Multicylinder Diesel Engine Design for HCCI operation · Multicylinder Diesel Engine Design for...
Transcript of Multicylinder Diesel Engine Design for HCCI operation · Multicylinder Diesel Engine Design for...
Multicylinder Diesel Engine Design for HCCI operation
William de Ojeda
Alan Karkkainen
International Truck and Engine Corporation
Diesel Engine DevelopmentDOE DEER CONFERENCE
Detroit, MichiganAugust 20-24, 2006
TM
Acknowledgements: DOE LTC consortium project, Low Temperature Combustion Demonstrator for High Efficiency Clean Combustion (DE-FC2605NT42413) .
Industrial Partners: Jacobs Vehicle System, UCB, LLNL, Siemens, ConocoPhillips, BorgWarner, Mahle, Ricardo.
Contents Development of a Multi-Cylinder
Diesel Engine for HCCI Operation
1. Objectives of Program
Reconfigure ITEC V8 6.4L engine to operate on HCCI ITEC throughout the speed and load range. 6.4L
2. Engine Development (a) Based on “best” engine hardware, the engine lug curve is defined.(b) Optimization tools are applied to FIE,turbocharger, cooling systems.(c) Control Strategy and hardware are developed tosustain combustion process based on cylinderpressure feedback.
3. Next Phase Engine Steady State TestingTransient operation
Key Enabler Technologies Loss motion valve control
Hardware: 1. Variable valve actuation system 2. Flexible FIE
Spray3. CAC with bypass and heater modeling
4. Cooled EGR 5. Two-stage turbocharger unit
Simulation 1. Spray CFD analysis 2. Chemical Kinetics 3. 1-D Engine Performance
Control System Two-stage
turbochargertechnology
Engine Layout P8 P6 P4 P2
Laboratory Set-up: 1. Establish overall manifold TCAC
temperature, boost control: a. Boost regulationb. CAC / heater control c. EGR control
2. Commence control over singlecylinder to later expand to multi-cylinder operation. a. Validate single cylinder emission
probe
b. Validate control diagnostics andalgorithms
3. Implement injection system 4. Implement turbocharger 5. Implement cylinder head 6. Implement VVA system
CAC
Engine
EGR Texh Pexh Tw Tegr
Pim Tim
Mair = f(DP) Tamb Pamb
Pc2 Tc2
T1
Tstack
Pstack
Hea
terT3T5T7
T2T4T6T8
TBP
CO2
CO2
CO2
Smoke NOx HC CO CO2
Smoke NOx HC CO CO2
N V(reg)
Tcharge Pcharge
P1P3P5P7
N
emissions
IVC
IVC
FIE
FIE
Design Procedure Goal: 1. Define LTC conditions 2. Define Engine Torque and Performance
Φ , EGR reference
TQ curve
Engine boundary conditions Φ, EGR Ma, Mf Ps, Ts
Clean Combustion
Engine Hardware Selection
Injection Hardware optimization
(1) no. holes, size (2) inj pressure – duration
(3) SOI
vaporization Mixture
Φ EGR
Vaporized Homogeneous
AIR MANAGEMENT Turbo
EGR / CAC coolers
COMBUSTION SYSTEM Piston, swirl
VVA CR - VCR
Mf, Tivc, Pivc
CR, IVC
Piston bowl
Controls Supervisor
Ma, Megr
KIVA
WA
VE
CH
EMK
IN3. Define Engine Hardware 4. Optimize FIE 5. Establish Controls Supervisor
Inj press,Mf (duration)Multiple InjectionsSOI
Pcyl (TQ, SOC) , Boost
Mf VVA EGR SOI BOOST Prail CAC/HEATER
Boundary Conditions
BCs are established based on:• Torque line • EGR and CAC specs • CR=14 • Φ = 0.4 • EGR rates 40-50%
With hardware requirements to yield:Max in-cylindertemperatures to sustain auto-ignition control(compression maxtemperatures of 900K)Capable turbochargeroutput
Effects of IVC
Illustrated for rated condition
Capabilities of IVC: • Lower in-cylinder
temperatures, pressures
Penalties associated with IVC: • Extra boost required
from compressor
Added Notes: Same effects obtained with varying the geometric compression ratio without the associated penalties IVC gives the capability for cylinder-to-cylinder trimming
