- Email: [email protected]
Evaluation of methyl ester of microalgae oil as fuel in a diesel engine
Fuel 112 (2013) 203–207
Contents lists available at SciVerse ScienceDirect
Fuel journal homepage: www.elsevier.com/locate/fuel
Evaluation of methyl ester of microalgae oil as fuel in a diesel engine Gökhan Tüccar ⇑, Kadir Aydın Çukurova University, Department of Mechanical Engineering, 01330 Adana, Turkey
h i g h l i g h t s The manuscript presents availability of methyl ester of microalgae oil as fuel. Fuel properties of diesel fuel, microalgae biodiesel and its blends were determined. The engine performance tests were carried out. Microalgae biodiesel was identified as a promising alternative fuel.
a r t i c l e
i n f o
Article history: Received 22 July 2011 Received in revised form 29 April 2013 Accepted 1 May 2013 Available online 25 May 2013 Keywords: Microalgae Biodiesel Fuel properties Engine performance Exhaust emissions
a b s t r a c t Biodiesel can be obtained from various resources. However, the usage of vegetable oils as biodiesel source may impact global food market. Therefore, scientists focus on searching new biodiesel sources which are non-edible and easy to obtain. Microalgae have gained much attention recently due to their high growing rates and high oil contents. The objective of this study is to identify availability of microalgae biodiesel in diesel engines as alternative fuel. Microalgae biodiesel was blended with diesel fuel with the volumetric ratio of 5%, 10%, 20% and 50%. Fuel properties of blends and pure microalgae biodiesel were found out and the performance characteristics and exhaust emissions of the engine fueled with blends were analyzed. The results showed that, although microalgae biodiesel caused a slight reduction in torque and brake power values, the emission values of the engine using microalgae biodiesel were improved. Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction Due to their higher thermal efficiency and durability, compression ignition engines are more useful than spark ignition engines in field of heavy transportation and agriculture sectors. However, rapid increase in transportation fuel demand, environmental concerns and depletion of fossil fuels forces scientists to develop vegetable oil-based derivatives that approximate the properties and performance of petroleum-based diesel fuel. Vegetable oils can be directly used in diesel engines as they have a high cetane number and calorific value, which are very similar to those of diesel. However, the brake thermal efficiency of vegetable oils is inferior to that of diesel. This leads to problems of high smoke, HC and CO emissions, however transesterification of vegetable oils results in better performance and reduced emissions. Biodiesel has a more favorable combustion emission profile, such as low emissions of carbon monoxide, particulate matter and unburned hydrocarbons. Due to its relatively high flash point and good lubrication properties, biodiesel became popular as a new alternative energy source [1–6]. Combustion of biodiesel alone provides over a 90% reduction ⇑ Corresponding author. Tel.: +90 5052106272; fax: +90 3223386741. E-mail address: [email protected] (G. Tüccar). 0016-2361/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.fuel.2013.05.016
in total unburned hydrocarbons (HC), and a 75–90% reduction in polycyclic aromatic hydrocarbons (PAHs). Biodiesel further provides significant reductions in particulates and carbon monoxide than petroleum diesel fuel. Biodiesel provides a slight increase or decrease in nitrogen oxides depending on engine family and testing procedures [7]. Recent investigations have indicated that the use of biodiesel can decrease 90% of air toxicity and 95% of cancers compared to common diesel source [8]. Currently, vegetable oils, waste cooking oils and animal fats are generally used as biodiesel feed stock; however, the limited supply of these feed stocks limits the further expansion of biodiesel production and the price of these feedstocks accounts for 60–75 of the total cost of biodiesel [9]. In addition to, the usage of vegetable oils as biodiesel feedstock has generated a lot of controversy, mainly due to its impact on global food markets and on food security. Currently, about 84% the world biodiesel production is met by rapeseed oil. The remaining portion is from sunflower oil (13%), palm oil (1%) and soybean oil and others (2%). Thus, instead of arable land being utilized to grow food, it is being used to grow fuel, in other words; by converting edible oils into biodiesel, food resources are actually being converted into automotive fuels [10,11]. The use of edible vegetable oils might cause starvation especially in the developing countries [12]. These problems have raised doubts about the potential of biodiesel to
204
G. Tüccar, K. Aydın / Fuel 112 (2013) 203–207
replace fossil fuels and sustainability of its production [13,14]. To reduce the dependency on edible oil, alternative biofuel sources, such as non-food feedstocks, have been developed to produce biodiesel since it is necessary to find new feedstock suitable for biodiesel production, which does not drain on the edible vegetable oil supply [15,16]. Recently, non-edible vegetable oils have been considered as prospective feedstocks for biodiesel production. This is mainly attributed to their ability to overcome the problems of food versus fuel crisis related to edible oils [17]. Microalgae are microscopic photosynthetic organisms that are found in both marine and freshwater environments [18]. Microalgae are considered as a second generation feedstock for production of biofuels since they have ability to synthesize high amount of lipids [19,20]. In addition to, biodiesel could be produced from various species of microalgae [21]. Two biggest advantages of microalgae are their fast growing ability and their high oil contents. Microalgae which can grow faster than terrestrial crops have doubling times down to 3.5 h during their exponential growth phase. Oil content in microalgae can exceed 80% by weight of dry biomass; however, oil levels of 20–50% are quite common [22]. Microalgae require much less land area than other biodiesel feed stocks of agricultural origin, up to 49 or 132 times less when compared to rapeseed or soybean crops [23]. A lot of researches have been conducted about usage of different oils in existing diesel engines as fuel [24–32]. However, most of these oils are edible. The emphasis of the present work is to experimentally evaluate the possibilities of using biodiesel developed from one of the most important non-edible resources: microalgae. Therefore, the objective of this study was to identify availability of microalgae biodiesel in diesel engines. Fuel properties of microalgae biodiesel and its blends were determined and the performance, emission and combustion characteristics of biofuel blends were evaluated. 2. Materials and methods 2.1. Biodiesel production Microalgae oil used in biodiesel production was purchased from Soley Biotechnology Institute. During the microalgae biodiesel production, the necessary amount of catalyst (NaOH) for the transesterification reaction (0.4% by weight of the oil) was dissolved in methanol and added to the reactor after heating the microalgae oil to 65 °C; the reaction was performed at 60–61 °C and the mixture was stirred by the help of a magnetic stirrer at about 600 rpm during 1 h. After completion of the transesterification reaction, the mixture was cooled to room temperature and then transferred to a separatory funnel and separation of the ester and glycerin phases was performed by letting them stand for 8 h in the separatory funnel. The crude ester phase was washed 3 times with hot water at 1/ 5 water to ester phase ratio. After washing process, the mixture was waited in seperatory funnel during 30 min and by this way water is separated from methyl ester. Since purity level has strong effects on fuel properties, in order to provide water content to be less than 0.1, drying process was conducted by heating the biodiesel to 105 °C during 1 h until bright color occurred. Finally, filtering process was done in order to ensure that the end product is of excellent quality. Two batches of transesterification reaction were conducted. Therefore, two number of fuel samples were prepared in order to see the difference from batch to batch. 2.2. Property analysis In this study, mixtures consisting of methyl ester produced from microalgae oil and diesel fuel were used as alternative fuel.
