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Experimental investigation on performance and exhaust emissions of castor oil biodiesel from a diesel engine a
a
a
M. H. Shojaeefard , M. M. Etgahni , F. Meisami & A. Barari
b
a
School of Automotive Engineering , Iran University of Science and Technology , Tehran , Iran b
Department of Civil Engineering , Aalborg University , Aalborg , Denmark
To cite this article: M. H. Shojaeefard , M. M. Etgahni , F. Meisami & A. Barari (2013) Experimental investigation on performance and exhaust emissions of castor oil biodiesel from a diesel engine, Environmental Technology, 34:13-14, 2019-2026, DOI: 10.1080/09593330.2013.777080 To link to this article: http://dx.doi.org/10.1080/09593330.2013.777080
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Environmental Technology, 2013 Vol. 34, Nos. 13–14, 2019–2026, http://dx.doi.org/10.1080/09593330.2013.777080
Experimental investigation on performance and exhaust emissions of castor oil biodiesel from a diesel engine M.H. Shojaeefarda,∗ , M.M. Etgahnia , F. Meisamia and A. Bararib,∗ a School
of Automotive Engineering, Iran University of Science and Technology, Tehran, Iran; b Department of Civil Engineering, Aalborg University, Aalborg, Denmark
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(Received 25 November 2012; final version received 5 February 2013 ) Biodiesel, produced from plant and animal oils, is an important alternative to fossil fuels because, apart from dwindling supply, the latter are a major source of air pollution. In this investigation, effects of castor oil biodiesel blends have been examined on diesel engine performance and emissions. After producing castor methyl ester by the transesterification method and measuring its characteristics, the experiments were performed on a four cylinder, turbocharged, direct injection, diesel engine. Engine performance (power, torque, brake specific fuel consumption and thermal efficiency) and exhaust emissions were analysed at various engine speeds. All the tests were done under 75% full load. Furthermore, the volumetric blending ratios of biodiesel with conventional diesel fuel were set at 5, 10, 15, 20 and 30%. The results indicate that lower blends of biodiesel provide acceptable engine performance and even improve it. Meanwhile, exhaust emissions are much decreased. Finally, a 15% blend of castor oil–biodiesel was picked as the optimized blend of biodiesel–diesel. It was found that lower blends of castor biodiesel are an acceptable fuel alternative for the engine. Keywords: biodiesel; castor oil; transesterfication; performance; emissions; diesel engine
Introduction Nowadays, most of our energy is provided by fossil fuels, which are considered non-renewable; that is, they are not replaced as soon as we use them. So, fossil sources are depleting [1]. Moreover, fossil fuel combustion is considered to be the main reason for air pollution. Since internal combustion engines are counted as the greatest application of fossil fuels, a large part of research has concentrated on them. [2,3] Although a considerable number of technologies were invented and implemented on engines, it seems that they will not meet more stringent pollution legislation in future. So, attention is being focused on fossil fuel alternatives. It looks as if renewable fuels are a proper choice for solving the above-mentioned problems. [4] Developing renewable energy has become an important part of worldwide energy policy to reduce gas emissions caused by fossil fuel. Alternative fuels such as alcohols, natural gas and biofuels are seen as an option to help the transport sector to decrease its dependency on oil and reduce its environmental impact. [5–8] Diesel engines are widely used in the automotive market for their better efficiency than their similarly rated spark ignition counterparts over the entire operating range. Due to the fact that biodiesels significantly reduce greenhouse gases and air pollution, scientists highly recommend biodiesels among other renewable fuels for ∗ Corresponding
diesel engines. [9] Furthermore, they may reduce fuel costs because they decrease some of the world’s fuel demands. [10] Biodiesel fuels can be extracted from vegetable oils, such as sesame, peanut, corn, canola, sunflower, soyabean, waste cooking oil [11–17] or animal fats such as fish oil. [18] Since biodiesels retain all the benefits of a diesel engine, there is no need to alter or change the basic engine when applying alternative fuels; therefore, they are suitable alternatives for diesel. However, regarding heating value and other fuel characteristics, some calibrations on injection advance and duration should be considered. [19] Rudolf Diesel, famous for the invention of the diesel engine, was the first to apply vegetable oil (peanut oil) to a diesel engine at the 1900 World Exhibition in Paris. [20] He also proclaimed that every diesel engine could be supplied with vegetable oil and it can vastly help in agriculture development. Nowadays, his prediction has come true and a lot of countries are moving toward producing and using biodiesels. [21] Castor oil is the proper choice for converting to biodiesel, because it is a non-edible oil and as its availability in many countries makes it accessible [22]. But unfortunately there are just a few studies relating to castor biodiesel properties and its application in the engine as an alternative fuel. This is mainly due to the presence of high amounts of ricinoleic acid in original castor oil structure. Ricinoleic acid is a major factor in some biodiesel
author. Email: [email protected]; [email protected]
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specifications that exceed standard limits. It is also called castor oil acid, which belongs to the unsaturated fatty acid family. It is a viscous yellow liquid, melting at 5.5◦ C, boiling at 245◦ C and insoluble in water but soluble in most organic solvents. [23] Castor oil consists of 80–90% ricinoleic acid, 3–6% linoleic acid, 2–4% oleic acid and 1–5% other saturated fatty acids. [24] As has already been mentioned, ricinoleic acid is highly viscous. Thus, a high proportion of castor oil biodiesel should not be used in engines. [25] It should be noted that due to the high viscosity of castor oil biodiesel, blends more than 30% cannot be used as fuel for diesel engines without modifications to the engine. [26] But the high viscosity of castor oil has better lubricity than other plant oils. [27] Berman et al. investigated the properties of neat castor biodiesel (B100) and its blend with diesel in 10% volume fraction (B10). They have indicated that only two properties of neat biodiesel exceed standard limits. These properties are kinematic viscosity (15.17 mm2 /s) and distillation temperature (398.70◦ C). While for B10, all characteristics of biodiesel are within the standard limit. Consequently, since diesel engines often are supplied with low proportions of biodiesel, it is reasonable to use castor oil biodiesel in engines. [28] It should be noted that crude oil can also be used directly in engine as fuel. Due to its lack of chemical esterification reactions, [29] this method has some benefits, such as easy transportation, higher heating values than biodiesel, saving time, energy and money. On the other hand, crude oil has more disadvantages, such as high viscosity, intensive corrosion, failure mechanisms of combustion duo to presence of matters in unrefined oil, rapid pollution of lubricant oil, low volatility and carbon sediment formation on engine components. Hence, the direct use of crude oil is not an appropriate method. Four possible solutions were proposed to change some oil properties in order to make it more suitable: transesterification; pyrolysis; dilution with conventional petroleumderived diesel fuel; micro-emulsification. [30] For this aim, the most common method is transesterification. [31] Some basic parameters that dominate transesterfication reaction are type and amount of catalyst, temperature and time of reaction, alcohol/oil molar ratio and mixture intensity, free fatty acids and water content. [32] The effects of these parameters have been investigated on castor oil transesterfication reaction. There are four kinds of catalysts (NaOCH3 , NaOH, KOCH3 and KOH) and it was found that using KOH results in maximum biodiesel yield. [33] In another study, the best reaction condition for castor oil transesterfication was obtained by 6:1 alcohol/oil molar ratio and 0.5% catalyst weight. [34] Numerous studies have been performed on the effect of various biodiesels on engine performance and emissions. While castor oil feasibility as a biodiesel has been known, a few studies have been carried out about the effects of castor oil biodiesel on engine characteristics. Panwar et al. evaluated the performance of a diesel engine
fuelled with castor oil methyl ester. They kept the engine speed at 1500 rpm and tried different loads. It was revealed that the lower blends of biodiesel improved engine performance and, finally, B10 was chosen as the optimum biodiesel fraction. [35] Valente et al. examined the impacts on fuel consumption and exhaust emissions of a diesel power generator operating with castor oil biodiesel. In their experimental study, fuel blends containing 5, 20 and 35% of castor oil biodiesel in diesel oil were tested and the engine load was varied from 9.6 to 35.7 kW. The results demonstrated that optimization of fuel injection system is required for proper engine operation with biodiesel. [36] In the present study, castor oil was converted to castor oil biodiesel by the transesterfication method and its properties were measured and compared with the ASTM biodiesel standard. Performance and exhaust emission characteristics of the diesel engine were tested and analysed under different speeds and various biodiesel blends. Castor oil transesterfication The presence of water in castor oil reduces the efficiency of biodiesel production and in some cases may result in transesterfication reaction failure. [37] For that reason, first, castor oil was heated to 70◦ C and kept for 30 minutes, then cooled at room temperature for 24 hours. Water was then removed through a drain valve, which had been embedded at the bottom. In the transesterification approach, potassium hydroxide (KOH) was used as a catalyst and because KOH naturally is in solid form, KOH tablets should be dissolved in alcohol to have a more effective reaction. The alcohol type that was chosen to be employed as a solvent was methanol (CH3 OH), due to its lower cost. KOH and methanol should possess a high degree of purity. If there is some water in methanol, the transesterfication reaction will not be done completely and ester production efficiency will reduce. Dissolving KOH in methanol is an exothermic reaction, which causes extreme methanol evaporation. A magnetic stirrer was used to enhance the efficiency of the solution and to prevent excessive methanol evaporation. KOH was dissolved (by 1% oil weight) in methanol. The solution was then mixed with castor oil in 1:5 molar ratio. This solution was stirred with oil for 45 minutes at a temperature of 60◦ C. Water is more nucleophile than methanol, it attacks carbonyl groups of triglyceride and decomposes them, which produces fatty acid and glycerol. [38] The fatty acids react and produce soap, which reduces the methyl ester yield. On the other hand, the fatty acids soap tends to be solid at ambient temperatures and this tendency makes the mixture gelatinous and difficult to recycle. For risk elimination of reaction failure, adding excessive methanol is common. When the reaction is finished, this amount of methanol can be retrieved by heating. Since the excessive amount of methanol in laboratory scale is not considerable, this process was not performed. However, it should be considered for use on an industrial scale.
