Investigation of performance and emission characteristics of waste cooking oil as biodiesel in a diesel engine
Investigation of performance and emission characteristics of waste cooking oil as biodiesel in a diesel engine
Yahya Ulusoy 0 1 2 3
Rıdvan Arslan 0 1 2 3
Yu¨ cel Tekin 0 1 2 3
Ali S u¨rmen 0 1 2 3
Alper Bolat 0 1 2 3
Remzi S¸ahin 0 1 2 3
0 Tu ̈rk Trakto ̈r ve Ziraat Makineleri Co. , Ankara , Turkey
1 Department of Automotive Engineering, Uludag ̆ University , Bursa , Turkey
2 & Yahya Ulusoy
3 Department of Mechanical Engineering, KTO Karatay University , Konya , Turkey
Biodiesel is one of the most popular prospective alternative fuels and can be obtained from a variety of sources. Waste frying oil is one such source along with the various raw vegetable oils. However, some specific technical treatments are required to improve certain fuel properties such as viscosity and calorific value of the biodiesel being obtained from waste cooking oil methyl ester (WCOME). Various treatments are applied depending on the source and therefore the composition of the cooking oil. This research investigated the performance of WCOME as an alternative biofuel in a four-stroke direct injection diesel engine. An 8-mode test was undertaken with diesel fuel and five WCOME blends. The best compromise blend in terms of performance and emissions was identified. Results showed that energy utilization factors of the blends were similar within the range of the operational parameters (speed, load and WCOME content). Increasing biodiesel content produced slightly more smoke and NOx for a great majority of test points, while the CO and THC emissions were lower.
Waste cooking oil
Alternative fuel resources will play an important role in
replacing the dwindling world supply of fossil fuels.
Increasing industrialization and mechanization has led to a
steep rise in the demand for fossil fuel. As a result, limited
reserves and environmental degradation have mandated the
search for alternative fuels
(He et al. 2010)
, which are
gaining worldwide acceptance as a partial solution to the
problems of environmental degradation, energy security,
import restrictions, rural employment and agricultural
economy. Generally, different ratios of biodiesel are
Edited by Xiu-Qin Zhu
Department of Agricultural Machinery/Automotive
Technology, Uludag˘ University, Bursa, Turkey
blended with fossil fuel for use in diesel engines, which are
recognized for energy generation and are a power source
providing higher efficiency and ruggedness in the field of
transportation. One of the biodiesel sources is waste
cooking oil methyl ester (WCOME). WCOME presents a
twofold gain, as it can provide benefits both as an
environmental strategy for municipalities as well as for the
safeguarding of human health due to the lowered gas
Hamasaki et al. (2001)
that biodiesel could be used as an alternative fuel instead of
existing conventional diesel engines without requiring any
modifications. Compared to conventional fossil diesel fuel,
biodiesel provides significant reductions in particulate
matter (PM) emissions
(Canakci and Van Gerpen 2003;
Lapuerta et al. 2008; Tat 2003)
, carbon monoxide (CO)
(Mittelbach and Tritthart 1988)
hydrocarbon (THC) emissions (Payrı et al. 2005). The
performance of biodiesel-fueled engines is better than that
of diesel-fueled engines in terms of thermal efficiency,
brake-specific energy consumption, and smoke opacity,
wear of vital components and exhaust emissions for an
entire range of operations
(Agarwal and Das 2001)
findings are supported by researchers who observed similar
behavior for all biodiesel blends with fuel of various
origins (Cetinkaya et al. 2005;
Felizardo et al. 2006
Mangesh and Dalai 2006; Ulusoy et al. 2004). Gopal et al.
(2014) have observed that there is significant reduction in
CO, unburned HC and smoke emissions for biodiesel and its blends compared to diesel fuel. However, NOx emission of WCO biodiesel is marginally higher than of petroleum diesel.
Many studies have been conducted on the use of alter
native input products such as rape seed and soybean
WCOME in the production of biodiesel for use in diesel
Altıparmak et al. 2007
Felizardo et al. 2006
Kaplan et al. 2006
Mangesh and Dalai 2006
Nachid et al.
Selvan and Nagarajan 2013
Ulusoy et al.
