Homogeneous Charge Compression Ignition (HCCI) R&D › sites › prod › files › 2014 › 03 ›...
Transcript of Homogeneous Charge Compression Ignition (HCCI) R&D › sites › prod › files › 2014 › 03 ›...
Salvador Aceves, Daniel Flowers, Joel Martinez, Francisco EspinosaLawrence Livermore National Laboratory
and Robert Dibble
University of California, Berkeley
2003 DEER MeetingSan Diego, CA
August 28, 2002
Homogeneous Charge Compression Ignition (HCCI) R&D
Homogeneous Charge Compression Ignition (HCCI) R&D
Objectives:Develop a new combustion system that can provide the high efficiency and durability of diesel engines with very low NOx and particulate matter emissions.
Plans:Find inexpensive, practical solutions for the problems of HCCI engines:< control< multi-cylinder balancing< high HC and CO emissions< low power output< startability
LLNL HCCI combustion simulation results for thermal autoignition of the fuel during compression. Scientific American, June 2001
We are addressing the problems of HCCI combustion through a combination of analysis and experiments
Control:Detailed analysis of possible control strategiesExperimental testing Additives
Multi-cylinder balancing:Achieved balanced combustion in VW TDI engine
High HC and CO emissions:Detailed analysis for optimized engine geometry
Low power output:Optimization of engine performance mapTransition to SI/CI combustion
Startability:Analysis of transition between SI/CI and HCCI combustion
i,wo,w
3supercharger
5
EGRchamberwater
2intercooler
4 exhaustintake
Burner
catalyticconverter
0
56
exhaust
5'
7
01
preheaterintake
9
valve10
13
exhaust
8
valve
air and fuelair and fuel and EGR
exhaust gasescooling water
1211
We have analyzed potential methodologies for control of HCCI combustion (SAE 2000-01-2869)
HCT Detailed Chemical Kinetics
SuperCode Optimization
Example of thermal control system
We have successfully operated the TDI engine with an EGR-equivalence ratio control with no intake heating
0
20
40
60
-90 -60 -30 0 30 60 90
Crank Angle (DEG)
Pre
ssu
re (P
a)
Cyl 1Cyl 2Cyl 3Cyl 4
TDI EnginePropaneNo PreheatEGR=45%ER=0.48
We are looking at the use of additives for control of HCCI engines
-20 -10 0 10 20
crank angle, degrees
0
10
20
30
40
50
60
70
80
pres
sure
, bar
HCCI combustion of iso-octane
no ozone
10 ppm ozone
Control of multi-cylinder HCCI engines is a challenge
-10 0 10 20 30
Crank angle, degrees
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Fra
ctio
n of
hea
t rel
ease
T1 = 280 K
T1 = 290 K
T1 = 300 KT1 = 320 K
T1 = 310 K
20
25
30
35
40
45
50
55
-10 0 10 20 30Crank Angle (degrees)
Pre
ssu
re (
bar
)
Cylinder 1Cylinder 2Cylinder 3Cylinder 4
We are exploring many means of cylinder-by-cylinder timing control
Control systems are being implemented for two generic, low cost control options:
Electrical Trim Heaters
Individual cylinder EGR Control by Exhaust Throttling
Multi-cylinder engine operation requires balancing of combustion timing between cylinders
Trim heaters using less than 1% of mechanical energy output can effectively balance the cylinders in steady operation
20
25
30
35
40
45
50
55
60
65
-10 0 10 20 30Crank Angle (degrees)
Pre
ssu
re (b
ar)
Cylinder 1 (+75 Watts)Cylinder 2 (+35 Watts)Cylinder 3 (+15 Watts)Cylinder 4 (+ 0 Watts)
20
25
30
35
40
45
50
55
-10 0 10 20 30Crank Angle (degrees)
Pre
ssu
re (
bar
)
Cylinder 1Cylinder 2Cylinder 3Cylinder 4
Unbalanced Balanced
We have successfully demonstrated two possible means of individual cylinder combustion timing control
20
30
40
50
60
70
-10 0 10 20 30
Crank Angle (degrees)
Pre
ssu
re (
bar
)
EGR=5%EGR=9%EGR=12%