Environmental Technology Table 1.
Properties of castor oil methyl ester.
Parameter
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Acid number Oxidation stability Copper corrosion @100◦ C for 3 hours IBP@760 mmHg Distillation temp (90%) Cloud point Pour point Heat of combustion Density @20◦ C Kinematic viscosity @40◦ C Sulphated ash Flash point Carbon residue Phosphorous content Relative molecular mass Water content Cetane number
Unit
Test method
Result
ASTM limit
Mg KOH/gr min – ◦C ◦C ◦C ◦C MJ/kg g/mL mm2 /s Mass% ◦C Mass% Mg/kg gr/mol Mass% –
ASTM D664 ASTM D525 ASTM D130 ASTM D6352 ASTM D6352 ASTM D2500 ASTM D97 ASTM D240 ASTM D7042 ASTM D7042 ASTM D874 ASTM D92 ASTM D524
0.25 >480 1a 329 409 −21 −39 37.195 0.9278 19.268 0.01 193 0.039 3.8 334 0.32 49.1
Max 0.8(ASTM D664) Min 3 hours (EN 14112) Max 3a No Limit Max 360(ASTM D1160) No limit No limit No limit No limit 1.9-6 @40◦ C (ASTM D445) Max0.02(ASTM D874) Min 93(ASTM D93) Max 0.05(ASTM D4530) Max 0.001% (ASTM D4951) No limit Max 0.05%vol (ASTM D2709) Min 47 (ASTM D613)
When the transesterfication reaction was complete, the bottom layer of mixture contained glycerine, methanol and most of the KOH. Glycerine is denser than biodiesel and it leaves a deposit at the bottom of the container. Full glycerine deposition time lasted about a week. Note that approximately 90% of glycerine was separated in the first four hours. When the bottom layer of mixture was drained out, the upper layer, which contains biodiesel, methanol and traces of catalyst, was purified by washing four times with distilled warm water. Finally, for complete separation of water from the biodiesel, the solution was heated to 90◦ C for 30 minutes. Some of the neat biodiesel properties were determined in a modern laboratory by the Research Institute of Petroleum Industry. The properties are listed in Table 1. As shown in Table 1, several pure biodiesel properties, especially kinematic viscosity, are outside the standard range. But according to some researcher’s studies, the engine can be supplied with lower blend of castor methyl ester. [28] Fatty acid composition of castor methyl ester was measured in Chemistry and Chemical Engineering Research Center of Iran and this is shown in Table 2. According to Table 2, castor oil biodiesel has a high percentage of ricinoleic acid, which is an unsaturated 18 carbon fatty acid. As regards the existence of a hydroxyl group at the 12th carbon, it shows some unusual properties, such as high viscosity, which is due to hydrogen bonding in the hydroxyl group.
Experimental methodology The engine used for the study was an agricultural, fourcylinder, four-stroke, water-cooled, direct injection diesel engine. The main specifications of the engine are listed in Table 3.
Osmomat ASTM D7042 ASTM D613
Table 2.
Fatty acid composition of castor oil methyl ester.
Fatty acid
Structure
Fatty acid composition (%)
Ricinoleic acid Linoleic acid Oleic acid Stearic acid Palmitic acid Linolenic acid Eicosenoic acid Lignoceric acid Nervonic acid
18:1-OH 18:2 18:1 18:0 16:0 18:3 20:1 24:0 24:1
88.18 5.02 3.80 1.12 1.04 0.49 0.28 0.04 0.02
Table 3.
Technical specifications of the test engine.
Name Bore × Stroke Number of cylinders Volume capacity Cycle Aspiration Combustion system Injection timing Compression ration Max. power Fuel pump Governing Cooling Weight Length × Width × Height
MT4.244 100 mm × 127 mm 4 3.99 Lit 4 stroke Wastegated turbocharger Fast ram direct injection -8 bTDC 17.25:1 82 hp in 2000 rpm Bosch rotary with boost control Mechanical Water, belt driven water pump 265 Kg 678.7 mm × 655 mm × 748.5 mm
A 190 Kw eddy-current dynamometer was used in the experiments with digital data acquisition systems. Figure 1 depicts a schematic of the test set-up. Because of its agricultural application, the engine nominal speed range is less than other conventional engines. So, the range of test speeds was selected from 1200 to 2000 rpm.
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Figure 1.
M.H. Shojaeefard et al.
Schematic diagram of test set-up.
According to the original performance diagram, the two speeds of 1200 rpm (maximum torque) and 2000 rpm (maximum power) are critical and should be considered. Hence, the experiments were carried out with different engine speeds. Moreover, a tractor engine usually runs at a relatively high load (neither low load nor full load). So the 75% engine load was selected for the experiment. Because of the high viscosity of castor methyl ester, lower blends of biodiesel-diesel (0, 5, 10, 15, 20 and 30% of biodiesel) were used in the experiment. First, the engine was warmed up with pure diesel, until the cooling water temperature reached 80◦ C. Then, the engine was subjected to the abovementioned speeds and load. After the engine was stabilized, power, torque, brake specific fuel consumption (BSFC), thermal efficiency, exhaust gas temperature, nitrogen oxides (NOx ), hydrocarbon (HC), carbon monoxide (CO) and particle matter (PM) were measured. Result and discussions Engine performance Engine power and torque variations versus speed for various blends of biodiesel–diesel are shown in Figures 2 and 3. It is obvious from Figure 2 that engine power decreases with the increase of biodiesel content. This is primarily related to the lower heating value and higher viscosity of biodiesel blends. Note that, as it can be seen in Figure 2, the blend of B10 has roughly equal power and is even slightly more than pure diesel. Looking closer, the power of the B10 blend was observed to be higher by 0.3% than that of the diesel fuel. For B5, B15, B20 and B30 fuels, the engine power decreases by 1.94, 1.16, 4.46 and 8.05% respectively in comparison with diesel. Some reasons can be expressed regarding the power enhancement in B10 and slight reduction in B15. First, biodiesel contains a higher oxygen content than diesel (usually 10–12%), [39] which
Figure 2. Power variation for different biodiesel blends versus engine speed.
improves the combustion process, especially in the fuelrich zone. [40,41] Second, a higher biodiesel density causes more fuel mass flow rate in a specified volume. In B10 and even B15, some properties such as density, viscosity, injection specifications and oxygen content are optimized. This optimal condition causes no loss in torque and power. Another point that can be perceived from Figure 2 is that there is no significant difference between power of biodiesel blends at lower engine speed (especially at 1200 rpm). Also, with increasing engine speed, this difference gradually becomes greater. The main reason that justifies this behaviour is that at lower speeds the fuel-rich zones have enough time to burn fully. Figure 3 shows the variation of engine torque versus engine speed. The maximum torque occurs at 1200 rpm and
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Environmental Technology
Figure 3. Torque variation for different biodiesel blends versus engine speed.