100% diesel fuel was also used as reference. MB (microalgae biodiesel) fuel and diesel fuel were mixed at the volumetric ratios of 5%, 10%, 20% and 50%. Mixtures were prepared just before the tests. Important physical fuel properties of diesel fuel, microalgae biodiesel and the mixtures were determined. The tests were performed three times, and averages of three results were taken for both fuel samples obtained from separate batches of transesterification reaction. The maximum coefficients of variation between the results were about 0.4% and 0.7% for three experiments and for two separate fuel samples, respectively. Therefore, the differences between results obtained from three experiments were insignificant for two separate fuel samples. 2.3. Experimental set-up In this study, experiments were conducted on a four stroke, four cylinder diesel engine. Specifications and the schematic diagram of the engine are presented in Table 1 and Fig. 1, respectively. This engine was coupled to a hydraulic dynamometer which has torque range of 0–1700 N m and speed range of 0–7500 rpm to measure engine torque. Before starting to the experiment, the engine was operated with the new fuel for sufficient time to clean out the remaining fuel from the previous experiment. Engine performance values such as torque and specific fuel consumption were read by the help of a computer program of dynamometer control unit which can take values in two second time intervals and exhaust emissions such as CO and NOX were obtained by the help of another computer program. 3. Results and discussion 3.1. Fuel properties The measured physical fuel properties of microalgae oil, and methyl ester of microalgae oil are compared with those of diesel fuel and given in Table 2. The measured physical properties of microalgae biodiesel like density, viscosity, pour point and heating value are comparable with those of diesel fuel. It can also be observed from the Table 2 that except its low cetane number, all other measured properties of microalgae biodiesel are within the European Biodiesel Standard (EN 14214). However, low cetane number of microalgae can be compensated by mixing it with diesel fuel, as it can be seen from the Table 2, cetane numbers of all blends meet EN 14214 Standard. 3.2. Engine performance 3.2.1. Brake power and torque output Fig. 2 shows the variation of brake power according to different engine speed values. As it can easily be seen in Fig. 2, power of the engine was reduced with increasing percentage of microalgae biodiesel in the blends (there is an average of about 6% reduction for B100 compared to diesel fuel). The reason of this reduction can be because of incomplete combustion of the fuel due to low cetane
Table 1 Technical specifications of the test engine. Brand
Mitsubishi canter
Model Type Displacement Bore Stroke Power Torque
4D34-2A Direct injection diesel with glow plug 3907 cc 104 mm 115 mm 89 kW @ 3200 rpm 295 N m @ 1800 rpm
205
G. Tüccar, K. Aydın / Fuel 112 (2013) 203–207 65 60
Brake Power (kW)
55 50 45 40 Diesel B5 B10 B20 B50 B100
35 30 25 1000
Fig. 1. Layout of experimental setup.
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
Engine Speed (rpm) Fig. 2. Brake power output versus engine speed for the test fuels.
number of microalgae biodiesel. For all fuels the maximum power output was obtained at about 2400 rpm. The torque output of test fuels is shown in Fig. 3. Torque output values reduced with the increasing concentration of microalgae biodiesel in the blends (there is an average of 5.3% reduction for B100 compared to diesel fuel). The value of the power reduction amount is higher at high engine speeds (about 13% at 2800 rpm) than that of at lower engine speeds (about 3.8% at 1200 rpm). The maximum torque values for all fuels were obtained at an engine speed of 1400–1600 rpm. The torque output reduced through higher engine speeds. There are also publications reporting decreases in brake power or torque when using biodiesel [33–37].
280 260
Torque (Nm)
240
3.2.2. Carbon monoxide emission CO emission is due to incomplete combustion and depends on many parameters such as engine temperature, and air/fuel ratio. [38]. Generally a reduction in CO emission values occur when biodiesel is used instead of diesel fuel since biodiesel contains additional oxygen and this additional oxygen enhances complete combustion [39]. The variation of CO emissions for different fuels is compared in Fig. 4. It can be observed from the Fig. 4 that there is an average of 9.4% reduction in CO emission values when microalgae biodiesel was used instead of diesel fuel. With regard to most of the other authors, also a decrease in CO emissions occurs when substituting diesel fuel with biodiesel [40–41]. These lower CO emissions of biodiesel may be due to its high oxygen content as compared to diesel. The extra oxygen molecule present in the biodiesel chain might have been used to convert some of the CO into CO2 during combustion, thus CO formation is reduced [42]. For all of the test fuels, CO emissions increased with increasing engine speed. This trend may occurred due to injected fuel amount which increases parallel to increasing engine load.
220 200
160
Diesel B5 B10 B20
140
B50 B100
180
120 1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
Engine Speed (rpm) Fig. 3. Torque output versus engine speed for the test fuels.
engine. NOX formation is primarily a function of pressure, reaction temperature, residence time of combustion products, premixed portion of combustion, availability of excess oxygen, ignition delay period, heat removal rate and the operational parameters of the engine [43]. The variation of NOX emission values for different test fuels is presented in Fig. 5. On an average, 9.3% reduction in NOX was obtained for biodiesel and as compared to diesel. Fig. 5 shows that high oxygen content does not lead to increases in NOX formation. Reduction in NOX value can be due to less air drawn into the cylinder during the combustion of microalgae biodiesel. Heat release rate of microalgae biodiesel is also lower due to its lower heating value which will lead to lower peak temperatures. Nitrogen oxides formation strongly depends on peak temperature, which explains the observed phenomenon.
3.2.3. Nitric oxides emission Another significant diesel emissions are nitric oxides. There are many factors that have an impact on NOX formation from diesel Table 2 Properties of test fuels. Properties
Diesel fuel
B5
B10
B25
B50
MB
European biodiesel standard (EN 14214)
Density (kg/L) Cetane number Viscosity (at 40 °C) (mm2/s) Pour point (°C)
0.833 56.46 2.37 10
0.835 56.04 2.62 12
0.838 55.08 2.84 12
0.843 54.19 2.88 12
0.859 51.55 3.51 12
0.886 48.31 4.47 12
Flash point (°C) Heating value (kJ/kg)
58.5 45,254
68.5 44,674
78.5 44,107
78.5 43,5676
78.5 42,890
165.5 40,045
0.860–0.900 >51 3.5–5.0 Summer <4.0 Winter < 1.0 >120 –
206
G. Tüccar, K. Aydın / Fuel 112 (2013) 203–207
of oil would be something like $1.40 and $1.81 for photobioreactors and raceways, respectively [22]. However, for microalgal biodiesel to be competitive with petrodiesel, algal oil price should be less than $0.48/L [58].