Cylinder Head Optimization Performance at 30% flow over baseline
cylinder head
1. The middle lightblue sticks show the original ports andthe darker sticks are from the developed flow box
2. These sticks will be digitized andimported to CAD toupdate the cylinderhead drawing.
3. The cylinder headwill be recast and used in the HCCI engine testing.
Short side radius
modified
Port straightenedand widened
Helical features removed
Bench Marking Simulation Code
1. High speed Photography (top) is compared with KIVA modeling (below)
2. KIVA penetration estimates correlates well with “quiescent” conditions for conditions below.
3. Both compare well with estimates of Hirayasu.
400µs 600µs 12 hole 81 micron hole diameter
Prail = 1600 bar, rho = 25 kg/m3, T= 293 K
60
50
40
30
20
10
0
0 200 400 600 800 1000 1200 1400 1600
time (microsec)
measurements KIVA simulation Hirayasu
pene
tratio
n (m
m)
800µs 1000µs
Spray Data: Optimizing Mixture rated condition (3000 rpm, 12.4 bar) SOI = 120 BTDC
Hole size affects homogeneity of mixtureHistograms of Φ help determine the mixture formationMiddle hole size (111µm) shows tighter histogram around average Φ
310º
33
0º
350º
157 111 85Hole size
0.10
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0.00
157micron
0.00 0.50 1.00 1.50 EQR
0.00 0.50 1.00 1.50
EQR
111micron
0.00 0.50 1.00 1.50
EQR
350deg 330deg 310deg
085 micron
Combustion – 3000 rpm Full LoadEffect of SOI, Tin, EGR, other
Goal:
Optimize the heat release curves to maximize power output and keep peak in-cylinder temperatures below NOx generation.
Here, the effects of SOI, EGR and Temperature are pronounced. The insight is positive in regards to the capability to control each of these quantities.
T= 370K 40%EGR
SOI= -90 40%EGR
80
90
100
120
SOI= -90 T= 370K
T= 400K BL
Control Strategy
1. The engine under developmentwill rely on a supervisorcontroller to adjust the FIE and VVA systems on a cycle-to-cycle or angle base.
2. The controller will also be able to adjust boost and EGR levels on a periodic base.
3. The controller is to demonstrate it is capable to run at maximum speed (target 3600 rpm) with capability to:
a. Process combustion parameters (SOC, 50% burn,etc)
b. Interface with auxiliary systems on a cycle-to-cycle base.
FIE strategies
Feedback criteria: BDC TDC
180º 0ºLight loads(ignition trigger)
Medium loads FAST High loads Cylinder
Pressure Feedback
CR
EGR cooling CAC cooling
ECR
fuel
BOOST
EGR%
swirl
VVA
Slow N,TQVGT setting
Mapping +EGR setting Transient
adaptation
To be assessed In early phase
CR~14-8 (lower compression temps)
Fixed
CN~40 (increase ID)
Cylinder Timing Sequence
TDC BDC TDC BDC TDC
90 180 8.33
270 360 16.66
630 720 33.33
4500 0
Power Exhaust Intake PowerComp Comp
540 25.00
IVC range
Baseline 591º
IVC lim
it 470º
4º 4º1º1º
VVA controller
Early SOI ~ 120º BTDC
SOI range
CA msec @3600 rpm
P(ө) acquisition window FIEP(ө) reduction controller and resolution LTC strategy
VVA/FIE command output
Summary
1. DESIGN AND PERFORMANCE: specifications were outlined for a production engine to operate with a low temperature combustion mode. Specifically:
a. Target peak torque was set at 670 Nm at 2000 rpm (12.6 bar BMEP), rated set to 620 Nm at 3000 rpm, maximum engine speed set to 3600 rpm. The power output is within the target range proposed.
b. Equivalence ratio targets are from 0.3 - 0.4 with EGR levels of 40 -50%.
2. HARDWARE DEFINITION:
a. Compression ratio was set at 14. b. VVA concept was selected with flexible IVC, capable to control valves
independently at each cylinder and cycle-to-cycle. c. A two-stage series turbocharger system with VGT turbines at each stage. d. FEI hardware was identified to yield optimum vaporization of fuel and adequate
mixing. e. The base engine cylinder head was modified to improve the flow capacity into the
engine. Improvements of 30% were attained with a final swirl of 0.5. 3. COMBUSTION SIMULATION provided heat release profiles, in-cylinder maps of
temperature, equivalence ratio, soot, NOx. 4. CYLINDER PRESSURE BASED ALGORITHM execution is being benchmarked.