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Figure 5. Thermal efficiency variation for different biodiesel blends versus engine speed.
So the heating value of various blends must be considered in BTE calculation. Diesel and biodiesel heating values are respectively 44,800 and 37,195 kJ/kg. As a simple method, a linear formula can be used for the calculation of heating values in various biodiesel–diesel blends. As can be seen in Figure 5, using biodiesel causes BTE reduction. The maximum reduction is about 7.5%, which occurs in B30. BTE quantity is related to engine power, fuel mass flow rate and heating value. When using biodiesel, the whole effect of these parameters causes BTE reduction.
Figure 4. Brake specific fuel consumption variation for different biodiesel blends versus engine speed.
decreases with speed increase. Similar to the power diagram, the torque of B15 blend is slightly more than diesel torque. For B5, B10, B20 and B30 fuels, the engine torque decreases by 1.38, 0.95, 2.44% and 5.11% respectively in comparison with diesel. It can be observed from Figure 4 that BSFC increases with increasing biodiesel content in blends. Because of the higher density of castor oil biodiesel, the engine is supplied by more fuel mass flow, which causes an increase in specific fuel consumption. On the other hand, the lower heating value of biodiesel forces the engine to burn more fuel to attain the same diesel engine power. [42] As shown in Figure 5, there is a direct relation between brake thermal efficiency (BTE) and engine power. Also it is affected inversely by fuel mass flow rate and heating value.
Exhaust emissions Exhaust gas temperature behaviour, which is shown in Figure 6, is so strange and interesting. At lower engine speeds (1200 rpm), due to high density and viscosity of biodiesel, which leads to longer spray penetration, the fuel cannot be atomized very well. [43] Poor atomization results in incomplete combustion and lower exhaust gas temperature. While at 1400 rpm, the afore-mentioned problem (long spray penetration), is almost solved. On the other hand, the engine is still working at a lower speed range, so biodiesel has enough time to burn completely. This condition can cause an exhaust gas temperature rise. At higher speeds, the lack of time causes the exhaust gas temperature drop. Various behaviours of biodiesel blends can be justified by a trade-off between fuel viscosity and oxygen content. More oxygen content leads to more complete combustion and thereby more exhaust gas temperature. Conversely, with increasing fuel viscosity, exhaust gas temperature will decrease. For example, in a B30 blend, the oxygen content factor overcomes the viscosity factor, which results in a higher exhaust gas temperature. For a B5 blend, lower viscosity results in better atomization and a higher exhaust
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Figure 6. Exhaust gas temperature variation for different biodiesel blends versus engine speed.
gas temperature. However, in B15, these two factors are involved in a special condition that leads to the lowest exhaust gas temperature. There is a direct relationship between NOx emission and exhaust gas temperature. It is expected that with increasing engine speed, NOx emission increases; Figure 7 shows behaviour to the contrary. It should be noted that NOx emission depends on many factors, such as, volumetric efficiency, combustion duration, fuel oxygen content, adiabatic flame temperature and spray characteristics. [44] An increase in engine speed leads to an increase in volumetric efficiency and mixture turbulence. This situation increases the air-fuel mixing rate and reduces ignition delay. Hence, the reaction time in each cycle decreases and the residence time of the gas temperature becomes shorter, which leads to lower NOx emission under higher engine speeds. [45] Because of a higher oxygen content in biodiesel, the NOx emission difference between various blends of biodiesel can be explained by an exhaust gas temperature diagram. All NOx emissions of biodiesel blended fuel are higher than that of pure diesel. Maximum increase in NOx emission occurs in a B30 biodiesel blend, which is 11.31% higher than that of diesel. Due to a low exhaust gas temperature in B15, it has the lowest NOx emission among other biodiesel blends and its NOx emission is just 1.45% higher than diesel NOx emission. As shown in Figure 8, CO emission decreases with increasing biodiesel content in blends. The maximum and minimum decrease in CO emission occurs in B30 and B5, which are about 37% and 3.5% respectively. The CO reduction in other fuel blends is spread between these values. The biodiesel effect is more dominant at lower speeds because, at lower speeds, the oxygen content that enters the engine is lower than that of higher speeds. Thus, the existent oxygen in biodiesel has an apparent effect on CO reduction.
Figure 7. NOx variation for different biodiesel blends versus engine speed.
Figure 8. CO variation for different biodiesel blends versus engine speed.
The HC emission behaviour, shown in Figure 9, has no specific trend in various biodiesel blends. But it can be observed from the diagram that HC is reduced by using biodiesel. HC reduction in B5, B10, B15, B20 and B30 is about 5.9, 20.9, 18.18, 0 and 19.31% respectively. The most likely reason for HC reduction is the presence of more oxygen in biodiesel, which leads to better combustion and HC reduction. The PM formation mechanism is almost similar to CO. As shown in Figure 10, biodiesel has a remarkable effect on PM reduction. The PM formation process mainly occurs in fuel-rich zones and high temperatures. Since biodiesel contains more oxygen than diesel, the fuel-rich zones reduce
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Environmental Technology
Figure 9. HC variation for different biodiesel blends versus engine speed.
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Due to the lower calorific value of castor oil biodiesel and higher viscosity in comparison with those of diesel fuel, engine power and torque slightly decrease by using the biodiesel. The power and torque reduction in B10 and B15 were not as large as other blends and, even in B15, it was observed that the torque was slightly more than diesel. This was primarily due to a higher biodiesel density and oxygen content. The BSFC values for all biodiesel blends were higher than diesel values. A lower heating value and higher density of biodiesel were declared as related parameters in regard to BSFC increase. The usage of castor oil biodiesel had positive effects on exhaust emissions. A decrease was detected in all emissions, except NOx . The NOx emission for all blends of biodiesel was more than diesel NOx emission. However, among biodiesel blends, B15 had the minimum NOx emission. The maximum decrease in CO, HC and PM emissions was respectively 37% in B30, 20.9% in B10 and 52% in B30. The reasons that B15 of castor oil biodiesel blend was selected as an optimum blend for this engine are small increase in torque, the lowest increase in NOx emission among other blends, admissible CO, HC and PM emissions. Acknowledgements The authors would like to acknowledge Iranian Fuel Conservation Company for supporting us in doing this research.
References
Figure 10. PM variation for different biodiesel blends versus engine speed.
and thereby PM emission decreases and, due to lower airfuel mixing, it is apparent in lower speeds. The maximum PM reduction is about 52%, which occurs in a B30 blend.
Conclusion In this study, biodiesel fuel was produced from castor seed oil by a transesterfication method. Its characteristics were measured and it was found that some of its properties, especially viscosity, were not in standard range. Diluting castor biodiesel with conventional petroleum diesel fuel is the logical solution. Hence, based on the above-mentioned reason, blends of up to 30% can be substituted as fuel for diesel engines without any modifications to the engine.
