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COTTONSEED OIL BIODIESEL WITH ETHANOL AS AN ADDITIVE-AN
ALTERNATIVE FUEL FOR DIESEL ENGINE
S. Madiwale1, A. Karthikeyan2, V. Bhojwani3 and S. Chougule4 1Sathyabama University, Chennai, Tamil Nadu, India
2Deptatment of Automobile Engineering, Sathyabama University,Chennai,Tamil Nadu, India 3Department of Mechanical Engineering, JSPM’s, College of Engineering, Hadapsar, Pune, Maharashtra, India
4JSPM’s, College of Engineering., Hadapsar, Pune, Maharashtra, India
E-Mail: shrikantmadiwale@gmail.com
ABSTRACT
Non conventional, alternative and as different energy source of energy, biodiesel attracted many scientists and researchers to consider him as an alternative fuel for automotive sector in last few years by large. Biodiesel is an oxygenated fuel, which contains 10 % to 11% oxygen, no aromatics, higher cetane number and reduce harmful pollutants from engine exhaust. Higher viscosity, higher flashpoint, poor cloud point, poor pour point and poor cold filter plugging point of pure biodiesel limits its direct usage as fuel in the diesel engine. So it is required to prepare the blend of biodiesel /diesel with addition of ethanol as an additive in order to improve hot flow and cold flow properties of the blend. Improved hot flow and cold flow properties will enhance engine performance, combustion and exhaust emissions. In the present study feedstock of cottonseed biodiesel/diesel blend is used as fuel with the addition of 5% of ethanol as an additive. Blend properties were investigated as per IS 1448 standards. Experimental investigations were carried out on single cylinder diesel engine with eddy current dynamometer. Experimental investigation shows that addition of ethanol improves kinematic viscosity by 7% .cloud point by 9%, and pour point by 10% but density was increased by 3% and calorific value decreased by 9% .Engine performance , combustion characteristics and reduction in emissions , are improved drastically by addition of an ethanol as an additive in the cottonseed biodiesel/diesel blend . Improved hot flow and cold flow properties , improved combustion , improved performance and reduced emissions proves that cottonseed oil biodiesel/diesel blend with ethanol as an additive stands as an alternative fuel for diesel engine.
Keywords: cottonseed oil biodiesel, ethanol, combustion analysis, properties.
INTRODUCTION
As we know diesel engine has popular for its low fuel consumption, reliability and durability characteristics, because of its higher brake thermal efficiency [1]. On the other side diesel engine has become the main air pollution resource due to its combustion products. Combustion products lead to environmental changes, and affects animals, plants and humans lives. Due to the rapid increase in use of automobiles, the demand for petroleum products will increases ,expected rise in demand is around 465 million metric tones by 2031-32 [2].Thus most of the scientists and researchers are doing experimentation in order to give the substitute as alternative fuel [3, 4]. The fuel blending method is widely used by many researchers, to enhance fuel properties which improve the performance and emission outcomes from a diesel engine without any modification in the existing engine [2]. The limited resources of fossil fuel reserve made renewable fuels more attractive [5]. Renewable energy conversion technologies are now a day’s more environmental friendly than conventional energy options, their acceptance is very slow because of factors such as lack of supply, economic constraints etc. [6]. As an alternative fuel, cottonseed biodiesel will be able to fulfil the present and future energy demand. It is obtained from seeds oil which is non-toxic and bio degradable, eco-friendly and are more
and increasing overall earth’s temperature [9-11]. On the other hand biodiesel has higher molecular weight, higher density, viscosity, cloud point and pour point than conventional diesel fuel [12-14]. Because of higher molecular weight and higher viscosity, poor atomization takes place in the cylinder through the injector [15]. So direct use of biodiesel in the engine limits its application as a fuel. It is necessary to lower all these properties in order to increase suitability of biodiesel in an engine as an alternative fuel. Cottonseed oil can be transterified with the alcoholysis process and is converted in to biodiesel. This biodiesel is further blended with diesel in order to form biodiesel/diesel blends. Conversion of cottonseed oil in to biodiesel is the function of reaction time, reaction temperature and pressure. Transtrification process is also affected by the type of the catalyst and purity of the feedstock of the cottonseed oil. High viscosity of the blend and higher cloud point and pour point of the blend require addition of ethanol as an additive, which significantly improves these properties and performance and emissions from an engine.
Ethyl alcohol is also known as Ethanol
[CH3CH2OH]. Higher octane number is the most
Table-1. Properties of 99.99% pure ethanol [16, 17, 18].