400
CO (ppm)
350
4. Conclusions
300
250
Eurodiesel MB
200
150 1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
Engine Speed (rpm) Fig. 4. Comparison of CO values for diesel fuel and microalgae biodiesel.
Fuel properties of diesel fuel, microalgae biodiesel and its blends were determined. It is found that except its low cetane number, microalgae biodiesel satisfies European Biodiesel Standards (EN 14214), however; its low cetane number can be compensated by mixing microalgae biodiesel with diesel fuel. The power and torque output of engine fueled with microalgae biodiesel decreased when microalgae biodiesel was used. CO and NOX emission values improved with microalgae biodiesel usage. Finally, it can be concluded that, microalgae biodiesel can be used as alternative fuel in conventional diesel engines, by this way exhaust emission values can be improved.
1300
References 1200
NOx (ppm)
1100
1000
900
800
Eurodiesel MB
700 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000
Engine Speed (rpm) Fig. 5. Comparison of NOx values for diesel fuel and microalgae biodiesel.
Although most of the literature shows a slight increase in NOX emissions when using biodiesel fuel [44–52], some works showing different effects have been found [53]. Some researchers also reported lower NOX emissions with biodiesel [54–56]. 3.3. Cost analysis of microalgae biodiesel Cost analysis is needed to evaluate the feasibility and profitability of algae biodiesel and to determine if it is competitive enough to be commercialized. The process of making biodiesel fuel from microalgae involves several steps: growing algae in engineered ponds (growth), harvesting the biomass in settling ponds (harvest), extracting the algal oils from the biomass (extraction), and converting the algal oil into biodiesel (conversation). The first three sub-processes are performed at an aquatic farm using agricultural engineering principles. Conversion of algal oil to biodiesel is generally accomplished in a chemical plant using a simple process to reduce the size and viscosity of the algal oil molecular compounds. [57]. Harvesting costs contribute 20–30% to the total cost of algal cultivation with majority of the cost contribute to cultivation expenses [58]. The estimated cost of producing a kilogram of microalgal biomass is $2.95 and $3.80 for photobioreactors and raceways, respectively for the facilities. If the annual biomass production capacity is increased to 10,000 t, the cost of production per kilogram reduces to roughly $0.47 and $0.60 for photobioreactors and raceways, respectively. Assuming that the biomass contains 30% oil by weight, the cost of biomass for providing a liter
[1] Devan PK, Mahalakshmi NV. Utilization of unattended methyl ester of paradise oil as fuel in diesel engine. Fuel 2009;88:1828–33. [2] Enweremadu CC, Rutto HL. Combustion, emission and engine performance characteristics of used cooking oil biodiesel – a review. Renew Sust Energy Rev 2010;14:2863–73. [3] Lapuerta M, Armas O, Ballesteros R, Fernandez J. Diesel emissions from biofuels derived from Spanish potential vegetable oils. Fuel 2005;84(6):773–80. [4] Devan PK, Mahalakshmi NV. A study of the performance, emission and combustion characteristics of a compression ignition engine using methyl ester of paradise oil–eucalyptus oil blends. Appl Energy 2009;86:675–80. [5] Knothe G, Gerpen JV, Krahl J. The biodiesel handbook. Illinois: AOCS Press; 2004. [6] Hu J, Du Z, Li C, Min E. Study on the lubrication properties of biodiesel as fuel lubricity enhancers. Fuel 2005;84:1601–6. [7] Demirbas A. Importance of biodiesel as transportation fuel. Energy Policy 2007;35:4661–70. [8] Sharp CA. Emissions and lubricity evaluation of rapeseed derived biodiesel fuels. Final Report for Montana Department of Environmental Quality. Southwest Research Institute; 1996. [9] Canakci M, Sanli H. Biodiesel production from various feedstock’s and their effects on the fuel properties. J Ind Microbiol Biotechnol 2008;35:431–41. [10] Gui MM, Lee KT, Bhatia S. Feasibility of edible oil vs. non-edible oil vs. waste edible oil as biodiesel feedstock. Fuel 2009;33:1646–53. [11] Kansedo J, Lee KT, Bhatia S. Cerbera odollam (sea mango) oil as a promising non-edible feedstock for biodiesel production. Fuel 2009;88:1148–50. [12] Atabani AE, Silitonga AS, Ong HC, Mahlia TMI, Masjuki HH, Irfan Anjum Badruddin, et al. Non-edible vegetable oils: a critical evaluation of oil extraction,fatty acid compositions, biodiesel production, characteristics,engine performance and emissions production. Renew Sust Energy Rev 2013;18:211–45. [13] Brennan L, Owende P. Biofuels from microalgae – a review of technologies for production, processing, and extractions of biofuels and co-products. Renew Sust Energy Rev 2010;14:557–77. [14] Ahmad AL, Mat Yasin NH, Derek CJC, Lim JK. Microalgae as a sustainable energy source for biodiesel production: a review. Renew Sust Energy Rev 2011;15:584–93. [15] Atabani AE, Badruddin IA, Masjuki HH, Chong WT. Investigation of physical and chemical properties of potential edible and non-edible feedstocks for biodiesel production, a comparative analysis. Renew Sust Energy Rev 2013;21:749–55. [16] Huang G, Chen F, Wei D, Zhang X, Chen G. Biodiesel production by microalgal biotechnology. Appl Energy 2010;87:38–46. [17] Umdu ES, Tuncer M, Seker E. Transesterification of nannochloropsis oculata microalga’s lipid to biodiesel on Al2O3 supported CaO and MgO catalysts. Bioresour Technol 2009;100:2828–31. [18] Demirbas A. Use of algae as biofuel sources. Energy Conv Manag 2010;51:2738–49. [19] Khan SA, Rashmi Hussain MZ, Prasad S, Banerjee UC. Prospects of biodiesel production from microalgae in India. Renew Sust Energy Rev 2009;13:2361–72. [20] Chisti Y. Biodiesel from microalgae beats bioethanol. Trends Biotechnol 2008;26:126–31. [21] Elshahed MS. Microbiological aspects of biofuel production: current status and future directions. J Adv Res 2010;1:103–11. [22] Chisti Y. Biodiesel from microalgae. Biotechnol Adv 2007;25:294–306. [23] Mata TM, Anto´nio AM, Nidia SC. Microalgae for biodiesel production and other applications: a review. Renew Sust Energy Rev 2010;14:217–32.
