Modern Mechanical Engineering, 2011, 1, 77-83
doi:10.4236/mme.2011.12010 Published Online November 2011 (http://www.SciRP.org/journal/mme)
Bio-Diesel from Mustard Oil: A Renewable Alternative
Fuel for Small Diesel Engines
Zannatul Moiet Hasib1, Jomir Hossain2, Saikat Biswas2, Asif Islam3
1Ryerson University, Toronto, Canada
2Department of Mechani cal Engineering, Bangladesh Uni versi t y of Engi neeri ng an d Technology, Dhaka, Bangladesh
3Energypac Engineeri ng Lt d. C / A , Dhaka, Bangladesh
Received October 8, 2011; revised November 8, 2011; accepted November 15, 2011
Abstract
This paper represents the prospect of mustard oil as a renewable and alternative fuel. To cope up with present
load-shedding situation and to reduce the dependency on imported fuel, Bangladesh government is encour-
aging the use of renewable energy sources. Since diesel engines have versatile uses including small irrigation
pumping systems, and standby small electricity generators, use of diesel fuel is much higher than any other
gasoline fuels. In Bangladesh mustard oil has been in use as edible oil throughout the country. Mustard is a
widely growing plant in Bangladesh and every year the production of mustard seed exceeds the demand. So
the endeavor was to use the surplus mustard oil as an alternative to diesel fuel. Fuel properties are deter-
mined in the fuel testing laboratory with standard procedure. An experimental set-up is then made to study
the performance of a small diesel engine in the heat engine laboratory using different blends of bio-diesel
converted from mustard oil. It is found that bio-diesel has slightly different properties than diesel fuel. It is
also observed that with bio-diesel, the engine is capable of running without difficulty but with a deviation
from its optimum performance. Initially different blends of bio-diesel (i.e. B20, B30, B50 etc.) have been
used to avoid complicated modification of the engine or the fuel supply system. Finally, a comparison of en-
gine performance for different blends of bio-diesel has been carried out to determine the optimum blend for
different operating conditions.
Keywords: Transesterification, Mustard Oil, Bio-Diesel, Heating Value, Pyrolysis, Viscosity
1. Introduction
Modern civilization is much dependent on fossil energy.
Energy obtained from fossil resources is much higher than
any other resources. Majority of the world’s energy needs
are supplied thorough petrochemical resources, coal, oil
and natural gas. The consumption of fossil fuels is on in-
crease from year to year. As the fossil resource is non-
renewable, so fuel price is gouging as a consequence of
spiraling demand and diminishing supply.
Diesel fuel has higher energy density than other gaso-
line fuel. Therefore, diesel engines are widely used in hea-
vy-duty transportation, power generation and also in ag-
ricultural sectors. As a result, the depletion rate of diesel
fuel is much higher than other gasoline fuels, which sub-
sequently causes higher price of diesel fuel than other
gasoline. In Bangladesh, resource of petrochemical fuels
is very limited. So, for energy demand, Bangladesh is fully
dependent on crude oil import from Middle Eastern coun-
tries. Moreover, as Bangladesh imports Arabian Light
Crude oil (ALC), so the cost associated with oil refining
is also huge. Moreover, the growing concern about envi-
ronmental issues in the 90’s (i.e. clean air act) has in-
creased the interest in alternative fuels paving the way to
greater funding and effort for research studies. The in-
creaseing amount of Green-House Gases (GHG) such as
CO2 which is causing global warming and climate change,
as well as the declining reserve of fossil fuels, and more
importantly, the high fuel prices have strongly increased
the interest in the use of bio-oils and biodiesel for land,
transport and power generation. The sources of bio-fuels
are renewable, and the use of bio-fuels ensures reduced
amount of particulate matter, HC and NOX emission to
the environment. Thus bio-fuels can emerge as an excel-
lent alternative to fossil fuels.
