Multicylinder Diesel Engine Design for HCCI operation · Multicylinder Diesel Engine Design for HCCI operation William de Ojeda Alan Karkkainen International Truck and Engine Corporation

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

PDF

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.