G. Tüccar, K. Aydın / Fuel 112 (2013) 203–207 [24] Banapurmath NR, Tewari PG, Hosmath RS. Performance and emission characteristics of a DI compression ignition engine operated on Honge, Jatropha and sesame oil methyl esters. Renew Energy 2008;33(9):1982–8. [25] Panwar NL, Shrirame HY, Rathore NS, Jindal S, Kurchania AK. Performance evaluation of a diesel engine fueled with methyl ester of castor seed oil. Appl Therm Eng 2010;30(2–3):245–9. [26] Puhan S, Jegan R, Balasubbramanian K, Nagarajan G. Effect of injection pressure on performance, emission and combustion characteristics of high linolenic linseed oil methyl ester in a DI diesel engine. Renew Energy 2009;34(5):1227–33. [27] Puhan S, Vedaraman N, Ram BVB, Sankarnarayanan G, Jeychandran K. Mahua oil (Madhuca Indica seed oil) methyl ester as biodiesel-preparation and emission characterstics. Biomass Bioenergy 2005;28(1):87–93. [28] Raheman H, Phadatare G. Diesel engine emissions and performance from blends of karanja methyl ester and diesel. Biomass Bioenergy 2004;27(4):393–7. [29] Sahoo PK, Das LM. Combustion analysis of Jatropha, Karanja and Polanga based biodiesel as fuel in a diesel engine. Fuel 2009;88(6):994–9. [30] Sahoo PK, Das LM, Babu MKG, Naik SN. Biodiesel development from high acid value polanga seed oil and performance evaluation in a CI engine. Fuel 2007;86(3):448–54. [31] Srivastava PK, Verma M. Methyl ester of karanja oil as an alternative renewable source energy. Fuel 2008;87(8–9):1673–7. [32] Serin H, Ozcanli M, Gokce MK, Tuccar G. Biodiesel production from tea seed (camellia sinensis) oil and its blends with diesel fuel. Int J Green Energy 2013;10(4):370–7. [33] Kaplan C, Arslan R, Surmen A. Performance characteristics of sunflower methyl esters as biodiesel. Energy Sources 2006;Part A 28:751–5. [34] Cetinkaya M, Ulusay Y, Tekin Y, Karaosmanoglu F. Engine and winter road test performances of used cooking oil originated biodiesel. Energy Convers Manage 2005;46:1279–91. [35] Lin YC, Lee WJ, Wu TS, Wang CT. Comparison of PAH and regulated harmful matter emissions from biodiesel blends and paraffinic fuel blends on engine accumulated mileage test. Fuel 2006;85:2516–23. [36] Carraretto C, Macor A, Mirandola A, Stoppato A, Tonon S. Biodiesel as alternative fuel: experimental analysis and energetic evaluations. Energy 2004;29:2195–211. [37] Silva FN, Prata AS, Teixeira JR. Technical feasibility assessment of oleic sunflower methyl ester utilization in diesel bus engines. Energy Convers Manage 2003;44:2857–78. [38] Hazar H. Cotton methyl ester usage in a diesel engine equipped with insulated combustion chamber. Appl Energy 2010;85:134–40. [39] Ozgur T, Tuccar G, Ozcanli M, Aydin K. Prediction of emissions of a diesel engine fueled with soybean biodiesel using artificial neural networks. Energy Edu Sci Technol 2011;Part A 27:301–12. [40] Pinto AC, Guarieiro LLN, Rezende JC, Ribeiro NM, Torres EA, Lopes EA, et al. Biodiesel: an overview. J Braz Chem Soc 2005;16(6B):1313–30.
207
[41] Shi X, Yu Y, He H, Shuai S, Wang J, Li R. Emission characteristics using methyl soyate–ethanol–diesel fuel blends on a diesel engine. Fuel 2005;84: 1543–9. [42] Godiganur S, Suryanarayana Murthy CH, Reddy RP. a6BTA 5.9 G2–1 Cummins engine performance and emission tests using methyl ester mahua (Madhuca indica) oil/diesel blends. Renew Energy 2009;34(10):2172–7. [43] Varatharajana K, Cheralathanb M. Influence of fuel properties and composition on NOx emissions from biodiesel powered diesel engines: a review. Renew Sust Energy Rev 2012;16:3702–10. [44] Zhu L, Zhang W, Liu W, Huang Z. Experimental study on particulate and NOx emissions of a diesel engine fueled with ultra low sulfur diesel, RME-diesel blends and PME-diesel blends. Sci Total Environ 2010;408:1050–8. [45] Celikten I, Koca A, Arslan M. Comparison of performance and emissions of diesel fuel, rapeseed and soybean oil methyl esters injected at different pressures. Renew Energy 2010;35:814–20. [46] Ghai S, Das L, Babu G. Emissions and performance study with sunflower methyl ester as diesel engine fuel. J Eng Appl Sci 2008;3(5):75–80. [47] Sugozu I, Oner C, Altun S. The performance and emissions characteristics of a diesel engine fueled with biodiesel and diesel fuel. Int J Eng Res Dev 2010;2(1):50–3. [48] Nabi M, Rahman M, Akhter M. Biodiesel from cotton seed oil and its effect on engine performance and exhaust emissions. Appl Therm Eng 2009;29: 2265–70. [49] Tan P, Hu Z, Lou D, Li Z. Exhaust emissions from a light-duty diesel engine with Jatropha biodiesel fuel. Energy 2012;39:356–62. [50] Keskin A, Abdulkadir Y, Guru M, Altıparmak D. Usage of methyl ester of tall oil fatty acids and resinic acids as alternative diesel fuel. Energy Convers Manage 2010;51:2863–8. [51] Ragu R, Ramadoss G, Sairam K, Arulkumar A. Experimental investigation on the performance and emission characteristics of a DI diesel engine fueled with preheated rice bran oil. Eur J Sci Res 2011;64(3):400–14. [52] Nabi M, Hoque N. Biodiesel production from linseed oil and performance study of a diesel engine with diesel bio-diesel. JME 2008;39(1):40–4. [53] Lapuerta M, Armas O, Rodriguezfernandez J. Effect of biodiesel fuels on diesel engine emissions. Progr Energy Comb Sci 2008;34(2):198–223. [54] Ng J, Ng H, Gan S. Characterisation of engine-out responses from a lightduty diesel engine fueled with palm methyl ester. Appl Energy 2010;90: 58–67. [55] Rajit S, Mahabatra S, Kundu K. Performance and emission evaluation of a diesel engine fueled with methyl ester of neem oil and filtered neem oil. J Sci Ind Res 2010;69:62–6. [56] Rao P. Effect of properties of Karanja methyl ester on combustion and NOx emissions of a diesel engine. JPTAF 2011;2(5):63–75. [57] Gallagher BJ. The economics of producing biodiesel from algae. Renew Energy 2009;36(1):158–62. [58] Demirbas A, Demirbas MF. Importance of algae oil as a source of biodiesel. Energy Conv Manag 2011;52(1):163–70.
