652
Energy & Fuels 2008, 22, 652–656
Experimental Investigation on the Fuel Properties of Biodiesel and
Its Blends at Various Temperatures
Seung Hyun Yoon,† Su Han Park,† and Chang Sik Lee*,‡
Graduate School of Hanyang UniVersity, 17 Haengdang-dong, Sungdong-gu, Seoul 133-791, Korea
Department of Mechanical Engineering, Hanyang UniVeristy, 17 Haengdang-dong,
Sungdong-gu, Seoul 133-791, Korea
ReceiVed April 25, 2007. ReVised Manuscript ReceiVed September 13, 2007
An experimental investigation was performed to find out the fuel properties including specific gravity, density,
and viscosity of diesel and biodiesel fuel in the temperature range from 0 to 200 °C. Test fuels used were a
conventional diesel, neat biodiesel (100% methyl ester of soybean oil), and their blends with blending ratios
of 20%, 40%, 60%, and 80%. In order to analyze the fuel properties, the experiments were carried out at
various temperatures for each of the six test fuels and the resulting measurements of the biodiesel and its
blends were compared with the properties of conventional diesel fuel. In this work, the specific gravity of
biodiesel fuel increased with the increase of the blending ratio of biodiesel and gradually decreased as the fuel
temperature increased linearly. The density value measurement was correlated as a function of fuel temperature
and blending ratio by an empirical equation. The viscosity of the test fuels was found to decrease linearly with
increasing temperature and decreasing blending ratio. The kinematic viscosity obtained by this investigation
agrees well with the empirical equation which is derived from the measured results.
1. Introduction
Biodiesel fuels derived from vegetable oils or animal fats and
which are used as substitutes for conventional petroleum fuel in
diesel engines have recently received increased attention. This
interest is based on a number of properties of biodiesel including
its biodegradability and the fact that it is produced from a renewable
resource. These features of biodiesel lead to its greatest advantage,
which is its potential for emission reduction.
Though the environmental potential for emissions reduction
exists, vegetable oils have high viscosity and high pour points
relative to diesel fuel. The high viscosity of vegetable oils such
as biodiesel and its blends tend to alter the injector spray pattern
inside the engine, causing fuel impingement on the piston and
other combustion chamber surfaces. This leads to the formation
of carbon deposits in the engine, eventually resulting in problems
such as stuck piston rings in the cylinder and subsequent engine
failures, which would not otherwise occur using diesel fuel. The
undesirable characteristics of vegetable oils can be substantially
mitigated by replacing the triglyceride molecules present in the
oils with lighter alcohol molecules such as methanol or ethanol.
This reaction is carried out in the presence of a catalyst and
produces glycerol in addition to transesterfied vegetable oils that
are given the generic name of biodiesel.1,2
The positive effects of biodiesel on diesel engine emissions have
been demonstrated by a number of previous studies.3–6 The
regulated and unregulated exhaust emissions from diesel engines
* Corresponding author. Tel.: +82-2-2220-0427. Fax: +82-2-2281-5286.
E-mail: [email protected].
† Graduate School of Hanyang University.
‡ Hanyang Univeristy.
(1) Bechtold R. L. AlternatiVe Fuels; Society of Automotive Engineers:
Warrendale, PA, 2002.
(2) McDonald, J.; Kittelson, D. B. 950400, Society of Automotive
Engineers: Warrendale, PA, 1995.
(3) Sharp, C. A.; Howell, S. A.; Jobe, J. 2000-01-1967, Society of
Automotive Engineers: Warrendale, PA, 2000.
with biodiesel and blended fuel were measured by Sharp et al.3,4
In their research, it was shown that the measurable HC emissions
were generally eliminated, while CO was reduced roughly 40%
by using a neat biodiesel. However, the NOx emissions increased
by 12% due to the oxygen content in biodiesel.
