Representative load changes

10 x 5 x +

Correction factor


Current turbocharger model based on SAE922


Thermodynamics Mechanics

61

Turbocharger



Compressor map

•  Relation of and

•  Compressor air mass flow

with

•  Normalised compressor air mass flow

0,Vm!tV ,π

ref

t

t

refVV T

Tpp

mm ,1

,10, ⋅⋅= !!

0

02TRppAm ev ⋅

⋅Δ⋅⋅⋅⋅= εα!

ττ

κτκ

εκκ

κ

−

−⋅

−

⋅=

−

11

1

12

kritV ππ ≤

skgin

skgin

0

0

ppp Δ−

=τ



Compressor map • Total absolute pressure

• Density

• Velocity

• Compressor pressure ratio

2,1

2,12,1 TR

p⋅

=ρ

2,12,12,1 A

mc v

⋅=ρ!

2

22,1

2,12,12,1

cpp tt ⋅+= ρ

t

ttV pp

,1

,2, =π

defines the ratio of total absolute pressure at compressor outlet to total absolute pressure at compressor inlet

tV ,π

static + dynamic part 2s



Compressor map

Turbocharger Measurement Technology | KTH Stockholm 2013 | September 2013

• Isentropic compressor efficiency

κκ

π1

,,1,2 )(−

⋅= tVtts TT

Assumed:

•  Adiabatic compression

•  Mean values of in temperature range R,κ

tV

V

tt

ttssV h

Yhhhh

,,1,2

,1,2

Δ=

−

−=η

2s



Turbine map • Represents steady state operation

• Reduced turbine air mass flow

• Density

• Velocity

• Total absolute pressure at turbine inlet

• Turbine pressure ratio

t

tTredT p

Tmm

,3

,3, ⋅= !!

2

23

333cpp t ⋅+= ρ

4

,3

pp t

T =π

3

33 TR

p⋅

=ρ

333 A

mc T

⋅=ρ!



Turbine map

Turbocharger Measurement Technology | KTH Stockholm 2013 | September 2013

•  Turbocharger power balance

•  Turbocharger efficiency

•  Turbine efficiency

sV

TL

tT

ttsV

sVmsTT hhm

hhmηη

ηηηη =

−⋅

−⋅⋅=⋅=

)()(1

43

1,2

!!

sT

sV

tT

ttsVmsTsVTL P

Phhmhhm

=−⋅

−⋅=⋅⋅=

)()(

43

1,2

!!

ηηηη

msTtTsV

ttsV hhmhhm ηηη

⋅⋅−⋅=⋅−⋅ )(1)( 43,1,2 !!

Assumed:

•  turbocharger mechanical losses are assigned to the turbine )( mηPotentials and limits of turbochargers | Prof. Dr.-Ing. Roland Baar | 04-2016


Modeling in engine process simulation Comparison cylinder - turbocharger

Heat transfer

Combustion

Wall temperature

Friction

Cylinder Turbocharger

Aerodynamics

Heat transfer

Pulsation

Friction

Model extension requirement


Advanced turbocharger model


a)  Pulsation

Problem: engine process simulation uses steady state maps in transient cycle simulation


Simulation CFD Pulse Simulation

•  Separation in volute and turbine wheel by using different evaluation planes

•  Mass flow in volute is following a loop around the steady state results due to storage effects

•  Loop size widens with higher pulse frequency

•  The turbine wheel does not exhibit this behavior

•  Major effect on isentropic efficiency that leads to (physically impossible) values greater one

filling

emptying


Simulation 1-D Pulse Simulation Volute and wheel separated

MF

P [k

g*(K

^0.5

)/(s

*bar

)]

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

turbine pressure ratio ΠT_tt [-]1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2

mturbine;standard mturbine; ideal volute mturbine,volute sparation

mturbine;standard,MW mturbine; ideal volute,MW mturbine;volute sparation;MW

•  Pulse simulation with different amplitudes and frequencies

•  Volute approaches small show differences in their loops

•  Average values are identical •  Increased amplitude has no

additional effect towards mean values


Simulation 1-D Pulse Simulation Volute and wheel separated

turb

ine

effic

ienc

y η

T [-

]

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

turbine pressure ratio ΠT_tt [-]1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2

ηturbine;classic ηturbine;Chen ηturbine,VS

ηturbine;classic,MW ηturbine;Chen,MW ηturbine;VS;MW

mturbine;standard mturbine; ideal volute mturbine,volute sparation

mturbine;standard,MW mturbine; ideal volute,MW mturbine;volute sparation;MW

Difference in efficiency 3 %p.