[1] Demirbas A. Biodiesels-a realistic fuel alternative for diesel engines. Springer-Verlag, London Limited; 2008. [2] Fan M, Vidic R, Dionysiou D, Ferrara R. Recent developments in CO2 emission control technology, SPECIAL ISSUE: recent developments in CO2 emission control technology. J Environ Eng. 2009;135:377–377. [3] Elbir T. Estimation of engine emissions from commercial aircraft at a midsized Turkish airport. J Environ Eng. 2008;134:210–215. [4] Dowaki K, Ohta T, Kasahara Y, Kameyama M, Sakawaki K, Mori S. An economic and energy analysis on bio-hydrogen fuel using a gasification process. Renew Energ. 2007;32: 80–94. [5] Arapatsakosa CI, Karkanis AN, Spare PD. Gas emissions and engine behavior when gasoline-alcohol mixtures are used. Environ Technol. 2003;24:1069–1077. [6] Schifter I, Díaz L, González U. Impact of reformulated ethanol-gasoline blends on high emitting vehicles. Environ Technol. 2013;34:911–922. [7] Zou L, Atkinson S. Characterising vehicle emissions from the burning of biodiesel made from vegetable oil. Environ Technol. 2003;24:1253–1260. [8] Nabi Md. N. and Hustad JE. Investigation of engine performance and emissions of a diesel engine with a blend of marine gas oil and synthetic diesel fuel. Environ Technol. 2012;33:9–15. [9] Brune D, Lundquist T, Benemann J. Microalgal biomass for greenhouse gas reductions: potential for replacement of fossil fuels and animal feeds. J Environ Eng. 2009;135: 1136–1144.
Downloaded by [Colorado State University] at 18:34 31 October 2013
2026
M.H. Shojaeefard et al.
[10] Safieddin Ardebili M, Ghobadian B, Najafi G, Chegeni A. Biodiesel production potential from edible oil seeds in Iran. Renew Sust Energ Rev. 2011;15:3041–3044. [11] Aydin F, Kafadar AB, Erdogan S, Saydut A, Kaya C, Hamamci C. The basic properties of transesterified corn oil and biodiesel-diesel blends. Energ Source Part A. 2011;33:745–751. [12] Saydut A, Duz MZ, Kaya C, Kafadar AB, Hamamci C. Transesterified sesame (Sesamum indicum L.) seed oil as a biodiesel fuel. Bioresour Technol. 2008;99:6656–6660. [13] Kaya C, Hamamci C, Baysal A, Akba O, Erdogan S, Saydut A. Methyl ester of peanut (Arachis hypogea L.) seed oil as a potential feedstock for biodiesel production. Renew Energ. 2009;34:1257–1260. [14] Ozsezen AN, Canakci M. Determination of performance and combustion characteristics of a diesel engine fueled with canola and waste palm oil methyl esters. Energ Convers Manage. 2011;52:108–116. [15] Ghanei R, Moradi GR, TaherpourKalantari R, Arjmandzadeh E. Variation of physical properties during transesterification of sun flower oil to biodiesel as an approach to predict reaction progress. Fuel Process Technol. 2011;92:1593–1598. [16] Qi DH, Geng LM, Chen H, Bian YZH, Liu J, Ren XCH. Combustion and performance evaluation of a diesel engine fueled with biodiesel produced from soybean crude oil. Renew Energ. 2009;34:2706–2713. [17] Ayhan D. Progress and recent trends in biofuels. Prog Energ Combust. 2007;33:1–18. [18] Lin C-Y, Li R-J. Engine performance and emission characteristics of marine fish-oil biodiesel produced from the discarded parts of marine fish. Fuel Process Technol. 2009;90:883–888. [19] Sapuan SM, Masjuki HH, Azlan A. The use of palm oil as diesel fuel substitute. P I Mech Eng A-J Pow. 1996;210:47– 53. [20] Nabi MN, Hoque SMN, Akhter MS. Karanja (Pongamia Pinnata) biodiesel production in Bangladesh, characterization of karanja biodiesel and its effect on diesel emissions. Fuel Process Technol. 2009;90:1080–1086. [21] Barnwal BK, Sharma MP. Prospects of biodiesel production from vegetable oils in India. Renew Sust Energ Rev. 2005;9:363–378. [22] Araújo SV, Luna FMT, Rola EM Jr., Azevedo DCS, Cavalcante CL. Jr. A rapid method for evaluation of the oxidation stability of castor oil FAME: influence of antioxidant type and concentration. Fuel Process Technol. 2009;90:1272– 1277. [23] Hilditch TP, Williams PN. The Chemical Constitution of Natural Fats, Fifty-fifth scientific meeting hospitals center. Birmingham, 1949. [24] Achaya K. Chemical derivatives of castor oil. J Am Oil Chem Soc. 1971;48:758–763. [25] Hincapié G, MondragÓn F, LÓpez D. Conventional and in situ transesterification of castor seed oil for biodiesel production. Fuel. 2011;90:1618–1623. [26] Shojaeefard MH, Etghani MM, Akbari M, Khalkhali A, Ghobadian B. Artificial Neural Networks based prediction of performance and exhaust emissions in DI engine using Castor oil biodiesel- diesel blends. J Renew Sust Energ. 2012;4:063130–063149.
[27] Kinney AJ, Clemente TE. Modifying soybean oil for enhanced performance in biodiesel blends. Fuel Process Technol. 2005;86:1137–1147. [28] Berman P, Nizri S, Wiesman Z. Castor oil biodiesel and its blends as alternative fuel. Biomass Bioenerg. 2011;35: 2861–2866. [29] Auld DL, Bettis BL, Peterson CL. Production and fuel characteristics of vegetable oil from oilseed crops in the Pacific Northwest. International conference on plant and vegetable oils as fuels, Fargo, ND, USA, 1982. [30] Knothe G, Gerpen JV, Krahl J. The biodiesel handbook. Urbana, IL: AOCS Press; 2005. [31] Leung DYC, Wu X, Leung MKH. A review on biodiesel production using catalyzed transesterification. Appl Energ. 2010;87:1083–1095. [32] Kansedo J, Lee KT, Bhatia S. Biodiesel production from palm oil via heterogeneous transesterification. Biomass Bioenerg. 2009;33:271–276. [33] Ramezani K, Rowshanzamir S, Eikani MH. Castor oil transesterification reaction: a kinetic study and optimization of parameters. Energy 2010;35:4142–4148. [34] Sousa LL, Lucena IL, Fernandes FAN. Transesterification of castor oil: effect of the acid value and neutralization of the oil with glycerol. Fuel Process Technol. 2010;91:194–196. [35] 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;30:245–249. [36] Valente OS, da Silva MJ, Duarte Pasa VM, Pereira Belchior CR, Sodré JR. Fuel consumption and emissions from a diesel power generator fuelled with castor oil and soybean biodiesel. Fuel 2010;89:3637–3642. [37] Kumari A, Mahapatra P, Garlapati VK, Banerjee R. Enzymatic transesterification of Jatropha oil. Biotecnol Biofuels. 2009;2:1–7. [38] Demirbas A. Biodiesel production from vegetable oils via catalytic and non-catalytic supercritical methanol transesterification methods. Prog Energ Combust. 2005;31:466–487. [39] Sendzikiene E, Makareviciene V, Janulis P. Influence of fuel oxygen content on diesel engine exhaust emissions. Renew Energ. 2006;31:2505–2512. [40] Usta N, Öztürk E, Can Ö, Conkur ES, Nas S, Çon AH, Can AÇ, Topcu M. Combustion of biodiesel fuel produced from hazelnut soapstock/waste sunflower oil mixture in a diesel engine. Energ Convers Manage. 2005;46:741–755. [41] Kalam MA, Husnawan M, Masjuki HH. Exhaust emission and combustion evaluation of coconut oil-powered indirect injection diesel engine. Renew Energ. 2003;28: 2405–2415. [42] Raheman H, Ghadge SV. Performance of diesel engine with biodiesel at varying compression ratio and ignition timing. Fuel 2008;87:2659–2666. [43] Enweremadu CC, Rutto HL. Combustion, emission and engine performance characteristics of used cooking oil biodiesel-a review. Renew Sust Energ Rev. 2010;14: 2863–2873. [44] Heywood J. Internal combustion engine fundamentals. New Yark, NY: McGraw-Hill; 1988. [45] Buyukkaya E. Effects of biodiesel on a DI diesel engine performance, emission and combustion characteristics. Fuel 2010;89:3099–3105.
