HCCI – Diagnostics and ControlProf. Bengt Johansson

Div. of Combustion Engines,Dept. of Heat and Power Engineering,

bengt.johansson@vok.lth.sewww.vok.lth.se

Outline

• Current engines• HCCI in general• HCCI in Lund, some results• Production

Normal SI engine fuel consumption

Introduction

100%

99%

98% Cat

alys

t E

ffic

ien

cy

SI engine - part load improvementLean limit Stoichiometric premixed charge SI

engine

- Low part load efficiency

+ Low emissions with 3-way catalystLean burn premixed charge SI engine

+ Reduced pumping work improved part load efficiency

- Increased HC and NOx

Stratified charge SI engine - GDI

+ Removed pumping work much improved part load efficiency

- Large problem with NOx and PM

HCCI+ Removed pumping work much improved part load efficiency

+ Shorter combustion period improved overall efficiency

- Engine control problem

0.8 1.0 1.5

2.0 2.5 5.0

HCCI vs. GDI and CAI

Diesel Engine (CI)

•Large problems with emissions of NOx and PM

•High fuel efficiency (low CO2 emission)

HCCI Emissions

HCCI

0,01

0,500,00

NOx

PM *

0,05

USA 2007

AutoTechnologyOct. 2002, p 54

HCCI in Lund

HCCI activities in Lund

1. Basic engine studies2. Laser diagnostics 3. Combustion modeling - Chemical

kinetics4. Closed loop combustion control

Experimental facilities – single cylinder engines

(Volvo 1.6 liter)Scania 2 liter

Volvo/Alvar 0.5 liter VCR

Old Hot bulb engine

Multicylinder engines for HCCI control

Scania 12 liter 6 cylinder dual fuel

Volvo 12 liter 6 cylinder VGT

Volvo 3 liter 6 cylinder VVT

Saab 1.6 liter 5 cylinder VCR/FTM

Current optical engines

HCCI activities in Lund

1. Basic engine studies2. Laser diagnostics 3. Combustion modeling - Chemical

kinetics4. Closed loop combustion control

Volvo TD100 engine

First VCR

system

Multifuel capability

Multifuel capability

Low NOx from HCCI mode

10 15 20 250

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

0.05

Compression Ratio

Spe

cific

NO

x em

issi

ons

[g/k

Wh]

Gasoline & Diesel fuel

100% Gas65% Gas 40% Gas 20% Gas 0% Gas

=3.0 n=1000 rpm

With Variable Compression Ratio,

VCR, the HCCI engine can use

ANY

liquid or gaseous fuel!

Basic engine tests…

The effect of turbulence on HCCI combustion

Turbulence and geometry effects on HCCI

Experimental setupSquare bowl-in-piston

54 21

42

27

120

Piston body

6

Disc

22

120

Swirl Ratio=2.8HS case

Swirl Ratio=2.0LS case

Turbulence and geometry effects on HCCI

-50 -40 -30 -20 -10 0 10 20 30 40 500

0.5

1

1.5

2

2.5

3

3.5

4

Crank Angle [CAD]

Tur

bule

nce

[m/s

]

Centre Position Disc, LS Head Disc, HS Head Square, LS HeadSquare, HS Head

Turbulence

2

2

uu'u

2'y

2'x

Turbulence and geometry effects on HCCI

-50 -40 -30 -20 -10 0 10 20 30 40 500

1

2

3

4

5

6

7

8

Crank Angle [CAD]

Tur

bule

nce

[m/s

]Side Position Disc, LS Head

Disc, HS Head Square, LS HeadSquare, HS Head

Turbulence

2

Different scale

Turbulence and geometry effects on HCCI

-5 0 5 100

100

200

300

400

500

600

700

800

Crank Angle [° ATDC]

Rat

e of

Hea

t R

elea

se [

J/C

AD

]

SOC=-2 CAD

TDC

Disc, LS Head Disc, HS Head Square, LS HeadSquare, HS Head

Rate of Heat Release

HCCI activities in Lund

1. Basic engine studies2. Laser diagnostics 3. Combustion modeling - Chemical

kinetics4. Closed loop combustion control

The influence of Charge Heterogeneity on the HCCI Combustion Process (?)

Fuel Distribution Prior to Combustion

With port-injectionWith port-injection With mixing tankWith mixing tank

Tracer PLIF after Auto-ignition

With port-injectionWith port-injection With mixing tankWith mixing tank

OH PLIF Imaging

With port-injectionWith port-injection With mixing tankWith mixing tank

High Speed Fuel LIF

Multi YAG-Laser System

t

Ordinary laserOrdinary laser

t

Multiple pulse laser

• Single/Double pulse operation• 4 Pulses:

Time separation (0-100ms)• 8 Pulses:

Time separation (6-145µs)

• Wavelengths:532nm and 266nm

• Dye-laser for tuneable operation

High Speed Camera

CC

D 1

CC

D 8

Be

am

sp

litte

r

Op

tion

al

imag

ein

tens

ifier

MC

P 1

MC

P 8

Fra

me

sto

re

Ma

ss s

tora

ge

Ir is

Le

ns

mo

un

t

CC

D 2

-6

Mirro r

Mirr

or

Beam splitter optics

• 8 independent CCD’s, 576x384 pixels8 independent CCD’s, 576x384 pixels 10 ns temporal 10 ns temporal resolutionresolution• Optional image intensifier Optional image intensifier UV sensitive UV sensitive 1 µs temporal 1 µs temporal resolutionresolution