•  Efficiencies show characterisitic loops

•  Average values for volute approaches are similar – standard approach deviates

•  Increased amplitude has no additional effect towards mean values


b) heat transfer and T4

Problem: heat losses in turbine influence turbine efficiency inhomogeneous outlet temperature does generally not allow to compute isentropic turbine efficiency

74 Department of Internal Combustion Engines

Heat-transfer in a turbocharger


Experiment (diabatic) Simulation (adiabatic)

Turbine Compressor

outTH ,!

TP CP

inCH ,!

outCH ,!

inTH ,!

System boundary

Turbine Bearing Compressor

outTH ,!

TP FrP CP

inCH ,!

outOilH ,!

inOilH ,!

outCH ,!

TQ! CQ!

inTH ,!

System boundary

CTH →!

OilTH →!


!  Compressor

Turbocharger performance map


isen

tropi

c co

mpr

esso

r effi

cien

cy η

C,is

[-]

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75

corrected mass flow ṁC,0 [kg/s]0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18

40000

100000

nTC, corr=160000 min-1

Exp. T3=600°C, TOil=90°CTRef=298KpRef=1000mbar


!  Compressor



TRef=298KpRef=1000mbar

isen

tropi

c co

mpr

esso

r effi

cien

cy η

C,is

[-]

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75


100000


Exp. T3=600°C, TOil=90°C CFD

40000


!  Compressor



isen

tropi

c co

mpr

esso

r effi

cien

cy η

C,is

[-]

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75


100000


Exp. T3=600°C, TOil=90°C Exp. cold T3=25°C, TOil=25°C CFD


40000


isen

tropi

c co

mpr

esso

r effi

cien

cy η

C,is

[-]

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75


100000


Exp. T3=600°C, TOil=90°C Exp. cold T3=25°C, TOil=25°C CFD Uncertainty envelope


40000

!  Compressor



CFD only at small rpms inside the envelope.


Turbine outlet temperature

Heat loss

V-Element Mixer

Problems: •  Inhomogeneous temperature at turbine outlet •  Heat loss through convection, thermal radiation (to environment) and thermal

conduction (to turbo charger housing " compressor)


Turbine

Mixer

V-Element Mixer - Concept

!  ideal for blending of turbulent gas flows within pipes

!  Principle: homogenization of the fluid through vortex detachment

!  high mixing qualities, even at short lengths; modular design

!  pressure drop ∆p=0,01…0,12 bar


Effects of mixer and isolation

!  Significant influence of heat losses to temperature measurement !  Positive effect of mixer especially at low mass flow !  Positive effect of isolation in the complete range of operation

ṁT=54 kg/h

Markerohne Isolierungohne Mischer

mit Isolierungohne Mischer

mit Isolierungmit Mischer

ṁT=103 kg/h

ṁT=138 kg/h ṁT=278 kg/h

Länge in mm0 400 800 1200

Tem

pera

tur i

n °C

440460480500520540560580600620

T

T4** T4*

T3*

T4

T3

Tem

pera

tur i

n °C

440460480500520540560580600620

Länge in mm0 400 800 1200

ṁT=54 kg/h




ṁT=103 kg/h


Länge in mm0 400 800 1200

Tem

pera

tur i

n °C

440460480500520540560580600620

T

T4** T4*

T3*

T4

T3

Tem

pera

tur i

n °C

440460480500520540560580600620

Länge in mm0 400 800 1200

ṁT=54 kg/h




ṁT=103 kg/h


Länge in mm0 400 800 1200

Tem

pera

tur i

n °C

440460480500520540560580600620

T

T4** T4*

T3*

T4

T3

Tem

pera

tur i

n °C

440460480500520540560580600620

Länge in mm0 400 800 1200



Adiabatic Measurement Conditions

!  Problem: creating an adiabatic situation for a component which normally shows high temperature gradients

!  T2, T3 (and Oil temperature) are primarily responsible for heat flows within the turbo charger housing.