The use of vegetable oils as an alternative fuel for

Z. M. HASIB ET AL.
78
diesel engines dates back to around a century. Depending
upon soil condition and climate, different nations are look-
ing for different vegetable oils for example, soybean oil
in U.S.A., rapeseed and sunflower oil in Europe, palm oil
in Malaysia and Indonesia, coconut oils in Philippines
are being considered to substitute of diesel fuel [1]. The
potential of bio-diesel production from mustard oil have
been found to be a promising fuel for diesel engine in a
number of studies [2]. Mustard (Brassica juncea) is a
widely growing seed in Bangladesh. Many countries con-
sider mustard oil as unsuitable for human consumption
as it has a high content of a substance known as Uric
Acid which is harmful to the body. Mustard plant is cha-
racterized by yellowish green leaves and round stems with
long inter-nodes. The grayish brown seeds are tiny and
round in shape and on reacting with water emit a strong
smell. It is generally used in cooking. Every year the pro-
duction of mustard seed in Bangladesh surpluses the de-
mand for it. So the endeavor was to use the surplus mus-
tard oil as an alternative to diesel fuel. This paper shows
the prospect of mustard oil as a renewable and alternative
source to diesel fuel
2. Bio-Diesel vs. Straight Vegetable Oil
Biodiesel is produced from vegetable oils. The main com-
ponents of vegetable oil are triglycerides. Triglycerides
are esters of glycerol with long chain acids, commonly
called fatty acids. Bio-diesel is defined as mono alkyl
esters of long chain fatty acids derived from renewable
feed stock-such as vegetable oil or animal fats, for use in
compression ignition (CI) engines [3-11]. This name is
given to the esters when they are for use as fuel.
Problems associated with using straight vegetable oil
(SVO) in diesel engine, can be classified in two groups,
viz, operational and durability problems. Operation pro-
blems are related to starting ability, ignition, combustion
and performance. Durability problems are related to de-
posit formation, carbonization of injection tip, ring sticking
and lubrication oil dilution. The problems associated with
using straight vegetable oil (SVO) can be listed as below:
 It has been observed that SVO when used for long
hours, tend to choke the fuel filter because of high vis-
cosity and insoluble present in the SVO.
 High viscosity of SVO causes poor fuel atomization,
large droplet size, and thus high spray jet penetration.
The jet also tends to be a solid stream instead of a spray
of small droplets. As a result, the fuel is not distributed
or mixed with the air required for burning in the combus-
tion chamber. This result in poor combustion accompa-
nied by loss of power and economy.
 SVO has lower energy density than fossil diesel. So
this leads to higher BSFC of the engine.
 To use SVO efficiently in diesel engine, modifica-
tion of fuel supply system and engine redesign is re-
quired; which is much costly.
Blending, Cracking/Pyrolysis, Emulsification or Trans-
esterification of vegetable oil may overcome these prob-
lems. Heating and blending of vegetable oil reduces the
viscosity and improve volatility of vegetable oil but its
molecular structure remains unchanged; hence polyun-
saturated character remains. Blending of vegetable oils
with diesel however reduces the viscosity drastically and
the fuel handling system of engine can handle the vege-
table oil diesel blends without any problems. On the ba-
sis of experimental investigations, it is found that con-
verting vegetable oils into simple esters is an effective
way to overcome all the problems associated with the ve-
getable oils.
3. Trans-Esterification Reaction
Transesterification, also called as alcoholysis is the dis-
placement of alcohol from an ester by another alcohol in
a process similar to hydrolysis except that an alcohol is
used instead of water [4]. This has been widely used to
reduce the viscosity of the triglycerides. The transesteri-
fication is expressed by the following reaction.
Experimental study shows that the major variables af-
fecting the trans-esterification reaction are [5]:
 The free fatty acid (FFA) and the moisture content.
 Type of Catalyst.
 A literature (Freedmen et al. 1984) has revealed
that, the rate of reaction is strongly influenced by the
reaction temperature. (Figure 1)
 Murugesan et al. reported that, after completion of
the reaction, the product is kept for a certain time interval
for separation (approx. 25 h +) of bio-diesel and glycerol
separation.
Figure 1. Variation of biodiesel production with reaction
temperature.

79 Z. M. HASIB ET AL
 Murugesan et al. reported that, washing is a proc-
ess to remove catalyst, soap and excess methanol.
4. Synthesis of Bio-Diesel from Mustard Oil
For the transesterification of mustard oil, Dr. Peepers
style has been followed in our work [6,7]. First 250 ml
(90% pure) methanol was mixed with 150 ml (1 N) NaOH.
