Vegetable Oil Methyl Esters with a High Iodine Number
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Fourth Biomass Conference of the Americas
29 August - 2 September 1999
Oakland, California, USA
Technical Performance of Vegetable Oil Methyl Esters With a High Iodine
Number
Heinrich Prankl, Manfred Wörgetter, Josef Rathbauer
BLT Wieselburg - Federal Institute of Agricultural Engineering
A-3250 Wieselburg, Austria
ABSTRACT
The Federal Institute of Agricultural Engineering in Austria has been gaining more
experience about the technical performance of biodiesel with a high iodine number. Long term
tests were carried out on the test bench with rape seed oil methyl ester, sunflower oil methyl
ester and camelina oil methyl ester with an iodine number of 107 to 150. The oil viscosity was
observed and the engine parts were inspected after each run.
To demonstrate the suitability of a methyl ester with a high iodine number a fleet test with 9
vehicles and 1 stationary engine was carried out over a period of 1 to 3 engine oil drain intervals.
Camelina oil methyl ester was used with a content of 37% linolenic acid (C18:3). No unusual
deposits could be observed after dismantling the engines.
1
INTRODUCTION
Methyl ester (biodiesel) produced from several raw material sources has reached a
considerable market position in the last years. The use of methyl esters in diesel engines might
cause an engine oil dilution by the fuel [1]. A high content of unsaturated acids in the esters
(which is expressed by the iodine number) increases the risk of polymerization in the engine oil
[4], [5], and [6].
The engine oil dilution leads to a decrease of viscosity. In several publications a sudden
increase could be found after some time. It is supposed that the oil breakdown is related to fuel
dilution followed by oxidation and polymerization of unsaturated fuel constituents.
The influence of the iodine number of biodiesel on the engine performance was investigated
in a previous project [2], [3]. Investigations were carried out on a single-cylinder-engine on the
test bench. Biodiesel test fuels were used with iodine numbers of 100 to 180 for long-term tests
over 250 hours. The results showed no clear difference between the test fuels with an iodine
number of 100 to 140. The need for further investigations was recognized. Therefore a project
was started to demonstrate if it is possible to use biodiesel with an iodine number of 150 as fuel
for diesel engines.
4th Biomass Conference of the Americas
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Vegetable Oil Methyl Esters with a High Iodine Number
2
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OBJECTIVES
The aim of the project was to gain more experience about the technical performance of biodiesel
with a high iodine number. The overall objectives of the project are as follows:
∗ Analysis of the physical and chemical properties of rape seed oil methyl ester (RME),
sunflower oil methyl ester (SME) and camelina oil methyl ester (CME)
∗ Investigation of several methyl esters with a varying fatty acid distribution in long term tests
on the test bench
∗ Doing a fleet test with 10 vehicles using a fatty acid methyl ester with a high content of
unsaturated acids over a period of 2 engine oil change intervals.
3
MATERIALS AND METHODS
3.1
Test fuels
The following methyl esters were used:
• Rapeseed oil methyl ester (RME), Iodine number 107
• Sunflower oil methyl ester (SME), Iodine number 132 and
• Camelina oil methyl ester (CME), Iodine number 150
Table 1: Analyses of the test fuels in comparison to the Austrian and
the German standard for biodiesel
Density 15°C
Flash point
Viscosity 40 °C
CCR (100 %)
Sulfated Ash
Cetane number
Methanol content
Mono-glycerol
Di-glycerol
Tri-glycerol
Free glycerol
Total glycerol
Iodine number
C18:3 content
[g/cm³]
[°C]
[mm2/s]
[%mass]
[%mass]
[-]
[%mass]
[%mass
[%mass]
[%mass]
[%mass]
[%mass]
[-]
[%mass]
4th Biomass Conference of the Americas
RME
SME
CME
0.881
>150
4.4
0.02
<0.01
60
0.08
0.18
0.12
0.08
0.01
0.08
107
11
0.882
>151
4.2
0.02
<0.01
56
0.01
0.41
0.10
0.05
0.01
0.13
132
0.7
0.887
>152
4.2
0.03
<0.01
52
0.09
0.20
0.05
0.03
0.003
0.06
150
37
ON C1191
DIN
51606
0.85-0.89 0.875-0.90
>100
>110
3.5-5.0
3.5-5.0
0.05
0.05
0.02
0.03
>49
>49
0.2
0.3
0.8
0.4
0.4
0.02
0.02
0.24
0.25
120
115
15
-
BLT Wieselburg (1999)
Vegetable Oil Methyl Esters with a High Iodine Number
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The test fuels were produced in a 700 l pilot plant at the BLT. The high iodine number of
SME is caused by a high content of linoleic acid (66% C18:2) and in case of CME by a high
content of linolenic acid (37% C18:3).
3.2
Test engine and engine oil
A direct injection single cylinder engine, type 1D41 Z of the Hatz company, Germany,
was used. It is an air cooled 4-stroke diesel engine with a crankshaft and cylinder head of light
metal. Bore x stroke is 85 x 65 mm, the capacity is 337 cm³, the performance is 5.6 kW at 3000
rev/min.
Engine oil:
Type:
Specification:
Viscosity 100 °C:
OMV Truck M plus
MIL-L-2104 E, API SG/CE, SAE 15W-40
14.0 mm²/s
In order to have hard conditions for the tests the engine oil was pre-mixed with each test
fuel. Therefore the start viscosity is 10.5 mm²/s (instead of 14 for the pure engine oil).
