Homogeneous Charge Compression Ignition (HCCI) R&D › sites › prod › files › 2014 › 03 › f9 › 2002_dee… · Homogeneous Charge Compression Ignition (HCCI) R&D Objectives:

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