, 2016). The performance and smoke results obtained
from an electricity generator engine operating on WCOME
showed that the smoke reduction, compared to that of
conventional diesel fuel, was around 60% for B100 (100%
biodiesel) and around 25% for B20 (20% biodiesel)
(Cetinkaya and Karaosmanoglu 2005)
. Dorado et al. (2003)
conducted an 8-mode test using waste olive oil in a
fourstroke, three-cylinder, direct injection, 34 kW engine and
results showed that 8.6% reduction in CO2, a 58.9%
reduction in CO and a 57.7% reduction in SO2 emissions.
However, increases of 8.5% and 32% were observed in
specific fuel consumption and NOx emissions, respectively.
Murillo et al. (2007) tested a four-stroke diesel outboard
engine running on conventional diesel, conventional diesel
blended with 10%, 30% and 50% biodiesel derived from
WCOME and pure biodiesel. The biodiesel blends proved
to be environmentally friendly alternatives to conventional
diesel fuel. They noticed reductions in power of
approximately 5% with B10 and B30, and 8% with B50 and B100.
Despite the positive performance tendencies of WCOME
mentioned above, contradictory results have also been
Lin et al. (2007)
found sharp increases in both
NOx and particulate emissions when WCOME was used.
In this study, we investigated the performance of
WCOME as an alternative biofuel in a four-stroke, four
cylinder, direct injection diesel engine. The test was carried
out in compliance with ISO 8178-C1 8-modes test cycle as
commonly applied for off-road engine applications.
Emission results, besides the engine characteristics, are reported as instantaneous pollutant concentrations (in ppm or %) and cumulative values determined based on weighted average modal pollutant values in g/kW-h.
2 Materials and methods
2.1 Test fuel
Diesel fuel (D2) and a set of blends of diesel with WCOME
were used in this research. D2 was used as the reference
fuel. The WCOME–diesel blends included B10, B20, B30,
B40 and B50 (according to WCOME, %). Test fuel specifications are shown in Table 1.
The experiments were carried out in the Research and
Development department of the Tu¨ rk Trakto¨r ve Ziraat
Makineleri Co. in Turkey. Throughout the tests, WCOs
from industrial sources in the Marmara region were used.
To eliminate the effects of fuel composition on the measured emission levels, low-sulfur diesel fuel (maximum sulfur content 50 ppm) was used as a reference fuel in the experiments.
2.2 Experimental setup
The engine test laboratory provided a complete system for
measuring all parameters relating to diesel engine
performance and exhaust gas emissions analyses. The
experimental system consisted of an AC dynamometer and a
HORIBA MEXA-7100D emission measuring system.
A HORIBA MDLT-1300 partial-flow mini-dilution tunnel
was used for PM measurement. Figure 1 gives a schematic
layout of the experimental system used. Descriptions of the
test devices are given in Table 2, and the engine
specifications are summarized in Table 3.
2.3 Test methods
The engine was run for a preliminary period until the
cooling water and oil reached stable temperatures. This
stabilization typically took 30 min. After warming up, the
test conditions were set and the engine was allowed to
reach a steady state before any data were taken. Emissions
were measured according to the regulatory test procedures
AVL Fuel conditioning
unit & fuel meter
Water cooling tower
3 Results and discussion
A set of typical performance curves showed that apart from the percentage of WCOME in the blends, there was no unusual difference in the performance indicators, except for the emission parameters.
Load, % Weighting factor 100 75
The power curves are given in Fig. 2. Both figures in
Fig. 2 show very small fluctuations in the torque and power
values for different blends at different loads. These
fluctuations seem to be arbitrary and can be considered as
The specific fuel consumption curves in Fig. 3 show an
obvious increase with increasing WCOME content, which
is a natural consequence of the decreasing calorific value of
the blends. However, the energy efficiency of the blends
relative to that of the diesel fuel, i.e., the energy utilization
factor, was a more reliable measure for comparison of the
combustion performance of the fuels. The energy
utilization factor (relative energy efficiency) is defined as the
overall efficiency of the blend fuel divided by the overall
efficiency of the diesel fuel (gei/ged). In Table 5, the energy
utilization factors of the blends are given at the defined
operational modes. The changes in the energy utilization
factor seem to be a function of load rather than engine
speed and WCOME content. Despite the exceptions at a
few points, it can generally be concluded that the energy
utilization factor decreased with increasing load, as was
One of the most interesting results was that the
utilization factor decreased from B10 to B20, then began to
increase and reached the greatest value at B50. There were
almost no exceptions to this case at any speed–load
combination. In Table 5, the relative energy efficiencies (gei/
ged) of the blends are given at the defined operational
The test engine was tested under the steady-state 8-mode
ISO 8178 test cycle. Emission levels at various engine speeds–loads and fuel blends were observed in terms of filter smoke number (FSN), CO, THC, NOx emissions and PM.
