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
1
Ryerson University, Toronto, Canada
2
Department of Mechanical Engineering, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
3
Energypac Engineering Ltd. C/A, Dhaka, Bangladesh
E-mail: zannatulmoiet.hasib@ryerson.ca, jomir_h@yahoo.com, {saikat.buet, asif038}@gmail.com
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 dependent on crude oil import from Middle Eastern coun-

tries. Moreover, as Bangladesh imports Arabian Light
Modern civilization is much dependent on fossil energy. Crude oil (ALC), so the cost associated with oil refining
Energy obtained from fossil resources is much higher than is also huge. Moreover, the growing concern about envi-
any other resources. Majority of the world’s energy needs ronmental issues in the 90’s (i.e. clean air act) has in-
are supplied thorough petrochemical resources, coal, oil creased the interest in alternative fuels paving the way to
and natural gas. The consumption of fossil fuels is on in- greater funding and effort for research studies. The in-
crease from year to year. As the fossil resource is non- creaseing amount of Green-House Gases (GHG) such as
renewable, so fuel price is gouging as a consequence of CO2 which is causing global warming and climate change,
spiraling demand and diminishing supply. as well as the declining reserve of fossil fuels, and more
Diesel fuel has higher energy density than other gaso- importantly, the high fuel prices have strongly increased
line fuel. Therefore, diesel engines are widely used in hea- the interest in the use of bio-oils and biodiesel for land,
vy-duty transportation, power generation and also in ag- transport and power generation. The sources of bio-fuels
ricultural sectors. As a result, the depletion rate of diesel are renewable, and the use of bio-fuels ensures reduced
fuel is much higher than other gasoline fuels, which sub- amount of particulate matter, HC and NOX emission to
sequently causes higher price of diesel fuel than other the environment. Thus bio-fuels can emerge as an excel-
gasoline. In Bangladesh, resource of petrochemical fuels lent alternative to fossil fuels.
is very limited. So, for energy demand, Bangladesh is fully The use of vegetable oils as an alternative fuel for

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78 Z. M. HASIB ET AL.

diesel engines dates back to around a century. Depending  To use SVO efficiently in diesel engine, modifica-
upon soil condition and climate, different nations are look- tion of fuel supply system and engine redesign is re-
ing for different vegetable oils for example, soybean oil quired; which is much costly.
in U.S.A., rapeseed and sunflower oil in Europe, palm oil Blending, Cracking/Pyrolysis, Emulsification or Trans-
in Malaysia and Indonesia, coconut oils in Philippines esterification of vegetable oil may overcome these prob-
are being considered to substitute of diesel fuel [1]. The lems. Heating and blending of vegetable oil reduces the
potential of bio-diesel production from mustard oil have viscosity and improve volatility of vegetable oil but its
been found to be a promising fuel for diesel engine in a molecular structure remains unchanged; hence polyun-
number of studies [2]. Mustard (Brassica juncea) is a saturated character remains. Blending of vegetable oils
widely growing seed in Bangladesh. Many countries con- with diesel however reduces the viscosity drastically and
sider mustard oil as unsuitable for human consumption the fuel handling system of engine can handle the vege-
as it has a high content of a substance known as Uric table oil diesel blends without any problems. On the ba-
Acid which is harmful to the body. Mustard plant is cha- sis of experimental investigations, it is found that con-
racterized by yellowish green leaves and round stems with verting vegetable oils into simple esters is an effective
long inter-nodes. The grayish brown seeds are tiny and way to overcome all the problems associated with the ve-
round in shape and on reacting with water emit a strong getable oils.
smell. It is generally used in cooking. Every year the pro-
duction of mustard seed in Bangladesh surpluses the de- 3. Trans-Esterification Reaction
mand for it. So the endeavor was to use the surplus mus-
tard oil as an alternative to diesel fuel. This paper shows Transesterification, also called as alcoholysis is the dis-
the prospect of mustard oil as a renewable and alternative placement of alcohol from an ester by another alcohol in
source to diesel fuel a process similar to hydrolysis except that an alcohol is
used instead of water [4]. This has been widely used to
2. Bio-Diesel vs. Straight Vegetable Oil reduce the viscosity of the triglycerides. The transesteri-
fication is expressed by the following reaction.
Biodiesel is produced from vegetable oils. The main com- Experimental study shows that the major variables af-
ponents of vegetable oil are triglycerides. Triglycerides fecting the trans-esterification reaction are [5]:
are esters of glycerol with long chain acids, commonly  The free fatty acid (FFA) and the moisture content.
called fatty acids. Bio-diesel is defined as mono alkyl  Type of Catalyst.
esters of long chain fatty acids derived from renewable  A literature (Freedmen et al. 1984) has revealed
feed stock-such as vegetable oil or animal fats, for use in that, the rate of reaction is strongly influenced by the
compression ignition (CI) engines [3-11]. This name is reaction temperature. (Figure 1)
given to the esters when they are for use as fuel.  Murugesan et al. reported that, after completion of
Problems associated with using straight vegetable oil the reaction, the product is kept for a certain time interval
(SVO) in diesel engine, can be classified in two groups, for separation (approx. 25 h +) of bio-diesel and glycerol
viz, operational and durability problems. Operation pro- separation.
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 Figure 1. Variation of biodiesel production with reaction
this leads to higher BSFC of the engine. temperature.