Properties Ethanol
Viscosity (Cst) 1.4
Calorificvalue (MJ/Kg) 26.95
Cloud point°C ˂-26
Density (kg/m³) 790
Cetane number 8
Flash point °C 13
COTTONSEED OIL BIODIESEL
Cottonseed oil is cooking oil. It is extracted from a seeds of famous cotton plant. As cost of production of edible cottonseed oil is comparatively higher than the other conventional vegetable oil, because of this the cottonseed oil lost his market in the edible oil sector. The scientist and researchers found that the cottonseed oil biodiesel which was prepared by transesterification process performs very well in an engine as compare to other feed stock of biodiesels. But higher density and viscosity and lower calorific value of the cottonseed biodiesel limits its usage in the diesel engine. So it is highly necessary to prepare the blend of biodiesel with diesel fuel. Table-2 shows the basic properties of 100% pure cottonseed oil biodiesel. All properties are investigated as per IS 1448 standards in NABL accredited laboratory.
Table-2. Properties of cottonseed oil biodiesel.
S. No. Test parameters Units Results
1 Gross Calorific Value kJ/kg 36802
2 Viscosity@40Kinematic 0C cSt 7.5
3 Cloud Point 0 C -17
4 Pour Point 0 C -15
5 Density kg/m3 904.8
6 Flash Point 0 C 142
7 Fire Point 0 C 190
BLENDS PREPARATION
The cottonseed oil biodiesel /diesel blends were prepared in blending ratio of 20%, 40%, 60% and 80% cottonseed oil biodiesel with diesel fuel but without ethanol and 25%, 45%, 65% and 85% cottonseed oil biodiesel with 5% ethanol by volume in diesel fuel. On the basis of volumetric analysis all blends were prepared.
FUEL PROPERTIES INVESTIGATION AND DISCUSSIONS
Thermo physical properties of fuel plays crucial role in the combustion characterisation of the fuel. Mixing of ethanol in the blends of biodiesel/diesel blend enhances and changes these properties to some extent [19]. Table-3 shows properties of cottonseed oil biodiesel with and without mixing of an ethanol as an additive. All these properties are compared with standard diesel fuel.
Table-3. Properties of cottonseed oil biodiesel/diesel blends with and without ethanol.
Fuel
CV kJ
/k
g
Kinematic visc
os
ity
cS
t
Clo
ud po
int
°C
Pour p
oi
nt
°C
D
en
sit
y
K
g/m
³
Flash
poin
t
°C
F
ire
p
oi
n
t °
C
C100 36802 7.5 -17 -15 904.8 142 190
Diesel 43851 2.5 -23 -21 817.4 40 42
C20D80 43221 2.8 -22 -18 850.1 30 42
C40D60 42298 2.8 -21 -18 865.6 32 50
C60D40 40911 5.3 -19 -16 878.1 32 55
C80D20 39658 5.9 -18 -15 891.5 36 62
C20D75E5 39761 2.6 -24 -20 842.9 14 20
C40D55E5 38175 2.8 -21 -18 850.6 16 20
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Figure-1. Variation of gross calorific value of Cottonseed
oil biodiesel with and without ethanol for different blend ratio.
Figure-1 shows the variation of Gross Calorific value of blends of cottonseed oil biodiesel with and without ethanol for different blend ratio. Heat release capacity of the fuel is measure by calorific value. Poor calorific value of ethanol and biodiesel is mainly responsible for decrease of overall calorific value of the blends. Figure-1 shows overall decrease in calorific value of the blends of biodiesel with ethanol. For C20D75E5 calorific value was reduced by 9% as compared to diesel and for C20D80 by 2% as compared to diesel. So as the percentage of cottonseed oil biodiesel increases in the blends the overall calorific value is decreases.
Figure-2. Variation of density of cottonseed oil biodiesel
with and without ethanol for different blend ratio.
Figure-2 shows the variation of density of blends of cottonseed oil biodiesel with and without ethanol for different blend ratio. For all ethanol added blends it is observed that there is a reduction in the density of ethanol added blends. This is due to the lower density of ethanol.
Figure-3. Variation of kinematic viscosity of
Cottonseed oil biodiesel with and without ethanol for different blend ratio.
Figure-3 shows variation of kinematic viscosity of Cottonseed oil biodiesel with and without ethanol for different blend ratio. Lower viscosity of the fuel always helps the process of atomization of the fuel in the combustion chamber. Good atomization improves the combustion characteristics and able to build good pressure over the piston. By adding the cottonseed oil biodiesel in the diesel increases the kinematic viscosity of the blend. So addition of ethanol helps to reduce the viscosity of the blend. It is observed that by adding the ethanol in the C20D75E5 blend the viscosity reduced by 7% as compared to C20D80.Similare trends were observed for all remaining blends.