As shown in Fig. 4, the smoke emission increased with
increasing load and with decreasing speed (at the same
load). However, the positive effect of increasing WCOME
content on smoke emissions was more prominent at higher
loads and lower speeds.
Besides some contradicting conclusions reported in
(Jeong et al. 2006; De Almeida et al.
, we observed a slight decrease in NOx emissions
with increasing WCOME content for all loads and speeds,
as shown in Fig. 5. These results of this study were in good
agreement with the results reported by Yu¨ cesu and Ilkilic¸
Rakopoulos et al. (2006)
Fan et al. (2008)
similarly reported that the NOx emission of biodiesel
blends decreased when the percentage of biodiesel in the
blend increased. This decrease, despite the higher oxygen
content of blends with higher biodiesel content, might be
attributed to lower heat release and thus the temperature
rose due the lower calorific value of WCOME. But we need
to express the conclusion that there are many different
factors contradictorily affecting the NOx release with
increasing biodiesel content of the blends and their effects
are not definitely dominating so that it is possible to get
contradicting results in different studies depending on the
various experimental atmosphere and physical conditions
of test equipment, especially the combustion chamber of
For all WCOME contents, however, NOx emission
increased with increasing engine load up to 75%, but
thereafter remained nearly constant. This increase is
definitely a result of higher energy release, and thus,
temperature increases with increasing fuel/air ratio.
Plots of CO concentration (Fig. 6) showed that almost
regardless of load and speed, a minimum value of CO
appeared between B10 and B20 and there was a stable and
continuous increase above B20, except relatively
unstable appearance at 100% load. Another important result was
that in 50%–75% load band there was not a remarkable
change in CO emissions, while it increased considerably at
extremes of 10% and 100% (10% is not reported for
1800 rpm). All these results showed that increasing oxygen
content in the combustion atmosphere, either by an
increase in excess air coefficient (decreasing load) or
oxygen content of the fuel, results in a decrease in CO
concentration up to some extent, but later this trend is
variation in CO2 with that of CO for a specific fuel, we see
that in terms of combustion efficiency the 50%–75% load
band is the best, i.e., [CO]/[CO2] is the smallest, regardless
of the fuel type.
Hydrocarbon emission in internal combustion engines is a function of both oxygen available in the combustion
atmosphere and temperature; higher oxygen concentration
and temperature reduce the HC emissions. Figure 8 shows
that at 1800 rpm THC is the smallest with the B10 blend
and increases remarkably as the WCOME content
increases for a specific load. Since oxygen content increases with
increasing biodiesel content, that means this increase in HC
is not dominated by oxygen concentration but should be a
result of a remarkable decrease in temperature. This
conclusion confirms well that the decrease in NOx emissions
with increase in WCOME content, as shown in Fig. 5, can
be attributed to a decrease in combustion temperature at the
same load (but for all loads). But similar confirmation of
THC emissions with NOx emissions cannot be made for
the effect of increasing load. If THC emissions were
dominated purely by temperature, increase in NOx
emissions with increasing load in Fig. 5 should have resulted
with decreasing THC emissions. But this effect is not
distinguishable for 1800 rpm as shown in Fig. 8. This
means at 1800 rpm, a possible effect of temperature
increase in THC with increasing load, which should be to
decrease THC emissions, is compensated by decrease in
oxygen concentration with increasing load and there is
almost no significant change.
At 2800 rpm, an increase in CO concentration with
increasing WCOME content at all loads is not as sharp as it
is at 1800 rpm and it shows a clear turn after B40. Also,
unlike 1800 rpm results, there is a substantial decrease in
THC emissions with increasing load with some exceptions
between 10% and 50% after B20. This means the
thermochemical effect of an increase in engine speed is very
prominent on THC emissions. The combined effect of
increasing load and speed and hence increasing the
temperature results in a decrease in THC values.