Timing Control with Exhaust Throttle EGR
20
30
40
50
60
70
-10 0 10 20 30
Crank Angle (degrees)
Pre
ssu
re (
bar
)
0 Watts15 Watts30 Watts50 Watts65 Watts
Timing Control withTrim Electrical Heater
Our multi-zone methodology can successfully predict geometry effects on HC and CO emissions
1 32 4 5 6 7 8 9 10
Zone
109
9
87 6
5
4
3
3
2
1
Location of isothermal zones in cylinder (SAE 2000-01-0327)
Temperature history of 10 zones during compression stroke
-50 -40 -30 -20 -10 0
crank angle, degrees
500
600
700
800
900
1000
1100
1200
aver
age
zone
tem
pera
ture
, K
zone 1zone 2zone 3zone 4zone 5zone 6zone 7zone 8zone 9zone 10
19:1 CR 2 atm boost
KIVA
HCT
Our multi-zone model generates accurate predictions for HCCI combustion
-40 -30 -20 -10 0 10 20 30 40
crank angle, degrees
0
20
40
60
80
100
120
pres
sure
, bar
case 1 case 2
experimentalreduceddetailed
Iso-octane data from CumminsCase 1: 1010 rpm, 2.41 bar intake, φ=0.346Case 2: 2007 rpm, 3.11 bar intake, φ=0.348
We have applied the multi-zone methodology to four engine designs to evaluate their effect on emissions
Base case
Hot wall (600K)
No crevice
Low swirl(0.43 vs. 4.3)
All — Low swirl, hot wall, no crevice
We have analyzed three engine geometries experimentally tested at the Lund University
Ring Carrier
hRCPiston Ring
Cylinder Head
Cylinder Liner
w
h Piston Crownremovable
Crevice width w=0.26 mm, 1.6 mm and 2.1 mmConstant compression ratio 17:1
Our analysis can explain the non-monotonic behavior in HC emissions as a function of equivalence ratio
λ=2.5
λ=3.0
λ=4.0
λ=3.5
λ=4.5
Complete Combustion
Partial Reaction
No Reaction
Engine with narrow crevice0.26 mm
2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4
air-fuel equivalence ratio
0
1000
2000
3000
4000
5000
6000
7000
hydr
ocar
bon
emis
sion
s, p
pm
0.26 mm crevice1.3 mm crevice2.1 mm crevice solid lines: experimental
dotted lines: numerical
Our analysis can explain the non-monotonic behavior in HC emissions as a function of equivalence ratio
λ=2.5
λ=3.0
λ=4.0
λ=3.5
λ=4.5
Complete Combustion
Partial Reaction
No Reaction
Engine with wide crevice
2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3
air-fuel equivalence ratio
0
1000
2000
3000
4000
5000
6000
7000
hydr
ocar
bon
emis
sion
s, p
pm
0.26 mm crevice1.3 mm crevice2.1 mm crevice solid lines: experimental
dotted lines: numerical
We have applied the system simulation and optimization tool to evaluate transition between HCCI and SI ignition
SAE 2001-01-3613
Decision variables:
1. equivalence ratio
2. EGR
3. intake pressure
We are collaborating with multiple industrial and academic partners
• Cummins– 2-year long CRADA, 2 joint papers– working on establishing a new CRADA
• Caterpillar– donated experimental engine 3401
• Sandia National Laboratories– detailed analysis of experimental data
• Lund Institute of Technology– 2 joint papers, collaboration on analysis
• University of Wisconsin– joint work on KIVA analysis– 3 joint papers
• UC Berkeley– joint experimental and numerical work, 18 joint
papers– four graduate students obtaining degrees on HCCI
HCCI roadmap
FY02 FY03 FY04 FY05
Analysis
Experimental
Single-zoneOptimized
controlsimulation
Fuel characterization
and optimization
Multi-zoneiso-octane
TDI enginecylinder
balancing
CAT 34011800 rpm
visualization
Control strategies and transition to
SI and CI
Multi-zonegasoline
TDI enginefuels testing
CAT 3401performance
CAT 3401fuels testing
TDI engineimplementation ofcontrol strategies
Multi-zoneengine
optimization
Fuel-engine optimization
TDI engine φ-EGR
operation
CAT engineimplementation ofcontrol strategies