3.3
Test cycles on the test bench
The test period comprised 256 hours with each test fuel. A test cycle with variable load
was chosen corresponding to ISO 8178-4:1995. To guarantee the same conditions for each test,
the piston, the cylinder and the injector were changed before the start and the temperature was
controlled during the run. In the evaluation the engine parts were checked and oil samples were
analyzed.
4
4.1
RESULTS
Long term tests on the test bench
Table 2Error! Unknown switch argument.: Evaluation of the engine parts
Engine part
1st piston ring
1st ring groove
Area 1st/2nd ring
2nd piston ring
2nd ring groove
Area 2nd/3rd ring
3rd piston ring
Injector, injector holes
RME
free movable
deposits on 80% *
partly detached
deposits on 5% *
free movable
deposits on 25% *
Clean
free movable, clean
Clean
4th Biomass Conference of the Americas
SME
free moveable
Deposits on 100% *
partly detached
Deposits on 10% *
Free movable
Deposits on 40% *
clean
free movable, clean
clean
CME
free moveable
deposits on 100% *
partly detached
deposits on 30% *
free movable
deposits on 50% *
clean
free movable, clean
clean
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Vegetable Oil Methyl Esters with a High Iodine Number
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* deposits as % of the area
The evaluation of the engine parts showed considerable differences between the test fuels
only on the deposits of the bottom of the 2nd ring groove and in the area between 1st and 2nd
piston ring.
4.2
Fleet test
In 1998 a fleet test was carried out with 9 vehicles (5 tractors, 4 passenger cars) and one
stationary engine for irrigation. The engines were operated during 1 to 3 engine oil drain
intervals (max. 750 hours, 30.000 km) with camelina oil methyl ester (CME).
At the beginning and at the end of the test period the engines were examined carefully.
The engine performance was determined on the test bench. The cylinder head was dismantled
before and after the test period. Oil samples were taken every 50 hours and 3000 km
respectively. On some engines the oil temperature was recorded.
In some cases a decrease of the oil viscosity could be found. It was caused by a dilution
of the engine oil by unburned fuel and depends on the type of the engine.
4th Biomass Conference of the Americas
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Vegetable Oil Methyl Esters with a High Iodine Number
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5.
Combustion Chamber Picture - Nozzle after 418 h with CME
after 760 h with CME
The results of the engine inspection seemed to be well-known from former projects [1]. No
unusual deposits could be found on the cylinder liner, in the combustion chamber, injector or
valves.
6 SUMMARY AND CONCLUSIONS
Long term tests were carried out on the test bench with rape seed oil methyl ester, sunflower
oil methyl ester and camelina oil methyl ester with an iodine number of 107 to 150. The oil
viscosity was observed and the engine parts were inspected after each run. A correlation could be
4th Biomass Conference of the Americas
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found between the increase of the engine oil viscosity and the iodine number. The results differ
from a former project where nearly no differences could be found up to an iodine number of 160.
A fleet test with 9 vehicles and 1 stationary engine was carried out over a period of 1 to 3
engine oil drain intervals. Camelina oil methyl ester was used with an iodine number of 150 and
a content of 37% linolenic acid (C18:3). The engines were dismantled before and after the tests.
No unusual deposits could be found in the cylinder liner, the combustion chamber, the injector
and the valves.
The experiences have shown that it is possible to operate an engine with a methyl ester
containing more than 30% of unsaturated acids. Further investigations are necessary especially
in the interaction between methyl ester fuel and engine oil.
ACKNOWLEDGEMENTS
The current investigations are part of an international project funded by the European
Commission in the frame of the ALTENER program (XVII/4.1030/Z/96-013) .
Special acknowledgements are given to:
- European Commission
- Federal Ministry of Agriculture and Forestry
- Bundesversuchswirtschaften, Austria
- Ölmühle Bruck, Austria
- OMV, Austria
- Hatz, Germany
- John Deere, Austria/Germany/France
- Steyr, Austria
REFERENCES
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PRANKL, H., WÖRGETTER, M.: Influence of the Iodine Number of Biodiesel to the
Engine Performance. International Conference on Standardization and Analysis of Biodiesel, 6-7
Nov 1995, Vienna. ISBN 3 9014 5701 1 (1995).
PRANKL, H., WÖRGETTER, M.: Influence of the Iodine Number of Biodiesel to the
Engine Performance. ASAE 'Liquid Fuels and Industrial Products from Renewable Resources', 1517 Sep 1996, Nashville, Tennessee. ISBN 0-929355-79-2 (1996).
BLACKBURN, J.H., et.al.: Performance of Lubricating Oils in Vegetable Oil Ester-Fuelled
Diesel Engines. SAE Technical Papers 831355 (1983).
SIEKMANN, R.W., et.al.: The Influence of Lubricant Contamination by Methylesters of
Plant Oils on Oxidation Stability an Life. Proceedings of the International Conference on Plant and
Vegetable Oils as Fuels. ASAE (1982).
KORUS, R.A., MOUSETIS, T.L.: Polymerization of Safflower and Rapeseed Oils. JAOCS,
vol. 61, no. 3 (1984).
PRANKL, H.: Technical Performance of Vegetable Oil Methyl Esters with a High Iodine
Number. Interim Report. BLT Wieselburg, (1997).
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