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WFL Publisher
Science and Technology
Meri-Rastilantie 3 B, FI-00980
Helsinki, Finland
e-mail: [email protected]
Journal of Food, Agriculture & Environment Vol.14 (1): 46-50. 2016
www.world-food.net
Performance analysis of a diesel cycle engine running on biodiesel from waste
frying oil and its reduction on gas emissions
Mireille Sato*, Jair Antonio da Cruz Siqueira, Maurício Guy de Andrade, Helton Aparecido Rosa,
Samuel Nelson Melegari de Souza, Carlos Eduardo Camargo Nogueira and Elisandro Pires Frigo
State University of West Paraná – Master´s Degree in Energy Applied to Agriculture Program Rua Universitária, 2069,
CEP: 85.819-130 Bairro Faculdade, Cascavel-PR, Brazil. *e-mail:[email protected]
Received 7 September 2015, accepted 20 December 2015
Abstract
The growing environmental concern along with the need for finding a replacement for fossil energy have led to the development of alternative fuels
made from vegetable oils by the process of transesterification, producing biodiesel, which can be used in diesel cycle engines with no alterations.
Biodiesel from waste frying oil shows an advantage over other types of biodiesel, as it does not require the process of oil extraction, thus providing
a sustainable destination to the discard of residual oil as well as not competing with food production. Thus, the present work aimed to assess the
specific fuel consumption (SFC), thermal efficiency and emissions of carbon monoxide (CO), nitric oxide (NO) and nitrogen oxides (NOx), in a cycle
diesel engine-generator set, using biodiesel from waste frying oil (B 100) and diesel (B 0) as fuel. The engine-generator set used in the study was a
model BD 6500CF with 7.36 kW (10 cv) of power and 5.5 kVA/5.0 kW of nominal power, with an average output tension of 120/240 V monophase.
Nominal loads applied varied between 1.0 and 5.0 kW. In order to quantify gas emissions, a combustion and emission quality analyzer was used,
model PCA®3, Bacharach Inc. This study showed higher efficiency and lower exhaust gas emissions with the use of biodiesel when compared to
regular diesel.
Key words: Combustion gases, energy generation, specific fuel consumption.
Introduction
During the twentieth century environmental movements emerged
in a global scale, their goal was to spread environmental awareness
and the importance of environmental conservation. In 1972 the
Club of Rome and the Stockholm Conference emerged. Currently,
sustainability is an essential factor to the development of nations,
and it requires the replacement of fossil, non-renewable and
polluting energies by the so-called clean energy.
Biodiesel integrates the set of renewable energy sources that
enable the reduction of petroleum use. It is an alternative fuel
indicated for compression ignition (diesel cycle) engines over the
use of diesel oil 1. Biodiesel can be chemically defined as a monoalkyl ester of long chain fatty acids, obtained by the
transesterification process 2 derived from vegetable oils such as
sunflower, castor, soybean, babassu and other oilseed plants, as
well as from animal fats or waste frying oil 3.
Transesterification consists of the transformation of triglycerides
into lower molecules of fatty acid esters, in other words, it is a
chemical reaction of a vegetable oil or animal fat with an alcohol
such as methanol in the presence of a catalyst, which is usually a
strong base such as sodium or potassium hydroxide, and produces
new chemical compounds called methyl esters 4.
Under the environmental viewpoint, the use of biodiesel
becomes advantageous when compared to diesel oil, as it
46
eliminates the emission of sulfur and aromatics, releases less
particles, HC, CO and CO2 and also presents a biodegradable and
nontoxic character. In what concerns to its performance in diesel
cycle engines the advantage lies in increased viscosity and higher
flash point than the conventional diesel, besides showing high
cetane levels 5.
Regarding biodiesel production, Brazil is among the largest
producers and consumers worldwide, reaching in 2010 the annual
production of 2.4 billion litres, of which 69.24% came from soybean
and only 0.65% from waste frying oil 6. However, one should recall
that the production of biodiesel from soybean is questionable,
since the price of that oilseed, whose initial function was to supply
food, has increased after a resolution of the National Council for
Energy Policies in 2009, which increased the required percentage
of biodiesel blend with diesel from 4% to 5% 7.
