A New Application Area for Used Cooking Oil Originated Biodiesel

cooking oil originated biodiesel + 80% of No. 2 Diesel fuel) utilizations showed improved results on engine performance and emissions. B100 applicatio...
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Energy & Fuels 2005, 19, 645-652

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A New Application Area for Used Cooking Oil Originated Biodiesel: Generators Merve C¸ etinkaya and Filiz Karaosmanogˇlu* Chemical Engineering Department, Istanbul Technical University, Maslak 34469, Istanbul, Turkey Received April 29, 2004. Revised Manuscript Received December 29, 2004

Biodiesel has proven itself as a technically sufficient alternative diesel fuel in the fuel market since the beginning of 1990s. Its applications in automobiles, ships, and heating systems have been accepted by both European countries and the U.S.A. Generators are crucial equipment of industry and have a wide usage area in agriculture. Also, engine performance and emissions of electric generators get very important due to their indoor applications. The objective of this study was to investigate the engine performance and smoke results of used cooking oil originated biodiesel utilization in electric generators. The engine performance and emission tests were conducted with 90-mm stroke, 1 cylinder, and a 9-kW 3 LD 510 coded diesel engine, and generator performance tests were performed in a generator set consisting of 90-mm stroke, 1 cylinder, 4 LD 640 code, and a 10.5-kW diesel engine and 10-kVA max output, 14.4-A current, and 400-V A 100 LB coded Rotating Field Three Phases AC Generator. Consecutive tests on No. 2 Diesel fuel, B100, and B20 were conducted, and the results were compared with each other. When compared to No. 2 Diesel fuel, both B100 (100% used cooking oil originated biodiesel) and B20 (20% used cooking oil originated biodiesel + 80% of No. 2 Diesel fuel) utilizations showed improved results on engine performance and emissions. B100 application resulted in lower smoke production than that of B20, whereas B20 resulted in higher power generation and lower brake specific fuel consumption when compared to B100. According to the result obtained, used cooking oil originated biodiesel can be utilized as a neat fuel or as a blend component during generator applications in rural areas and indoor applications.

Introduction Diesel fuel and diesel fuel emissions have serious environmental effects. Biodiesel has proven itself as a technically sufficient alternative diesel fuel in the fuel market since the beginning of 1990s in several commercial applications. Advantages of the fuel can be listed as follows: it reduces greenhouse gas emissions; it helps to reduce a country’s reliance on crude oil imports and supports agriculture by providing a new market for domestic crops; it enhances the lubricating property; and it is widely accepted by vehicle manufacturers.1-3 The most important characteristic of biodiesel is its blend-component characteristic. A simple classification of the fuel applications can be defined in three major categories for biodiesel: biodiesel or B100; blended with No. 2 Diesel fuel to various levels (typically 20 or 50%, named B20 and B50); an additive at very low levels such as 1, 2, and 5% (B1, B2, and B5).4 * To whom correspondence should be addressed. E-mail: [email protected]. Tel.: +90 212 285 68 37. Fax: +90 212 285 29 25. (1) Palz, W.; Spitzer, J.; Maniatis, K.; Kwant, N.; Helm, P.; Grassi, A. Proceeedings of 12th International European Biomass Conference; ETA-Florence, WIP-Munich: Amsterdam, The Netherlands, 2002; Vols. 1 and 2. (2) Bockey, D.; Ko¨rbitz, W. Situation and Development Potential for the Production of BiodieselsAn International Study. Available via the Internet at www.ufop.de, 2002. (3) Clarke, L. J.; Crawshaw, E. H.; Lilley, L. C. Fatty Acid Methyl Esters (FAMEs) as Diesel Blend Component. In 9th Annual Fuels & Lubes Asia Conference and Exhibition, Singapore, January 21-24, 2003.