Experimental setup(Scania)

Cyl. Volume 1951 cm3

Bore 127 mmStroke 154 mmComp. Ratio 16:1Chamber design PancakeFuel EthanolLambda 3.85

Fuel Tracer PLIF(resolved single-cycle)

W16mars_4W16mars_4

2 ATDC2 ATDC 2.5 ATDC2.5 ATDC 3 ATDC3 ATDC 3.5 ATDC3.5 ATDC 4 ATDC4 ATDC 4.5 ATDC4.5 ATDC 5 ATDC5 ATDC 5.5 ATDC5.5 ATDC

• Fuel: ethanol

• Tracer: 10% acetone

• 3.85

• Rc: 16:1

Conceptual model of HCCI

t

dttRRtEGRttPtTfI0

))(),%(),(),(),((

Ignition occurs when I reaches a critical value

t

dttTfI0

))((

Assuming homogeneous distributions of P, , EGR% and RR:

Arbitrary distance x

Temperature

Wall

Critical ignition temperature

T (x,t=0) T (x,t=1) Ignition at T (t=0)

Ignition at T (t=1) Reactions at T(t=1), releasing significant heat

Conceptual model of HCCI

t

dtttTfI0

))(),((

Effect of heterogeneous air/fuel ratio

Ignition Temperature

Turbulence and geometry effects on HCCI

Suppression of hot and reactive zones

Piston

T+T

T

Transport of”cold” gases

Transport ofheat & radicals

Bulk

Boundary layer

Bulk & boundarylayer interaction

T-T

+2

+5.5

+2.5 +3 +3.5

+4 +4.5 +5

Single cycle fuel tracer LIF sequences

HCCI activities in Lund

1. Basic engine studies2. Laser diagnostics 3. Combustion modeling - Chemical

kinetics4. Closed loop combustion control

The 6-cylinder HCCI Engine

Closed loop combustion control, CLCC

WaveBook516

WaveBook516

NI PCI 6054NI PCI 6054 Status Calculation

PID Controllers

HEATERS

Injector Actuator

Injector Actuator

UserInputs

PC

PressureTraces

Inlet Conditions

(pin,Tin)

n-he

ptan

ei-o

ctan

e

Control Parameters

-40 -20 0 20 40 60 800

5

10

15x 10

6

Max PressureMax dp/dCA

Cyl

inde

r P

ress

ure

[Pa]

-40 -20 0 20 40 60 80-1000

0

1000

2000

3000

CA50

Heat Release

Crank Angle [deg ATDC]

Hea

t Rel

ease

, Q [J

]

Controlled

CA50

Net IMEP:s

Constraints

Peak pressure

Peak dp/dCA

Net heat release

dCAdp

VdCAdV

pdCAdQ

11

1

Combustion phasing=combustion duration

Combustion Timing

Ignition Diagram

-10

Octane Number

-5

0

5

10

15

40 50 60 70 80 90 100

Co

mb

us

tio

n p

ha

sin

g [

CA

50

]

S = d(CA50%) / d(Octane Number)S = d(CA50%) / d(Octane Number)

Sensitivity Estimation

50fOfmfTfNfS OffiTN

Unstable Operation

0 100 200 300 4000

5

10

15

20

25

30

35

Cycle Index

CA

50 [

°AT

DC

]

Stable Unstable

@ 3 bar IMEP

@ 4.5 bar IMEP

Closed loop control switched off

1000 1200 1400 1600 1800 20000

2

4

6

8

10

12

14

16

Engine Speed (rpm)

BM

EP

(bar

)Operating range

280 kW (380 hk)

HCCI Diesel16 21 bar280 310

kW

HCCI Diesel16 21 bar280 310

kW

Typical high load cycle

-30 -20 -10 0 10 20 300

20

40

60

80

100

120

140

160

180

200

Cyl

inde

r P

ress

ure

[bar

]

Crank angle [CAD]-30 -20 -10 0 10 20 30

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Rat

e of

Hea

t Rel

ease

[kJ

/CA

D]

Load limited by Peak Cylinder Pressure at 200 bar and maximum rate of pressure at 30 bar/CAD

Load limited by Peak Cylinder Pressure at 200 bar and maximum rate of pressure at 30 bar/CAD

IMEP net 17.4 bar

IMEP gross 20.4 bar

Animation Power

Fuel consumption and emissions

Engine speed 1200 rpm

BMEP 6.06 bar

Power 70.9 kW

Brake efficiency

42.8 %

NOx 0.024 g/kWh

HC 5.9 g/kWh

CO 4.4 g/kWh

And now to something completely different:

HCCI in production 1890!

Akroyd Hot Bulb Engine 1890

Photo of model at the Science Museum, London UK

•Low pressure early direct injection

•Fuel mix with residual gas and air before combustion

•Combustion started as temperature increase due to compression

2-Stroke Hot Bulb Engine

Photo of drawing displayed at the Smithsonian Museum ,Washington, US

Efficiency

Efficiency

0 2 4 6 8 10 120

10

20

30

40

BMEP [bar]

b [

%]

DIPCSCSIHTHB

Efficiency Efficiency

2002-01-0115

Hot Bulb Engine in Tractor

Cold Start of Hot Bulb Engine

Thank you for your attention!