Figure 9 shows the weighted cumulative 8-mode THC
and PM emission results for conventional diesel fuel and
various blends. Results showed a clear reduction in PM
emissions and an increase in THC emissions as the amount
cumulative NOx emissions did not show a meaningful
variation with content of the blend, while CO emissions
show a stable decrease with decreasing WCOME content
and stabilized almost at the same value between B10 and
Although WCOME is of a slightly different nature and of a
lower quality than various other vegetable oil methyl
esters, the results of the tests presented above show that it
exhibits very good performance. At a majority of the test
points, the relative energy efficiencies of the blends are
greater than unity. This research confirms the common
conclusion of biodiesel studies that, if WCOME content
cannot be kept high enough due to the shortage of sources,
then 10% is the best blend ratio in terms of energy
efficiency. Blends with WCOME content yielded much better
emission results than the diesel fuel, and this advantage
increased with increasing WCOME content in terms of
smoke and NOx emissions. However, only the B10 blend
carried the same advantage in terms of both CO and THC
emissions. So only the emission results with B10 were
better than those with diesel fuel almost under all
operational conditions. The blends with higher WCOME content
yielded worse or at best equal CO and THC emissions,
except for CO values at several points at full load.
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Agarwal AK , Das LM . Biodiesel development and characterization for use as a fuel in compression ignition engines . Trans ASME . 2001 ; 123 ( 2 ): 440 - 7 . https://doi.org/10.1115/1.1364522.
Altıparmak D , Keskin A , Koca A , Guru M. Alternative fuel properties of tall oil fatty acid methyl ester-diesel fuel blends . Biores Technol . 2007 ; 98 ( 2 ): 241 - 6 . https://doi.org/10.1016/j.biortech. 2006 . 01 .020.
Arslan R. Emission characteristics of a diesel engine using waste cooking oil as biodiesel fuel . Afr J Biotech . 2011 ; 10 ( 19 ): 3790 - 4 . https://doi.org/10.5897/AJB10.2202.
Canakci M , Van Gerpen JH. Comparison of engine performance and emissions for petroleum diesel fuel, yellow grease biodiesel and soybean oil biodiesel . Trans ASAE . 2003 ; 46 ( 4 ): 937 - 44 . https:// doi.org/10.13031/ 2013 .13948.
Cetinkaya M , Karaosmanoglu F . A new application area for used cooking oil originated biodiesel generators . Energy Fuels . 2005 ; 19 ( 2 ): 645 - 52 . https://doi.org/10.1021/ef049890k.
Cetinkaya M , Ulusoy Y , Tekin Y , Karaosmanog˘lu F. Engine and winter road test performances of used cooking oil originated biodiesel . Energy Convers Manag . 2005 ; 46 ( 7-8 ): 1279 - 91 . https://doi.org/10.1016/j.enconman. 2004 . 06 .022.
De Almeida SC , Belchior CR , Nascimento MV , dos SR Vieira L , Fleury G . Performance of a diesel generator fuelled with palm oil . Fuel . 2002 ; 81 ( 16 ): 2097 - 102 . https://doi.org/10.1016/S0016- 2361 ( 02 ) 00155 - 2 .
Dorado M , Ballesteros E , Arnal J , Gomez J , Lopez F . Exhaust emissions from a diesel engine fueled with transesterified waste olive oil . Fuel . 2003 ; 82 : 1311 - 5 . https://doi.org/10.1016/S0016- 2361 ( 03 ) 00034 - 6 .
Fan X , Wang X , Chen F , Geller DP , Wan JP. Engine performance test of cottonseed oil biodiesel . Open Fuels Energy Sci J . 2008 ; 1 : 40 - 5 .
Felizardo P , Correia MJN , Raposo I , Mendes JF , Berkemeier R , Bordado JM . Production of biodiesel from waste frying oils . Waste Manag . 2006 ; 26 ( 5 ): 487 - 94 . https://doi.org/10.1016/j.was man. 2005 . 02 .025.
Gopal KN , Pal A , Sharma S , Samanchi C , Sathyanarayanan K , Elango T. Investigation of emissions and combustion characteristics of a CI engine fueled with waste cooking oil methyl ester and diesel blends . Alex Eng J . 2014 ; 53 ( 2 ): 281 - 7 . https://doi.org/ 10.1016/j.aej. 2014 . 02 .003.
Hamasaki K , Kinoshita E , Tajima H , Takasaki K , Morita D. Combustion characteristics of diesel engines with waste vegetable oil methyl ester . In: The fifth international symposium on diagnostics and modeling of combustion in internal combustion engines . (COMODIA 2001 ). 2001 .