Generators convert mechanical energy to electrical energy in the form of alternative or direct currents. Because of difficulties in transforming direct currents to long distances, today commercial generators produce, mainly, alternative currents. Temporary backup petroleum diesel-fueled generators typically operate in emergencies without the benefit of exhaust after-treatment to reduce emissions. Using alternative fuels for these necessary backup power sources is a cost-effective method for environment protection. Biodiesel, as a generator fuel alternative, reduces particulate matter, CO, CO2, total hydrocarbon, and SO2 emissions. Perhaps the next most critical pollutant from the perspectives of human health and environmental quality is NOx. The triumvirate of CO, THC (total hydrocarbons), and NOx is the key to controlling groundlevel ozone and smog in urban areas. Biodiesel effectively reduces tailpipe emissions of CO and THC. However, both B100 and B20 have life cycle and tailpipe emissions of NOx that are higher than those of petroleum diesel. Total particulate matter (PM), PM10 (particulate matter smaller than 10 microns), and NOx emissions are inversely related in diesel engine exhaust; reducing one often leads to increasing the other. The amount of SOx in the emissions from a diesel engine is (4) Clements, D. L. Identification and Development of Markets. Presented at Business Management for Biodiesel ProducerssWorkshop I; Iowa State University, Mechanical Engineering Department: Ames, IA, October 23-25, 2003.

10.1021/ef049890k CCC: $30.25 © 2005 American Chemical Society Published on Web 02/23/2005

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a function of sulfur content in the fuel. With this in mind, the Environmental Protection Agency regulates diesel fuel’s sulfur content rather than tailpipe SOx emissions. The latest requirements for diesel fuel include 0.05 wt % sulfur for on-highway fuel. Biodiesel can eliminate tailpipe SOx emissions because it is sulfurfree. If we summarize the emission characteristics of biodiesel, biodiesel can dramatically reduce particulate matter emissions. Unburned hydrocarbons and carbon monoxide are also reduced, although they are not usually a problem with diesel engines. Although the gradual start of combustion of biodiesel would be expected to cause a lower level of NOx emissions, in fact, the opposite occurs. NOx is generally found to increase with the use of biodiesel. The reason for the NOx increase is still an area of active research, but it is at least partially due to injection timing advances associated with property differences between biodiesel and No. 2 diesel fuel.5-9 These characteristics of biodiesel makes the fuel a better choice than No. 2 diesel fuel for indoor and agricultural generator applications. In this study, the diesel engine and generator performances of used cooking oil originated biodiesel as a neat fuel (B100) and a blend component (B20) were investigated. The two alternative diesel fuel candidates are presented to the literature as a candidate for generator fuel applications. Literature Review Since the beginning of the 1980s, diesel engine performance of biodiesel (automobiles, fleet vehicles, tractors, etc.) has been extensively tested by government agencies, university researchers, and private industry in the United States, Canada, and Europe. Nye investigated the vehicle performance of soybean oil originated used cooking oil on 1981 Volkswagen Rabbit automobiles for 4157 km. At the end of the test drives, all vehicle-performance parameters were similar to No. 2 diesel fuel other than reductions in engine power.10 Also, Guo et al. studied three different feedstocks for biodiesel production. The aim of the study was to investigate the optimum conditions for biodiesel production and to study the fuel properties and engine performance of produced biodiesel samples at a light diesel van on a chassis dynamometer. Experiments showed that utilization of biodiesel produced reduced smoke and HC emissions, while the NOx emissions changed slightly. An unnoticeable drop in the maximum engine power output was observed even at 100% biodiesel.11 Another study on used cooking oil originated (5) Biodiesel, Report of National Renewable Energy Laboratory; Task No. BF 88 6002, Golden, CO, 1998. (6) Biodiesel Development Corporation. Biodiesel Report; USA, 2002. (7) Sharp, C. A., Howell, S. A.; Jobe, J. The Effect of Biodiesel Fuels on Transient Emissions from Modern Diesel Engines, Part I. Regulated Emissions and Performance, 2000, SAE Paper 2000-01-1967. (8) Tat, M.; Gerpen, J. V. Physical and Chemical Property Effects on Biodiesel NOx Emission. Presented at the 94th AOCS Annual Meeting and Expo, Kansas City, MO, May 4-7, 2003. (9) McCormick, R. L., Alvarez, J. R.; Graboski, M. S. NOx Solutions for Biodiesel. National Renewable Energy Laboratory Final Report; NREL/ SR-510-31465, Golden, CO, 2003. (10) Nye, M. J. Methyl Ester from Used Frying Oil as a Diesel Fuel. Bioenergy 1984, 84, 211-214. (11) Guo, Y.; Leung, Y. C.; Koo, C. P. A Clean Biodiesel Fuel Produced from Recycled Oils and Grease Trap Oils. Presented at Better Air Quality in Asian and Pacific Rim Cities (BAQ 2002), Hong Kong, Japan, December 16-18, 2002.

