2006 Asian DME conference

Engine Lab.

Combustion Phasing in DME fuelledCombustion Phasing in DME-fuelled HCCI Engine

Kitae Yeom, Hyeonsook Yoon and Choongsik BaeDepartment of Mechanical Engineering, KAIST

Combustion Engineering Research Center

ContentsEngine Lab.

Backgrounds

DME HCCI test with high CR (based on CI engine)DME HCCI test with high CR (based on CI engine)

Experimental results

DME HCCI test with low CR (based on SI engine)

Experimental resultsp

Conclusions

BackgroundsEngine Lab.

Homogeneous Charge Compression Ignition

Homogeneous Compression +Charge (SI engine) Ignition (CI engine)+

Homogeneous ChargeHomogeneous Charge Compression Ignition

(HCCI engine)

BackgroundsEngine Lab.

Problems of HCCI Engine

Problems

High Load• Early combustion

Combustion h

y o o

• Heavy knocking

• IMEP loss

phase controlIMEP loss

EGR, additivesEGR, additives and etc.

Research topics of KAIST DME HCCIEngine Lab.

Neat DME HCCI combustionDME HCCI combustion with LPG

DME HCCI combustion with gasolineDME HCCI combustion with hydrogen

DME HCCI b ti i PFIDME HCCI combustion using PFI

EGR rateIntake valve timing

Fuel quantityInjection timingFuel pressure

Establish the DME HCCI engine combustion D/BEstablish the DME HCCI engine combustion D/B

Engine Lab.

DME HCCI test with hi h CRhigh CR

(based on CI engine)(based on CI engine)

Experimental SetupEngine Lab.

Engine TypeEngine Type Single Cylinder, DISingle Cylinder, DI--diesel basediesel baseg ypg yp diesel basediesel base

Bore x Stroke Bore x Stroke 83 x 92 mm83 x 92 mm

VolumeVolume 498cc498cc

Compression Compression ratioratio 18.718.7

I j tI j tøø0.168mm*5holes 0.168mm*5holes

minimini sac typesac typeInjectorInjector minimini--sac typesac type(150(150°°, 100, 100°°))

DME HCCIEngine Lab.

4.0

2 5

3.0

3.5

800rpm 1200rpmMixing controlled combustion

region

1.5

2.0

2.5

IMEP

[ba

r]Homogeneous charge compression ignition region

0.0

0.5

1.0Stratified charge compression ignition region

0 50 100 150 200 250 300

SOI [CA BTDC]SCCI region can improve the IMEP with late combustion

Injection pressure 55 MPaInjection pressure 55 MPa

Engine speed 800, 1200 rpm

λDME 3

DME HCCI with hydrogenEngine Lab.

6080

[b

ar]

motoring RH2= 0% RH2= 5% RH2= 10%

AD

]

Low temperature oxidation

H + O → O + OH

Engine speed : 800 rpm, Tin : 30 ℃

0204060

80

er P

ress

ure[ RH2= 15%

RH2= 20% RH2= 25%

e ra

te[J

/CA H + O2→ O + OH

O + H2→ H + OH

020406080

Incy

linde

Hea

t rel

ease

H2 +OH → H2O +HCH3OCH3 + OH → CH3OCH2 + H2O

320 340 360 380 400 420

H

Crank angle degree[CAD]

Controlled the H dH d3.2

Controlled the ignition timing By HydrogenHydrogen

2 8

3.0

EP

[bar

]

hydrogen

2.6

2.8 IME hydrogen

combustion phase control

0 5 10 15 20 252.4

Fraction rates of hydrogen[%] IMEP increase

p

Engine Lab.

DME HCCI test with l CRlow CR

(based on SI engine)(based on SI engine)

Experimental SetupEngine Lab.

Engine Specification

Type Descriptions

Number of Cylinder 1

Displacement cc 494Displacement, cc 494

Bore, mm 82

Stroke, mm 93.5

Compression ratio 13

Intake duration 228

Exhaust duration 228Exhaust duration 228

DME injection pressure, MPa 5

I j t t Slit i j tInjector type Slit injector

Valve

Retard Advance

IVO, ATDC 11 -29Timing IVC, ABDC 59 19

DME HCCI using Direct InjectionEngine Lab.

5.0

5.5

6.0

MP

a]

Injection timing 22 CAD ATDC122 CAD ATDC No cool flame at 322 CAD ATDC

2.5

3.0

3.5

4.0

4.5

ion

Pre

ssu

re [

M 122 CAD ATDC 222 CAD ATDC 322 CAD ATDC

Mixing controlled combustion

300 310 320 330 340 350 360 370 380 390 4000.0

0.5

1.0

1.5

2.0

IVO timing was fixed at 11 CAD ATDC

Com

bust

i

1000 rpm, λDME=3

Mixing controlled combustion

300 310 320 330 340 350 360 370 380 390 400

Crank angle degree

6.0

Combustion retardation due to lower volumetric efficiency and

3.5

4.0

4.5

5.0

5.5 IVO timing -29 CAD ATDC -19 CAD ATDC -9 CAD ATDC 1 CAD ATDC11 CAD ATDCsu

re [

MP

a]

yinternal residual gas

IVO timings Volumetric efficiency

1.0

1.5

2.0

2.5

3.0

ombu

stio

n P

ress

-29 CAD 80.0%

-19 CAD 79.5%

-9 CAD 77.2%

decrease

300 310 320 330 340 350 360 370 380 390 4000.0

0.5Injection timing was fixed at 122 CAD ATDC

Crank angle degree

Co

1 CAD 70.8%

11 CAD 66.2%

e

Gasoline – DME HCCI combustionEngine Lab.

