Article
Combustion of Microalgae Oil and Ethanol Blended
with Diesel Fuel
Saddam H. Al-lwayzy 1, * and Talal Yusaf 2
Received: 12 October 2015; Accepted: 7 December 2015; Published: 10 December 2015
Academic Editor: Thomas E. Amidon
1
2
*
National Centre for Engineering in Agriculture (NCEA), University of Southern Queensland, Toowoomba,
QLD 4350, Australia
School of Mechanical and Electrical Engineering, Faculty of Health, Engineering and Sciences (HES),
University of Southern Queensland, Toowoomba, QLD 4350, Australia; yusaft@usq.edu.au
Correspondence: allwayzs@usq.edu.au or sadmaree@yahoo.com; Tel.: +61-7-4631-1906
Abstract: Using renewable oxygenated fuels such as ethanol is a proposed method to reduce diesel
engine emission. Ethanol has lower density, viscosity, cetane number and calorific value than
petroleum diesel (PD). Microalgae oil is renewable, environmentally friendly and has the potential
to replace PD. In this paper, microalgae oil (10%) and ethanol (10%) have been mixed and added
to (80%) diesel fuel as a renewable source of oxygenated fuel. The mixture of microalgae oil, ethanol
and petroleum diesel (MOE20%) has been found to be homogenous and stable without using
surfactant. The presence of microalgae oil improved the ethanol fuel demerits such as low density
and viscosity. The transesterification process was not required for oil viscosity reduction due to
the presence of ethanol. The MOE20% fuel has been tested in a variable compression ratio diesel
engine at different speed. The engine test results with MOE20% showed a very comparable engine
performance of in-cylinder pressure, brake power, torque and brake specific fuel consumption
(BSFC) to that of PD. The NOx emission and HC have been improved while CO and CO2 were
found to be lower than those from PD at low engine speed.
Keywords: microalgae oil; ethanol; diesel engine; performance; exhaust gas emission
1. Introduction
The increasing demands on fuels have encouraged the researchers and industry to focus
on renewable alternative fuels. Diesel engine emission is another factor pushing towards the
development of alternative fuels. The fuel mixture with less engine emission giving a comparable
power and/or enhancing the combustion efficiency using renewable resources is favorable. Rinaldini
and Mattarelli [1] highlighted a current increased pressure on the engine manufacturer to limit the
CO2 and other emissions from the diesel engine, which can only be achieved by enhancing the engine
technology to increase the energy efficiency and/or reduce the carbon to hydrogen ratio. Renewable
oxygenated fuels such as alcohol and vegetable oil are proposed to reduce diesel engine emission.
Diesel engines can be operated using vegetable oil without or with minor modifications.
Microalgae oil has the potential to overcome the problems associated with vegetable oil production
for fuel that lead to increasing human food prices [1–3]. One of the concerns of using vegetable
oil directly in diesel engines is the high viscosity. Viscosity is an important factor that affects the
atomization process of the fuel in the combustion [4]. High viscosity was reported to reduce the
fuel flow rate, which makes the engine starve for fuel under certain operating conditions, especially
at low temperatures [5]. Transesterification is the most common method used to reduce oil viscosity.
However, vegetable oil has a higher viscosity and pour point and lower volatility compared to PD [6].
Microalgae biodiesel 20% was tested in diesel engines by Rinaldini and Mattarelli [1]; the results
Energies 2015, 8, 13985–13995; doi:10.3390/en81212409
www.mdpi.com/journal/energies
Energies 2015, 8, 13985–13995
showed a slight reduction in the engine torque at high load and slight increase in SFC. The NOx was
found to be 20% higher than diesel fuel at low speed with high load. The CO2 also dropped at low
to mid speed. Similarly, Al-lwayzy and Yusaf [2] reported no significant difference in tractor diesel
engine performance parameters with microalgae biodiesel 20% compared to PD, and a significant
reduction in CO, CO2 and NOx emission was found when microalgae 20% was used.
Ethanol is a promising renewable alternative fuel that has been used as an additive to PD to run
the diesel engine and reduce the engine emission [7]. The mixture of ethanol and PD fuel is called
diesohol or e-diesel [8]. Bioethanol as fuel can increase the farmers income when it is locally produced
from the agricultural waste material [9]. The main drawback of ethanol in diesel engine is the low
cetane number, low viscosity and low density. Moreover, it is immiscible in diesel at wide range of
temperature and depend on its water content [9].
The stability of ethanol in PD depends on the carbon structure, water content and
temperature [8,10]. It has been reported that anhydrous ethanol (ethanol containing less than
1% water) should be blended with diesel for better fuel properties [8,11]. The low viscosity of ethanol
increases the fuel leakage in the fuel injection pump that reduces the injection fuel pressure and
amount injected to the combustion chamber. Several studies have been conducted aiming to increase
the cetane number of the blend of ethanol with diesel fuel [9].
Adding biodiesel to the blend of ethanol and PD, the stability of the mixture was enhanced at
a wide range of temperatures and enhances other fuel properties, some of them even better than
the PD [11]. Recently, Shahir et al. [8] stated that among the renewable alternative fuels, the blend
of biodiesel, ethanol and PD is getting more and more attractive due to the presence of biodiesel
improving the mixture fuel properties and engine performance. Using a mixture of biodiesel and
alcohol with diesel fuel produces less CO, PM and UHC [9]. The cold flow has been improved
by adding ethanol to the Mahua biodiesel and the CO emission reduced. The reduction in the
NOx emission was due to the high latent heat of ethanol which reduced the overall combustion
temperature [12].
Kannan and Anand [6] have compared the engine performance end exhaust gas emission of
diesel fuel with biodiesel, and diestrol fuel of diesel biodiesel with ethanol water emulsion. The
results showed that the in-cylinder pressure of the diestrol was dependent on the load. At medium
and high loads, the in cylinder pressure was identical to diesel. The engine emission of CO, CO2 , HC
and NOx were found to be lower than PD at all loads. The ternary blend of ethanol-biodiesel-diesel
fuel physical properties and emission of NOx , HC, CO and CO2 were found to be very close to PD
depending on the operating conditions of the test [8]. Adding ethanol and biodiesel to PD fuel has
the advantage of reducing the sulphur content in the fuel. In addition, the lower freezing point of
ethanol enhance the biodiesel blend at low temperature conditions [13]. Shahir et al. [8] concluded
that there is a need to study the performance of ternary fuel of ethanol biodiesel and PD and the best
blend ratio.