This mixture was swirled in a glass container until NaOH
is fully dissolved in methanol. As this is an exothermic
reaction, so the mixture would get hot. This solution is
known as methoxide, which is a powerful corrosive base
and is harmful for human skin. So, safety precautions
should be taken to avoid skin contamination during meth-
oxide producing [10-15].
Next, methoxide was added with 1 liter of mustard oil,
which was preheated about 55 degree Celsius. Then the
mixture was jerked for 5 minutes in a glass container.
After that, the mixture was left for 24 hours (the longer is
better) (Figures 2(a) and (b)) for the separation of glyc-
erol and ester. This mixture then gradually settles down
(a) (b)
(c)
Figure 2. (a) Biodiesel production after 3 hours of separa-
tion. (b) Biodiesel production after 24 hours of separation.
(c) Produced biodiesel is separated and then heated to re-
move methanol and water.
in two distinctive layers. The upper more transparent la-
yer is 100% bio-diesel and the lower concentrated layer
is glycerol. The heavier layer is then removed either by
gravity separation or with a centrifuge. In some cases if
the mustard oil contains impurities, then a thin white
layer is formed in between the two layers. This thin layer
composes soap and other impurities.
Bio-diesel produced in the above process contains mois-
ture (vaporization temperature 100 degree Celsius) and
methanol (vaporization temperature 60 degree celsius)
and usually some soap. If the soap level is low enough
(300 ppm - 500 ppm), the methanol can be removed by
vaporization and the methanol will usually be dry enough to
directly recycle back to the reaction. Methanol tends to
act as a co-solvent for soap in biodiesel; so at higher soap
levels the soap will precipitate as a viscous sludge when
the methanol is removed. Anyway, heating the biodiesel
at temperature above 100 degree Celsius would cause the
removal of both the moisture and methanol as well.
In our study, food grade quality mustard oil was used,
other than raw mustard oil to ensure that the vegetable
oil contains lesser impurities.
5. Fuel Properties of Biodiesel and Their
Blends
Biodiesel produced from mustard oil has comparable fuel
properties with the conventional fossil diesel. A com-
parative study of fuel properties for fossil diesel, neat
biodiesel and their blends have been carried out in this
work to find out the suitable blending of biodiesel. In our
study, we have prepared B20, B30, B40, B50 and B100
blend to compare the fuel properties for different blends.
5.1. Heating Value
Heating value indicates the energy density of the fuel. In
our study, ASTM 2382 method has been applied to mea-
sure the heating value of biodiesel and their blends. Table
1 shows the heating value of diesel, neat biodiesel and
their blends in MJ/Kg.
Table 1. Comparison of heating value of different fuels.
Heating value (MJ/Kg)
Fossil Diesel 44.00
Neat biodiesel B100 39.51
B50 41.97
B40 42.18
B30 42.21
B20 42.65

Z. M. HASIB ET AL.
80
From Table 1 it is observed that, diesel fuel has heat-
ing value about 44 MJ/Kg. Heating values of the fuel de-
creases as we choose higher blending of biodiesel. Figure
3 indicates that diesel fuel has Bsfc about 210 gm/Bhp hr,
and B50 blend has Bsfc about 220 gm/Bhp hr which is
5% higher than the diesel fuel. As heating value of the
fuel decreases for higher blending of biodiesel, so Bsfc
of the fuel also increases for higher and higher blending
of biodiesel. This is because, as biodiesel has lower en-
ergy density than diesel fuel, so higher amount of biodiesel
is required for producing same amount of energy as com-
pared to diesel fuel.
5.2. Density
Density is an important property of CI engine fuel. Fig-
ure 4 shows density for diesel, biodiesel and their blends.
From Figure 4 it is observed that B20 and B30 have
almost same density as that of fossil diesel at room tem-
perature (30˚C). So preheating is not required for using
B20 and B30. B40 has about 1.50% higher density than
fossil diesel, and it attains same density as that of diesel
fuel at 55˚C. So preheating B40 fuel at this temperature
is necessary for using it in CI engine. Similarly B50 has
2.5% higher density than that of diesel fuel. And at tem-
perature 60˚C, it attains the same density as that of diesel
fuel. For B100, it has about 5% higher density than die-
sel fuel, and it requires preheating at 120˚C to attain si-
milar density as that of diesel fuel. From Figure 4 we
find that, density of the fuel increases with the increase
in blending number. On the other hand, the exhaust from
CI engine has temperature around 250˚C. So, for using
higher blending number, the intake manifold of the en-
gine should be redesigned so that preheating can be done
utilizing the exhaust of CI engine.
