Biodiesel Impact on Engine Oil Performancewebpages.eng.wayne.edu/nbel/nbb-conference/Cummins... ·...

AMMRE Mid-Year Review Form 2006

Biodiesel Impact on Engine Oil Performance

Howard L. Fang, Cummins Inc.

National Biodiesel Conf & Expo

Kissimmee, Florida

Feb. 4, 2008


0

20

40

60

80

100

100 150 200 250 300 350 400

Temperature (C)

% R

eco

very

D-1

D-2

B100

DT=50C

§ Higher distillation temperature

§ Higher surface tension and higher specific gravity-larger fuel droplet size to condense on cylinder wall

§ Lower volatility and higher affinity toward oil additives-less likely to vaporize from crankcase oil

Biodiesel promotes fuel dilution


Adverse biodiesel effects on engine oil

§ Methyl ester and its degradation products may compete with antiwear

ZDDP additive towards metal surfaces

-Wear/corrosion performance determines the limit for oil drain intervals

-Wear increase can be related to the film stability of the protection layer

§ Biodiesel promotes fuel dilution in oil particularly with late-injection

in aftertreatment regeneration

-SAE2006-01-3301 and SAE2007-01-4036

-High biodiesel dilution carries more water into the oil that may de-stabilize the overbased

detergents (Normally 1% fuel dilution will introduce 10 ppm additional water into the oil)

-Sludge derived from oxidation or interaction with additives can degrade piston cleanliness


Beneficial effects on engine oil

§ Biodiesel and degradation products are potent friction modifiers

-Biodiesel blends assist fuel lubricity and can minimize the use of lubricity additives

-It needs to be verified

§ Dispersancy improvement by biodiesel soot

-Dispersancy improvement is caused by different PM morphology using biodiesel fuel

where more oxygenates are coupled into the soot structure resulting in a better soot

suspension by dispersant

-The dispersancy benefit can be evaluated by viscosity measurement

-It is important to determine the blending threshold for viscosity benefit


Oil tracer approach on fuel dilution

174017601780180018201840

-0.07

-0.06

-0.05

-0.04

-0.03

-0.02

-0.01

0

Wavenumbers (cm-1)

Sig

na

l str

en

gth

7% Fuel Dilution

9% Fuel Dilution

4% Fuel Dilution

1% Fuel Dilution

For fuel tracer approach, including IR, GC and isotope labeling, the quantification of fuel dilution (FD) in oil is based on an appropriate calibration with ‘known’ amount of the biodiesel in engine oil. The unknown FD value is predicted through the slope of such calibration function. However, the exact concentration of biodiesel in the oil on cylinder wall is actually ‘unknown’ due to low distillation. Oil tracer approach is needed


Sample selection

Sample

Soln -A: 2 % HPE in S150N

Soln -B: 4 % HPE in S150N

Soln -C: 5 % HPE in S150N

Soln -D: 8 % HPE in S150N

Soln -E: 2 % PE in S150N

Soln -F: 5 % PE in S150N

Soln -G: 8 % PE in S150N

ZDDP: Oloa 262

Baseoil : S150N

O

R-C-O

R-C-O

O

O-C-R

O

O

R-C-O

R-C-O

O

O-C-R

O

OH

OO-C-R

Partially esterfied pentaerythritol (HPE)Hydroxy # 60

Fully esterified pentaerythritol (PE)


Hydroxy ester interaction with ZDDP

• Both nCOP (974 cm-1) and nP=S (652 cm-1) of ZDDP are sensitive to

environment

• Hydroxy ester (partially esterified species) can form complex with ZDDP

through hydrogen-bonding

• Under complex formation, the absorption strength of nCOP (974 cm-1) and

nP=S (652 cm-1) will be reduced following the hydroxy concentration

• Fully esterified esters should show little interaction with ZDDP

RO S S OR

P Zn P

RO S S OR

O H

H O


Differential IR data of ZDDP in ester solutions

52.196

2.90117.008

Soln-G

(2% ZDDP in Soln-G) – (Soln-G)

31.889

2.94417.015

Soln-F

(2% ZDDP in Soln-F) – (Soln-F)

12.674

3.14917.582

Soln-E

(2% ZDDP in Soln-E) – (Soln-E)

41.001

2.64515.138

Soln-D

(2% ZDDP in Soln-D) – (Soln-D)

25.758

2.79815.757

Soln-C

(2% ZDDP in Soln-C) – (Soln-C)

20.403

2.84116.498

Soln-B

(2% ZDDP in Soln-B) – (Soln-B)

10.315

2.99817.221

Soln-A

(2% ZDDP in Soln-A) – (Soln-A)

Ester Cabonyl

(1789-1720 cm-1)

ZDDP nP=S

(690-620 cm-1)

ZDDP nCOP

(1050-910 cm-1)

Sample

52.196

2.90117.008

Soln-G

(2% ZDDP in Soln-G) – (Soln-G)

31.889

2.94417.015

Soln-F

(2% ZDDP in Soln-F) – (Soln-F)

12.674

3.14917.582

Soln-E

(2% ZDDP in Soln-E) – (Soln-E)