Figure-4. Variation of cloud point of cottonseed oil
biodiesel with and without ethanol for different
Figure-5. Variation of pour point of cottonseed oil biodiesel with and without ethanol for different
blend ratio.
Figure-4 and Figure-5 shows the variation of cloud point and pour point of Cottonseed oil biodiesel with and without ethanol for different blend ratio. Higher cloud point and pour point is the main disadvantage of biodiesel and that limits its usage in the cold weather conditions. But this issue can be addressed by the addition of ethanol, whose cloud point and pour point is lower than the cottonseed oil biodiesel /diesel blends. Cloud point of C20D80 is increased by 4% than diesel and for C20D75E5 it is 9% lower than C20D80. Similarly pour point of C20D80 is 14 % higher than diesel but pour point of C20D75E5 is 10% lower than C20D80.
Figure-6. Variation of flash point of cottonseed oil
biodiesel with and without ethanol for different blend ratio.
Figure-7. Variation of fire point of cottonseed oil
biodiesel with and without ethanol for different blend ratio.
Higher flash point and fire point are not at all desirable properties for good combustion. Higher flash point and fire point increases the ignition delay phenomenon in the combustion process which has ultimate effect on the built up of the maximum pressure and temperature in the combustion chamber. Ethanol is having low kinematic viscosity than the cottonseed oil biodiesel. So addition of the ethanol reduces the flash point and fire point of the blend. Flash point of the C20D75E5 decreases by 46% than C20D80, and fire point of the C20D75E5 decreases by 47% than C20D80. Figures 6 and 7 shows the variation of flash point and fire point of cottonseed oil biodiesel with and without ethanol for different blend ratios.
EXPERIMENTAL TRIAL SET UP AND FUEL
The test fuels were prepared on the volumetric basis. The constitute of the test fuels were 20% cottonseed oil biodiesel + 75% diesel + 5% ethanol i.e. C20D75E5. The performance and emission analysis of C20D75E5 were tested and compared with the C20D80 i.e. 20% cottonseed oil biodiesel + 80% diesel and with pure diesel. The test engine was variable compression ratio, single cylinder, four stroke engine. Eddy current dynamometer was used for loading purpose. Engine test rig was equipped with pressure transducer and crank angle sensor. Data logger was used and interface with computer for real
time data recording and for the production of P-ߠ and
P-V diagrams. Air box, U-tube manometer and fuel measuring systems were also equipped on the test rig in order to facilitate air measurement, fuel measurement etc as and when required. The loads were varied on the engine in the range of 3 kg, 6kg, 9kg and 12 kg running at 1500 rpm. Labview software was interface with test rig to
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RESULTS AND DISCUSSIONS
a) Performance analysis
Figure-8. Variation of brake power with load.
Figure-8 shows the variation of brake power with the different load condition. It is noticed that the brake power of C20D75E5 is reduces in the range of 8 to 9% as compared with diesel. This is due to the lower calorific value of C20D75E5 as compared with C20D80 and diesel fuel. Figure-9 shows the variation of brake mean effective pressure with load. Lower kinematic viscosity of the cottonseed oil biodiesel with ethanol ensures the maximum combustion and increase in the mean effective pressure in the combustion chamber. The BMEP of C20D75E5 is increased by 2 to 7% as compared with C20D80 and Diesel fuel.
Figure-9. Variation of brake mean effective
pressure with load.
Figure-10. Variation of brake thermal efficiency
with load.
Figure-10 shows the variation of brake thermal efficiency with Load. It is noticed that for C20D75E5 the brake thermal efficiency is increases from 7% to 12% than conventional diesel fuel. Figure-11 shows the variation of Specific fuel consumption with load. It is observed that for C20D75E5 the fuel consumption is increased from 1 to 3% as compared to diesel. This is because of the lower calorific value of the blends of biodiesel and ethanol.