Based on the work reviewed above, the ternary mixture of ethanol, biodiesel has several
advantages. In this work, microalgae oil will be used instead of biodiesel to eliminate the cost of
the transesterification process and further improve the mixture properties. The main objectives of
this work are to:
1.
2.
3.
Use up to 20% of renewable oxygenated fuel of microalgae oil and ethanol as an alternative to
the commonly used fossil fuel.
Enhance the fuel properties by adding 10% of microalgae oil and along with 10% of ethanol to
80% PD. The blending process aims to overcome the problems of high viscosity of microalgae
oil and low viscosity of ethanol and the high latent heat of evaporation of the ethanol.
Reduce the exhaust gas emission such as CO, CO2 , NOx and HC and maintain the engine BP
and torque.
13986
Energies 2015, 8, 13985–13995
Energies 2015, 8, page–page 2. Methodology
2. Methodology 2.1. Fuel Preparation and Properties
2.1. Fuel Preparation and Properties Three
fuels were used in this experiment. PD from British Petroleum (BP, Toowoomba,
Australia),
ethanol
(100%)
Australia)
and
microalgae
Chlorella protothecoides
oil (Soley
Three fuels were (Sigma-Aldrich,
used in this experiment. PD from British Petroleum (BP, Toowoomba, Australia), ethanol (100%) Ethanol
(Sigma‐Aldrich, Australia) microalgae Chlorella institutes,
Istanbul,
Turkey).
is immiscible
in PDand and/or
microalgae
oilprotothecoides (MO) whichoil makes
(Soley institutes, Istanbul, Turkey). Ethanol is immiscible in PD and/or microalgae oil (MO) which the use of surfactant/solvent imperative (see Figure 1a). Mixing MO, ethanol and PD together was
foundmakes the use of surfactant/solvent imperative (see Figure 1a). Mixing MO, ethanol and PD together to form a very homogenous mixture as shown in Figure 1b. The stability of the mixture
was found to form a very homogenous mixture as shown in Figure 1b. The stability of the mixture was tested over a period one month. The density was measured for all the fuels using volumetric
was tested over a period one month. The density was measured for all the fuels using volumetric (Labco pipette, Brisbane, Australia) and weighing (Explorer OHAUS E12140 balance, Melbourne,
(Labco pipette, Brisbane, Australia) and weighing (Explorer OHAUS E12140 balance, Melbourne, Australia)
measurements as an average of 10 readings at 15 ˝ C. The viscosity of the fuels was
Australia) measurements as an average of 10 readings at 15 °C. The viscosity of the fuels was measured
usingusing Brookfield
Viscometer
DV-II+Pro
Extra
(Middleboro,
MA,
USA).
TheThe suitable
spindle
measured Brookfield Viscometer DV‐II+Pro Extra (Middleboro, MA, USA). suitable and rotational
speed were selected to obtain a torque percentage within the working range of the
spindle and rotational speed were selected to obtain a torque percentage within the working range device
[3]. The heating values of the fuels were obtained from the suppliers and calculated for the
of the device [3]. The heating values of the fuels were obtained from the suppliers and calculated for the MOE20% based on the percentage of the components. MOE20%
based on the percentage of the components.
Figure 1. Samples (a) (left) petroleum diesel (PD) mixed with ethanol, (right) MO mixed with ethanol; Figure
1. Samples (a) (left) petroleum diesel (PD) mixed with ethanol, (right) MO mixed with ethanol;
(b) mixtures of microalgae oil (MO), ethanol PD in different percentage sample in the (b) mixtures
of microalgae
oil (MO),
ethanol
andand PD in
different
percentage
(the(the sample
in the
middle
middle is adopted for engine test). is adopted for engine test).
2.2. Engine Test 2.2. Engine
Test
G.U.N.T. Variable Compression Engine was used to test the fuels. The engine is connected to an G.U.N.T. Variable Compression Engine was used to test the fuels. The engine is connected
electrical dynamometer and full set of instrumentation and gas analyzer to measure BP, in‐cylinder to an electrical dynamometer and full set of instrumentation and gas analyzer to measure BP,
pressure, fuel consumption and exhaust gas emission. Table 1 presents the engine test bed in-cylinder
pressure, fuel consumption and exhaust gas emission. Table 1 presents the engine test
specification. The engine test started with engine speed of 2900 rpm then the load was applied until bed specification.
The engine test started with engine speed of 2900 rpm then the load was applied
the maximum load (at this speed) was reached. The engine was kept at this condition for 10 min to until record the data. The engine speed was reduced by 300 rpm increment to reach 2600, 2300, 2000 and the maximum load (at this speed) was reached. The engine was kept at this condition for 10 min
to record
the data. The engine speed was reduced by 300 rpm increment to reach 2600, 2300, 2000 and
1700 rpm. The data are an average of three tests. 1700 rpm. The data are an average of three tests.
Table 1. Engine test bed specifications. Table 1. EngineEngine
test bed specifications.
Manufacturer Farymann EngineDirect injection diesel Combustion type Number of cylinders 1 Manufacturer
Farymann
Displacement (cc) 470 diesel
Combustion
type
Direct injection
Number
of cylinders
1
Compression ratio 5.0–19.0:1 Displacement
(cc)
470
Maximum power (kW) Approx. 6 kW Compression
ratio
5.0–19.0:1
Speed range (RPM) 900–3000 Maximum power (kW)
Approx. 6 kW
Speed range (RPM)
900–3000
3
13987
Energies 2015, 8, 13985–13995
Table 1. Cont.