Thus, although biodiesel from frying oil corresponds to a small
portion of the Brazilian annual production, this feedstock does
not compete with food production, and has positive aspects, as
not requiring the biodiesel extraction process and being
economical, as its oil is residual. Finally, it brings a sustainable
solution to the disposal issue 8.
Within this context, this work aims to analyze the specific fuel
consumption, emissions of carbon monoxide (CO), nitric oxide
Journal of Food, Agriculture & Environment, Vol.14 (1), January 2016
(NO), nitrogen oxide (NOx) and performance of a diesel cycle engine
running on biodiesel from waste frying oil (B100) compared to
diesel.
Materials and Methods
The experiment was conducted in the laboratory of biofuels at the
State University of West Paraná, where the biodiesel from waste
frying oil was produced by means of transesterification. This
process used potassium hydroxide (KOH) as catalyst and
methanol, both measured according to the initial oil volume, 1%
and 25% were added, respectively.
The conventional diesel oil used was supplied by REPAR and
did not contain any biodiesel addition to its composition. Finally,
a diesel cycle engine-generator set was used, model BD 65000C
with 7.36 kW (10 hp) of power and nominal power of 5.5 kVA/5.0
kW, and output voltage of 120/240 V (monophase).
In order to obtain data of fuel consumption during the tests
with the engine-generator set, the fuel mass, which was already
stored in a tank, was weighed on a precision scale, model BG-2000
by GEHACA. The duration of each test was recorded using a
digital stopwatch, thereby obtaining the fuel consumption.
Eq. 1 shows the calculation of fuel consumption performed in
each test of set performance.
ሶ ൌ ቆ
ሺ ൅ ሻ െ ሺ ൅ ሻ
ቇ
ο
(1)
in which
– Fuel consumption, kg s-1;
Mr – Mass of the tank in which the fuel is stored, kg;
Mi – Initial fuel mass, kg;
Mf – Final fuel mass, kg;
∆t – test duration, s.
The load simulation in the generator was performed by means of
a bank of electrical resistances whose powers were controlled by
an electrical panel. The nominal loads used were 1.0, 2.0, 3.0, 4.0
and 5.0 kW. One should note that the loads used were same for
comparison purposes between mineral diesel and biodiesel.
Performance evaluation of the set was based on the specific
fuel consumption (SFC) and energy conversion efficiency (η) of
the engine-generator set. The SFC was determined by the load
variation in the engine-generator set running on mineral diesel oil
B(0) and waste frying oil biodiesel (B100) (Eq. 2).
͵Ǥ͸Ǥ ͳͲଷ ሶ
ൌ ቆ
ቇ

(2)
pump to pressurize the adiabatic container with the sample; this
container is coupled to the ignition wire. The pressure maintained
in the E2K calorimeter was 30 atm (3.00 MPa). Incomplete
combustion trials were discarded. Thus, it was possible to
determine the superior calorific value of the fuels.
The inferior calorific power (Eq. 3) of each compound was
determined by the equation described by Volpato et al.9, which
takes into account the superior calorific power:
ICP = SCP – 3.052
(3)
in which
SCP – Superior calorific power, MJ kg-1, and
ICP – Inferior calorific power, MJ kg-1
Another parameter used in the assessment of the enginegenerator set was its efficiency in converting the fuel chemical
energy into electricity. The calculation of the set’s efficiency was
performed according to Eq. 4.
͵͸ͲͲ
Ʉൌ൬
൰ ͳͲͲ
(4)
in which:
η - Set efficiency, %;
SFC – Specific fuel consumption, kg kW-1h-1;
ICP – Inferior calorific power, MJ kg-1;
In order to quantify the emission of gases, an ignition quality
analyzer model PCA3-285KIT/24-8453 by Bacharach was used. It
presents a calibration certificate N° 1011/ AN5420 dated from 24/
11/2010 for temperature and concentration items. For the emissions
test, the equipment’s capture catheter was exposed in the
combustion gases exhaust area until values were stabilized. This
process was repeated four times in a row. The quantified gases
were carbon monoxide (CO), nitric oxide (NO) and nitrogen oxides
(NOx). Treatment means were compared by Tukey’s test at 5%
significance.