Dorado et al.5 investigated the reduction characteristics of
biodiesel fuel in a diesel engine in a comparison between the
emissions of diesel fuel and the exhaust emissions of biodiesel
derived from waste olive oil. This revealed that used olive oil
methyl ester can significantly reduce emissions of CO (emission
reduction of 58.9%), CO2 (8.6%), NO (37.5%), and SO2 (57.7%)
compared to diesel fuel.
While biodiesel does have numerous advantages, it has
different properties compared with diesel fuel, as listed in Table
1. It has a higher viscosity, specific gravity, density, cloud point,
and pour point than petroleum diesel fuel, and these specificities
have a significant influence on the fuel spray atomization and
evaporation characteristics, resulting in changes in the combustion process.6,7
In actual engine operation, fuel temperature in the injector
nozzle sac ranges from 160 to 260 °C.8 Therefore, the effect of
fuel temperature on fuel properties such as specific gravity,
density, and viscosity behavior is very important.
Many researchers have developed methods and empirical
models for measuring and predicting specific gravity,9,10 den(4) Sharp, C. A.; Howell, S. A.; Jobe, J. 2000-01-1968, Society of
Automotive Engineers: Warrendale, PA, 2000.
(5) Dorado, M. P.; Ballesteros, E.; Arnal, J. M.; Gomez, J.; Lopez, F. J.
Fuel 2003, 82, 1311–1315.
(6) Lee, C. S.; Park, S. W.; Kwon, S. I. Energy Fuels. 2005, 19, 2201–
2208.
(7) Arregle, J. M.; Desantes, J. M.; Pastor, J. V.; Delage, A. 980802,
Society of Automotive Engineers: Warrendale, PA, 1998.
(8) Kato, M.; Takeuchi, H.; Koie, K.; Sekijima, H.; Kajitani, S.; Chen,
Z. L.; Hashimoto, S. 2004-01-0081, Society of Automotive Engineers:
Warrendale, PA, 2004.
10.1021/ef7002156 CCC: $40.75  2008 American Chemical Society
Published on Web 11/15/2007
Properties of Biodiesel and Blends
Energy & Fuels, Vol. 22, No. 1, 2008 653
Table 1. Specifications of Diesel and Biodiesel Fuels16
Table 2. Test Fuels
fuel property
diesel
biodiesel
fuel type
abbreviation
fuel standard
lower heating value, Btu/gal
kinematic viscosity, @ 40 °C
specific gravity, kg/L @ 60 °F
density, lb/gal @ 15 °C
water and sediment, vol %
carbon, wt %
hydrogen, wt %
oxygen, by dif. wt %
sulfur, wt %
boiling point, °C
flash point, °C
cloud point, °C
pour point, °C
cetane number
lubricity SLBOCLE, g
lubricity HFRR, µm
ASTM D 975
∼129050
1.3–4.1
0.85
7.079
0.05 max
87
13
0
0.05 max
180–340
60–80
-15 to 5
-35 to -15
40–55
2000–5000
300–600
ASTM D 6751
∼118170
4.0–6.0
0.88
7.328
0.05 max
77
12
11
0.01–0.0024
315–350
100–170
-3 to 12
-15 to 10
48–65
>7000
<300
diesel (ULSD) 100%
diesel 80% + biodiesel 20% (vol)
diesel 60% + biodiesel 40% (vol)
diesel 40% + biodiesel 60% (vol)
diesel 20% + biodiesel 80% (vol)
biodiesel (methyl ester of soybean) 100%
D100
B20
B40
B60
B80
B100
sity,11 dynamic viscosity,12,13 kinematic viscosity,13–15 and pour
and cloud point12 of biodiesel and its blends dependent on fuel
temperature.
In general, combustion and emission characteristics of diesel
engine are greatly affected by the atomization of fuel sprays.
In turn, fuel atomization and evaporation are strongly influenced
by fuel properties such as specific gravity, density, and viscosity.
Even though there has been much research on the physical
properties, the liquid properties of biodiesel fuel and its blends
with diesel fuel in the higher temperature region have not yet
been sufficiently investigated.