41.001

2.64515.138

Soln-D

(2% ZDDP in Soln-D) – (Soln-D)

25.758

2.79815.757

Soln-C

(2% ZDDP in Soln-C) – (Soln-C)

20.403

2.84116.498

Soln-B

(2% ZDDP in Soln-B) – (Soln-B)

10.315

2.99817.221

Soln-A

(2% ZDDP in Soln-A) – (Soln-A)

Ester Cabonyl

(1789-1720 cm-1)

ZDDP nP=S

(690-620 cm-1)

ZDDP nCOP

(1050-910 cm-1)

Sample


ZDDP decay rates are faster in hydroxy

ester (HPE) than in full ester (PE)

14.5

15.5

16.5

17.5

18.5

0 2 4 6 8 10[Ester] % in S150N

ZD

DP

str

en

gth

@9

74

cm

-1

HPE (ZDDP@974)

PE (ZDDP@974)

2.5

2.7

2.9

3.1

3.3

3.5

0 2 4 6 8 10[Ester]% in S150N

ZD

DP

str

eng

th @

652 c

m-1

HPE (ZDDP@652)

PE (ZDDP@652)

At 8% concentration, the nCOP band drop is

12 % for HPE and only 3 % for PE

At 8 % concentration, the nP=S band drop is

12 % for HPE and only 2% for PE


31P NMR data2°-ZDDP 1°-ZDDP

Sample Basic Neutral Basic Neutral

1% ZDDP in PAO 100.6 94.5 102.5 96.4 as is and @70ºC (14.2%) (61.6%) (12.8) (11.6%)

1% ZDDP in a mixture of 100.5 94.4 102.5 96.4

10% HPE/PAO @25°C (12.7%) (57.5%) (16.8) (13%)


10% HPE/PAO @50°C (9.9%) (58.2%) (17.5) (14.4%)


10% HPE/PAO @70°C (7.4%) (65.3%) (11.5%) (15.8%)

1% ZDDP in a mixture 100.3 94.0 * 96.1

10% HPE/PAO @90°C (4%) (63%) (16%)

*: area not integratible


Electric Contact Resistance (ECR) data

ECR WSD

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0 0.01 0.02 0.03 0.04 0.05 0.06

Dose (fraction)

WS

D (

mm

)

WSD A

WSD F

WSD CD

CALC WSD A

CALC WSD F

CALC WSD CD

A: aged biodiesel F: fresh biodiesel CD: certified ULSD

Biodiesel aging was conducted by heating @110C for 20 hr under air flow


High Frequency Reciprocating Rig (HFRR) data

HFRR WSD

0

50

100

150

200

250

300

350

400

0 0.01 0.02 0.03 0.04 0.05 0.06

Dose (fraction)

WS

D(m

icro

mete

r)CalcHFRR F CalcHFRR A

CalcHFRR CD WSD F

WSD A WSD CD

A: aged biodiesel F: fresh biodiesel CD: certified ULSD


Four-ball wear test data

0

0.3

0.6

0.9

1% ULSD 1% Fresh SME 1% Aged SME

4-b

all w

ear

scar

(mm

)

1800 rpm

1600 rpm

40 kg load, 60 minute period, 120ºC with 1600 and 1800 rpm speed


IR data of interaction between aged biodieseland ZDDP

0

0.3

0.6

0.9

16501700175018001850 cm-1

AB

S

fresh SME

aged SME

1780 1710

0

0.3

0.6

0.9

16501700175018001850 cm-1

AB

S

fresh RME

aged RME

0

0.3

0.6

0.9

16501700175018001850cm-1

AB

S

fresh palm

aged palm

1780 1700

1790 1720

0

0.3

0.6

0.9

55065075085095010501150 cm-1

AB

S

f resh SME

aged SME

0

0.3

0.6

0.9

55065075085095010501150 cm-1

AB

S

f resh RME

aged RME

0

0.3

0.6

0.9

55065075085095010501150cm-1

AB

S

f resh palm

aged palm


Concentration dependence of wear scar on hydroxy ester as evaluated by four-ball

0.5

1.5

2.5

0 4 8 12

Ester Content (wt%) in PAO

Wear

Sca

r (m

m)

10% HE

10% Full Ester


Dispersancy evaluation by KV100

4

5

6

7

8

0 0.2 0.4 0.6 0.8 1 1.2

[PM]% in PAO4 (300ppm dispersant)

KV

100

(cS

t)

B50

B20

ULSD

Break -off point of viscosity increase with [PM]

Dispersant: PIBSA/PAM (MW=5000m, 300 ppm in PAO4)


Conclusions

§ Oil dilution by aged biodiesel may increase engine wear even at

concentration of 5% or less

§ Excessive fuel dilution of biodiesel can lead to complex formation

between oxidized biodiesel species and ZDDP

-Even under different tribological conditions, HFRR and four-ball give similar

results for oil containing aged biodiesel

§ Aged biodiesel causes wear increase while fresh biodiesel might

actually decrease wear

§ B50 seems to be the limit for soot suspension benefit when a level

of 300 ppm dispersant is used in PAO4

SAE2007-01-4141

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