Results and Discussion
Fig. 1 shows the SFC behavior of the engine as a function of the
load bank subjected to the generator. No statistical difference
was observed between the tested fuels. The average consumption
of all loads regarding waste frying oil biodiesel was 600.81 and
602.30 g kW-1 h-1 with conventional diesel. The waste frying oil
biodiesel presented higher consumption only with loads 1 and 5
kW, which corresponded to 3.40% and 7.93%, respectively.
in which:
SFC – Specific fuel consumption, kg kW-1h-1;
– Fuel consumption, kg s-1;
V – Output voltage, V;
I – Electric current, Å.
A calorimeter (model E2K) was used in order to define the calorific
value of the fuel blends. For this trial, portions of approximately
0.5 g of fuel were separated. The method for determining the
superior calorific value with the calorimeter consists of using a
Figure 1. Specific fuel consumption as a function of the load
applied. Treatment means followed by different letters differ
from each other significantly by Tukey’s test at 5% significance.
47
Table 1. Analyzed properties of waste frying oil biodiesel and
mineral diesel.
Properties
Superior calorific power (MJ.kg-1)
Inferior calorific power (MJ.kg-1)
Kinematic viscosity, 20ºC (mm2.s-1)
Density (g.cm-3)
Waste frying
oil biodiesel
38.81
35.76
4.96
0.881
Mineral
diesel
43.61
40.56
3.01
0.845
One can observe that biodiesel’s kinematic viscosity and density
values are slightly superior to those of mineral diesel and only the
superior calorific power and inferior calorific power are lower. The
superior calorific power values obtained in this study were similar
to those found by Costa Neto et al.13: 42.30 MJ.kg -1 with diesel
and 37.5 MJ.kg -1 with waste frying oil biodiesel. Similar values
were also observed for density, showing similarities in SFC and
physical properties.
The following results were reached (Fig. 2) regarding the
efficiency of converting the fuel chemical energy into electric
energy in the engine-generator set.
matches Chaves et al.10, whose waste frying oil biodiesel means
were higher under the entire load bank, as well as with loads of 1
and 1.5 kW, considered statistically different. Ferrari et al.14 also
obtained higher efficiency with the use of biodiesel. Lapuerta et
al. 15 observed that B(100) reached the highest power in
comparison to mineral diesel blends. Finally, Valente 16 affirmed
that there is a significant increase in efficiency with the proportional
raise of soybean concentration throughout the entire load band
under study.
According to Costa Neto et al.13, the higher efficiency of
biodiesel over conventional diesel described above and observed
in this study is attributed to its lower calorific power, as the maximum
power to be achieved by the engine depends on it. It also
conditions the global engine development, what shows in cold
start. The same author also states that, when compared to diesel
oil, vegetable oils present less ignition heat and similar cetane
number, which is responsible for the ignition, what leads to higher
engine efficiency.
Biodiesel is known as a solution for reducing the emission of
toxic gases; the reduction of CO is shown in Fig. 3. The waste
frying oil biodiesel released less CO under all loads, at an average
of 297.6 ppm, whereas diesel released an average of 748.4 ppm.
Therefore, CO emission was 39.7% lower with the use of biodiesel.
The load of 2 kW with conventional diesel provided the lowest
CO emission in the load bank: 424.0 ppm. Under the same load,
biodiesel produced only 401.9 ppm of CO. Such reduction was
also observed in a test performed by Kalam et al.17, in which
biodiesel from coconut oil and residual palm oil in comparison to
conventional diesel provided a decrease of 7.3% and 21%,
respectively.