Contents lists available at SciVerse ScienceDirect
Fuel journal homepage: www.elsevier.com/locate/fuel
Evaluation of methyl ester of microalgae oil as fuel in a diesel engine Gökhan Tüccar ⇑, Kadir Aydın Çukurova University, Department of Mechanical Engineering, 01330 Adana, Turkey
h i g h l i g h t s The manuscript presents availability of methyl ester of microalgae oil as fuel. Fuel properties of diesel fuel, microalgae biodiesel and its blends were determined. The engine performance tests were carried out. Microalgae biodiesel was identified as a promising alternative fuel.
a r t i c l e
i n f o
Article history: Received 22 July 2011 Received in revised form 29 April 2013 Accepted 1 May 2013 Available online 25 May 2013 Keywords: Microalgae Biodiesel Fuel properties Engine performance Exhaust emissions
a b s t r a c t Biodiesel can be obtained from various resources. However, the usage of vegetable oils as biodiesel source may impact global food market. Therefore, scientists focus on searching new biodiesel sources which are non-edible and easy to obtain. Microalgae have gained much attention recently due to their high growing rates and high oil contents. The objective of this study is to identify availability of microalgae biodiesel in diesel engines as alternative fuel. Microalgae biodiesel was blended with diesel fuel with the volumetric ratio of 5%, 10%, 20% and 50%. Fuel properties of blends and pure microalgae biodiesel were found out and the performance characteristics and exhaust emissions of the engine fueled with blends were analyzed. The results showed that, although microalgae biodiesel caused a slight reduction in torque and brake power values, the emission values of the engine using microalgae biodiesel were improved. Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction Due to their higher thermal efficiency and durability, compression ignition engines are more useful than spark ignition engines in field of heavy transportation and agriculture sectors. However, rapid increase in transportation fuel demand, environmental concerns and depletion of fossil fuels forces scientists to develop vegetable oil-based derivatives that approximate the properties and performance of petroleum-based diesel fuel. Vegetable oils can be directly used in diesel engines as they have a high cetane number and calorific value, which are very similar to those of diesel. However, the brake thermal efficiency of vegetable oils is inferior to that of diesel. This leads to problems of high smoke, HC and CO emissions, however transesterification of vegetable oils results in better performance and reduced emissions. Biodiesel has a more favorable combustion emission profile, such as low emissions of carbon monoxide, particulate matter and unburned hydrocarbons. Due to its relatively high flash point and good lubrication properties, biodiesel became popular as a new alternative energy source [1–6]. Combustion of biodiesel alone provides over a 90% reduction ⇑ Corresponding author. Tel.: +90 5052106272; fax: +90 3223386741. E-mail address: [email protected] (G. Tüccar). 0016-2361/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.fuel.2013.05.016
in total unburned hydrocarbons (HC), and a 75–90% reduction in polycyclic aromatic hydrocarbons (PAHs). Biodiesel further provides significant reductions in particulates and carbon monoxide than petroleum diesel fuel. Biodiesel provides a slight increase or decrease in nitrogen oxides depending on engine family and testing procedures [7]. Recent investigations have indicated that the use of biodiesel can decrease 90% of air toxicity and 95% of cancers compared to common diesel source [8]. Currently, vegetable oils, waste cooking oils and animal fats are generally used as biodiesel feed stock; however, the limited supply of these feed stocks limits the further expansion of biodiesel production and the price of these feedstocks accounts for 60–75 of the total cost of biodiesel [9]. In addition to, the usage of vegetable oils as biodiesel feedstock has generated a lot of controversy, mainly due to its impact on global food markets and on food security. Currently, about 84% the world biodiesel production is met by rapeseed oil. The remaining portion is from sunflower oil (13%), palm oil (1%) and soybean oil and others (2%). Thus, instead of arable land being utilized to grow food, it is being used to grow fuel, in other words; by converting edible oils into biodiesel, food resources are actually being converted into automotive fuels [10,11]. The use of edible vegetable oils might cause starvation especially in the developing countries [12]. These problems have raised doubts about the potential of biodiesel to
204
G. Tüccar, K. Aydın / Fuel 112 (2013) 203–207
replace fossil fuels and sustainability of its production [13,14]. To reduce the dependency on edible oil, alternative biofuel sources, such as non-food feedstocks, have been developed to produce biodiesel since it is necessary to find new feedstock suitable for biodiesel production, which does not drain on the edible vegetable oil supply [15,16]. Recently, non-edible vegetable oils have been considered as prospective feedstocks for biodiesel production. This is mainly attributed to their ability to overcome the problems of food versus fuel crisis related to edible oils [17]. Microalgae are microscopic photosynthetic organisms that are found in both marine and freshwater environments [18]. Microalgae are considered as a second generation feedstock for production of biofuels since they have ability to synthesize high amount of lipids [19,20]. In addition to, biodiesel could be produced from various species of microalgae [21]. Two biggest advantages of microalgae are their fast growing ability and their high oil contents. Microalgae which can grow faster than terrestrial crops have doubling times down to 3.5 h during their exponential growth phase. Oil content in microalgae can exceed 80% by weight of dry biomass; however, oil levels of 20–50% are quite common [22]. Microalgae require much less land area than other biodiesel feed stocks of agricultural origin, up to 49 or 132 times less when compared to rapeseed or soybean crops [23]. A lot of researches have been conducted about usage of different oils in existing diesel engines as fuel [24–32]. However, most of these oils are edible. The emphasis of the present work is to experimentally evaluate the possibilities of using biodiesel developed from one of the most important non-edible resources: microalgae. Therefore, the objective of this study was to identify availability of microalgae biodiesel in diesel engines. Fuel properties of microalgae biodiesel and its blends were determined and the performance, emission and combustion characteristics of biofuel blends were evaluated. 2. Materials and methods 2.1. Biodiesel production Microalgae oil used in biodiesel production was purchased from Soley Biotechnology Institute. During the microalgae biodiesel production, the necessary amount of catalyst (NaOH) for the transesterification reaction (0.4% by weight of the oil) was dissolved in methanol and added to the reactor after heating the microalgae oil to 65 °C; the reaction was performed at 60–61 °C and the mixture was stirred by the help of a magnetic stirrer at about 600 rpm during 1 h. After completion of the transesterification reaction, the mixture was cooled to room temperature and then transferred to a separatory funnel and separation of the ester and glycerin phases was performed by letting them stand for 8 h in the separatory funnel. The crude ester phase was washed 3 times with hot water at 1/ 5 water to ester phase ratio. After washing process, the mixture was waited in seperatory funnel during 30 min and by this way water is separated from methyl ester. Since purity level has strong effects on fuel properties, in order to provide water content to be less than 0.1, drying process was conducted by heating the biodiesel to 105 °C during 1 h until bright color occurred. Finally, filtering process was done in order to ensure that the end product is of excellent quality. Two batches of transesterification reaction were conducted. Therefore, two number of fuel samples were prepared in order to see the difference from batch to batch. 2.2. Property analysis In this study, mixtures consisting of methyl ester produced from microalgae oil and diesel fuel were used as alternative fuel.