Dyno
Manufacturer
Type
Torque measurement
G.U.N.T. hamburg
Asynchronous motor
Planar beam load cell 0.03% error
Instrumentation
Parameter
Torque
Speed
Exhaust temperature
Fuel flow (Diesel)
Source
Load cell on dynamometer
Tachometer on output shaft
Thermocouple in exhaust manifold
Static pressure sensor
Exhaust gas composition
EMS 5 gas analyzer
In cylinder pressure
Pressure transducer in cylinder head
Resolution
0.0001 Nm
0.0001 RPM
0.0001 ˝ C
0.0001 L/h
0.1% O2 , 0.1% CO2 , 1 ppm NOx ,
100 ppm HC, 0.01% CO, 0.01 AFR
0.01
3. Results and Discussion
Table 2 presents the chemical concentration profile of microalgae Chlorella protothecoides oil which
provided by the oil supplier (Soley institute, Istanbul, Turkey) [14]. The highest component is the
saturated palmitic acid of 51% and 2% of stearic acid. The higher percentage of palmitic acid (C16)
that might cause a problem at cold flow conditions was overcome by adding ethanol, which reduces
the viscosity of the mixture. The rest of the components are unsaturated. The highest percentage is
oleic acid of 39%. Table 3 shows the properties of the PD, ethanol, microalgae oil and the mixtures.
It is shown that the density of the MEO-20 is relatively close to that of PD. This is due to the lower
density of the ethanol 0.785 kg/L compensated by the higher density of 0.908 kg/L of microalgae
oil. The differences in the density of MOE20% compared to PD is negligible as shown in Figure 2.
The viscosity of all fuels was measured at 15 ˝ C that resulted in higher values of the viscosity. The
viscosity of the MOE20% is 3.5 mm2 /s which is higher than that of the PD (3.34 mm2 /s) by about
4.9%. The calorific value of the MOE20% is lower than PD by 5.38%, as shown in Figure 2. This is due
to the lower heating value of the ethanol and microalgae oil.
Table 2. Summary of the fatty acid composition of Chlorella protothecoides oil (%) [14].
Fatty Acid
Fatty Acid
Fatty Acid
%
Palmitic
Stearic
Oleic
Linoleic
Others
C 16:0
C 18:0
C 18:1
C 18:2
-
C16 H32 O2
C18 H36 O2
C18 H34 O2
C18 H32 O2
-
51
2
39
7
1
Table 3. The fuel properties for the fuels used.
Fuel
Density
kg/L@15 ˝ C
Viscosity
(mm2 /s) @15 ˝ C
Calorific
Value kJ/kg
Chemical
Formula
Molecular
Weight
g/mole
H/C Ratio
Microalgae oil
Ethanol
Diesel
MOE50-50
MOE20%
0.908 ˘ 0.015
0.785 ˘ 0.015
0.821 ˘ 0.015
8.22 ˘ 0.015
56.3
1.94
3.34
35,800
29,700
44,800
42,390
C16.94 H32.86 O2
C2 H5 OH
C12 H23 [15–17] *
C9.4 H19.43 O1.5
C11.48 H22.29 O0.3
268.57
46
167
156.5
164.85
1.94
2.5
1.92
2.06
1.94
3.5
* Average chemical formula, ranging from C10 H20 to C15 H28 .
13988
Energies 2015, 8, 13985–13995
Energies 2015, 8, page–page Energies 2015, 8, page–page 6.00
6.00
4.00
4.00
2.00
2.00
0.00
0.00
‐2.00
‐2.00
‐4.00
‐4.00
‐6.00
‐6.00
Density kg/L
Density kg/L
Viscosity cp
Viscosity cp
Calorific value
Calorific value
kg/kj
kg/kj
0.12
0.12
4.90
4.90
‐5.38
‐5.38
%
%
Figure 2. The percentage of the differences of microalgae oil, ethanol and petroleum diesel (MOE20%) Figure 2. The percentage of the differences of microalgae oil, ethanol and petroleum diesel (MOE20%) Figure
2. The percentage of the differences of microalgae oil, ethanol and petroleum diesel (MOE20%)
specification than PD. specification than PD. specification
than PD.
The The combustibility combustibility extent of of ethanol ethanol depends depends on on a number of of parameters parameters such as as time, The
combustibility extent extent
of
ethanol
depends
on
aa number number
of
parameters such such
as time, time,
temperature and the availability of oxygen. Hydrogen to carbon ratio H/C significantly affects the temperature and the availability of oxygen. Hydrogen to carbon ratio H/C significantly affects the temperature
and the availability of oxygen. Hydrogen to carbon ratio H/C significantly affects the
energy from the combustion reaction. shows that the highest H/C energy released released from
from the
the combustion
combustion reaction.
reaction. Table Table 3 shows
shows that
that the
the highest
highest H/C
H/C ratio ratio was for energy
released
Table 33 ratio was was for for
ethanol (2.5) while the lowest H/C ratio was for diesel (1.92). The higher H/C ratio in the fuel led to ethanol (2.5) while the lowest H/C ratio was for diesel (1.92). The higher H/C ratio in the fuel led to ethanol
(2.5) while the lowest H/C ratio was for diesel (1.92). The higher H/C ratio in the fuel led to
more energy release from combustion. Adding ethanol to the fuel helps in reducing the amount of more energy release from combustion. Adding ethanol to the fuel helps in reducing the amount of more
energy release from combustion. Adding ethanol to the fuel helps in reducing the amount of
carbon entered to the combustion chamber, which results in less total carbon emitted and increases carbon entered to the combustion chamber, which results in less total carbon emitted and increases carbon
entered to the combustion chamber, which results in less total carbon emitted and increases
the the H/C H/C ratio. ratio. However, adding MO increases the carbon amount in the fuel chemical structure the
H/C
ratio. However, However,adding addingMO MOincreases increases the the carbon carbon amount amount in in the the fuel fuel chemical chemical structure structure
(16.94). The presence of MO, which has a molecular weight of 268.57 g/mol, increases the molecular (16.94). The presence of MO, which has a molecular weight of 268.57 g/mol, increases the molecular (16.94).
The presence of MO, which has a molecular weight of 268.57 g/mol, increases the molecular
weight of MOE20% to 164.85 g/mol. This molecular weight is very close to that of diesel 167 g/mol. weight of MOE20% to 164.85 g/mol. This molecular weight is very close to that of diesel 167 g/mol. weight
of MOE20% to 164.85 g/mol. This molecular weight is very close to that of diesel 167 g/mol.