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This result is similar to that obtained by Chaves et al.10 in a
study in which waste frying oil biodiesel, B(0) and B(20), showed
results closer to that of mineral diesel. The authors affirm that in
most trials both fuels presented a statistically similar specific
consumption, just as in a research carried out by Andrade et al.3,
in which the SFC of soybean biodiesel and mineral diesel did not
present statistical difference, however, there was a SFC fluctuation
between B(0) and B(100) according to load variation. As stated by
Soranso et al.11, residual oil biodiesel and diesel showed equal
values of specific consumption. Volpato et al.9 performed a study
on a four-stroke diesel cycle engine with nominal power of 75 hp
(56 kW) running on soybean oil biodiesel and obtained a reduction
of 14.66% in the SFC in relation to mineral diesel
According to Wang et al.12, the SFC differences between diesel
and biodiesel described above happen because of a superior
kinematic viscosity value and biodiesel density in the cycle diesel
engine system, as it can cause incomplete ignition and then lead
to higher specific consumption. Thus, Table 1 shows the physical
properties of conventional diesel and waste frying oil biodiesel
obtained in a laboratory, both used in the trials with the enginegenerator set.
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Figure 3. Means of CO emissions under different resistive loads.
Treatment means followed by different letters differ from each
other significantly by Tukey’s test at 5% significance.
Figure 2. Engine-generator set’s efficiency in converting chemical energy
into electric energy. Treatment means followed by different letters differ
Under all loads biodiesel efficiency was superior to conventional
diesel, their efficiency means were 94.41% and 81.70%, respectively.
Therefore, biodiesel has proven to be 13% more efficient.
It is noteworthy that only loads of 3 and 4 kW provided
statistically higher efficiency to the use of biodiesel; this result
48
When carrying out a research on biodiesel from frying oil, Arslan
et al.18 achieved a CO decrease of 2% with B(25) and 13% with
B(75), in comparison to B(0). Makareviciene and Julis19 observed
an average reduction of 50% in CO levels. To Haas et al.20, CO
which is a byproduct from the combustion of hydrocarbons, can
be reduced by increasing oxygen in the fuel. As biodiesel presents
higher amounts of oxygen molecules in its composition its ignition
produces less CO.
Fig. 4 shows that there was a clear reduction of NO emissions
with the use of waste frying oil biodiesel over mineral diesel, means
were 91.5 and 261.3 ppm, respectively, that is, a global reduction
of 35.8%. The load of 3 kW showed the higher amount of NO
emission, with 126.5 ppm with biodiesel. Conventional diesel
behavior was crescent according to the increase of loads.The
results obtained in this study match those found by Rosa et al.21,
in which crambe biodiesel had expressive reductions under all
loads and the average reduction was 38.56%. Just as carbon
monoxide, the reduction of nitric oxide is also influenced by the
amount of oxygen available at ignition. Rakopoulos and
Giakoumis22 affirm that biodiesel stoichiometric composition favors
the reduction of NO.
Conclusions
The results obtained in this research show that the use of waste
frying oil biodiesel was advantageous in all criteria assessed,
presenting SFC values similar to those of diesel, a factor that
could make its use onerous, as well as presenting higher efficiency
and significant reduction in the emissions of all toxic gases
analyzed. Finally, waste frying oil biodiesel does not require an
extraction process and provides an environmentally friendly end
to residual oils without competing with food production.
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References
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Figure 4. NO emission means of both fuels under different resistive
loads. Treatment means followed by different letters differ from
each other significantly by Tukey’s test at 5% significance.
Nitrogen oxide (NOx) emissions are shown in Fig. 5, in which
once again biodiesel emissions were significantly lower under all
resistive loads to those of conventional diesel, with an average
reduction of 40.4%. Pereira et al.23 obtained a reduction of 9%
with the use of soybean biodiesel in comparison to diesel.
McCarthy et al.24 explains that NOx emissions are influenced by
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with diesel and biodiesel.
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Figure 5. NOx emission means of both fuels under different
resistive loads. Treatment means followed by different letters differ
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