100% diesel fuel was also used as reference. MB (microalgae biodiesel) fuel and diesel fuel were mixed at the volumetric ratios of 5%, 10%, 20% and 50%. Mixtures were prepared just before the tests. Important physical fuel properties of diesel fuel, microalgae biodiesel and the mixtures were determined. The tests were performed three times, and averages of three results were taken for both fuel samples obtained from separate batches of transesterification reaction. The maximum coefficients of variation between the results were about 0.4% and 0.7% for three experiments and for two separate fuel samples, respectively. Therefore, the differences between results obtained from three experiments were insignificant for two separate fuel samples. 2.3. Experimental set-up In this study, experiments were conducted on a four stroke, four cylinder diesel engine. Specifications and the schematic diagram of the engine are presented in Table 1 and Fig. 1, respectively. This engine was coupled to a hydraulic dynamometer which has torque range of 0–1700 N m and speed range of 0–7500 rpm to measure engine torque. Before starting to the experiment, the engine was operated with the new fuel for sufficient time to clean out the remaining fuel from the previous experiment. Engine performance values such as torque and specific fuel consumption were read by the help of a computer program of dynamometer control unit which can take values in two second time intervals and exhaust emissions such as CO and NOX were obtained by the help of another computer program. 3. Results and discussion 3.1. Fuel properties The measured physical fuel properties of microalgae oil, and methyl ester of microalgae oil are compared with those of diesel fuel and given in Table 2. The measured physical properties of microalgae biodiesel like density, viscosity, pour point and heating value are comparable with those of diesel fuel. It can also be observed from the Table 2 that except its low cetane number, all other measured properties of microalgae biodiesel are within the European Biodiesel Standard (EN 14214). However, low cetane number of microalgae can be compensated by mixing it with diesel fuel, as it can be seen from the Table 2, cetane numbers of all blends meet EN 14214 Standard. 3.2. Engine performance 3.2.1. Brake power and torque output Fig. 2 shows the variation of brake power according to different engine speed values. As it can easily be seen in Fig. 2, power of the engine was reduced with increasing percentage of microalgae biodiesel in the blends (there is an average of about 6% reduction for B100 compared to diesel fuel). The reason of this reduction can be because of incomplete combustion of the fuel due to low cetane
Table 1 Technical specifications of the test engine. Brand
Mitsubishi canter
Model Type Displacement Bore Stroke Power Torque
4D34-2A Direct injection diesel with glow plug 3907 cc 104 mm 115 mm 89 kW @ 3200 rpm 295 N m @ 1800 rpm
205
G. Tüccar, K. Aydın / Fuel 112 (2013) 203–207 65 60
Brake Power (kW)
55 50 45 40 Diesel B5 B10 B20 B50 B100
35 30 25 1000
Fig. 1. Layout of experimental setup.
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
Engine Speed (rpm) Fig. 2. Brake power output versus engine speed for the test fuels.
number of microalgae biodiesel. For all fuels the maximum power output was obtained at about 2400 rpm. The torque output of test fuels is shown in Fig. 3. Torque output values reduced with the increasing concentration of microalgae biodiesel in the blends (there is an average of 5.3% reduction for B100 compared to diesel fuel). The value of the power reduction amount is higher at high engine speeds (about 13% at 2800 rpm) than that of at lower engine speeds (about 3.8% at 1200 rpm). The maximum torque values for all fuels were obtained at an engine speed of 1400–1600 rpm. The torque output reduced through higher engine speeds. There are also publications reporting decreases in brake power or torque when using biodiesel [33–37].
280 260
Torque (Nm)
240
3.2.2. Carbon monoxide emission CO emission is due to incomplete combustion and depends on many parameters such as engine temperature, and air/fuel ratio. [38]. Generally a reduction in CO emission values occur when biodiesel is used instead of diesel fuel since biodiesel contains additional oxygen and this additional oxygen enhances complete combustion [39]. The variation of CO emissions for different fuels is compared in Fig. 4. It can be observed from the Fig. 4 that there is an average of 9.4% reduction in CO emission values when microalgae biodiesel was used instead of diesel fuel. With regard to most of the other authors, also a decrease in CO emissions occurs when substituting diesel fuel with biodiesel [40–41]. These lower CO emissions of biodiesel may be due to its high oxygen content as compared to diesel. The extra oxygen molecule present in the biodiesel chain might have been used to convert some of the CO into CO2 during combustion, thus CO formation is reduced [42]. For all of the test fuels, CO emissions increased with increasing engine speed. This trend may occurred due to injected fuel amount which increases parallel to increasing engine load.
220 200
160
Diesel B5 B10 B20
140
B50 B100
180
120 1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
Engine Speed (rpm) Fig. 3. Torque output versus engine speed for the test fuels.
engine. NOX formation is primarily a function of pressure, reaction temperature, residence time of combustion products, premixed portion of combustion, availability of excess oxygen, ignition delay period, heat removal rate and the operational parameters of the engine [43]. The variation of NOX emission values for different test fuels is presented in Fig. 5. On an average, 9.3% reduction in NOX was obtained for biodiesel and as compared to diesel. Fig. 5 shows that high oxygen content does not lead to increases in NOX formation. Reduction in NOX value can be due to less air drawn into the cylinder during the combustion of microalgae biodiesel. Heat release rate of microalgae biodiesel is also lower due to its lower heating value which will lead to lower peak temperatures. Nitrogen oxides formation strongly depends on peak temperature, which explains the observed phenomenon.
3.2.3. Nitric oxides emission Another significant diesel emissions are nitric oxides. There are many factors that have an impact on NOX formation from diesel Table 2 Properties of test fuels. Properties
Diesel fuel
B5
B10
B25
B50
MB
European biodiesel standard (EN 14214)
Density (kg/L) Cetane number Viscosity (at 40 °C) (mm2/s) Pour point (°C)
0.833 56.46 2.37 10
0.835 56.04 2.62 12
0.838 55.08 2.84 12
0.843 54.19 2.88 12
0.859 51.55 3.51 12
0.886 48.31 4.47 12
Flash point (°C) Heating value (kJ/kg)
58.5 45,254
68.5 44,674
78.5 44,107
78.5 43,5676
78.5 42,890
165.5 40,045
0.860–0.900 >51 3.5–5.0 Summer <4.0 Winter < 1.0 >120 –
206
G. Tüccar, K. Aydın / Fuel 112 (2013) 203–207
of oil would be something like $1.40 and $1.81 for photobioreactors and raceways, respectively [22]. However, for microalgal biodiesel to be competitive with petrodiesel, algal oil price should be less than $0.48/L [58].