The objective of this study is to investigate experimentally
the effect of temperature on the specific gravity, density, and
dynamic and kinematic viscosity for diesel, biodiesel, and
blending fuels over the temperature range of 0–200 °C. In order
to analyze the physical properties of biodiesel fuel, six kinds
of test fuels such as neat methyl ester soybean oil, diesel fuel,
and various biodiesel blended with diesel fuel were investigated.
On the basis of results of the experiments, the variation of
dynamic viscosity, density, and their properties due to the fuel
temperature were compared with those of diesel fuel. In order
to obtain the correlation between the temperature and fuel
properties, the measured results of density and viscosity are
correlated and analyzed as empirical equations based on the
results of biodiesel fuels at various temperature conditions.
2. Experimental Apparatus and Procedure
2.1. Test Fuels. In the measurement of fuel properties, test fuels
used in this work were a neat biodiesel (100%) and its blends of
20%, 40%, 60%, and 80% with a conventional diesel fuel. The
biodiesel fuel is a 100% methyl ester of soybean oil (Kaya Energy,
B100), meeting the ASTM D 6751 specifications. The diesel fuel
(ultra low sulfur diesel fuel (ULSD)) with 18 ppm sulfur (maximum) is used as the reference fuel for this study of biodiesel and
blends, and it meets the ASTM D 975 standard specification for
diesel fuel.
(9) Tat, M. E.; Van Gerpen, J. H. Oil Chem. Soc. 2000, 77, 115–119.
(10) Yuan, W.; Hansen, A. C.; Zhang, Q. Agric. Eng. Int.: CIGR J. Sci.
Res. DeV. 2004, 4, EE 04 004.
(11) Tate, R. E.; Watt, K. C.; Allen, C. A.; Wilkie, K. I. Fuel 2006, 85,
1004–1009.
(12) Joshi, R. M.; Pegg, M. J. Fuel 2007, 86, 143–151.
(13) Rinke, K. G. Fuel 2004, 83, 287–291.
(14) Tate, R. E.; Watt, K. C.; Allen, C. A. W.; Wilkie, K. I. Fuel 2006,
85, 1010–1015.
(15) Krisnangkura, K.; Yimsuwan, T.; Pairintra, R. Fuel 2006, 85, 107–
113.
(16) Biodiesel handling and use guidelines. In Energy Efficiency and
Renewable Energy, 3rd Ed.; DOE/GO-102006-2358, Department of Energy:
Washington, DC, September 2006.
Figure 1. Schematic of experimental apparatus.
Biodiesel blends are made on the basis of volume (vol %) and
the blending ratios range from 20% to 80% by intervals of 20%.
During the blending process, diesel and biodiesel fuels were stirred
continuously to ensure proper and uniform mixing. All the blends
were stored in dark brown, hermetically sealed glass bottles, kept
at the room temperature to prevent contamination and alteration of
the test fuels. Table 2 lists the tests fuels and their compositions
used in this experiment.
2.2. Specific Gravity and Viscosity Measurements. Figure 1
shows a schematic of the experimental apparatus. A hydrometer, a
viscometer (Brookfield, LVT), and a sample tube (Brookfield, UL
adapter) were used to measure the specific gravity and the dynamic
viscosity of the test fuels. The principle of a viscometer is to
measure the torque necessary to overcome viscous resistance to
the induced movement when the sensing element (spindle) is
rotating in a test fluid. In order to measure the fuel properties at
the fuel temperature range of 0–200 °C, two devices were designed.