MO has a high number of carbons in the chemical structure (around 16.94). This makes the carbon MO has a high number of carbons in the chemical structure (around 16.94). This makes the carbon MO
has a high number of carbons in the chemical structure (around 16.94). This makes the carbon
content of MOE20% close to or slightly less than that of PD with slightly higher H/C ratio. This can content of MOE20% close to or slightly less than that of PD with slightly higher H/C ratio. This can content
of MOE20% close to or slightly less than that of PD with slightly higher H/C ratio. This can
enhance the combustion process along with the presence of oxygen from ethanol and biodiesel. enhance the combustion process along with the presence of oxygen from ethanol and biodiesel. enhance
the combustion process along with the presence of oxygen from ethanol and biodiesel.
3.1. In‐Cylinder Pressure 3.1.
In-Cylinder Pressure
3.1. In‐Cylinder Pressure The results of the engine performance using MOE20% and PD are presented in this section at a The
results of the engine performance using MOE20% and PD are presented in this section at
The results of the engine performance using MOE20% and PD are presented in this section at a compression ratio of 18:1. The in‐cylinder pressure results for the engine speeds of 2000 and 2600 are acompression ratio of 18:1. The in‐cylinder pressure results for the engine speeds of 2000 and 2600 are compression ratio of 18:1. The in-cylinder pressure results for the engine speeds of 2000 and 2600
given in 3 respectively. figures are
given
in Figure
3a,b
respectively.These These
figuresrevealed revealedalmost almostthe thesame sameresults results for for PD PD and and
given in Figure Figure 3 a,b a,b respectively. These figures revealed almost the same results for PD and MOE20% at all the studied engine speeds. This is in line with the hypothesis that the studied blend MOE20%
at all the studied engine speeds. This is in line with the hypothesis that the studied blend
MOE20% at all the studied engine speeds. This is in line with the hypothesis that the studied blend properties, properties,
which
are close close
to those those of of PD, PD, result result in in the the same same output output at at the the combustion combustion chamber. chamber. properties, which which are are close to to those of PD, result in the same output at the combustion chamber. The fuel properties of density, viscosity and heating value are presented in Figure 2. Kannan and The
fuel properties of density, viscosity and heating value are presented in Figure 2. Kannan and
The fuel properties of density, viscosity and heating value are presented in Figure 2. Kannan and Anand [6] and Kannan and Anand [18] reported similar findings with diestrol fuel as the in‐cylinder Anand
[6] and Kannan and Anand [18] reported similar findings with diestrol fuel as the in-cylinder
Anand [6] and Kannan and Anand [18] reported similar findings with diestrol fuel as the in‐cylinder pressure at high (up to 100% load) to medium load is identical to that of PD. pressure
at high (up to 100% load) to medium load is identical to that of PD.
pressure at high (up to 100% load) to medium load is identical to that of PD. Figure 3.
In-cylinder pressure
at engine
speed (a) (a) 2000 rpm;rpm; and (b) 2600
rpm when
the engine
fuelled
Figure Figure 3. 3. In‐cylinder In‐cylinder pressure pressure at at engine engine speed speed (a) 2000 2000 rpm; and and (b) (b) 2600 2600 rpm rpm when when the the engine engine with
MOE20%
and
PD.
fuelled with MOE20% and PD. fuelled with MOE20% and PD. 13989
55
Energies 2015, 8, 13985–13995
Energies 2015, 8, page–page 3.2. Engine Performance and Emissions 3.2.
Engine Performance and Emissions
The overall variations between the engine test parameters of MOE20% than PD for the average The
overall variations between the engine test parameters of MOE20% than PD for the average
results obtained at the engine speeds of 1700, 2000, 2300, 2600 and 2900 are illustrated in Figure 4. results obtained at the engine speeds of 1700, 2000, 2300, 2600 and 2900 are illustrated in Figure 4.
This figure shows that in comparison to PD, using MOE20% slightly reduced torque, exhaust gas This
figure shows that in comparison to PD, using MOE20% slightly reduced torque, exhaust gas
temperature and CO22 by 1.73, 1.77, 0.67 and 1.2%, by only
only by 1.73, 1.77, 0.67 and 1.2%, respectively, while respectively, while the the BSFC BSFC increased increased by
temperature and CO
0.47%. This
This BSFC
BSFC increase
increase is
is regarded
regarded negligible
negligible due
due to
to the
the experimental
experimental error
error and
and the
the results 0.47%.
results
averaging from different engine speeds. This demonstrates that, generally, MOE20% is relatively averaging from different engine speeds. This demonstrates that, generally, MOE20% is relatively
similar to PD in the performance parameters. However, substantial reductions by 11.41, 5.3 and 4.13 similar
to PD in the performance parameters. However, substantial reductions by 11.41, 5.3 and 4.13
in the emission parameters of HC, NO
and CO, respectively were recorded for MOE20% compared in
the emission parameters of HC, NOx xand
CO, respectively were recorded for MOE20% compared to
to PD. The reduction in the CO indicates the combustion is more in
complete in MOE20%
the case as
of PD. The reduction in the CO indicates that thethat combustion
is more complete
the case of
MOE20% as opposed to PD due to the presence of oxygen and the higher H/C ratio in the MOE20%. opposed to PD due to the presence of oxygen and the higher H/C ratio in the MOE20%. Discussions
Discussions of the test parameters at individual engine speeds are addressed in the next sections. of
the test parameters at individual engine speeds are addressed in the next sections.
4
2
0
‐2
‐4
‐6
‐8
‐10
‐12
BP
% ‐1.73
Turque BSFC
‐1.77
0.47
Exh.
Temp
HC
CO2
NOX
CO
O2
‐0.67
‐11.41
‐1.20
‐5.30
‐4.13
3.70
Figure
4. The overall variation in the engine test parameters at average of all tested speed when the
Figure 4. The overall variation in the engine test parameters at average of all tested speed when the engine
fuelled
with MOE20% compared to PD.
engine fuelled with MOE20% compared to PD. 3.3.
Brake Power (BP) and Torque
3.3. Brake Power (BP) and Torque Figures
5 and 6 manifest the relationship between engine speeds and the engine BP and engine
Figures 5 and 6 manifest the relationship between engine speeds and the engine BP and engine torque,
The engine engine BP BP and and torque torque
torque, respectively,
respectively, when
when the
the engine
engine is
is fueled
fueled with
with PD
PD and
and MO20%.
MO20%. The curves
have
the
same
pattern
for
both
fuels
at
all
engine
speeds.
