HCCI – Diagnostics and ControlProf. Bengt Johansson
Div. of Combustion Engines,Dept. of Heat and Power Engineering,
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!