Environmental Technology Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tent20
Experimental investigation on performance and exhaust emissions of castor oil biodiesel from a diesel engine a
a
a
M. H. Shojaeefard , M. M. Etgahni , F. Meisami & A. Barari
b
a
School of Automotive Engineering , Iran University of Science and Technology , Tehran , Iran b
Department of Civil Engineering , Aalborg University , Aalborg , Denmark
To cite this article: M. H. Shojaeefard , M. M. Etgahni , F. Meisami & A. Barari (2013) Experimental investigation on performance and exhaust emissions of castor oil biodiesel from a diesel engine, Environmental Technology, 34:13-14, 2019-2026, DOI: 10.1080/09593330.2013.777080 To link to this article: http://dx.doi.org/10.1080/09593330.2013.777080
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Environmental Technology, 2013 Vol. 34, Nos. 13–14, 2019–2026, http://dx.doi.org/10.1080/09593330.2013.777080
Experimental investigation on performance and exhaust emissions of castor oil biodiesel from a diesel engine M.H. Shojaeefarda,∗ , M.M. Etgahnia , F. Meisamia and A. Bararib,∗ a School
of Automotive Engineering, Iran University of Science and Technology, Tehran, Iran; b Department of Civil Engineering, Aalborg University, Aalborg, Denmark
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(Received 25 November 2012; final version received 5 February 2013 ) Biodiesel, produced from plant and animal oils, is an important alternative to fossil fuels because, apart from dwindling supply, the latter are a major source of air pollution. In this investigation, effects of castor oil biodiesel blends have been examined on diesel engine performance and emissions. After producing castor methyl ester by the transesterification method and measuring its characteristics, the experiments were performed on a four cylinder, turbocharged, direct injection, diesel engine. Engine performance (power, torque, brake specific fuel consumption and thermal efficiency) and exhaust emissions were analysed at various engine speeds. All the tests were done under 75% full load. Furthermore, the volumetric blending ratios of biodiesel with conventional diesel fuel were set at 5, 10, 15, 20 and 30%. The results indicate that lower blends of biodiesel provide acceptable engine performance and even improve it. Meanwhile, exhaust emissions are much decreased. Finally, a 15% blend of castor oil–biodiesel was picked as the optimized blend of biodiesel–diesel. It was found that lower blends of castor biodiesel are an acceptable fuel alternative for the engine. Keywords: biodiesel; castor oil; transesterfication; performance; emissions; diesel engine
Introduction Nowadays, most of our energy is provided by fossil fuels, which are considered non-renewable; that is, they are not replaced as soon as we use them. So, fossil sources are depleting [1]. Moreover, fossil fuel combustion is considered to be the main reason for air pollution. Since internal combustion engines are counted as the greatest application of fossil fuels, a large part of research has concentrated on them. [2,3] Although a considerable number of technologies were invented and implemented on engines, it seems that they will not meet more stringent pollution legislation in future. So, attention is being focused on fossil fuel alternatives. It looks as if renewable fuels are a proper choice for solving the above-mentioned problems. [4] Developing renewable energy has become an important part of worldwide energy policy to reduce gas emissions caused by fossil fuel. Alternative fuels such as alcohols, natural gas and biofuels are seen as an option to help the transport sector to decrease its dependency on oil and reduce its environmental impact. [5–8] Diesel engines are widely used in the automotive market for their better efficiency than their similarly rated spark ignition counterparts over the entire operating range. Due to the fact that biodiesels significantly reduce greenhouse gases and air pollution, scientists highly recommend biodiesels among other renewable fuels for ∗ Corresponding
diesel engines. [9] Furthermore, they may reduce fuel costs because they decrease some of the world’s fuel demands. [10] Biodiesel fuels can be extracted from vegetable oils, such as sesame, peanut, corn, canola, sunflower, soyabean, waste cooking oil [11–17] or animal fats such as fish oil. [18] Since biodiesels retain all the benefits of a diesel engine, there is no need to alter or change the basic engine when applying alternative fuels; therefore, they are suitable alternatives for diesel. However, regarding heating value and other fuel characteristics, some calibrations on injection advance and duration should be considered. [19] Rudolf Diesel, famous for the invention of the diesel engine, was the first to apply vegetable oil (peanut oil) to a diesel engine at the 1900 World Exhibition in Paris. [20] He also proclaimed that every diesel engine could be supplied with vegetable oil and it can vastly help in agriculture development. Nowadays, his prediction has come true and a lot of countries are moving toward producing and using biodiesels. [21] Castor oil is the proper choice for converting to biodiesel, because it is a non-edible oil and as its availability in many countries makes it accessible [22]. But unfortunately there are just a few studies relating to castor biodiesel properties and its application in the engine as an alternative fuel. This is mainly due to the presence of high amounts of ricinoleic acid in original castor oil structure. Ricinoleic acid is a major factor in some biodiesel
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M.H. Shojaeefard et al.
specifications that exceed standard limits. It is also called castor oil acid, which belongs to the unsaturated fatty acid family. It is a viscous yellow liquid, melting at 5.5◦ C, boiling at 245◦ C and insoluble in water but soluble in most organic solvents. [23] Castor oil consists of 80–90% ricinoleic acid, 3–6% linoleic acid, 2–4% oleic acid and 1–5% other saturated fatty acids. [24] As has already been mentioned, ricinoleic acid is highly viscous. Thus, a high proportion of castor oil biodiesel should not be used in engines. [25] It should be noted that due to the high viscosity of castor oil biodiesel, blends more than 30% cannot be used as fuel for diesel engines without modifications to the engine. [26] But the high viscosity of castor oil has better lubricity than other plant oils. [27] Berman et al. investigated the properties of neat castor biodiesel (B100) and its blend with diesel in 10% volume fraction (B10). They have indicated that only two properties of neat biodiesel exceed standard limits. These properties are kinematic viscosity (15.17 mm2 /s) and distillation temperature (398.70◦ C). While for B10, all characteristics of biodiesel are within the standard limit. Consequently, since diesel engines often are supplied with low proportions of biodiesel, it is reasonable to use castor oil biodiesel in engines. [28] It should be noted that crude oil can also be used directly in engine as fuel. Due to its lack of chemical esterification reactions, [29] this method has some benefits, such as easy transportation, higher heating values than biodiesel, saving time, energy and money. On the other hand, crude oil has more disadvantages, such as high viscosity, intensive corrosion, failure mechanisms of combustion duo to presence of matters in unrefined oil, rapid pollution of lubricant oil, low volatility and carbon sediment formation on engine components. Hence, the direct use of crude oil is not an appropriate method. Four possible solutions were proposed to change some oil properties in order to make it more suitable: transesterification; pyrolysis; dilution with conventional petroleumderived diesel fuel; micro-emulsification. [30] For this aim, the most common method is transesterification. [31] Some basic parameters that dominate transesterfication reaction are type and amount of catalyst, temperature and time of reaction, alcohol/oil molar ratio and mixture intensity, free fatty acids and water content. [32] The effects of these parameters have been investigated on castor oil transesterfication reaction. There are four kinds of catalysts (NaOCH3 , NaOH, KOCH3 and KOH) and it was found that using KOH results in maximum biodiesel yield. [33] In another study, the best reaction condition for castor oil transesterfication was obtained by 6:1 alcohol/oil molar ratio and 0.5% catalyst weight. [34] Numerous studies have been performed on the effect of various biodiesels on engine performance and emissions. While castor oil feasibility as a biodiesel has been known, a few studies have been carried out about the effects of castor oil biodiesel on engine characteristics. Panwar et al. evaluated the performance of a diesel engine
fuelled with castor oil methyl ester. They kept the engine speed at 1500 rpm and tried different loads. It was revealed that the lower blends of biodiesel improved engine performance and, finally, B10 was chosen as the optimum biodiesel fraction. [35] Valente et al. examined the impacts on fuel consumption and exhaust emissions of a diesel power generator operating with castor oil biodiesel. In their experimental study, fuel blends containing 5, 20 and 35% of castor oil biodiesel in diesel oil were tested and the engine load was varied from 9.6 to 35.7 kW. The results demonstrated that optimization of fuel injection system is required for proper engine operation with biodiesel. [36] In the present study, castor oil was converted to castor oil biodiesel by the transesterfication method and its properties were measured and compared with the ASTM biodiesel standard. Performance and exhaust emission characteristics of the diesel engine were tested and analysed under different speeds and various biodiesel blends. Castor oil transesterfication The presence of water in castor oil reduces the efficiency of biodiesel production and in some cases may result in transesterfication reaction failure. [37] For that reason, first, castor oil was heated to 70◦ C and kept for 30 minutes, then cooled at room temperature for 24 hours. Water was then removed through a drain valve, which had been embedded at the bottom. In the transesterification approach, potassium hydroxide (KOH) was used as a catalyst and because KOH naturally is in solid form, KOH tablets should be dissolved in alcohol to have a more effective reaction. The alcohol type that was chosen to be employed as a solvent was methanol (CH3 OH), due to its lower cost. KOH and methanol should possess a high degree of purity. If there is some water in methanol, the transesterfication reaction will not be done completely and ester production efficiency will reduce. Dissolving KOH in methanol is an exothermic reaction, which causes extreme methanol evaporation. A magnetic stirrer was used to enhance the efficiency of the solution and to prevent excessive methanol evaporation. KOH was dissolved (by 1% oil weight) in methanol. The solution was then mixed with castor oil in 1:5 molar ratio. This solution was stirred with oil for 45 minutes at a temperature of 60◦ C. Water is more nucleophile than methanol, it attacks carbonyl groups of triglyceride and decomposes them, which produces fatty acid and glycerol. [38] The fatty acids react and produce soap, which reduces the methyl ester yield. On the other hand, the fatty acids soap tends to be solid at ambient temperatures and this tendency makes the mixture gelatinous and difficult to recycle. For risk elimination of reaction failure, adding excessive methanol is common. When the reaction is finished, this amount of methanol can be retrieved by heating. Since the excessive amount of methanol in laboratory scale is not considerable, this process was not performed. However, it should be considered for use on an industrial scale.