The
maximum
BP
for
both
fuels
is
curves have the same pattern for both fuels at all engine speeds. The maximum BP for both fuels is obtained
at the engine speed of 2600 rpm for both fuels. The maximum difference between the fuels is
obtained at the engine speed of 2600 rpm for both fuels. The maximum difference between the fuels about
3.45% in the engine BP and 3.01% for the engine torque at the engine speed of 2000 rpm. At all is about 3.45% in the engine BP and 3.01% for the engine torque at the engine speed of 2000 rpm. other
the BP and
are
relatively
close. Although
heatingthe value
of thevalue MOE20%
is
At all speeds,
other speeds, the torque
BP and torque are relatively close. the
Although heating of the lower
than the PD by 5.38%, the maximum reduction in the BP and torque is less than this percentage
MOE20% is lower than the PD by 5.38%, the maximum reduction in the BP and torque is less than due
to the extra oxygen in the MOE20% and higher H/C ratio. These results can be predicted from
this percentage due to the extra oxygen in the MOE20% and higher H/C ratio. These results can be the
results of the in-cylinder pressure that showed relatively similar results at all the engine speeds.
predicted from the results of the in‐cylinder pressure that showed relatively similar results at all the This
finding is in agreement with [13] who reported comparable power and torque from diestrol
engine speeds. This finding is in agreement with [13] who reported comparable power and torque fuel
and
PD. The
between
the two
studiesthe is two due studies to the comparable
fuel
properties fuel [8].
from diestrol fuel agreement
and PD. The agreement between is due to the comparable The
differences between the fuels in the BP and torque are insignificantly higher at low engine speed
properties [8]. The differences between the fuels in the BP and torque are insignificantly higher at (high
load) than high engine speed. The fuel injected in the combustion chamber is the same for both
low engine speed (high load) than high engine speed. The fuel injected in the combustion chamber is fuels
but
less than the injected fuel at high engine speed which makes the engine BP and torque more
the same for both fuels but less than the injected fuel at high engine speed which makes the engine sensitive
to the fuel calorific value.
BP and torque more sensitive to the fuel calorific value. 13990
6
Energies 2015, 8, 13985–13995
Energies 2015, 8, page–page Energies 2015, 8, page–page Diesel fuel 18
MOE20%
Diesel fuel 18
MOE20%
5
4
Diesel fuel 18
MOE20%
45
3
34
2
23
1
12
0
01
1700
2000
2300
2600
2900
1700
2000 Engine Speed (rpm)
2300
2600
2900
0
Engine Speed (rpm)
1700
2000
2300
2600
2900
Figure 5. The engine BP (kW) at different engine speeds using PD and MOE20%. Figure
5. The engine BP (kW) at different
engine speeds using PD and MOE20%.
Engine Speed (rpm)
Figure 5. The engine BP (kW) at different engine speeds using PD and MOE20%. BP (kW)
BP (kW)
BP (kW)
Energies 2015, 8, page–page 5
Torque (N.m)
Torque (N.m)
Torque (N.m)
Figure 5. The engine BP (kW) at different engine speeds using PD and MOE20%. 20
20
Diesel fuel 18
Diesel fuel 18
MOE20%
MOE20%
20
15
15
Diesel fuel 18
MOE20%
15
10
10
10
5
5
1700
1700
5
1700
2300
2600
2900
2300
2600
2900
Engine Speed (rpm)
Engine Speed (rpm)
2000
2300
2600
2900
Figure 6. The torque (N.m) at different engine speeds using PD and MOE20%. Engine Speed (rpm)
Figure 6. The torque (N.m) at different engine speeds using PD and MOE20%. Figure
6. The torque (N.m) at different engine speeds using PD and MOE20%.
3.4. Brake Spesific Fuel Consumption (BSFC) Figure 6. The torque (N.m) at different engine speeds using PD and MOE20%. 3.4. Brake Spesific Fuel Consumption (BSFC) 3.4. BrakeFigure 7 illustrates the variation of BSFC as a function of engine speed for MOE20% and PD. Spesific Fuel Consumption (BSFC)
Figure 7 illustrates the variation of BSFC as a function of engine speed for MOE20% and PD. 3.4. Brake Spesific Fuel Consumption (BSFC) The figure shows that, for the tested engine speed, the BSFC increases as the engine speed increases. Figure 7 illustrates the variation of BSFC as a function of engine speed for MOE20% and PD.
The figure shows that, for the tested engine speed, the BSFC increases as the engine speed increases. It can be seen that both fuels have the same pattern and almost same results of BSFC. This finding is Figure 7 illustrates the variation of BSFC as a function of engine speed for MOE20% and PD. The It can be seen that both fuels have the same pattern and almost same results of BSFC. This finding is figure
shows that, for the tested engine speed, the BSFC increases as the engine speed increases.
in agreement with Ali, Yusaf [19] and Shi, Yu [20] who reported that the difference in the heating The figure shows that, for the tested engine speed, the BSFC increases as the engine speed increases. It can
be seen that both fuels have the same pattern and almost same results of BSFC. This finding is in
in agreement with Ali, Yusaf [19] and Shi, Yu [20] who reported that the difference in the heating value of the mixture of PD, ethanol and biodiesel from Soyate is less than PD by only 3%, which It can be seen that both fuels have the same pattern and almost same results of BSFC. This finding is agreement
with
Ali, Yusaf
and Shi,and Yu biodiesel [20] whofrom reported
that
the difference
inonly 3%, which the heating value
value of the mixture of [19]
PD, ethanol Soyate is less than PD by resulted in a negligible BSFC. Shahir et al. [8] calculated the BSFC variation of ternary fuel of PD, in agreement with Ali, Yusaf [19] and Shi, Yu [20] who reported that the difference in the heating resulted in a negligible BSFC. Shahir et al. [8] calculated the BSFC variation of ternary fuel of resulted
PD, of the
mixture of PD, ethanol and biodiesel from Soyate is less than PD by only 3%, which
ethanol and biodiesel of others researchers such as [21] and reported that, for variation at a constant value of the mixture of PD, ethanol and biodiesel from Soyate is less than PD by only 3%, which in a ethanol and biodiesel of others researchers such as [21] and reported that, for variation at a constant negligible BSFC. Shahir
et al. Shahir et al. [8] calculated
BSFC variation
ternaryof ternary fuel of PD,
ethanol
load and variable speeds, the maximum increase in BSFC was in the range of 2%–5%. resulted in a negligible BSFC. [8] the
calculated the BSFC of
variation fuel of PD, and
load and variable speeds, the maximum increase in BSFC was in the range of 2%–5%. biodiesel
of
others
researchers
such
as
[21]
and
reported
that,
for
variation
at
a
constant
load
ethanol and biodiesel of others researchers such as [21] and reported that, for variation at a constant and
variable
speeds, the maximum increase in BSFC was in the range of 2%–5%.