5.3. Viscosity
Viscosity of the fuel exerts a strong influence on the
shape of the fuel spray; high viscosity for example, causes
low atomization (large-droplet size) and high penetration
of the spray jet. Note that a cold engine, with higher vis-
cous oil, discharge wills almost a solid stream of fuel into
Figure 3. Bsfc for diesel fuel and biodiesel blends at Bhp 3 Hp.
Figure 4. Temperature vs. density curve for diesel, biodiesel
and their blends.
the combustion chamber and starting may be difficult while
a smoky exhaust will almost invariably appear. On the
other hand, very low viscous fuel would cause to pass tho-
rough the leakage of piston and piston wall especially
after wear has occurred, which subsequently prevents ac-
curate metering of the fuel.
Figure 5 indicates that, B20 has 1.5 times higher vis-
cosity than fossil diesel at the room temperature. On the
other hand, B30, B40 and B50 have almost the same vis-
cosity at room temperature, and it is about 2.5 times higher
than the fossil diesel. But a slight preheating would cause
to achieve comparable viscosity as that of diesel fuel. So
using B20, B30, B40 and B50 blend would not cause
much change in the fuel spray pattern, and thus these fuels
can be used in the existing diesel engines without modi-
fication of the fuel supply system.
On the other hand B100 is a much viscous fuel, and its
viscosity is about 6 times higher than that of diesel fuel.
The high viscous fuel would exhibit almost a solid stream
of spray pattern in the combustion chamber and so cold
starting of the engine would be difficult. So, using B100
fuel in the existing diesel engine would require modifica-
tion of the fuel supply system so that the fuel supply
Figure 5. Temperature vs. kinematic viscosity curve for diesel,
biodiesel and their blends.

81 Z. M. HASIB ET AL
system exerts high spray pressure to achieve the desired
spray pattern inside the engine cylinder.
6. Engine Performance Testing and Analysis
The final product of biodiesel from mustard oil was used
as an alternative fuel to operate a diesel engine and the
performance data were recorded. All data was derated as
per BS5514 standard. The specification of the engine is
given in Table 2.
6.1. Experimental Setup
The experimental setup (Figure 6) consisted of engine
test bed with fuel supply system and different metering
and measuring devices with the engine. A water brake
dynamometer was coupled with the engine. Load was va-
ried by means of flow control of the dynamometer. Fuel
was supplied from an external source. Preheating of fuel
was done manually by gas burner. B40 blend was pre-
heated at 55˚C and B50 blend was preheated at 60˚C.
However B100 was not possible to use directly in the en-
gine as it causes excessive vibration. Engine speed was
measured by digital tachometer. Lube oil temperature and
exhaust gas temperature was measured by K-type ther-
mocouple. Operating condition of the engine is given in
Table 3.
Table 2. Engine specifications.
Model ZS 1110
Method of starting Hand starting
type Horizontal, 4-stroke, 1 cylinder
Cylinder dia 70 mm
Piston stroke 75 mm
Nominal speed 2600 rpm
Nominal power 3 Hp
Cooling system Air cooled
rotation Anti-clockwise
Fuel filter Present
Lube oil filter present
Figure 6. Experimental setup.
Table 3. Engine operating conditions.
Engine speed 2200 rpm
Engine load 1 kg to 3.5 kg
Fuels tested 100% diesel, B20, B30, B40 and B50.
Lube oil used SAE-40
6.2. Performance Analysis
Figure 7 shows the variation of Bsfc with Bhp for dif-
ferent fuels. The curve shows that, Bsfc for biodiesel
blends is higher at low % load. And it decreases with the
increase in % load. It is also observed from the curve that,
specific fuel consumption increases with the increase in
biodiesel blend. This is mainly due to the relationship
among volumetric fuel injection system, fuel specific grav-
ity, viscosity and heating value. As a result, more biodie-
sel blend is needed to produce the same amount of en-
ergy due to its higher density and lower heating value in
comparison to conventional diesel fuel. Again as bio-
diesel blends have different viscosity than diesel fuel, so
biodiesel causes poor atomization and mixture formation
and thus increases the fuel consumption rate to maintain
the power.