Environmental Technology Table 1.
Properties of castor oil methyl ester.
Parameter
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Acid number Oxidation stability Copper corrosion @100◦ C for 3 hours IBP@760 mmHg Distillation temp (90%) Cloud point Pour point Heat of combustion Density @20◦ C Kinematic viscosity @40◦ C Sulphated ash Flash point Carbon residue Phosphorous content Relative molecular mass Water content Cetane number
Unit
Test method
Result
ASTM limit
Mg KOH/gr min – ◦C ◦C ◦C ◦C MJ/kg g/mL mm2 /s Mass% ◦C Mass% Mg/kg gr/mol Mass% –
ASTM D664 ASTM D525 ASTM D130 ASTM D6352 ASTM D6352 ASTM D2500 ASTM D97 ASTM D240 ASTM D7042 ASTM D7042 ASTM D874 ASTM D92 ASTM D524
0.25 >480 1a 329 409 −21 −39 37.195 0.9278 19.268 0.01 193 0.039 3.8 334 0.32 49.1
Max 0.8(ASTM D664) Min 3 hours (EN 14112) Max 3a No Limit Max 360(ASTM D1160) No limit No limit No limit No limit 1.9-6 @40◦ C (ASTM D445) Max0.02(ASTM D874) Min 93(ASTM D93) Max 0.05(ASTM D4530) Max 0.001% (ASTM D4951) No limit Max 0.05%vol (ASTM D2709) Min 47 (ASTM D613)
When the transesterfication reaction was complete, the bottom layer of mixture contained glycerine, methanol and most of the KOH. Glycerine is denser than biodiesel and it leaves a deposit at the bottom of the container. Full glycerine deposition time lasted about a week. Note that approximately 90% of glycerine was separated in the first four hours. When the bottom layer of mixture was drained out, the upper layer, which contains biodiesel, methanol and traces of catalyst, was purified by washing four times with distilled warm water. Finally, for complete separation of water from the biodiesel, the solution was heated to 90◦ C for 30 minutes. Some of the neat biodiesel properties were determined in a modern laboratory by the Research Institute of Petroleum Industry. The properties are listed in Table 1. As shown in Table 1, several pure biodiesel properties, especially kinematic viscosity, are outside the standard range. But according to some researcher’s studies, the engine can be supplied with lower blend of castor methyl ester. [28] Fatty acid composition of castor methyl ester was measured in Chemistry and Chemical Engineering Research Center of Iran and this is shown in Table 2. According to Table 2, castor oil biodiesel has a high percentage of ricinoleic acid, which is an unsaturated 18 carbon fatty acid. As regards the existence of a hydroxyl group at the 12th carbon, it shows some unusual properties, such as high viscosity, which is due to hydrogen bonding in the hydroxyl group.
Experimental methodology The engine used for the study was an agricultural, fourcylinder, four-stroke, water-cooled, direct injection diesel engine. The main specifications of the engine are listed in Table 3.
Osmomat ASTM D7042 ASTM D613
Table 2.
Fatty acid composition of castor oil methyl ester.
Fatty acid
Structure
Fatty acid composition (%)
Ricinoleic acid Linoleic acid Oleic acid Stearic acid Palmitic acid Linolenic acid Eicosenoic acid Lignoceric acid Nervonic acid
18:1-OH 18:2 18:1 18:0 16:0 18:3 20:1 24:0 24:1
88.18 5.02 3.80 1.12 1.04 0.49 0.28 0.04 0.02
Table 3.
Technical specifications of the test engine.
Name Bore × Stroke Number of cylinders Volume capacity Cycle Aspiration Combustion system Injection timing Compression ration Max. power Fuel pump Governing Cooling Weight Length × Width × Height
MT4.244 100 mm × 127 mm 4 3.99 Lit 4 stroke Wastegated turbocharger Fast ram direct injection -8 bTDC 17.25:1 82 hp in 2000 rpm Bosch rotary with boost control Mechanical Water, belt driven water pump 265 Kg 678.7 mm × 655 mm × 748.5 mm
A 190 Kw eddy-current dynamometer was used in the experiments with digital data acquisition systems. Figure 1 depicts a schematic of the test set-up. Because of its agricultural application, the engine nominal speed range is less than other conventional engines. So, the range of test speeds was selected from 1200 to 2000 rpm.
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Figure 1.
M.H. Shojaeefard et al.
Schematic diagram of test set-up.
According to the original performance diagram, the two speeds of 1200 rpm (maximum torque) and 2000 rpm (maximum power) are critical and should be considered. Hence, the experiments were carried out with different engine speeds. Moreover, a tractor engine usually runs at a relatively high load (neither low load nor full load). So the 75% engine load was selected for the experiment. Because of the high viscosity of castor methyl ester, lower blends of biodiesel-diesel (0, 5, 10, 15, 20 and 30% of biodiesel) were used in the experiment. First, the engine was warmed up with pure diesel, until the cooling water temperature reached 80◦ C. Then, the engine was subjected to the abovementioned speeds and load. After the engine was stabilized, power, torque, brake specific fuel consumption (BSFC), thermal efficiency, exhaust gas temperature, nitrogen oxides (NOx ), hydrocarbon (HC), carbon monoxide (CO) and particle matter (PM) were measured. Result and discussions Engine performance Engine power and torque variations versus speed for various blends of biodiesel–diesel are shown in Figures 2 and 3. It is obvious from Figure 2 that engine power decreases with the increase of biodiesel content. This is primarily related to the lower heating value and higher viscosity of biodiesel blends. Note that, as it can be seen in Figure 2, the blend of B10 has roughly equal power and is even slightly more than pure diesel. Looking closer, the power of the B10 blend was observed to be higher by 0.3% than that of the diesel fuel. For B5, B15, B20 and B30 fuels, the engine power decreases by 1.94, 1.16, 4.46 and 8.05% respectively in comparison with diesel. Some reasons can be expressed regarding the power enhancement in B10 and slight reduction in B15. First, biodiesel contains a higher oxygen content than diesel (usually 10–12%), [39] which
Figure 2. Power variation for different biodiesel blends versus engine speed.
improves the combustion process, especially in the fuelrich zone. [40,41] Second, a higher biodiesel density causes more fuel mass flow rate in a specified volume. In B10 and even B15, some properties such as density, viscosity, injection specifications and oxygen content are optimized. This optimal condition causes no loss in torque and power. Another point that can be perceived from Figure 2 is that there is no significant difference between power of biodiesel blends at lower engine speed (especially at 1200 rpm). Also, with increasing engine speed, this difference gradually becomes greater. The main reason that justifies this behaviour is that at lower speeds the fuel-rich zones have enough time to burn fully. Figure 3 shows the variation of engine torque versus engine speed. The maximum torque occurs at 1200 rpm and
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Environmental Technology
Figure 3. Torque variation for different biodiesel blends versus engine speed.
