This study investigated the performance and emissions of a diesel engine fueled with corn oil methyl ester (COME) biodiesel that was preheated to different temperatures. COME was produced via transesterification of corn oil with methanol and tested in a single cylinder diesel engine. The viscosity of COME and its blends with diesel decreased with increasing preheat temperature up to 70°C. Testing found that preheating COME to 70°C improved brake thermal efficiency and reduced CO and HC emissions compared to diesel, but increased NOx emissions. Higher preheat temperatures like 90°C decreased performance due to vapor locking. Overall, preheating COME to 70°C allowed it to be used as a viable diesel alternative

1. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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PERFORMANCE AND EMISSION CHARACTERISTIC OF DI DIESEL
ENGINE WITH PREHEATING CORN OIL METHYL ESTER
R. SenthilKumar*, M. Loganathan#
, P. Tamilarasan$
*
Research Scholar, Mechanical Engineering Annamalai University, Chidambaram, 608001,
Tamilnadu
#
Associate Professor, Mechanical Engineering, Annamalai University
$
Assistant Professor, Mechanical Engineering, Annamalai University
ABSTRACT
In this experimental investigation, the corn oil methyl ester (COME) was prepared by
transesterification using corn oil, methyl alcohol and potassium hydroxide (KOH) as a catalyst. The
fuel properties of bio-diesel such as kinematic viscosity and specific gravity were found within
limited of BIS standard. At different preheated temperatures of COME, the performance and exhaust
emission characteristics of a diesel engine fuelled with preheated bio-diesel were obtained and
compared with neat diesel. Experiments were conducted at different load conditions in a single
cylinder, four stroke, direct injection (DI) diesel engine. The engine was run by diesel and biodiesel
blends. The COME was preheated to temperatures namely 50, 70, and 90°C before it was supplied to
the engine. The brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC)
calculated. The Exhaust gas temperature, smoke density, CO, HC, NOx emissions were measured
and compared with neat diesel operation. The results shown that the preheated bio-diesel is
favourable on BTE and CO, HC emissions when it is heated up to 70°C. At the same time the NOx
emission was increased. But at preheated temperature of 90°C, a considerable decrease in the BTE
and BSFC were observed due to the vapour locking in the fuel line caused by vapour formation due
to higher temperature of preheated biodiesel. The test results shows that bio-diesel preheated to 70°C
can be used as an alternate fuel for diesel fuel without any significant modification in expense of
increased NOx emissions.
Keywords: Fuel, Engine, Biodiesel, COME Methyl Ester, Vegetable Oil, Performance, Emission.
INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING
AND TECHNOLOGY (IJMET)
ISSN 0976 – 6340 (Print)
ISSN 0976 – 6359 (Online)
Volume 5, Issue 1, January (2014), pp. 79-89
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1. INTRODUCTION
Fast depletion of the fossil fuels, rising petroleum prices, increasing threat to the environment
from exhaust emissions and global warming have generated intense international interest in
developing alternative non-petroleum fuels for engines. In the context of fast depletion of fossil fuels
and increasing of diesel engine vehicle population, the use of renewable fuel like vegetable oils
become more important [Nadir Yilmaz et al., 2011; M.M, Conceicao et al., 2005; Yuan W., et al.,
2005]. Many alternative fuels like biogas, methanol, ethanol and vegetable oils have been evaluated
as a partial or complete substitute to diesel fuel. The vegetable oil directly can be used in diesel
engine as a fuel, because their percentage of energy content is high and nearly equal to diesel. The
technology of production, the collection, extraction of vegetable oil from oil seed crop and oil seed
bearing trees is well known and very simple. The oil is extracted from the corn seeds and converted
into methyl esters by the transesterification process. The methyl ester obtained from this process is
known as COME. Several researchers [T.W, Ryan et al., 1982] have used biodiesel as an alternate
fuel in the existing CI engines without any modification.
The emissions characteristics of diesel engines fuelled with neat biodiesel or its blends with
diesel fuel have been investigated by many researchers. They found that there are reductions in
carbon monoxide, hydrocarbon and smoke emissions [S. Puhan et al., 2005, ; M.E.G. Gomez et al.,
2000; S. Kalligeros et al., 2003], while there is increase in NOx emissions [Y. Lin,et al., 2007; M.P.
Dorado et al., 2003].The major drawback with the vegetable oils as fuel is its high viscosity [Deepak
Agarwala et al., 2008]. Higher viscosity of oils is having an adverse effect on the combustion in the
existing diesel engines [K. Babu et al., 2003]. Concept of preheating of biodiesel to bring the
viscosity equivalent to diesel. The viscosity of fuels have important effects on fuel droplet formation,
atomization, vaporization and fuel-air mixing process, thus influencing the exhaust emissions and
performance parameters of the engine. There have been some investigations on using preheated raw
vegetable oils such as cottonseed oil in diesel engines [Dilip Kumar et al., 2003]. However, it is
known that vegetable oils have considerably higher viscosity compared with diesel fuel. The main
objective of this experimental investigation is to determine the effects of the viscosity of corn oil
methyl ester, which is decreased by means of preheating process, on the performance parameters and
exhaust emissions of a diesel engine. For this aim, corn oil methyl ester was produced by
transesterification method using corn oil and methyl alcohol, and its properties were determined.
Then, this biodiesel was preheated up to three different temperatures and tested in the diesel engine
at all load conditions. Finally, the results for COME were compared with those for diesel fuel.
2. PRODUCTION OF BIODIESEL
2.1. Transesterification
Tranesterification is the most common method to produce biodiesel, which refers to a
catalyzed chemical reaction involving Vegetable oil, and an alcohol to yield fatty acid alkyl esters
and glycerol i.e. crude glycerine [Schwab A.W., et al., 1987; Antolin G., et al., 2003]. The process of
‘transesterification’ is sometimes named methanolysis or alcoholysis. This method is used to convert
the corn oil in to corn oil methyl ester. After transesterification, viscosity of Corn oil methyl esters
(COME) is reduced by 75-85% of the original oil value. It is also called fatty acid methyl esters, are
therefore products of transesterification of Corn oil and fats with methyl alcohol in the presence of a
KOH catalyst. During the reaction, high viscosity oil reacts with methanol in the presence of a
catalyst KOH to form an ester by replacing glycerol of triglycerides with a short chain alcohol.
[Triglycerides (Corn oil) + Methanol Corn oil methyl ester + Glycerol]