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biodiesel exhaust emissions was conducted by Dorado et al. Exhaust emissions of diesel direct injection Perkins engine fueled with waste olive oil methyl ester were investigated at several steady-state operating conditions. Emissions were characterized with biodiesel from used olive oil and No. 2 diesel fuel. The use of biodiesel resulted in lower emissions of CO, CO2, NO, and SO2 with an increase in emissions of NO2. Biodiesel also presented a slight increase in brake specific fuel consumption. Combustion efficiency remained constant using either biodiesel or No. 2 diesel fuel.12 Dorado et al. also conducted a study where they determined the feasibility of running a 10% waste vegetable oil-90% diesel fuel blend during a 500-h period in a 3-cylinder, direct-injection, 2500-cm3 Diter diesel engine. An approximate 12% power loss, slight fuel consumption increase, and normal smoke emissions were observed. The Diter diesel engine, without any modifications, ran successfully on a blend of 10% waste oil-90% diesel fuel without externally apparent damage to the engine parts. As a result, it was concluded that the long-term use of waste oil blended with diesel fuel may need further testing before use as a viable energy solution.13 Another study was conducted by Gomez et al. to investigate the exhaust emissions and performance characteristics of a Toyota van, powered by a 2l indirect injection (IDI) naturally aspirated diesel engine, operating on vegetablebased waste cooking oil methyl ester. Waste cooking oil methyl ester developed a significantly lower smoke opacity level and reduced CO, CO2, and SO2 values, whereas O2, NO2, and NO levels were higher when compared to No. 2 diesel fuel. Power values were comparable for the two fuels.14 The work of Zaher et al. had some different aspects than the above studies; they studied the utilization of used frying oil as an alternative fuel for diesel engines. Used frying oil was modified with thermal cracking in the presence of 2% CaO to reduce viscosity. The fuel properties of modified oil were determined, and the performance of the oil as 50% blend with No. 2 diesel fuel was evaluated. The product obtained after thermal cracking showed similar properties that of No. 2 diesel fuel. The output power, brake thermal efficiency, and brake specific fuel consumption of the diesel engine changed markedly by blending the cracked product and No. 2 diesel fuel.15 Another study where oil/No. 2 diesel fuel blends were tested was conducted by Jones et al. where the authors used an imaging system to compare injector coking when used vegetable oil from local grocery store deli fryers was used as a diesel fuel replacement in small portions. Fuel blends containing 2.5-20% used vegetable oil were studied to determine which oil fuel blend would be optimal for future engine testing. The 2.5% oil fuel blend had an injector coking level slightly more than that of (12) Dorado, M. P.; Ballesteros, E.; Arnal, J. M.; Gomez, J.; Gimenez Lopez, F. J. Exhaust Emissions from a Diesel Engine Fueled with Transesterified Waste Olive Oil. Fuel 2003, 82, 1311-1315. (13) Dorado, M. P.; Arnal, J. M.; Gomez, J.; Gil, A.; Lopez, F. J. The Effect of a Waste Vegetable Oil Blend with Diesel Fuel on Engine Performance. Trans. ASAE 2002, 45, 519-523. (14) Gomez, G.; Howard-Hildige, M. E.; Leahy, R.; O’Reilly, J. J.; Supple, B.; Malone, M. Emission and Performance Characteristics of a 2 Litre Toyota Diesel Van Operating on Esterified Waste Cooking Oil and Mineral Diesel Fuel. Environ. Monitor. Assess. 2000, 65, 1320. (15) Zaher, A. F.; Megahed, O. A.; El Kinawy, O. S. Utilization of Used Frying Oil as Diesel Engine Fuel. Energy Sources 2003, 25, 819826.