Figure-11. Variation of specific fuel consumption
with load.
b) Emission analysis
The variation of CO, HC, CO2 and NOx emission
with varying load are shown in Figure-12, Figure-13, Figure-14 and Figure-15 respectively. Experimental investigation reported that carbon monoxideemissions of C20D75E5 are higher than diesel but less than C20D80 by 10% to 30% for varying load conditions. It is noticed that hydrocarbon emissions of C20D75E5 blend are higher than diesel but lower than C20D80 by 30% to 60% for different load conditions. Carbon dioxide emissions of C20D75E5 is more only at load of 9kg &12 kg than diesel
-0.04 0.96 1.96 2.96 3.96 4.96 5.96
-3 2 7 12
BP
(kW
)
LOAD (kg)
DIESEL
C20D80
C20D75E5
-0.05 0.45 0.95 1.45 1.95 2.45 2.95 3.45 3.95 4.45
-3 2 7 12
BM
E
P
(
bar
)
LOAD(kg)
DIESEL C20D80 C20D75E5
-1 4 9 14 19 24
0 5 10 15
BT
hE
ff
(
%)
LOAD (kg)
DIESEL C20D80
C20D75E5
-1 1 3 5 7 9 11 13
-3 2 7 12
SF
C (kg/
kWh)
LOAD (kg)
DIESEL
C20D80
with C20D80 and diesel. As biodiesel is also having more contained oxygen so called oxygenated fuel which releases more amount of energy and increases in cylinder temperature? Higher temperature dissociates nitrogen in to nitrogen oxides.
Figure-12. Variation of carbon monoxide in (%)
[image:6.612.85.289.162.305.2]with load.
Figure-13. Variation of hydrocarbon in PPM with load.
Figure-14.Variation of carbon dioxide in (%) with load.
Figure-15. Variation of nitrogen oxides in PPM
with load.
c) Combustion analysis
[image:6.612.85.287.348.494.2]The variation of cylinder pressure with crank angle is shown in Figure-16. It is investigated from the figure that the maximum pressure is developed near the TDC in case of diesel as compared with C20D75E5 and C20D80. This is because of the higher calorific value of the diesel as compared with C20D75E5 and C20D80. C20D75E5 shows slightly more pressure than C20D80 but both have less pressure than diesel
Figure-16. Variation of pressure with crank angle.
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
-3 2 7 12
CO
(%
)
LOAD (kg)
DIESEL C20
C20E5
0 5 10 15 20 25 30
-3 2 7 12
HC
(ppm
)
LOAD (kg)
DIESEL
C20D80
C20D75E5
0 0.5 1 1.5 2 2.5 3 3.5
-3 2 7 12
CO
2
LOAD (kg)
DIESEL
C20D80
C20D75E5
0 200 400 600 800 1000 1200
-3 2 7 12
N
ox
(p
pm
)
LOAD (kg)
DIESEL C20
C20E5
0 70
-50 -30 -10 10 30 50
C
yli
nd
er
pr
es
su
re
(b
ar
)
Crank angle(degree)
Diesel
C20
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Figure-17. Variation of mass fraction burned with
crank angle.
Figure-17 shows the variation of fuel consumed vs crank angle for the combustion. Mass fraction of C20D75E5 is less than the C20D80 this is because of the lower kinematic viscosity, lower kinematic viscosity ensures good atomization and maximum combustion. The mass fraction of C20D75E5 and C20D80 is less than diesel fuel.
CONCLUSIONS
The hot flow and cold flow properties of blends of cottonseed oil biodiesel/diesel with 5% ethanol as an additives were investigated as per IS 1448 standards. Investigation concludes that addition of ethanol as an additive improves properties of blends of cottonseed oil biodiesel/diesel. Improvement in the kinematic viscosity of C20D75E5 by 7% than C20D80 enhances the good atomization of the fuel in the combustion chamber. Also cold flow properties such as cloud point and pour point were drastically changed for C20D75E5 by 9% and 10% than C20D80 respectively. This will increase the acceptability of biodiesel in cold weather conditions. Most importantly the flash point and fire point were enhanced for C20D75E5 by 46 % and by 47% than C20D80 respectively. Lower flash point and fire point helps in the reduction of ignition delay in the combustion process.
Performance, emission and combustion
parameters in an engine when fuelled with C20D75E5 were improved with ethanol as an additive than C20D80 i.e. without ethanol. The brake thermal efficiency was increased from 7 to 12 %, but there is slight drop down in the brake power of C20D75E5, because of lower calorific value of the blend. Experimental results reported that carbon monoxide emissions of C20D75E5 were higher than diesel but less than C20D80 by 10% to 30% for varying load conditions. It is also noticed that hydrocarbon emissions of C20D75E5 blend were higher than diesel but lower than C20D80 by 30% to 60% for different load
70% with increase in load, NOx emissions of C20D75E5 were reduced as compared with C20D80 and diesel.
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