Ethanol
159
5.5.6 engine Durability with e-Diesel
The impact of a biofuel on engine durability is of particular concern to the
engine manufacturers especially with reference to covering engine warranties and ensuring the longevity of their engines. In the early 1980s in-field
durability tests by Hansen et al. (1982) and Meiring et al. (1983) on blends
with diesel fuel containing 10% and 15% dry ethanol showed no abnormal
wear taking place. Corkwell and Jackson (2002) carried out the Scuffing Load
Ball-on-Cylinder Lubricity Evaluator (SBOCLE) test and 576 hour pump tests
on blends containing 10% anhydrous ethanol in low-sulfur, No. 2 diesel fuel.
The various blends also contained from 300 to 2000 ppm of water and various
levels of a lubricity improver. Except for the fuel without lubricity improver,
all of the diesel blends showed very good performance in the SBOCLE tests
and the injector pump tests. The fuel without lubricity improver passed the
SBOCLE test but failed the pump test. Further work was required to fully
understand the effects of impurities on lubricity.
Frame and McCormick (2005) tested six elastomers by soaking them in
certification diesel and in certification diesel containing 15% ethanol. The
elastomers, which are commonly used in fuel systems, included N674 general purpose nitrile rubber, N0497 high aceto-nitrile content rubber, N1059
peroxide-cured nitrile rubber, V747 flourocarbon filled with carbon black,
and V884 flourocarbon without carbon black. The following parameters were
evaluated after soaking: break load, break stress, O-ring inside diameter,
O-ring thickness, and O-ring volume. Samples soaked in the ethanol–diesel
blend exhibited a significant reduction in break load for all elastomers except
N0479. The largest increases in O-ring dimensions and volume were for the
elastomers soaked in the ethanol–diesel blends.
Wrage and Goering (1980) soaked the seals from a distributor-type injector
pump of a John Deere 830 diesel tractor in No. 2 diesel fuel blends containing
from 0 to 50% anhydrous ethanol. After one year of soaking, there was no
visible deterioration of any of the seals. However, Wrage and Goering did not
do strength tests on the soaked seals.
Recent test results reported by Marek and Evanoff (2001) concerning two
trucks accumulating over 400,000 km and a fleet of 15 buses amassing
434,500 km while operating on a 15% ethanol blend of E-diesel, also indicated that no abnormal deterioration in condition had taken place. Also in a
farm demonstration project with four tractors and two combine harvesters
running on a 10% ethanol blend of E-diesel, Hansen et al. (2001) reported
that no abnormal wear patterns could be detected according to oil analyses
after at least two seasons of operation.
In a laboratory-based 500 h durability test on an engine running on a 15%
ethanol blend of E-diesel, Hansen et al. (2000) found that with the exception
of the fuel injection system no abnormal deterioration in engine condition
could be detected. One nonmetal component in the fuel injection system
159
5.5.6 engine Durability with e-Diesel
The impact of a biofuel on engine durability is of particular concern to the
engine manufacturers especially with reference to covering engine warranties and ensuring the longevity of their engines. In the early 1980s in-field
durability tests by Hansen et al. (1982) and Meiring et al. (1983) on blends
with diesel fuel containing 10% and 15% dry ethanol showed no abnormal
wear taking place. Corkwell and Jackson (2002) carried out the Scuffing Load
Ball-on-Cylinder Lubricity Evaluator (SBOCLE) test and 576 hour pump tests
on blends containing 10% anhydrous ethanol in low-sulfur, No. 2 diesel fuel.
The various blends also contained from 300 to 2000 ppm of water and various
levels of a lubricity improver. Except for the fuel without lubricity improver,
all of the diesel blends showed very good performance in the SBOCLE tests
and the injector pump tests. The fuel without lubricity improver passed the
SBOCLE test but failed the pump test. Further work was required to fully
understand the effects of impurities on lubricity.
Frame and McCormick (2005) tested six elastomers by soaking them in
certification diesel and in certification diesel containing 15% ethanol. The
elastomers, which are commonly used in fuel systems, included N674 general purpose nitrile rubber, N0497 high aceto-nitrile content rubber, N1059
peroxide-cured nitrile rubber, V747 flourocarbon filled with carbon black,
and V884 flourocarbon without carbon black. The following parameters were
evaluated after soaking: break load, break stress, O-ring inside diameter,
O-ring thickness, and O-ring volume. Samples soaked in the ethanol–diesel
blend exhibited a significant reduction in break load for all elastomers except
N0479. The largest increases in O-ring dimensions and volume were for the
elastomers soaked in the ethanol–diesel blends.
Wrage and Goering (1980) soaked the seals from a distributor-type injector
pump of a John Deere 830 diesel tractor in No. 2 diesel fuel blends containing
from 0 to 50% anhydrous ethanol. After one year of soaking, there was no
visible deterioration of any of the seals. However, Wrage and Goering did not
do strength tests on the soaked seals.
Recent test results reported by Marek and Evanoff (2001) concerning two
trucks accumulating over 400,000 km and a fleet of 15 buses amassing
434,500 km while operating on a 15% ethanol blend of E-diesel, also indicated that no abnormal deterioration in condition had taken place. Also in a
farm demonstration project with four tractors and two combine harvesters
running on a 10% ethanol blend of E-diesel, Hansen et al. (2001) reported
that no abnormal wear patterns could be detected according to oil analyses
after at least two seasons of operation.
In a laboratory-based 500 h durability test on an engine running on a 15%
ethanol blend of E-diesel, Hansen et al. (2000) found that with the exception
of the fuel injection system no abnormal deterioration in engine condition
could be detected. One nonmetal component in the fuel injection system