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No. 2 diesel fuel, while higher blends tended to have significantly higher injector coking levels.16 Tashtoush et al.’s study can be given as an example for the application of biodiesel as a heating fuel. Tashtoush et al. examined the aspects of combustion performance and emissions of the ethyl ester of used palm oil relative to No. 2 diesel fuel in a water-cooled furnace. The tests were conducted at an air/fuel ratio ranging from 10:1 to 20:1 and at two different energy input values. At the low-energy rate, biodiesel burned more efficiently with higher combustion efficiency and exhaust temperatures, whereas at the high-energy rate, it showed a weak performance due to its viscosity, density, and low volatility. The common pollutants and emissions were lower for biodiesel, when compared to No. 2 diesel fuel at both levels and whole range of air/fuel ratios.17 Al-Widyan et al. investigated the potential of palm oil ethyl ester used as vegetable oil to substitute oilbased diesel fuel. The tests were conducted with several ester/diesel blends including 100% No. 2 diesel fuel and biodiesel as a baseline fuel. The experiments were conducted on a standard test rig of a single-cylinder, direct-injection diesel engine. As a result, it was investigated that the blends were burnt more efficiently with less specific fuel consumption, and resulted in higher engine thermal efficiency and less CO and unburned HC emissions. The best results were obtained with 100% biodiesel and 75:25 ester/ diesel blends, whereas the best results were obtained with 50:50 blend for emission amounts at all speed ranges tested.18 At Iowa State University, C¸ anakc¸ ı and Van Gerpen studied the effect of the biodiesel produced from high free fatty acid feedstocks on engine performance and emissions. Two different biodiesels were prepared from animal fat-based yellow grease with 9% free fatty acids and from soybean oil. The neat fuels and their 20% blends with No. 2 diesel fuel were studied at steady-state engine operating conditions in a 4-cylinder turbocharged diesel engine. A reduction in particulates, CO, and unburned HC were observed, whereas an increase of 11 and 13% in NOx emissions appeared for the yellow grease and soybean methyl esters. The conversions of biodiesel and No. 2 diesel fuels energy to work were equal.19 Studies on used cooking oil originated biodiesel go on in Turkish universities. The objective of the study of Ulusoy et al. was to investigate the effects of used frying oil originated biodiesel on engine performance and emissions in a Fiat Doblo 1.9 DS, four-cylinder, four-stroke, 46-kW power capacity diesel engine. Comparative measurements with No. 2 diesel fuel were done on both, engine power and emission characteristics of each fuel. Biodiesel, when compared to No. 2 diesel fuel, showed reduction in wheel force over 3.35%, and it also reduced the wheel power over by 2.03%. In the acceleration tests, 40-100 and (16) Jones, S. J.; Peterson, C. L.; Thompson, J. C. Used Vegetable Oil Fuel Blend Comparisons Using Injector Coking in a DI Diesel Engine. Presented at the 2001 ASAE Annual International Meeting; Sacramento, CA, July 30-August 1, 2001. (17) Tashtoush, G.; Al-Widyan, M. I.; Al-Shyoukh, A. O. Combustion Performance and Emissions of Ethyl Ester of a Waste Vegetable Oil in a Water-Cooled Furnace. Appl. Therm. Eng. 2003, 23, 285-293. (18) Al-Widyan, M. I.; Tashtoush, G.; Abu-Quadis, M. Utilization of Ethyl Ester of Waste Vegetable Oils as Fuel in Diesel Engines. Fuel Process. Technol. 2002, 76, 91-103. (19) C¸ anakc¸ ı, M.; Van Gerpen, J. Comparison of Engine Performance and Emissions for Petroleum Diesel Fuel, Yellow Grease Biodiesel, and Soybean Oil Biodiesel. Trans. ASAE 2003, 46, 937-944.