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Figure 5. Thermal efficiency variation for different biodiesel blends versus engine speed.
So the heating value of various blends must be considered in BTE calculation. Diesel and biodiesel heating values are respectively 44,800 and 37,195 kJ/kg. As a simple method, a linear formula can be used for the calculation of heating values in various biodiesel–diesel blends. As can be seen in Figure 5, using biodiesel causes BTE reduction. The maximum reduction is about 7.5%, which occurs in B30. BTE quantity is related to engine power, fuel mass flow rate and heating value. When using biodiesel, the whole effect of these parameters causes BTE reduction.
Figure 4. Brake specific fuel consumption variation for different biodiesel blends versus engine speed.
decreases with speed increase. Similar to the power diagram, the torque of B15 blend is slightly more than diesel torque. For B5, B10, B20 and B30 fuels, the engine torque decreases by 1.38, 0.95, 2.44% and 5.11% respectively in comparison with diesel. It can be observed from Figure 4 that BSFC increases with increasing biodiesel content in blends. Because of the higher density of castor oil biodiesel, the engine is supplied by more fuel mass flow, which causes an increase in specific fuel consumption. On the other hand, the lower heating value of biodiesel forces the engine to burn more fuel to attain the same diesel engine power. [42] As shown in Figure 5, there is a direct relation between brake thermal efficiency (BTE) and engine power. Also it is affected inversely by fuel mass flow rate and heating value.
Exhaust emissions Exhaust gas temperature behaviour, which is shown in Figure 6, is so strange and interesting. At lower engine speeds (1200 rpm), due to high density and viscosity of biodiesel, which leads to longer spray penetration, the fuel cannot be atomized very well. [43] Poor atomization results in incomplete combustion and lower exhaust gas temperature. While at 1400 rpm, the afore-mentioned problem (long spray penetration), is almost solved. On the other hand, the engine is still working at a lower speed range, so biodiesel has enough time to burn completely. This condition can cause an exhaust gas temperature rise. At higher speeds, the lack of time causes the exhaust gas temperature drop. Various behaviours of biodiesel blends can be justified by a trade-off between fuel viscosity and oxygen content. More oxygen content leads to more complete combustion and thereby more exhaust gas temperature. Conversely, with increasing fuel viscosity, exhaust gas temperature will decrease. For example, in a B30 blend, the oxygen content factor overcomes the viscosity factor, which results in a higher exhaust gas temperature. For a B5 blend, lower viscosity results in better atomization and a higher exhaust
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Figure 6. Exhaust gas temperature variation for different biodiesel blends versus engine speed.
gas temperature. However, in B15, these two factors are involved in a special condition that leads to the lowest exhaust gas temperature. There is a direct relationship between NOx emission and exhaust gas temperature. It is expected that with increasing engine speed, NOx emission increases; Figure 7 shows behaviour to the contrary. It should be noted that NOx emission depends on many factors, such as, volumetric efficiency, combustion duration, fuel oxygen content, adiabatic flame temperature and spray characteristics. [44] An increase in engine speed leads to an increase in volumetric efficiency and mixture turbulence. This situation increases the air-fuel mixing rate and reduces ignition delay. Hence, the reaction time in each cycle decreases and the residence time of the gas temperature becomes shorter, which leads to lower NOx emission under higher engine speeds. [45] Because of a higher oxygen content in biodiesel, the NOx emission difference between various blends of biodiesel can be explained by an exhaust gas temperature diagram. All NOx emissions of biodiesel blended fuel are higher than that of pure diesel. Maximum increase in NOx emission occurs in a B30 biodiesel blend, which is 11.31% higher than that of diesel. Due to a low exhaust gas temperature in B15, it has the lowest NOx emission among other biodiesel blends and its NOx emission is just 1.45% higher than diesel NOx emission. As shown in Figure 8, CO emission decreases with increasing biodiesel content in blends. The maximum and minimum decrease in CO emission occurs in B30 and B5, which are about 37% and 3.5% respectively. The CO reduction in other fuel blends is spread between these values. The biodiesel effect is more dominant at lower speeds because, at lower speeds, the oxygen content that enters the engine is lower than that of higher speeds. Thus, the existent oxygen in biodiesel has an apparent effect on CO reduction.
Figure 7. NOx variation for different biodiesel blends versus engine speed.
Figure 8. CO variation for different biodiesel blends versus engine speed.
The HC emission behaviour, shown in Figure 9, has no specific trend in various biodiesel blends. But it can be observed from the diagram that HC is reduced by using biodiesel. HC reduction in B5, B10, B15, B20 and B30 is about 5.9, 20.9, 18.18, 0 and 19.31% respectively. The most likely reason for HC reduction is the presence of more oxygen in biodiesel, which leads to better combustion and HC reduction. The PM formation mechanism is almost similar to CO. As shown in Figure 10, biodiesel has a remarkable effect on PM reduction. The PM formation process mainly occurs in fuel-rich zones and high temperatures. Since biodiesel contains more oxygen than diesel, the fuel-rich zones reduce
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Environmental Technology
Figure 9. HC variation for different biodiesel blends versus engine speed.
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Due to the lower calorific value of castor oil biodiesel and higher viscosity in comparison with those of diesel fuel, engine power and torque slightly decrease by using the biodiesel. The power and torque reduction in B10 and B15 were not as large as other blends and, even in B15, it was observed that the torque was slightly more than diesel. This was primarily due to a higher biodiesel density and oxygen content. The BSFC values for all biodiesel blends were higher than diesel values. A lower heating value and higher density of biodiesel were declared as related parameters in regard to BSFC increase. The usage of castor oil biodiesel had positive effects on exhaust emissions. A decrease was detected in all emissions, except NOx . The NOx emission for all blends of biodiesel was more than diesel NOx emission. However, among biodiesel blends, B15 had the minimum NOx emission. The maximum decrease in CO, HC and PM emissions was respectively 37% in B30, 20.9% in B10 and 52% in B30. The reasons that B15 of castor oil biodiesel blend was selected as an optimum blend for this engine are small increase in torque, the lowest increase in NOx emission among other blends, admissible CO, HC and PM emissions. Acknowledgements The authors would like to acknowledge Iranian Fuel Conservation Company for supporting us in doing this research.
References
Figure 10. PM variation for different biodiesel blends versus engine speed.
and thereby PM emission decreases and, due to lower airfuel mixing, it is apparent in lower speeds. The maximum PM reduction is about 52%, which occurs in a B30 blend.
Conclusion In this study, biodiesel fuel was produced from castor seed oil by a transesterfication method. Its characteristics were measured and it was found that some of its properties, especially viscosity, were not in standard range. Diluting castor biodiesel with conventional petroleum diesel fuel is the logical solution. Hence, based on the above-mentioned reason, blends of up to 30% can be substituted as fuel for diesel engines without any modifications to the engine.