Figure 8 shows the relation in between Bhp and brake
thermal efficiency ηb for different fuels. Bsfc is a meas-
ure of overall efficiency of the engine. Bsfc is inversely
related with efficiency. So, lower the value of Bsfc, higher
is the overall efficiency of the engine. However, for dif-
ferent fuels with different heating values, the Bsfc values
are misleading and hence brake thermal efficiency is em-
ployed when the engines are fueled with different types
of fuels. From the figure, it is evident that Bsfc for bio-
diesel blends is always higher and ηb is always lower
than that of diesel fuel. This is because biodiesel has lower
heating value than conventional diesel fuel. One other
cause for lower ηb for biodiesel blends is the poor at-
omization which is attributed to higher density and ki-
nematic viscosity of biodiesel blends.
Figure 9 depicts about variation in exhaust gas tem-
perature with Bhp for different fuels. From the curve it is
observed that except B30, all other biodiesel blends have
higher exhaust gas temperature than diesel fuel. At start-
ing condition, higher exhaust gas temperature but low
power output for biodiesel blends indicate late burning to
the high proportion of biodiesel. This would increase the
heat loss, making the combustion a less efficient. At
higher load condition, B30 and B40 have lower exhaust
temperature as compared to diesel fuel.
Figure 10 shows the relation in between lube oil tem-
perature and Bhp for different fuels. At lower Bhp, diesel
fuel and biodiesel blends have similar lube oil tempera-
ture. At higher % load condition, B50 shows higher lube

Z. M. HASIB ET AL.
82
Figure 7. Variation of Bsfc with Bhp for different fuels.
Figure 8. Variation of thermal efficiency ηb with Bhp for
different fuels.
Figure 9. Variation of exhaust gas temperature with Bhp
for different fuels.
Figure 10. Variation of lube oil temperature with Bhp for
different fuels.
Table 4. Cost of running engines with different fuels.
Fuel Cost (tk/lr)
Diesel 40
B20 58
B30 67
B40 76
B50 85
oil temperature than other fuels. This phenomenon can
be attributed to the preheating of the B50 fuel at 60˚C.
However, there is not wide variance in the lube oil tem-
perature for diesel fuel and biodiesel blends; which indi-
cates that SAE-40 lube oil is suitable for biodiesel run
engines.
7. Cost Analysis
The present costing of running a diesel engine with bio-
diesel blends derived from mustard oil are given in Table 4.
From Table 4 it is clear that, running diesel engine with
biodiesel blends is costly as compared to diesel fuel. How-
ever, cost can be drastically reduced, if methanol can be
recycled after the transesterification reaction. Moreover,
in our experiment we have used food grade mustard oil.
And using raw or unprocessed oil would also cause to
decrease the biodiesel production cost.
In Bangladesh, government grants a huge subsidy on
diesel fuel, which causes the lower price for diesel fuel.
So a thorough study is required for the feasibility analy-
sis of biodiesel by comparing it production cost with in-
ternational market price of diesel.
8. Conclusions
Experiment was conducted on a small four stroke diesel
engine to determine the feasibility of mustard oil as an
alternative to diesel engine. The following conclusions may
be drawn from the experiment.
 Biodiesel can be produced from mustard oil using
transesterification reaction.
 It is possible to run diesel engine with biodiesel
blends.
 Bsfc for biodiesel increases for higher blending of
biodiesel, because of the lower heating value of biodiesel
as compared to diesel fuel.
 For using higher blending of biodiesel, the fuel
must be preheated in order to reduce the density and vis-
cosity of the fuel.
Compared to diesel fuel, a little amount of power loss
occurs for biodiesel blends.

Z. M. HASIB ET AL
83
9. Acknowledgements
This research work was funded by Department of Me-
chanical Engineering, Bangladesh University of Engi-
neering & Technology (BUET). Laboratory support: Fuel
testing lab, Heat engine lab, ME dept. BUET.
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Definitions/Abbreviations
Bsfc: Brake specific fuel consumption, gm/Bhp-hr
Bhp: Brake horse power, hp
LV: Lower heating value of fuel, Mj/kg
T: Temperature, ˚C
Ηb: Brake thermal efficiency (%)