load and variable speeds, the maximum increase in BSFC was in the range of 2%–5%. Diesel fuel 18
MOE20%
550
Diesel fuel 18
MOE20%
550
500
Diesel fuel 18
MOE20%
500
550
450
450
500
400
400
450
350
350
400
300
300
3501700
2000
2300
2600
2900
1700
2000
2300
2600
2900
Engine Speed (rpm)
300
Engine Speed (rpm)
1700
2000
2300
2600
2900
Figure 7. The engine BSFC (g/kW.h) at different engine speeds using PD and MOE20%. Engine Speed (rpm)
Figure 7. The engine BSFC (g/kW.h) at different engine speeds using PD and MOE20%. BSFC (g/kW.h)
BSFC (g/kW.h)
BSFC (g/kW.h)
2000
2000
The fuel properties of viscosity, density and heating value are relatively close to PD, as given in Figure 7. The engine BSFC (g/kW.h) at different engine speeds using PD and MOE20%. Figure
7. The engine BSFC (g/kW.h) at different engine speeds using PD and MOE20%.
The fuel properties of viscosity, density and heating value are relatively close to PD, as given in Figure 2. However, there is a minor increase in BSFC at engine speed of 2000 rpm and 2300 rpm with Figure 2. However, there is a minor increase in BSFC at engine speed of 2000 rpm and 2300 rpm with The fuel properties of viscosity, density and heating value are relatively close to PD, as given in The fuel properties of viscosity, density and 7heating value are relatively close to PD, as given
Figure 2. However, there is a minor increase in BSFC at engine speed of 2000 rpm and 2300 rpm with in Figure 2. However, there is a minor increase in7 BSFC at engine speed of 2000 rpm and 2300 rpm
7
13991
Energies 2015, 8, 13985–13995
Energies 2015, 8, page–page with MOE20%, which can be expected due to the lower heating value than that of PD by 5.38%.
be expected to the heating value than that was
of PD by high
5.38%. This ThisMOE20%, finding iswhich not incan agreement
withdue Shahir
et lower al. [8] who
found
that
BSFC
very
compared
finding is not in agreement with Shahir et al. [8] who found that BSFC was very high compared to PD to PD using ternary fuel of ethanol, biodiesel and PD. The difference in BSFC depends on the ratio of
the using ternary fuel of ethanol, biodiesel and PD. The difference in BSFC depends on the ratio of the ethanol and biodiesel in the mixture. In addition, MOE20% contains microalgae oil rather than
ethanol which
and biodiesel in the mixture. In addition, MOE20% contains microalgae oil rather biodiesel,
has slightly
higher
density
and viscosity
than
biodiesel
to compensate
thethan lower
biodiesel, which has slightly higher density and viscosity than biodiesel to compensate the lower density, viscosity and heating value of ethanol.
density, viscosity and heating value of ethanol. 3.5. Exhaust Gas Temperature and NOx
3.5. Exhaust Gas Temperature and NOx The exhaust gas temperature variation with engine speed for MOE20% and PD is presented
The exhaust gas temperature variation with engine speed for MOE20% and PD is presented in in Figure 8. The exhaust gas temperature increased with increasing the speed for both fuels.
Figure 8. The exhaust gas temperature increased with increasing the speed for both fuels. TheThe variation in the exhaust gas temperature is minor at all engine speeds. The maximum variation variation in the exhaust gas temperature is minor at all engine speeds. The maximum variation
is found
at low
engine
speed
rpm of of 2.2% 2.2%and and1.65%, 1.65%,respectively, respectively,
while
at the
is found at low engine speed ofof 1700
1700 and
and 2000
2000 rpm while at the 26002600 rpm, the exhaust gas temperature of MOE20% is slightly higher. This variation is small due to rpm, the exhaust gas temperature of MOE20% is slightly higher. This variation is small due to
the the minor variation in the experimental test conditions and experimental error. minor variation in the experimental test conditions and experimental error.
Diesel fuel 18
MOE20%
Exhaust Temp (
Exhaust Temp (ooC)
C)
670
570
470
370
1700
2000
2300
2600
Engine Speed (rpm)
2900
Figure 8. The exhaust gas temperature (°C) at different engine speeds using PD and MOE20%. Figure
8. The exhaust gas temperature (˝ C) at different engine speeds using PD and MOE20%.
Figure 9 presents the relationship between the NO
Figure
9 presents the relationship between the NOxx emission and the engine speed when the emission and the engine speed when the
engine is fuelled PD MOE20%.
and MOE20%. The NOx emission of MOE20% was found to be engine is fuelled
with with PD and
The NO
x emission of MOE20% was found to be substantially
substantially lower than PD as elucidated in Figure 4. This finding is relatively in agreement with lower
than PD as elucidated in Figure 4. This finding is relatively in agreement with Kannan and
Kannan and Anand [6] and Kannan and Anand [18] who reported lower NOx from diestrol water Anand [6] and Kannan and Anand [18] who reported lower NOx from diestrol water emulsion by
emulsion by 19.72% compared to that of PD due to the higher latent heat of vaporization of ethanol 19.72% compared to that of PD due to the higher latent heat of vaporization of ethanol that reduced
that reduced the combustion temperature and produced less NOx emission. The variation between the combustion temperature and produced less NOx emission. The variation between PD and
PD and MOE20% fuel in producing NOx increased as the engine speed increases, with a difference of MOE20% fuel in producing NOx increased as the engine speed increases, with a difference of 6.87%
6.87% at 2300 rpm, 9.47% at 2600 rpm and 13.85% at the 2900 rpm. The reduction in NOx emission at 2300
rpm,
9.47% to at 2600
rpm and
13.85%
at the
rpm. The
reduction
in kJ/kg NOx emission
can be ascribed the higher latent heat of the 2900
evaporation of ethanol (904 compared can
to be
ascribed
to the[22] higher
of thevalue evaporation
of ethanol
(904 kJ/kg
compared
254 kJ/kg) [22]
254 kJ/kg) and latent
lower heat
calorific that reduces combustion temperature and toconsequently andNO
lower
calorific value that reduces combustion temperature and consequently NOx emission.
x emission. Diesel fuel 18
200
MOE20%
NO
NOx x (ppm)
(ppm)
150
100
50
0
1700
1900
2100
2300
2500
Engine Speed (rpm)
2700
2900
Figure 9. The engine NO
(ppm) at different engine speeds using PD and MOE20%. Figure
9. The engine NOx x(ppm)
at different engine speeds using PD and MOE20%.