In this investigation, thermoelectric refrigerating was installed
around the sample tube. In order to heat and maintain a constant
temperature range of 20–200 °C, a heating device and thermocouples were attached to the bath and wrapped with an adiabatic
insulator. Two 0.8 mm K-type thermocouples (Omega, KMTSS040U-12) were set up on the upper and lower sides of the measuring
cylinder for the measurement of specific gravity. In the viscosity
experiment, three K-type thermocouples (Omega, KMTSS-020G12) were set up in the refrigerated bath and sample tube to control
the fuel temperature. Measurements were obtained when the
temperature difference between two thermocouples was within (0.1
°C. All tests were carried out in a large chamber designed to
enhance the accuracy of measurement by isolation of the system
from external factors. Enough time was allowed before each
measurement started for the constant temperature bath and spindle
to reach a set temperature. Whenever test fuels were changed, the
sample tube was cleaned out, and the viscometer was verified using
a viscosity standard fluid (Brookfield, viscosity standard) to maintain
accuracy during the experiment.
The temperature was varied in steps of 10 °C from 0 to 200 °C.
The measurements of viscosity were carried out at different spindle
speeds as illustrated in Table 3. Spindle speeds (shear rates) adjusted
654 Energy & Fuels, Vol. 22, No. 1, 2008
Yoon et al.
Table 3. Setup for Viscosity Measurementsa
spindle speed (rpm)
shear rate (s-1)
factor (K)
60.0
30.0
12.0
6.0
73.38
36.69
14.68
7.34
0.1
0.2
0.5
1.0
a The viscometer reading value × conversion factor ) dynamic
viscosity (mPa · s).
Table 4. Measured Specific Gravities for the Temperature
Range from 0 to 200 °C
specific gravity
temperature (°C)
D100
B20
B40
B60
B80
B100
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
0.837
0.83
0.822
0.818
0.81
0.808
0.8
0.795
0.785
0.78
0.773
0.771
0.762
0.757
0.75
0.744
0.738
0.732
0.724
0.715
0.708
0.852
0.844
0.837
0.832
0.826
0.819
0.813
0.808
0.8
0.792
0.784
0.778
0.77
0.763
0.757
0.749
0.743
0.737
0.729
0.722
0.718
0.862
0.858
0.848
0.838
0.832
0.83
0.822
0.818
0.81
0.804
0.797
0.788
0.782
0.772
0.765
0.759
0.752
0.748
0.741
0.732
0.727
0.871
0.863
0.857
0.852
0.846
0.84
0.833
0.827
0.819
0.813
0.807
0.801
0.793
0.787
0.779
0.771
0.764
0.758
0.751
0.745
0.738
0.88
0.873
0.869
0.862
0.854
0.85
0.843
0.838
0.831
0.822
0.817
0.809
0.803
0.797
0.789
0.782
0.773
0.766
0.76
0.752
0.747
0.888
0.88
0.87
0.865
0.86
0.852
0.846
0.84
0.832
0.828
0.821
0.817
0.812
0.799
0.794
0.79
0.786
0.781
0.775
0.767
0.756
for viscosity range according to the different test fuels and fuel
temperatures.
3. Results and Discussion
3.1. Specific Gravity and Density. The specific gravity is
the ratio of the weight of a given volume of a substance to the
weight of an equal volume of some reference substance
(universally, water at 4 °C, FH2O ) 1000 kg/m3) or the ratio of
the mass of equal volumes of the two substances. The specific
gravity measured as a function of fuel temperature (0–200 °C)
is provided in Table 4 for various blending ratios (0–100%) of
biodiesel. Specific gravities of test fuels increased proportionally
to the blending ratio of biodiesel. As fuel temperature was
increased from 0 to 200 °C, specific gravities of the fuels
decreased in accordance with the increase in fuel temperature.
Figure 2 shows a comparison of the density for D100, B100,
and blends (B20–B80) and the density results obtained by Tat
et al.;9 the lines indicated first-order polynomial fits of the
density results as function of temperature. In the case of B100,
the results are nearly to equal those of Tat et al.9 such that the
maximum absolute deviations are about 0.805–1.123% error
over the entire temperature range, even though the test fuels
were made from different products. In the measured temperature
range, the densities of B100 and D100 decrease according to
the fuel temperature, as the slopes of the density curves have
similar reduction rates. The mean difference is about 47.619
kg/m3 for two test samples. These similar trends could be found
in other studies, such as those by Tat et al. and Yuan et al.9,10
The density of biodiesel fuel blended with diesel increases in
accordance with an increase in the blending ratio. In addition,
it can be seen that the density of blended fuel decreases with
increasing temperature from 20 to 200 °C. Further, with the
increase of blending ratio of biodiesel fuel, density values also
Figure 2. Relation between density and fuel temperature of diesel,
biodiesel, and blended fuels (B20–B80).