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 Z. M. HASIB ET AL 79

 Murugesan et al. reported that, washing is a proc- in two distinctive layers. The upper more transparent la-
ess to remove catalyst, soap and excess methanol. yer is 100% bio-diesel and the lower concentrated layer
is glycerol. The heavier layer is then removed either by
4. Synthesis of Bio-Diesel from Mustard Oil gravity separation or with a centrifuge. In some cases if
the mustard oil contains impurities, then a thin white
For the transesterification of mustard oil, Dr. Peepers layer is formed in between the two layers. This thin layer
style has been followed in our work [6,7]. First 250 ml composes soap and other impurities.
(90% pure) methanol was mixed with 150 ml (1 N) NaOH. Bio-diesel produced in the above process contains mois-
This mixture was swirled in a glass container until NaOH ture (vaporization temperature 100 degree Celsius) and
is fully dissolved in methanol. As this is an exothermic methanol (vaporization temperature 60 degree celsius)
reaction, so the mixture would get hot. This solution is and usually some soap. If the soap level is low enough
known as methoxide, which is a powerful corrosive base (300 ppm - 500 ppm), the methanol can be removed by
and is harmful for human skin. So, safety precautions vaporization and the methanol will usually be dry enough to
should be taken to avoid skin contamination during meth- directly recycle back to the reaction. Methanol tends to
oxide producing [10-15]. act as a co-solvent for soap in biodiesel; so at higher soap
Next, methoxide was added with 1 liter of mustard oil, levels the soap will precipitate as a viscous sludge when
which was preheated about 55 degree Celsius. Then the the methanol is removed. Anyway, heating the biodiesel
mixture was jerked for 5 minutes in a glass container. at temperature above 100 degree Celsius would cause the
After that, the mixture was left for 24 hours (the longer is removal of both the moisture and methanol as well.
better) (Figures 2(a) and (b)) for the separation of glyc- In our study, food grade quality mustard oil was used,
erol and ester. This mixture then gradually settles down 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
(a) (b) 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

(c) B50 41.97

B40 42.18
Figure 2. (a) Biodiesel production after 3 hours of separa-
tion. (b) Biodiesel production after 24 hours of separation. B30 42.21
(c) Produced biodiesel is separated and then heated to re-
move methanol and water. B20 42.65

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80 Z. M. HASIB ET AL.

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.
Figure 4. Temperature vs. density curve for diesel, biodiesel
5.2. Density and their blends.

Density is an important property of CI engine fuel. Fig- the combustion chamber and starting may be difficult while
ure 4 shows density for diesel, biodiesel and their blends. a smoky exhaust will almost invariably appear. On the
From Figure 4 it is observed that B20 and B30 have other hand, very low viscous fuel would cause to pass tho-
almost same density as that of fossil diesel at room tem- rough the leakage of piston and piston wall especially
perature (30˚C). So preheating is not required for using after wear has occurred, which subsequently prevents ac-
B20 and B30. B40 has about 1.50% higher density than curate metering of the fuel.
fossil diesel, and it attains same density as that of diesel Figure 5 indicates that, B20 has 1.5 times higher vis-
fuel at 55˚C. So preheating B40 fuel at this temperature cosity than fossil diesel at the room temperature. On the
is necessary for using it in CI engine. Similarly B50 has other hand, B30, B40 and B50 have almost the same vis-
2.5% higher density than that of diesel fuel. And at tem- cosity at room temperature, and it is about 2.5 times higher
perature 60˚C, it attains the same density as that of diesel
than the fossil diesel. But a slight preheating would cause
fuel. For B100, it has about 5% higher density than die-
to achieve comparable viscosity as that of diesel fuel. So
sel fuel, and it requires preheating at 120˚C to attain si-
using B20, B30, B40 and B50 blend would not cause
milar density as that of diesel fuel. From Figure 4 we
much change in the fuel spray pattern, and thus these fuels
find that, density of the fuel increases with the increase
in blending number. On the other hand, the exhaust from can be used in the existing diesel engines without modi-
CI engine has temperature around 250˚C. So, for using fication of the fuel supply system.
higher blending number, the intake manifold of the en- On the other hand B100 is a much viscous fuel, and its
gine should be redesigned so that preheating can be done viscosity is about 6 times higher than that of diesel fuel.
utilizing the exhaust of CI engine. The high viscous fuel would exhibit almost a solid stream
of spray pattern in the combustion chamber and so cold
5.3. Viscosity starting of the engine would be difficult. So, using B100
fuel in the existing diesel engine would require modifica-
Viscosity of the fuel exerts a strong influence on the tion of the fuel supply system so that the fuel supply
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 5. Temperature vs. kinematic viscosity curve for diesel,

Figure 3. Bsfc for diesel fuel and biodiesel blends at Bhp 3 Hp. biodiesel and their blends.

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 Z. M. HASIB ET AL 81

system exerts high spray pressure to achieve the desired Table 3. Engine operating conditions.
spray pattern inside the engine cylinder. Engine speed 2200 rpm
Engine load 1 kg to 3.5 kg
6. Engine Performance Testing and Analysis
Fuels tested 100% diesel, B20, B30, B40 and B50.

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

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82 Z. M. HASIB ET AL.

Table 4. Cost of running engines with different fuels.

Fuel Cost (tk/lr)

Diesel 40
B20 58
B30 67
B40 76
B50 85

Figure 7. Variation of Bsfc with Bhp for different fuels. 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-
Figure 8. Variation of thermal efficiency ηb with Bhp for ever, cost can be drastically reduced, if methanol can be
different fuels. 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

Figure 9. Variation of exhaust gas temperature with Bhp Experiment was conducted on a small four stroke diesel
for different fuels. 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.
Figure 10. Variation of lube oil temperature with Bhp for Compared to diesel fuel, a little amount of power loss
different fuels. occurs for biodiesel blends.

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 Z. M. HASIB ET AL 83

9. Acknowledgements Science in Engineering Project and Thesis, Bangladesh

University of Engineering and Technology, Dhaka, 2010
This research work was funded by Department of Me- [8] E. Ahn, M. Koncar, M. Mittelbach and R. Marr, “A Low
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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 (%)

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