Desired conditions for adiabatic measurements:

!  T2 = T3 = TOil.mean " reduced heat flow within the turbo charger

!  T4 = T0 = 20�C " reduced heat loss from Turbine to measurement point

!  Extensive isolation " reduction of heat loss to environment

Oil out

Oil in

T1 T4

T2 T3

Turbo charger test bench – TU-Berlin


Adiabatic criterion

Definition: •  Actual turbine enthalpy flow

plotted over the isentropic compressor efficiency

•  Interpolated straight line connects operation points of maximum isentropic compres-sor power

•  Distance between intersection of straight and y-axis determines heat transfer under current boundary conditions

Isentropic compressor power PC_is [kW]0.0 0.5 1.0 1.5 2.0 2.5

Turb

ine

enth

alpy

flow

ΔH

T [k

W]

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

Adiabatic speed lines

230 m/s

270 m/s

310 m/s

350 m/s

380 m/s


Adiabatic criterion

Experimental results: •  Red lines represent

SAE measurements •  Black lines represent

measurements under adiabatic conditions

•  Black straight lines all cut the y-axis almost at the point of origin

•  Red lines indicate significant offset

140k

Isentropic compressor power PC_is [kW]0.0 0.5 1.0 1.5 2.0 2.5

Turb

ine

enth

alpy

flow

ΔH

T [k

W]

0

2

4

6

8

160k185k

208k

233k

137k

TC 1

Isentropic compressor power PC_is [kW]0 1 2 3 4 5 6 7

Turb

ine

enth

alpy

flow

ΔH

T [k

W]

02468

10121416

80k100k

120k

160k180k

adiabatic speed linesspedd lines at 600∞C

TC 2

Isentropic compressor power PC_is [kW]0 1 2 3 4 5 6 7

Turb

ine

enth

alpy

flow

ΔH

T [k

W]

02468

10121416

210m/s

360m/s

440m/s

TC 3

Isentropic compressor power PC_is [kW]0 1 2 3 4 5

Turb

ine

enth

alpy

flow

ΔH

T [k

W]

0

2

4

6

8

10

12

60k80k

100k

120k

adiabatic speed lines speed lines at 600∞C

TC 4


Turbocharger thermal model

sour

ce; D

r. B

urke

et a

l, U

nive

rsity

of B

ath

Heat model extension for engine process simulation


c) friction

Problem: Measurement of friction losses complicated Influence of thrust force

87 Department of Internal Combustion Engines Potentials and limits of turbochargers | Prof. Dr.-Ing. Roland Baar | 04-2016

Technology for friction measurement

Shutdown experiment !  no thrust load variation !  ventilation losses !  rotor inertia needed

Motor test bench !  specific setup / complex !  unrealistic rotordynamics

Thermodynamic balance !  T4 measurement necessary !  adiabatic conditions necessary !  still not validated

020000400006000080000

100000120000140000160000180000

0 5 10 15 20

Sha

ft sp

eed

[1/m

in]

Time[s]

Run out experiment

Messreihe 1Messreihe 1Messreihe 3


Thermodynamic measurement

!  Friction calculated by PT = PV + PFriction using T4

!  Plausible values

!  Same order of magnitude as friction polynomial

!  Still poor understanding of friction mechanisms


Summary

!  Different advanced boosting technologies mainly focussing on transient response

!  Comparison difficult due to different level of maturity !  Potential for reduction of emissions and fuel

consumption unclear, advanced powertrain simulation necessary, issues:

!  complexity of powertrain model due to different details in time and space of sub-models

!  advanced turbocharger models necessary


Kontakt: Prof. Dr.-Ing. Roland Baar TECHNISCHE UNIVERSITÄT BERLIN Fachgebiet Verbrennungskraftmaschinen Carnotstr. 1A D-10587 Berlin Telefon: +49 30 314 26946 Fax: +49 30 314 26105 email: [email protected] Internet: www.vkm.tu-berlin.de


Turbochargers at the edge of a new generation – Prof. Dr ...isromac-isimet.univ-lille1.fr/upload_dir/finalpaper/167.finalpaper.pdf · Turbochargers at the edge of a new generation

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