Table 5. First-Order Polynomial Equations for the Density of
Test Fuels (0–200 °C)
fuel type
empirical eq for density
R2
D100
F ) 836.991 - 0.628T
(1)
0.998
B20
F ) 852.584 - 0.682T
(2)
0.999
B40
F ) 862.615 - 0.681T
(3)
0.998
B60
F ) 872.165 - 0.667T
(4)
0.999
B80
F ) 882.589 - 0.675T
(5)
0.998
B100
F ) 884.468 - 0.626T
(6)
0.997
increased linearly. The average difference of these densities is
about 10.222 kg/m3 within each blending fuel in steps of 20%
blending ratio.
In this study, the density results have been correlated as a
function of fuel temperature by empirical first-order polynomial
eqs 1–6 in Table 5. In eqs 1–6, the lowest correlation coefficient
squared (R2) is 0.997 and the average R2 is 0.998, which
indicates very close agreement between the measurements and
these equations. The empirical equation for the density of
biodiesel (B100) and its blends (B20–B80) as a function of
temperature is
Fcal ) 845.7616 + 0.41871rmix - 0.70115T + 5.844 × 10–4rmixT
(7)
where Fcal is the density (kg/m3), rmix is the blending ratio of
biodiesel (%), and T is the fuel temperature (°C).
Table 6 shows the comparison of calculated density values
(Fcal) from eq 7 with measured density values (Fmeasured)
dependent on the fuel temperature (0–200 °C) and blending ratio
(B20–B100) of biodiesel. Figure 3 shows the error rates between
the measured and calculated density from eq 7 for blends
(B20–B80) and biodiesel. At all blending ratio and test
temperature ranges, the highest error rate is within 0.6%. These
result means that eq 7 provides good accuracy for the density
of biodiesel and blends.
3.2. Dynamic and Kinematic Viscosity. Dynamic viscosity
(mPa · s) is a measure of the resistance to flow of a fluid under
an applied force. In this work, the spindle speed and shear rate
were adjusted during the experiment because the dynamic
viscosity changed with fuel temperature and type of samples.
Properties of Biodiesel and Blends
Energy & Fuels, Vol. 22, No. 1, 2008 655
Figure 3. Error rate between the measured and calculated density values
(B20–B100).
Kinematic viscosity (mm2/s) is a coefficient defined as the ratio
of the dynamic viscosity of a fluid to its density. The values of
kinematic viscosity obtained from the measurements of density
and dynamic viscosity are shown in Table 7.
Figure 4 shows the relationship between the dynamic viscosity
and fuel temperature for various test samples. In this figure,
excepting the results of B80 and B100 at 0 °C, the result of
dynamic viscosity decreased linearly as the fuel temperature
increased. The difference in viscosity among test fuels greatly
diminished when the temperature reached 200 °C. As the
blending ratio increased, the viscosity of the test fuel was a
slightly higher value in the temperature range 0–80 °C.
Comparison of measured kinematic viscosity between D100,
B100, and blends (B20–B80) and the results of Tate et al.14 are
shown in Figure 5. Tate et al.14 measured the viscosity of soy
methyl esters (West central soy, IA) over the range of 20–300
°C using a modified Saybolt viscometer, and their results have
a correlation coefficient squared (R2) of 0.951. In the case of
B100, there is a similar trend between the current results and
those of Tate et al.14 In particular, nearly equal values were
obtained when the temperature was over 100 °C. In the lowtemperature range (0–10 °C), the viscosity of B100 was several
times higher than that of D100, making it likely that fuel flow
problems will occur in the actual engine injection system. The
viscosity of all test blends diminished with rising temperature,
just like that of B100 and D100. At a temperature of 0 °C, the
B80 result was much higher than other blended fuels.