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Methanol/methyl alcohol is preferred for COME preparation by using transesterification as it
provides better separation of methyl ester and crude glycerin thus facilitating the post-reaction steps
of obtaining biodiesel. The properties of diesel and COME shown in table 1.
Table.1: Properties of diesel and COME
Fuel Diesel COME
Calorific value (MJ/kg) 46.22 42.56
Kinematic viscosity,(mm2
/s)@ 30°C 4.56 42.2
Density @ 20 C kg/m3
0.83 0.875
Flash Point °C 54 143
Fire Point °C 64 149
3. EXPERIMENTAL SETUP AND PROCEDURE
A single cylinder, water cooled, four stroke direct injection compression ignition engine with
a compression ratio of 16.5: 1 and developing 3.7 kW power at 1500 rpm was used for this work
(Figure. 1). The specification of the test engine is shown in table 2. The engine was coupled with an
eddy current dynamometer .Fuels used were diesel, corn oil methyl ester and blends at pre heated to
50°C, 70°C, 90°C. Load was applied in 5 levels namely, 20%, 40%, 60%, 80% and 100%. Load,
speed, air flow rate, fuel flow rate, exhaust gas temperature, exhaust emissions of HC, CO and
smoke were measured at all load conditions. The Redwood Viscometer is used to measure the
viscosity of fuels at various temperatures. The exhaust gas analyzer model Horiba MEXA-584L was
used to measure carbon monoxide (CO) and hydrocarbon (HC) levels. The analyzer is a fully
microprocessor controlled system employing non destructive infrared techniques.
Table.2: Specification of test engine
Make Kirloskar AV-1
Type Single cylinder, water cooled,
Max.power 3.7 kW at 1500 rpm
Displacement 550 CC
Bore x Stroke 80 x 110 mm
Compression ratio 16.5:1
Fuel injection timing 21deg BTDC
Loading device Eddy current dynamometer