8
13992
Energies 2015, 8, 13985–13995
Energies 2015, 8, page–page Energies 2015, 8, page–page 3.6.
Hydrocarbon (HC) (%)
3.6. Hydrocarbon (HC) (%) 3.6. Hydrocarbon (HC) (%) The
The hydrocarbon
hydrocarbon content
content of
of the
the exhaust
exhaust gas
gas emission
emission versus
versus the
the engine
engine speed
speed for
for PD
PD and
and The hydrocarbon content of the exhaust gas emission versus the engine speed for PD and MOE20%
is shown in Figure 10. The HC produced from MOE20% is considerably lower than that of
MOE20% is shown in Figure 10. The HC produced from MOE20% is considerably lower than that of MOE20% is shown in Figure 10. The HC produced from MOE20% is considerably lower than that of PD
ofof the
tested
speeds.
TheThe maximum
variation
between
the fuels
observed
at the engine
PD at
at most
most the tested speeds. maximum variation between the was
fuels was observed at the PD at most of the tested speeds. The maximum variation between the fuels was observed at the speed
of 2900 with 18.75% reduction compared to PD. This is due to the better combustion of the
engine speed of 2900 with 18.75% reduction compared to PD. This is due to the better combustion of engine speed of 2900 with 18.75% reduction compared to PD. This is due to the better combustion of microalgae
biodiesel and ethanol, the lower carbon content in the MOE20% and the higher H/C ratio.
the microalgae biodiesel and ethanol, the lower carbon content in the MOE20% and the higher H/C the microalgae biodiesel and ethanol, the lower carbon content in the MOE20% and the higher H/C Subbaiah
and Gopal [21] reported a reduction of 34.3% in the HC at the exhaust when 10% ethanol
ratio. Subbaiah and Gopal [21] reported a reduction of 34.3% in the HC at the exhaust when 10% ratio. Subbaiah and Gopal [21] reported a reduction of 34.3% in the HC at the exhaust when 10% was
blended with biodiesel and PD at full load condition. Similarly, Rahimi and Ghobadian [13]
ethanol was blended with biodiesel and PD at full load condition. Similarly, Rahimi and Ghobadian ethanol was blended with biodiesel and PD at full load condition. Similarly, Rahimi and Ghobadian found
that the HC from diestrol was lower than that of PD. This reduction is due to the extra oxygen
[13] found that the HC from diestrol was lower than that of PD. This reduction is due to the extra [13] found that the HC from diestrol was lower than that of PD. This reduction is due to the extra from
microalgae biodiesel and ethanol that enhances the combustion.
oxygen from microalgae biodiesel and ethanol that enhances the combustion. oxygen from microalgae biodiesel and ethanol that enhances the combustion. Diesel fuel 18
Diesel fuel 18
200
200
MOE20%
MOE20%
HC
HC
150
150
100
100
50
50
0
0
1700
1700
1900
1900
2100
2300
2500
2100
2300
2500
Engine Speed (rpm)
Engine Speed (rpm)
2700
2700
2900
2900
Figure 10. The engine HC (%) at different engine speeds using PD and MOE20%. Figure
10. The engine HC (%) at different engine speeds using PD and MOE20%.
Figure 10. The engine HC (%) at different engine speeds using PD and MOE20%. 3.7. Carbon Monoxide and Carbon Dioxide CO and CO
3.7.
Carbon Monoxide and Carbon Dioxide CO and CO222 (%) (%)
3.7. Carbon Monoxide and Carbon Dioxide CO and CO
(%) CO emission is an indication of the complete combustion. Figure 11 presents the CO emission at CO
emission is an indication of the complete combustion. Figure 11 presents the CO emission at
CO emission is an indication of the complete combustion. Figure 11 presents the CO emission at different engine speeds for PD and MOE20%. The figure shows that the CO emission of MOE20% is different
engine speeds for PD and MOE20%. The figure shows that the CO emission of MOE20% is
different engine speeds for PD and MOE20%. The figure shows that the CO emission of MOE20% is lower than PD at low engine speeds of 1700 rpm and 2000 rpm and almost the same as that of PD at lower
than PD at low engine speeds of 1700 rpm and 2000 rpm and almost the same as that of PD at
lower than PD at low engine speeds of 1700 rpm and 2000 rpm and almost the same as that of PD at high engine speed. The use MOE20% resulted in a maximum reduction parentage of CO level 16.7% high
engine speed. The use MOE20% resulted in a maximum reduction parentage of CO level 16.7%
high engine speed. The use MOE20% resulted in a maximum reduction parentage of CO level 16.7% at 1700 rpm as compared to the standard PD at the same speed. The CO level at 1700 for PD is 0.72% at
1700 rpm as compared to the standard PD at the same speed. The CO level at 1700 for PD is 0.72%
at 1700 rpm as compared to the standard PD at the same speed. The CO level at 1700 for PD is 0.72% and 0.6% for MOE20%. The difference between the readings is 0.12% This finding is in agreement and
0.6% for MOE20%. The difference between the readings is 0.12% This finding is in agreement
and 0.6% for MOE20%. The difference between the readings is 0.12% This finding is in agreement with Bhale, Deshpande [12] who reported an average reduction of 50% in CO when 20% ethanol was with
Bhale, Deshpande [12] who reported an average reduction of 50% in CO when 20% ethanol was
with Bhale, Deshpande [12] who reported an average reduction of 50% in CO when 20% ethanol was added to biodiesel. However, at 2300 rpm, the CO emission from MOE20% is higher than that from added
to biodiesel. However, at 2300 rpm, the CO emission from MOE20% is higher than that from
added to biodiesel. However, at 2300 rpm, the CO emission from MOE20% is higher than that from PD by about 4.9%. This could be to
due the experimental error. The lower CO with
emission with PD
4.9%.