The largest value of difference in kinematic viscosity between
biodiesel and diesel was at a temperature of 0 °C, and as fuel
temperature increased, the difference rapidly decreased in the
range of 0–100 °C. At a fuel temperature of 200 °C, the
difference between the two fuels shows the lowest value.
Considering that the fuel temperature in the injector sac volume
is over 200 °C in actual engine operation conditions,8 the
influence of the high viscosity of biodiesel is not significant.
However, when the fuel temperature is 0 °C, in the cases of
B80 and B100, wax crystals are partially distributed, especially
in B100. In contrast, wax crystals did not appear for blends of
20%, 40%, 60%, and diesel fuel.
An empirical equation for kinematic viscosity of test fuel as
a function of temperature is given by
( βT ) + γ
ηemp ) R exp -
(8)
where η is the kinematic viscosity (mm2/s), T is fuel temperature
(°C), and R, β, and γ are correlation constants that are correlated
with fuel types. The correlation constants and correlation
coefficient squared (R2) values for eq 8 are listed in Table 8. In
eq 8, the fuel temperature range is limited to between 10 and
200 °C. A bound of 0 °C is excluded because the kinematic
viscosity at that temperature is much too high when compared
to other measured values, making it hard to generate a
reasonable fit.
The correlation constants for kinematic viscosity over the
temperature range of 10–200 °C are shown in Table 8. As
shown, the lowest value mean values of squared correlation
constants are 0.994 and 0.995.
Table 6. Measured and Calculated Densities of Blends over the Temperature Range 0–200 °C
temperature (°C)
fuel type
B100
B80
B60
B40
B20
Fmeasured(kg/m3)
Fcalculated(kg/m3)
Fmeasured(kg/m3)
Fcalculated(kg/m3)
Fmeasured(kg/m3)
Fcalculated(kg/m3)
Fmeasured(kg/m3)
Fcalculated(kg/m3)
Fmeasured(kg/m3)
Fcalculated(kg/m3)
0
20
40
60
80
100
120
140
160
180
200
888
887.633
880
879.258
871
870.884
862
862.51
852
854.136
870
874.779
869
866.171
857
857.563
848
848.955
837
840.347
860
861.924
854
853.08
846
844.241
832
835.399
826
826.557
846
849.07
843
839.995
833
830.919
822
821.844
813
812.768
832
836.216
831
826.907
819
817.568
810
808.288
800
798.979
821
823.362
817
813.819
807
804.276
797
794.733
784
785.19
812
810.508
803
800.731
793
790.954
782
781.177
770
771.401
794
797.654
789
787.643
779
777.637
765
767.622
757
757.611
786
784.8
773
774.555
764
764.311
752
754.067
743
743.822
775
771.946
760
761.468
751
750.989
741
740.511
729
730.033
756
759.092
747
748.38
738
737.668
727
726.956
718
716.244
Table 7. Measurements of Dynamic and Kinematic Viscosity of Test Fuels (0–200 °C)
dynamic viscosity (mPa · s)
kinematic viscosity (mm2/s)
temp (°C)
D100
B20
B40
B60
B80
B100
D100
B20
B40
B60
B80
B100
0
20
40
60
80
100
120
140
160
180
200
5.390
3.220
2.310
1.710
1.370
1.100
0.910
0.720
0.620
0.550
0.480
6.320
3.580
2.450
1.940
1.390
1.120
0.960
0.770
0.670
0.580
0.510
6.690
4.320
2.790
2.350
1.580
1.220
0.990
0.850
0.740
0.640
0.540
7.910
4.610
3.150
2.700
1.930
1.470
1.240
1.000
0.890
0.710
0.610
16.160
5.660
3.910
2.590
1.910
1.510
1.220
1.050
0.900
0.750
0.650
34.650
6.050
4.080
2.755
2.085
1.570
1.255
1.045
0.950
0.790
0.690
6.440
3.917
2.852
2.138
1.745
1.423
1.194
0.960
0.840
0.760
0.678
7.418
4.277
2.966
2.386
1.738
1.429
1.247
1.017
0.902
0.796
0.710
7.761
5.094
3.353
2.859
1.951
1.531
1.266
1.111
0.984
0.864
0.743
9.082
5.379
3.723
3.241
2.357
1.822
1.564
1.284
1.165
0.945
0.827
18.364
6.513
4.578
3.072
2.298
1.848
1.519
1.331
1.164
0.987
0.870
39.020
6.954
4.744
3.257
2.506
1.912
1.546
1.316
1.209
1.019
0.913
656 Energy & Fuels, Vol. 22, No. 1, 2008
Yoon et al.