7

8

]

λTOTAL

IVO timing -29 ATDC

7

8

IVO timing ATDC λTOTAL

=2.12

300

350

400

2

3

4

5

6

e [

J/0

.17

6 C

AD

]

ress

ure

[M

Pa] 2.91

2.77 2.57 2.41 2.12

300

350

400

3

4

5

6

7 IVO timing, ATDC -29 -19 -9 1 11

[J/0

.17

6 C

AD

]

ssu

re [

MP

a]

TOTAL

50

100

150

200

250

0

1

2

eat

rele

ase

rate

Incy

linde

r pr

100

150

200

250

300

0

1

2

at r

elea

se r

ate

Incy

linde

r pr

es

300 310 320 330 340 350 360 370 380 390 4000

50

He

Crank angle degree [CAD]300 310 320 330 340 350 360 370 380 390 400

0

50 Hea

Crank angle degree [CAD]

Start of combustion timing was not changed due to same injection

quantity of DME

Combustion retardation due to reduced volumetric efficiency and

internal residual gas

Due to increased injection quantity of gasoline

Engine speed, rpm 1000

DME injection timing [ATDC] 110of gasoline [ATDC] 110

λDME 3.7

DME – LPG HCCI combustionEngine Lab.

7

8

λTOTAL

IVO timing -29 ATDC

7

8

]λTOTAL

=2.12IVO timing, ATDC

300

350

400

2

3

4

5

6

essu

re [

MP

a]

[J/

0.1

76

CA

D]TOTAL

2.91 2.77 2.57 2.41 2.12

300

350

400

2

3

4

5

6

ress

ure

[M

Pa]

[J/

0.1

76

CA

D]TOTAL -29

-19 -9 1 11

50

100

150

200

250

0

1

2

Incy

linde

r pr

e

eat

rele

ase

rate

50

100

150

200

250

0

1

2

Incy

linde

r pr

eat

rele

ase

rate

More retarded than gasoline-DME

300 310 320 330 340 350 360 370 380 390 4000

50

He

Crank angle degree [CAD]

300 310 320 330 340 350 360 370 380 390 4000

50

Crank angle degree [CAD]

He

gHCCI due to higher latent heat of

vaporization and octane number of LPG

Start of combustion timing was retarded due to increased injection

quantity of LPG

Due to increased injection quantity of LPG

Engine speed, rpm 1000

DME injection timing [ATDC] 110of LPG [ATDC] 110

λDME 3.7

IMEP of HCCI with LPG and gasoline

Engine Lab.

2 9

IMEP in Gasoline HCCI [bar]2 9

IMEP in LPG HCCI [bar]

2.3

2.4

2 52.7

2.8

2.9

2.902.852.802.752.702.652 60

2.3

2.4

2.7

2.8

2.9

3.73.63.53.43.33.22.5

2.6

2.7

2 8Lam

bda

tota

l

2.5

2.6

2.602.552.502.452.402.352.302.25

2.5

2.6

2.7

Lam

bda

tota

l

2.5

2.63.13.02.92.82.72.62.52.42.8

2.72.6

2.5

2.4

2 3

L

2.2

2.3

2.4 2.20 2.8

2.9

3 1

L

2.2

2.3

2.4 2.32.2

2.3

IVO timing-20 -10 0 10

Maximum IMEP region

3 3.1 3.2 3.3 3.4 3.5 3.6

IVO timing-20 -10 0 10

a u eg o

IMEP was decreased due to early b ti

Engine speed, rpm 1000

DME injection timing [ATDC] 110combustion [ATDC] 110

λDME 3.7

DME HCCI with hydrogenEngine Lab.

506070

re[b

ar] Inj.Timing BTDC300°

0% H2 add10%H2add

1500RPM

Fraction rates of hydrogen

01020304050

ylin

der P

ress

ur 10% H2 add 20% H2 add 30% H2 add 40% H2 add

Fraction rates of hydrogen

Retarded the combustion phase320 340 360 380 400 420 440

-100C

Ignition delay was increased asIMEP increase

Retarded the combustion phase

Ignition delay was increased as hydrogen fraction was increased

Knocking was observed

3.5

4.0

800rpm 1000rpm 1500rpm

g

1.0

1.5

2.0

2.5

3.0

IME

P[b

ar]

Incomplete combustion

0 10 20 30 400.0

0.5

R ate o f add ing H ydrogen[% ]

DME HCCI using PFIEngine Lab.

346.4

CA

D) IVO timing

1 CAD ATDC

344.0

344.8

345.6

λ = 2.5Star

t of

-ign

itio

n (C

2.0

- 19 CAD ATDC - 29 CAD ATDC

ar)

0 10 20 30 40 50 60343.2 1000 rpm

EGR rate (%)

auto

-

1.6

1.8

λ = 2.5

EPgr

oss (

ba

0 10 20 30 40 50 60

6

EGR rate (%)

IME

2.5 CAD retardation

• IVO timing

increased internal residual gas fraction

• 0.5 bar IMEP gain

EGR + IVO timing

• EGR

Dilution effects

• IMEP was increased due to late ignition as a results of EGR rate

ConclusionsEngine Lab.

DME HCCI combustion was tested to verify the combustion phase characteristics.

F ll i l i d f i tFollowing conclusions were drawn from experiments.

1. The reduced IMEP was observed due to negative work.

2. The addition of hydrogen was an effective way of phase control.y g y p

3. The combustion phase could be controlled by varying intake valve timing.

4. EGR can retard the combustion phase of DME HCCI engine.

This research is supported by CERC (Combustion Engineering Research Center), KAIST