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Figure.1: Schematic of Experimental setup
3. RESULT AND DISCUSSION
3.1 Variation of Kinematic Viscosity with temperature
Figure.2: The variation of viscosity of diesel, COME and blends at various temperatures
The figures.2 shows the variation of kinematic viscosity with temperature of diesel and
various blends of biodiesel namely COME20, COME40, COME60, COME80, COME100. The
diesel and blends of biodiesel are preheated for the temperature of 30°C, 50°C,70°C and 90°C. The
results shown that the kinematic viscosity of fuels decreased as preheated temperature increased. The
reduction percentage of kinematic viscosity increased upto the preheated temperature of 70°C. But
the variation of kinematic viscosity from 70° to 90°C is very small. The kinematic viscosity of
COME20, COME40, COME60, COME80 and COME100 are 3.1, 3.3, 4.6, 4.8, 4.8 and 8.3 mm2
/s
respectively at preheated temperature 70°C. The kinematic viscosity of COME20 blends falls from
8.3 to 3.1% at 70°C, which 62.65 % less than COME100 at the same temperature.

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3.2 Optimization of preheating temperature
The biodiesel and diesel are mixed in the proportion of 20% biodiesel and 80% diesel is
called B20. This blend was heated to the temperature 50°C, 70°C and 90o
C.The performance test
was conducted for all the above preheated blend for different load. The variation of BSFC and BTE
are shown in figure 3 and 4 respectively. The results shown that the BSFC decreased for the blends
of B20 at the preheated temperature of 70°C compared to other preheated temperature namely 50°C
and 90°C. This is due to reduction of viscosity by heating the blend and hence better fuel spray
causes the reduction of fuel consumption. But in higher temperature namely for 90°C the fuel
consumption is more due to vapor locking in the fuel injection line. The BTE increased for the
preheated blend temperature of 70°C. This is because of better combustion taking place due to
improved spray characteristics of low viscosity fuel. But for other preheated temperatures namely
50°C and 90°C the BTE decreased due to poor mixture formation of higher viscosity of fuel. Hence
the optimum preheated temperature of 70°C is choosed for all blends for further test.
Figure.3: Variation of BSFC with brake power
Figure.4: Variation of Brake thermal efficiency with brake power at B20

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3.3 Compression of performance and emission of all blends of biodiesel with diesel
3.3.1 Brake Specific fuel consumption
The variation of BSFC with brake power for different COME are presented in Fig.5. Here the
optimized preheated temperature of 70°C blends was used for test. The BSFC of all COME is higher
than that of diesel for all loads. For all COME tested, BSFC is found to decrease with increase in the
load. This is due to more blended fuel which is used to produce same power as compared to diesel.
The BSFC increased from 0.23Kg/Kwhr to 0.284Kg/Kwhr for diesel and COME 100 respectively at
full load. This is due to the effect of higher viscosity and poor mixture formation of COME.
Figure.5: Variation of Brake specific fuel consumption with brake powerat 70°C
3.3.2 Brake thermal efficiency
The variations of BTE of COME20, COME40, COME60, COME80, COME100 with
reference to diesel fuel are shown in Fig.6.The increase in BTE with COME operations can also be
attributed to the good combustion characteristics of bio-diesel owing to their decreased viscosity and
improved volatility by means of preheating process. It is seen that the BTE of COME decreased as
increasing the biodiesel quantity with diesel. The BTE of COME100 decreases 12.18 % as compared
to diesel at full loads. But BTE of COME 20 decreased 3.2% as compared to diesel at full load.
Figure.6: Variations of brake thermal efficiency with brake power