Table 8. Correlation Constants for the Kinematic Viscosity
Equation over the Temperature Range 10–200 °C
correlation constants
fuel type
R
β
γ
R2
B100
B80
B60
B40
B20
D100
10.120
8.544
6.726
6.103
5.642
5.052
40.843
46.872
53.791
53.441
47.462
50.495
0.972
0.830
0.767
0.635
0.706
0.654
0.998
0.999
0.994
0.995
0.996
0.997
viscosity increased about 12% for every 20% increase in
blending ratio due to the higher viscosity of biodiesel. On the
other hand, in the case of 180 °C, the dynamic and kinematic
viscosity increased about 6.1% and 7.4%, respectively.
Figure 4. Temperature effect on dynamic viscosity of test fuels
(0–200 °C).
Figure 5. Kinematic viscosity of test fuels (D100, B20–100) and Tate
et al.14
Figure 6. Kinematic and dynamic viscosities according to the blending
ratio at 20 and 180 °C (measured values).
Figure 6 shows the dynamic and kinematic viscosity according to the blending ratio at the constant fuel temperatures of 20
and 180 °C. At the temperature of 20 °C, dynamic and kinematic
4. Conclusions
In order to investigate the effect of various temperature
conditions on biodiesel and its blended fuel properties, the
specific gravity, density, dynamic viscosity, and kinematic
viscosity of pure biodiesel, neat diesel, and their blends
(20–80%) were measured in the temperature range from 0–200
°C. On the basis of the measured results of fuel properties, the
following conclusions were obtained.
1. The specific gravities measured increased proportionally
with the blending ratio of biodiesel and gradually decreased
according to the increasing fuel temperature. Moreover, as the
blending ratio of biodeisel increased, the density values are also
increased linearly. The average density difference according to
the blending ratio of biodiesel is about 10.222 kg/m3 in each
blending fuel.
2. An empirical equation to predict the density of biodiesel
(B100) and its blends (B20–B80) as a function of temperature
and blending ratio has been developed, and the predicted results
are in very good agreement with experimental results in this
work and other previous studies.
3. All viscosities of blends, diesel, and biodiesel decreased
with increasing fuel temperature. An empirical equation to
predict the kinematic viscosity of diesel, biodiesel, and blends
as a function of fuel temperature has been developed.
4. At a fuel temperature of 200 °C, the differences in
kinematic viscosity among the test fuels decreased rapidly. At
a temperature between 0 and 10 °C, wax crystals are partially
distributed especially in B100. The viscosity of biodiesel due
to the existence of wax crystals increased flow resistance
compared to a higher temperature range (20–200 °C).
Acknowledgment. This study was supported by the CEFV
(Center for Environmentally Friendly Vehicle) of the Eco-STAR
project from the MOE (Ministry of Environment, Republic of
Korea). Additional support for this work is from the Ministry of
Education and Human Resources Development (MOE), the Ministry
of Commerce, Industry and Energy (MOCIE), and the Ministry of
Labor (MOLAB) through the fostering project of the Lab of
Excellency. Also, this work was supported by the Second Brain
Korea 21 Project in 2006.
EF7002156