[1] Demirbas A. Biodiesels-a realistic fuel alternative for diesel engines. Springer-Verlag, London Limited; 2008. [2] Fan M, Vidic R, Dionysiou D, Ferrara R. Recent developments in CO2 emission control technology, SPECIAL ISSUE: recent developments in CO2 emission control technology. J Environ Eng. 2009;135:377–377. [3] Elbir T. Estimation of engine emissions from commercial aircraft at a midsized Turkish airport. J Environ Eng. 2008;134:210–215. [4] Dowaki K, Ohta T, Kasahara Y, Kameyama M, Sakawaki K, Mori S. An economic and energy analysis on bio-hydrogen fuel using a gasification process. Renew Energ. 2007;32: 80–94. [5] Arapatsakosa CI, Karkanis AN, Spare PD. Gas emissions and engine behavior when gasoline-alcohol mixtures are used. Environ Technol. 2003;24:1069–1077. [6] Schifter I, Díaz L, González U. Impact of reformulated ethanol-gasoline blends on high emitting vehicles. Environ Technol. 2013;34:911–922. [7] Zou L, Atkinson S. Characterising vehicle emissions from the burning of biodiesel made from vegetable oil. Environ Technol. 2003;24:1253–1260. [8] Nabi Md. N. and Hustad JE. Investigation of engine performance and emissions of a diesel engine with a blend of marine gas oil and synthetic diesel fuel. Environ Technol. 2012;33:9–15. [9] Brune D, Lundquist T, Benemann J. Microalgal biomass for greenhouse gas reductions: potential for replacement of fossil fuels and animal feeds. J Environ Eng. 2009;135: 1136–1144.
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M.H. Shojaeefard et al.
[10] Safieddin Ardebili M, Ghobadian B, Najafi G, Chegeni A. Biodiesel production potential from edible oil seeds in Iran. Renew Sust Energ Rev. 2011;15:3041–3044. [11] Aydin F, Kafadar AB, Erdogan S, Saydut A, Kaya C, Hamamci C. The basic properties of transesterified corn oil and biodiesel-diesel blends. Energ Source Part A. 2011;33:745–751. [12] Saydut A, Duz MZ, Kaya C, Kafadar AB, Hamamci C. Transesterified sesame (Sesamum indicum L.) seed oil as a biodiesel fuel. Bioresour Technol. 2008;99:6656–6660. [13] Kaya C, Hamamci C, Baysal A, Akba O, Erdogan S, Saydut A. Methyl ester of peanut (Arachis hypogea L.) seed oil as a potential feedstock for biodiesel production. Renew Energ. 2009;34:1257–1260. [14] Ozsezen AN, Canakci M. Determination of performance and combustion characteristics of a diesel engine fueled with canola and waste palm oil methyl esters. Energ Convers Manage. 2011;52:108–116. [15] Ghanei R, Moradi GR, TaherpourKalantari R, Arjmandzadeh E. Variation of physical properties during transesterification of sun flower oil to biodiesel as an approach to predict reaction progress. Fuel Process Technol. 2011;92:1593–1598. [16] Qi DH, Geng LM, Chen H, Bian YZH, Liu J, Ren XCH. Combustion and performance evaluation of a diesel engine fueled with biodiesel produced from soybean crude oil. Renew Energ. 2009;34:2706–2713. [17] Ayhan D. Progress and recent trends in biofuels. Prog Energ Combust. 2007;33:1–18. [18] Lin C-Y, Li R-J. Engine performance and emission characteristics of marine fish-oil biodiesel produced from the discarded parts of marine fish. Fuel Process Technol. 2009;90:883–888. [19] Sapuan SM, Masjuki HH, Azlan A. The use of palm oil as diesel fuel substitute. P I Mech Eng A-J Pow. 1996;210:47– 53. [20] Nabi MN, Hoque SMN, Akhter MS. Karanja (Pongamia Pinnata) biodiesel production in Bangladesh, characterization of karanja biodiesel and its effect on diesel emissions. Fuel Process Technol. 2009;90:1080–1086. [21] Barnwal BK, Sharma MP. Prospects of biodiesel production from vegetable oils in India. Renew Sust Energ Rev. 2005;9:363–378. [22] Araújo SV, Luna FMT, Rola EM Jr., Azevedo DCS, Cavalcante CL. Jr. A rapid method for evaluation of the oxidation stability of castor oil FAME: influence of antioxidant type and concentration. Fuel Process Technol. 2009;90:1272– 1277. [23] Hilditch TP, Williams PN. The Chemical Constitution of Natural Fats, Fifty-fifth scientific meeting hospitals center. Birmingham, 1949. [24] Achaya K. Chemical derivatives of castor oil. J Am Oil Chem Soc. 1971;48:758–763. [25] Hincapié G, MondragÓn F, LÓpez D. Conventional and in situ transesterification of castor seed oil for biodiesel production. Fuel. 2011;90:1618–1623. [26] Shojaeefard MH, Etghani MM, Akbari M, Khalkhali A, Ghobadian B. Artificial Neural Networks based prediction of performance and exhaust emissions in DI engine using Castor oil biodiesel- diesel blends. J Renew Sust Energ. 2012;4:063130–063149.
[27] Kinney AJ, Clemente TE. Modifying soybean oil for enhanced performance in biodiesel blends. Fuel Process Technol. 2005;86:1137–1147. [28] Berman P, Nizri S, Wiesman Z. Castor oil biodiesel and its blends as alternative fuel. Biomass Bioenerg. 2011;35: 2861–2866. [29] Auld DL, Bettis BL, Peterson CL. Production and fuel characteristics of vegetable oil from oilseed crops in the Pacific Northwest. International conference on plant and vegetable oils as fuels, Fargo, ND, USA, 1982. [30] Knothe G, Gerpen JV, Krahl J. The biodiesel handbook. Urbana, IL: AOCS Press; 2005. [31] Leung DYC, Wu X, Leung MKH. A review on biodiesel production using catalyzed transesterification. Appl Energ. 2010;87:1083–1095. [32] Kansedo J, Lee KT, Bhatia S. Biodiesel production from palm oil via heterogeneous transesterification. Biomass Bioenerg. 2009;33:271–276. [33] Ramezani K, Rowshanzamir S, Eikani MH. Castor oil transesterification reaction: a kinetic study and optimization of parameters. Energy 2010;35:4142–4148. [34] Sousa LL, Lucena IL, Fernandes FAN. Transesterification of castor oil: effect of the acid value and neutralization of the oil with glycerol. Fuel Process Technol. 2010;91:194–196. [35] 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;30:245–249. [36] Valente OS, da Silva MJ, Duarte Pasa VM, Pereira Belchior CR, Sodré JR. Fuel consumption and emissions from a diesel power generator fuelled with castor oil and soybean biodiesel. Fuel 2010;89:3637–3642. [37] Kumari A, Mahapatra P, Garlapati VK, Banerjee R. Enzymatic transesterification of Jatropha oil. Biotecnol Biofuels. 2009;2:1–7. [38] Demirbas A. Biodiesel production from vegetable oils via catalytic and non-catalytic supercritical methanol transesterification methods. Prog Energ Combust. 2005;31:466–487. [39] Sendzikiene E, Makareviciene V, Janulis P. Influence of fuel oxygen content on diesel engine exhaust emissions. Renew Energ. 2006;31:2505–2512. [40] Usta N, Öztürk E, Can Ö, Conkur ES, Nas S, Çon AH, Can AÇ, Topcu M. Combustion of biodiesel fuel produced from hazelnut soapstock/waste sunflower oil mixture in a diesel engine. Energ Convers Manage. 2005;46:741–755. [41] Kalam MA, Husnawan M, Masjuki HH. Exhaust emission and combustion evaluation of coconut oil-powered indirect injection diesel engine. Renew Energ. 2003;28: 2405–2415. [42] Raheman H, Ghadge SV. Performance of diesel engine with biodiesel at varying compression ratio and ignition timing. Fuel 2008;87:2659–2666. [43] Enweremadu CC, Rutto HL. Combustion, emission and engine performance characteristics of used cooking oil biodiesel-a review. Renew Sust Energ Rev. 2010;14: 2863–2873. [44] Heywood J. Internal combustion engine fundamentals. New Yark, NY: McGraw-Hill; 1988. [45] Buyukkaya E. Effects of biodiesel on a DI diesel engine performance, emission and combustion characteristics. Fuel 2010;89:3099–3105.