He C , Ge Y , Tan J , You K , Han X , Wang J . Characteristics of polycyclic aromatic hydrocarbons emissions of diesel engine fueled with biodiesel and diesel . Fuel . 2010 ; 89 : 2040 - 6 . https:// doi.org/10.1016/j.fuel. 2010 . 03 .014.
Jeong GT , Oh YT , Park DH . Emission profile of rapeseed methyl ester and its blend in a diesel engine . Appl Biochem Biotechnol . 2006 ; 129 ( 1-3 ): 165 - 78 .
Kaplan C , Arslan R , Surmen A . Performance characteristics of sunflower methyl esters as biodiesel . Energy Sources . 2006 ; 28 ( 8 ): 751 - 5 . https://doi.org/10.1080/009083190523415.
Lapuerta M , Agudelo JR , Rodriguez-Fernandez J . Diesel particulate emissions from used cooking oil biodiesel . Bioresour Technol . 2008 ; 99 : 731 - 40 . https://doi.org/10.1016/j.biortech. 2007 . 01 .033.
Lin Y , Wu YG , Chang CT . Combustion characteristics of waste oil produced biodiesel/diesel fuel blends . Fuel . 2007 ; 86 : 1772 - 80 . https://doi.org/10.1016/j.fuel. 2007 . 01 .012.
Mangesh GK , Dalai KA . Waste cooking oil-an economical source for biodiesel: a review . Ind Eng Chem Res . 2006 ; 45 ( 9 ): 2901 - 13 . https://doi.org/10.1021/ie0510526.
Mittelbach M , Tritthart P . Diesel fuel derived from vegetable oils, III. Emission tests using methyl esters of used frying oil . J Am Oil Chem Soc . 1988 ; 65 ( 7 ): 1185 - 7 .
Murillo S , Mıguez JL , Porteiro J , Granada E , Mora ´n JC. Performance and exhaust emissions in the use of biodiesel in outboard diesel engines . Fuel . 2007 ; 86 : 1765 - 71 . https://doi.org/10.1016/j.fuel. 2006 . 11 .031.
Nachid M , Ouanji F , Kacimi M , Liotta LF , Ziyad M. Biodiesel from Moroccan waste frying oil: the optimization of transesterification parameters impact of biodiesel on the petrodiesel lubricity and combustion . Int J Green Energy . 2015 ; 12 ( 8 ): 865 - 72 . https://doi. org/10.1080/15435075. 2014 . 888660 .
Payri F , Macian V , Arregle J , Tormos B , Martinez JL . Heavy-duty diesel engine performance and emission measurements for biodiesel (from cooking oil) blends used in the ECOBUS project . SAE paper , 2005 - 01 -2205. https://doi.org/10.4271/2005- 01-2205.
Rakopoulos CD , Antonopoulos KA , Rakopoulos DC , Hountalas DT , Giakoumis EG . Comparative performance and emissions study of a direct injection diesel engine using blends of diesel fuel with vegetable oils or bio-diesels of various origins . Energy Convers Manag . 2006 ; 47 ( 18 ): 3272 - 87 . https://doi.org/10.1016/j.encon man. 2006 . 01 .006.
Selvan T , Nagarajan G . Combustion and emission characteristics of a diesel engine fuelled with biodiesel having varying saturated fatty acid composition . Int J Green Energy . 2013 ; 10 : 952 - 65 . https://doi.org/10.1080/15435075. 2012 . 732157 .
Tat ME . Investigation of oxides of nitrogen emissions from biodieselfueled engines . Ph.D. thesis , Iowa State University. 2003 . http:// lib.dr.iastate.edu/rtd/922.
Ulusoy Y , Tekin Y , Cetinkaya M , Karaosmanog˘lu F. The engine tests of biodiesel from used frying oil . Energy Sources . 2004 ; 26 : 927 - 93 . https://doi.org/10.1080/00908310490473219.
Ulusoy Y , Arslan R , Kaplan C , Bolat A , Cedden H , Kaya A , Gunc G. An investigation of engine and fuel system performance in a diesel engine operating on waste cooking oil . Int J Green Energy . 2016 ; 13 ( 1 ): 40 - 4 . https://doi.org/10.1080/15435075. 2014 . 909360 .
Yu¨cesu HS , Ilkilic¸ C. Effect of cotton seed oil methyl ester on the performance and exhaust emission of a diesel engine . Energy Sources Part A . 2006 ; 28 ( 4 ): 389 - 98 . https://doi.org/10.1080/ 009083190927877.