400
CO (ppm)
350
4. Conclusions
300
250
Eurodiesel MB
200
150 1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
Engine Speed (rpm) Fig. 4. Comparison of CO values for diesel fuel and microalgae biodiesel.
Fuel properties of diesel fuel, microalgae biodiesel and its blends were determined. It is found that except its low cetane number, microalgae biodiesel satisfies European Biodiesel Standards (EN 14214), however; its low cetane number can be compensated by mixing microalgae biodiesel with diesel fuel. The power and torque output of engine fueled with microalgae biodiesel decreased when microalgae biodiesel was used. CO and NOX emission values improved with microalgae biodiesel usage. Finally, it can be concluded that, microalgae biodiesel can be used as alternative fuel in conventional diesel engines, by this way exhaust emission values can be improved.
1300
References 1200
NOx (ppm)
1100
1000
900
800
Eurodiesel MB
700 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000
Engine Speed (rpm) Fig. 5. Comparison of NOx values for diesel fuel and microalgae biodiesel.
Although most of the literature shows a slight increase in NOX emissions when using biodiesel fuel [44–52], some works showing different effects have been found [53]. Some researchers also reported lower NOX emissions with biodiesel [54–56]. 3.3. Cost analysis of microalgae biodiesel Cost analysis is needed to evaluate the feasibility and profitability of algae biodiesel and to determine if it is competitive enough to be commercialized. The process of making biodiesel fuel from microalgae involves several steps: growing algae in engineered ponds (growth), harvesting the biomass in settling ponds (harvest), extracting the algal oils from the biomass (extraction), and converting the algal oil into biodiesel (conversation). The first three sub-processes are performed at an aquatic farm using agricultural engineering principles. Conversion of algal oil to biodiesel is generally accomplished in a chemical plant using a simple process to reduce the size and viscosity of the algal oil molecular compounds. [57]. Harvesting costs contribute 20–30% to the total cost of algal cultivation with majority of the cost contribute to cultivation expenses [58]. The estimated cost of producing a kilogram of microalgal biomass is $2.95 and $3.80 for photobioreactors and raceways, respectively for the facilities. If the annual biomass production capacity is increased to 10,000 t, the cost of production per kilogram reduces to roughly $0.47 and $0.60 for photobioreactors and raceways, respectively. Assuming that the biomass contains 30% oil by weight, the cost of biomass for providing a liter
[1] Devan PK, Mahalakshmi NV. Utilization of unattended methyl ester of paradise oil as fuel in diesel engine. Fuel 2009;88:1828–33. [2] Enweremadu CC, Rutto HL. Combustion, emission and engine performance characteristics of used cooking oil biodiesel – a review. Renew Sust Energy Rev 2010;14:2863–73. [3] Lapuerta M, Armas O, Ballesteros R, Fernandez J. Diesel emissions from biofuels derived from Spanish potential vegetable oils. Fuel 2005;84(6):773–80. [4] Devan PK, Mahalakshmi NV. A study of the performance, emission and combustion characteristics of a compression ignition engine using methyl ester of paradise oil–eucalyptus oil blends. Appl Energy 2009;86:675–80. [5] Knothe G, Gerpen JV, Krahl J. The biodiesel handbook. Illinois: AOCS Press; 2004. [6] Hu J, Du Z, Li C, Min E. Study on the lubrication properties of biodiesel as fuel lubricity enhancers. Fuel 2005;84:1601–6. [7] Demirbas A. Importance of biodiesel as transportation fuel. Energy Policy 2007;35:4661–70. [8] Sharp CA. Emissions and lubricity evaluation of rapeseed derived biodiesel fuels. Final Report for Montana Department of Environmental Quality. Southwest Research Institute; 1996. [9] Canakci M, Sanli H. Biodiesel production from various feedstock’s and their effects on the fuel properties. J Ind Microbiol Biotechnol 2008;35:431–41. [10] Gui MM, Lee KT, Bhatia S. Feasibility of edible oil vs. non-edible oil vs. waste edible oil as biodiesel feedstock. Fuel 2009;33:1646–53. [11] Kansedo J, Lee KT, Bhatia S. Cerbera odollam (sea mango) oil as a promising non-edible feedstock for biodiesel production. Fuel 2009;88:1148–50. [12] Atabani AE, Silitonga AS, Ong HC, Mahlia TMI, Masjuki HH, Irfan Anjum Badruddin, et al. Non-edible vegetable oils: a critical evaluation of oil extraction,fatty acid compositions, biodiesel production, characteristics,engine performance and emissions production. Renew Sust Energy Rev 2013;18:211–45. [13] Brennan L, Owende P. Biofuels from microalgae – a review of technologies for production, processing, and extractions of biofuels and co-products. Renew Sust Energy Rev 2010;14:557–77. [14] Ahmad AL, Mat Yasin NH, Derek CJC, Lim JK. Microalgae as a sustainable energy source for biodiesel production: a review. Renew Sust Energy Rev 2011;15:584–93. [15] Atabani AE, Badruddin IA, Masjuki HH, Chong WT. Investigation of physical and chemical properties of potential edible and non-edible feedstocks for biodiesel production, a comparative analysis. Renew Sust Energy Rev 2013;21:749–55. [16] Huang G, Chen F, Wei D, Zhang X, Chen G. Biodiesel production by microalgal biotechnology. Appl Energy 2010;87:38–46. [17] Umdu ES, Tuncer M, Seker E. Transesterification of nannochloropsis oculata microalga’s lipid to biodiesel on Al2O3 supported CaO and MgO catalysts. Bioresour Technol 2009;100:2828–31. [18] Demirbas A. Use of algae as biofuel sources. Energy Conv Manag 2010;51:2738–49. [19] Khan SA, Rashmi Hussain MZ, Prasad S, Banerjee UC. Prospects of biodiesel production from microalgae in India. Renew Sust Energy Rev 2009;13:2361–72. [20] Chisti Y. Biodiesel from microalgae beats bioethanol. Trends Biotechnol 2008;26:126–31. [21] Elshahed MS. Microbiological aspects of biofuel production: current status and future directions. J Adv Res 2010;1:103–11. [22] Chisti Y. Biodiesel from microalgae. Biotechnol Adv 2007;25:294–306. [23] Mata TM, Anto´nio AM, Nidia SC. Microalgae for biodiesel production and other applications: a review. Renew Sust Energy Rev 2010;14:217–32.