This
could
be due
theto experimental
error. The
lower
CO
emission
MOE20%
PD by
by about
about 4.9%. This could be due to the experimental error. The lower CO emission with MOE20% is due to the higher oxygen content and H/C ratio. is
due to the higher oxygen content and H/C ratio.
MOE20% is due to the higher oxygen content and H/C ratio. Diesel fuel 18
Diesel fuel 18
CO(%)
(%)
CO
1.5
1.5
MOE20%
MOE20%
1
1
0.5
0.5
0
0
1700
1700
1900
1900
2100
2300
2500
2100
2300
2500
Engine Speed (rpm)
Engine Speed (rpm)
2700
2700
2900
2900
Figure 11. The engine CO (%) at different engine speeds using PD and MOE20%. Figure 11. The engine CO (%) at different engine speeds using PD and MOE20%. Figure
11. The engine CO (%) at different engine speeds using PD and MOE20%.
Figure 12 presents the CO2 level at different engine speeds for PD and MOE20%. The emission Figure 12 presents the CO2 level at different engine speeds for PD and MOE20%. The emission of CO2 is almost constant with the engine speed for both fuels. There is a marginal difference in the of CO2 is almost constant with the engine speed for both fuels. There is a marginal difference in the 13993
9
9
Energies 2015, 8, 13985–13995
Figure 12 presents the CO2 level at different engine speeds for PD and MOE20%. The emission of
Energies 2015, 8, page–page CO2 is almost constant with the engine speed for both fuels. There is a marginal difference in the CO2
emission
at medium
and high
speeds.speeds. A negligible
reduction
of 2.93%of and
2.8%and is depicted
CO2 emission at medium and engine
high engine A negligible reduction 2.93% 2.8% is at
low engine
speeds
of 1700
rpm
1900
rpm,
The maximum
difference
between
the
depicted at low engine speeds of and
1700 rpm and respectively.
1900 rpm, respectively. The maximum difference readings
of
CO
%
for
PD
and
MOE20%
is
0.3%
at
1700
rpm
(10.1%
for
PD
and
9.8%
for
MOE20%).
between the readings of CO
2% for PD and MOE20% is 0.3% at 1700 rpm (10.1% for PD and 9.8% for 2
However,
the reduction in the CO and CO2 level especially
at low engine speed could be due to the
MOE20%). However, the reduction in the CO and CO
2 level especially at low engine speed could be lower
H/C
ratio
of
the
MOE20%
(1.94)
compared
to
2.01
for
PD (see Table 3). This means that the
due to the lower H/C ratio of the MOE20% (1.94) compared to 2.01 for PD (see Table 3). This means amount
of carbon that enters the combustion chamber is less with MOE20% compared to PD as the
that the amount of carbon that enters the combustion chamber is less with MOE20% compared to PD amount
of fuel injected is the same. This justifies the lower CO and CO2 of MOE20%
compared to PD
as the amount of fuel injected is the same. This justifies the lower CO and CO
2 of MOE20% compared (less
by
1.2%
for
CO
and
4.13%
for
CO
as
given
in
Figure
4).
to PD (less by 1.2% for CO and 4.13% for CO
2 as given in Figure 4). 2
Diesel fuel 18
13
MOE20%
CO2 (%)
11
9
7
5
1700
1900
2100
2300
2500
Engine Speed (rpm)
2700
2900
Figure 12. The engine CO
Figure
12. The engine CO22 (%) at different engine speeds using PD and MOE20%. (%) at different engine speeds using PD and MOE20%.
4. Conclusions 4.
Conclusions
The use of renewable alcohol such as ethanol as an additive to PD can improve diesel engine The
use of renewable alcohol such as ethanol as an additive to PD can improve diesel engine
emission with a reduction in engine power and an increase in engine BSFC due to the lower calorific emission with a reduction in engine power and an increase in engine BSFC due to the lower calorific
value, low viscosity and low cetane number. Moreover, ethanol is immiscible in PD and requires the value,
low viscosity and low cetane number. Moreover, ethanol is immiscible in PD and requires the
use of surfactant to overcome this problem. Microalgae oil is a renewable fuel with higher density use of surfactant to overcome this problem. Microalgae oil is a renewable fuel with higher density
and viscosity than PD. A mixture of 10% ethanol, 10% microalgae oil and 80% PD has fuel properties and
viscosity than PD. A mixture of 10% ethanol, 10% microalgae oil and 80% PD has fuel properties
similar to those of PD highlighting its usability in diesel engine without modification. In comparison similar to those of PD highlighting its usability in diesel engine without modification. In comparison
to PD, the results of using MOE20% in single cylinder diesel engine indicated minor differences in to
PD, the results of using MOE20% in single cylinder diesel engine indicated minor differences
most of of
the engine fuel in
most
the
engineperformance performanceparameters parametersat atall allthe thetested tested speeds speeds due due to to the the comparable comparable fuel
properties. The engine emission of NO
x and HC was reduced at most of the engine speeds. CO and properties. The engine emission of NOx and HC was reduced at most of the engine speeds. CO and
CO2 of MOE20% were found to be lower than those of PD at low engine speeds. CO
2 of MOE20% were found to be lower than those of PD at low engine speeds.
Acknowledgments: The authors thank the National Centre for Engineering in Agriculture (NCEA) and Faculty Acknowledgments:
The authors thank the National Centre for Engineering in Agriculture (NCEA) and Faculty
of
Engineering
and
Sciences,
University
of Southern
Queensland.
The authors
thank
Soley
Institutes,
of Health,
Health, Engineering and Sciences, University of Southern Queensland. The also
authors also thank Soley Turkey for providing microalgae oil.
Institutes, Turkey for providing microalgae oil. Author Contributions: Both authors have contributed in developing the idea, conducting the test and writing
Author Contributions: Both authors have contributed in developing the idea, conducting the test and writing of
the manuscript.
of the manuscript. Conflicts of Interest: The authors declare no conflict of interest.
Conflicts of Interest: The authors declare no conflict of interest. References
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