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3.3.3 Exhaust gas temperature
The figure.7. shown the variation of exhaust gas temperature with power for all blends. There
is an increase Exhaust gas temperature with neat COME compared to other blends and diesel full
load. This is mainly due to higher viscosity of COME leads to delayed burning of fuel. In the exhaust
pipe. The exhaust gas temperature reduces as the proportion of diesel is raised due to the better
vaporization of mixture.
The exhaust gas temperature increased 7.7% for COME100 compared to diesel at full load.
The reduction in the exhaust gas temperature of the blends shows that the premixed combustion of
the blend has improved. This is mainly due to the reduction in the viscosity of the fuel.
Figure.7: Variation of exhaust gas temperature with brake power
3.3.4 Smoke density
The variation of smoke density for different COME is shown in Fig. 8. The Smoke density of
COME is lower than that of the diesel oil. The smoke density increased as the concentration of the
COME increased. This is due to poor mixture formation and uneven fuel spray pattern in the
combustion chamber. The smoke density increases from 76.9 to 81.8 HSU for diesel and COME100
at full load.
Figure.8: Variation of Smoke density with brake power

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3.3.5 CO, HC and NOx emissions
The CO emissions are shown in Fig. 9. As seen in the figure, the CO emission increase with
increase of engine load, due to rich fuel air mixture. Compared with the diesel fuel, the CO emissions
of COME are higher, because of the poor combustion. Therefore, the CO emissions increased due to
incomplete combustion.. The CO emission of COME 100 is 16.66 % higher than the diesel at full
load. The CO emission of COME 20 is 0.134 % by v and it is very close to diesel CO emission.
Figure.9: Variation of CO emission with brake power
Figure.10: Variation of HC emission with brake power
Fig. 10 shows the variation of HC emissions. Similar to the CO emissions, the HC emission
increases with increases % of the engine load. Compared with diesel fuel, COME give lower HC
emission. The HC emission of COME100 decrease 25.5 % at the maximum load of the engine in
comparison with diesel fuel. The higher oxygen content of COME leads to better combustion,
resulting in lower HC.

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Figure.11: Variation of NOx emission with brake power
Fig.11 shows the variation of the NOx emissions of the test engine for COME with reference
to diesel fuel. It is seen that the COME operations usually yield higher NOX emissions at all loads
compared to diesel fuel operations. The increase in NOx emissions with COME may be attributed to
various reasons, such as better combustion of biodiesel due to its high oxygen content and higher
temperatures in the cylinder as a result of preheating. The maximum increase in NOX emissions were
obtained in COME100. The NOX emissions with COME100 increase approximately 14.04 % as
compared to diesel fuel at full load.
5. CONCLUSION
Corn oil methyl ester (COME) was produced by means of transesterification process using
corn oil, which can be described as a renewable energy source. The viscosity of COME was reduced
by preheating it before supplied to the test engine. After the fuel properties of COME has been
determined, various performance parameters and exhaust emissions of the engine fuelled with
COME and COME blends preheated at different temperatures were investigated and compared with
those of diesel fuel. The experimental conclusions of this investigation can be summarized as
follows:
Preheating of COME makes significant decrease in its kinematic viscosity and a small
decrease in specific gravity. It is almost nearer to the values of diesel fuel.
The preheated temperature of COME20 was optimized for 70°C by considering maximum
BTE and minimum BSFC.
The Brake Specific Fuel Consumption (BSFC) increased from 0.23 kg/kwhr to 0.284
kg/kwhr for diesel and COME100 respectively at full load.
Lower BTE is found with the COME100 is 30.12 % compared to diesel 34.3 %. However for
the blend of COME20 the increases of 9.27% as compared with neat COME100.
The use of COME20 produced a considerable decrease in CO emissions. CO emissions
obtained with COME20 operations were 14.12 % lower than that of neat COME100 and 2.98
% higher than diesel fuel operations.
Compared with diesel fuel, COME100 gives nearly 25.5 % lower value of HC emissions at
the maximum load of the engine.

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NOx emissions were increased due to higher combustion temperatures caused by preheating
and oxygen content of COME100. The maximum increase in NOx emissions were obtained
in the case of COME100.
The smoke density of COME60 preheated oil is approximately equal to the neat diesel fuel
operations at full load.
The exhaust gas temperature COME100 increased 7.7% compared to diesel at full load.
In general, if is concluded that the preheated temperature of COME20 blends was optimized
from 70°C. Based on the performance and emission results of COME20 blends was choosed for
experiments.
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