G. Tüccar, K. Aydın / Fuel 112 (2013) 203–207 [24] Banapurmath NR, Tewari PG, Hosmath RS. Performance and emission characteristics of a DI compression ignition engine operated on Honge, Jatropha and sesame oil methyl esters. Renew Energy 2008;33(9):1982–8. [25] Panwar NL, Shrirame HY, Rathore NS, Jindal S, Kurchania AK. Performance evaluation of a diesel engine fueled with methyl ester of castor seed oil. Appl Therm Eng 2010;30(2–3):245–9. [26] Puhan S, Jegan R, Balasubbramanian K, Nagarajan G. Effect of injection pressure on performance, emission and combustion characteristics of high linolenic linseed oil methyl ester in a DI diesel engine. Renew Energy 2009;34(5):1227–33. [27] Puhan S, Vedaraman N, Ram BVB, Sankarnarayanan G, Jeychandran K. Mahua oil (Madhuca Indica seed oil) methyl ester as biodiesel-preparation and emission characterstics. Biomass Bioenergy 2005;28(1):87–93. [28] Raheman H, Phadatare G. Diesel engine emissions and performance from blends of karanja methyl ester and diesel. Biomass Bioenergy 2004;27(4):393–7. [29] Sahoo PK, Das LM. Combustion analysis of Jatropha, Karanja and Polanga based biodiesel as fuel in a diesel engine. Fuel 2009;88(6):994–9. [30] Sahoo PK, Das LM, Babu MKG, Naik SN. Biodiesel development from high acid value polanga seed oil and performance evaluation in a CI engine. Fuel 2007;86(3):448–54. [31] Srivastava PK, Verma M. Methyl ester of karanja oil as an alternative renewable source energy. Fuel 2008;87(8–9):1673–7. [32] Serin H, Ozcanli M, Gokce MK, Tuccar G. Biodiesel production from tea seed (camellia sinensis) oil and its blends with diesel fuel. Int J Green Energy 2013;10(4):370–7. [33] Kaplan C, Arslan R, Surmen A. Performance characteristics of sunflower methyl esters as biodiesel. Energy Sources 2006;Part A 28:751–5. [34] Cetinkaya M, Ulusay Y, Tekin Y, Karaosmanoglu F. Engine and winter road test performances of used cooking oil originated biodiesel. Energy Convers Manage 2005;46:1279–91. [35] Lin YC, Lee WJ, Wu TS, Wang CT. Comparison of PAH and regulated harmful matter emissions from biodiesel blends and paraffinic fuel blends on engine accumulated mileage test. Fuel 2006;85:2516–23. [36] Carraretto C, Macor A, Mirandola A, Stoppato A, Tonon S. Biodiesel as alternative fuel: experimental analysis and energetic evaluations. Energy 2004;29:2195–211. [37] Silva FN, Prata AS, Teixeira JR. Technical feasibility assessment of oleic sunflower methyl ester utilization in diesel bus engines. Energy Convers Manage 2003;44:2857–78. [38] Hazar H. Cotton methyl ester usage in a diesel engine equipped with insulated combustion chamber. Appl Energy 2010;85:134–40. [39] Ozgur T, Tuccar G, Ozcanli M, Aydin K. Prediction of emissions of a diesel engine fueled with soybean biodiesel using artificial neural networks. Energy Edu Sci Technol 2011;Part A 27:301–12. [40] Pinto AC, Guarieiro LLN, Rezende JC, Ribeiro NM, Torres EA, Lopes EA, et al. Biodiesel: an overview. J Braz Chem Soc 2005;16(6B):1313–30.
207
[41] Shi X, Yu Y, He H, Shuai S, Wang J, Li R. Emission characteristics using methyl soyate–ethanol–diesel fuel blends on a diesel engine. Fuel 2005;84: 1543–9. [42] Godiganur S, Suryanarayana Murthy CH, Reddy RP. a6BTA 5.9 G2–1 Cummins engine performance and emission tests using methyl ester mahua (Madhuca indica) oil/diesel blends. Renew Energy 2009;34(10):2172–7. [43] Varatharajana K, Cheralathanb M. Influence of fuel properties and composition on NOx emissions from biodiesel powered diesel engines: a review. Renew Sust Energy Rev 2012;16:3702–10. [44] Zhu L, Zhang W, Liu W, Huang Z. Experimental study on particulate and NOx emissions of a diesel engine fueled with ultra low sulfur diesel, RME-diesel blends and PME-diesel blends. Sci Total Environ 2010;408:1050–8. [45] Celikten I, Koca A, Arslan M. Comparison of performance and emissions of diesel fuel, rapeseed and soybean oil methyl esters injected at different pressures. Renew Energy 2010;35:814–20. [46] Ghai S, Das L, Babu G. Emissions and performance study with sunflower methyl ester as diesel engine fuel. J Eng Appl Sci 2008;3(5):75–80. [47] Sugozu I, Oner C, Altun S. The performance and emissions characteristics of a diesel engine fueled with biodiesel and diesel fuel. Int J Eng Res Dev 2010;2(1):50–3. [48] Nabi M, Rahman M, Akhter M. Biodiesel from cotton seed oil and its effect on engine performance and exhaust emissions. Appl Therm Eng 2009;29: 2265–70. [49] Tan P, Hu Z, Lou D, Li Z. Exhaust emissions from a light-duty diesel engine with Jatropha biodiesel fuel. Energy 2012;39:356–62. [50] Keskin A, Abdulkadir Y, Guru M, Altıparmak D. Usage of methyl ester of tall oil fatty acids and resinic acids as alternative diesel fuel. Energy Convers Manage 2010;51:2863–8. [51] Ragu R, Ramadoss G, Sairam K, Arulkumar A. Experimental investigation on the performance and emission characteristics of a DI diesel engine fueled with preheated rice bran oil. Eur J Sci Res 2011;64(3):400–14. [52] Nabi M, Hoque N. Biodiesel production from linseed oil and performance study of a diesel engine with diesel bio-diesel. JME 2008;39(1):40–4. [53] Lapuerta M, Armas O, Rodriguezfernandez J. Effect of biodiesel fuels on diesel engine emissions. Progr Energy Comb Sci 2008;34(2):198–223. [54] Ng J, Ng H, Gan S. Characterisation of engine-out responses from a lightduty diesel engine fueled with palm methyl ester. Appl Energy 2010;90: 58–67. [55] Rajit S, Mahabatra S, Kundu K. Performance and emission evaluation of a diesel engine fueled with methyl ester of neem oil and filtered neem oil. J Sci Ind Res 2010;69:62–6. [56] Rao P. Effect of properties of Karanja methyl ester on combustion and NOx emissions of a diesel engine. JPTAF 2011;2(5):63–75. [57] Gallagher BJ. The economics of producing biodiesel from algae. Renew Energy 2009;36(1):158–62. [58] Demirbas A, Demirbas MF. Importance of algae oil as a source of biodiesel. Energy Conv Manag 2011;52(1):163–70.