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60-100 km/h acceleration periods were measured, and reductions of 7.32 and 8.78% were observed, respectively. According to emission tests, as a result of biodiesel consumption, a reduction of 8.59% in CO emission and an increase of 2.62% were observed in CO2 emission. Also, as a result of biodiesel consumption, the NOx emissions increased by 5.03%. HC emissions and particulate emissions have significant effect on air pollution. As a result of biodiesel usage, HC and particulate emissions decreased by 30.66 and 63.33%, respectively. When the fuel consumption amounts were compared, it was observed that biodiesel consumption was 2.43% less than that of No. 2 diesel fuel.20 Another study of the same group was presented in C¸ etinkaya et al.’s study. The objective of C ¸ etinkaya et al.’s study was to investigate the engine performance test and the road test performance of used cooking oil originated biodiesel in Renault Me´gane automobile and 4-stroke, 4-cylinder, F9Q732 code and 75-kW Renault Me´gane diesel engine in winter conditions for 7500-km road tests in the urban and long-distance traffic. The results were compared to No. 2 diesel fuel. The results indicated that the torque and brake power output obtained during used cooking oil originated biodiesel application were 3-5% less than that of No. 2 diesel fuel. The engine exhaust gas temperature in each engine speed of biodiesel was less than that of No. 2 diesel fuel. Injection pressures of both fuels were similar. The higher values of exhaust pressures for No. 2 diesel fuel were achieved in each engine speed. As a result of No. 2 diesel fuel application, engine injectors were carbonized, normally. After the first period, as a result of winter conditions and insufficient combustion, carbonization in injectors was observed after biodiesel usage. As a result of second chamber, since the viscosity of biodiesel was decreased, injectors were observed to be cleaner. Also, no carbonization was observed on the surface of cylinders and piston heads. Catalytic converter was plugged because of viscosity in the first period. At the second period, no problem was observed on the catalytic converter.21 It was found out that there is limited number of studies on biodiesel’s generator application in the scientific literature. Leung conducted experiments on a Diesel generator (Robin GS 3300RD), which consisted of a generator and a 4-stroke single cylinder Diesel engine with rated power of 3.4 kW. CO levels decreased with increasing biodiesel percentages for both idle and loaded conditions. NOx levels showed a decreasing trend for the idling case, whereas at loaded conditions, the levels fluctuated within a narrow range. The fuel consumption showed a slight increase with increasing biodiesel percentage for idle and loaded conditions.22 As a part of the M.Sc. study conducted by Rothermal, emission level comparisons between No. 2 diesel fuels and methyl esters were investigated. Exhaust emission comparisons between biodiesel and No. 2 diesel fuels showed an average 10% increase in NOx for biodieselbased fuels at 80% of maximum engine power but an 11% decrease in NOx emissions at 100% of maximum (20) Ulusoy, Y.; Tekin, Y.; C¸ etinkaya, M.; Karaosmanogˇlu, F. Energy Sources 2004, 26 (10), 927-932. (21) C¸ etinkaya, M.; Ulusoy, Y.; Tekin, Y.; Karaosmanogˇlu, F. Energy Convers. Manage. 2005, 46, 1279-1291. (22) Leung, D. Y. C. Water, Air, Soil Pollut. 2001, 130, 277-282.

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Energy & Fuels, Vol. 19, No. 2, 2005 Table 1. EN 14214-2003 and Fuel Properties of Three Test Fuels test fuels test property

B100

B20

DF (ASTM D 6751)

water content, max (ppm) sulfur content, max (wt %) ash content, max (wt %) methyl ester composition (wt %) lauric acid C12:0 miristic acid C14:0 palmitic acid C16:0 stearic acid C18:0 arasitic acid C20:0 beheric acid C22:0 lignoseric acid C24:0 palmitoleic acid C16:1 oleic acid C18:1 linoleic acid C18:2 calcd mean molecular weight (kg/kg‚mol) linolenic acid methyl ester content, max (wt %) free glycerin content, max (wt %) total glycerin content, max (wt %) refractive index, n20 D acid value, max (mg KOH/g) iodine number, max (g I-/g) peroxide value (mg O-/kg) color specific gravity 25/25 °C kinematic viscosity @ 40 °C (cSt) flash point, max (°C) pour point (°C) cloud point (°C) cold filter plugging point (°C) cetane index, min Conradson carbon residue, CCR, 100% as 10%, max (wt %) copper strip corrosion, max (50 °C, 3 h) low heating value (MJ/kg) high heating value (MJ/kg)

480.07 0.034 0.03

258.86 0.378 none

66.53 0.494 none

0.06 0.25 12.26 3.75 0.34 0.51 0.20 0.26 26.56 55.81 278.08 none 0.011 0.206 1.4559 0.289 125.34 0.954 1.0 884.4 4.79 176 -3 9 -6 66.3 0.032 No. 1 42 42.89

engine power. Smoke tests showed significantly reduced particulate emissions for biodiesel at all operating conditions with an average 27% reduction at 80% of maximum engine power and a 54% reduction at 100% of maximum engine power. Exhaust gas temperatures were reduced under all operating conditions for the biodiesel-based fuels as compared to the No. 2 diesel fuels.23 Also, Bickel and Norris investigated little direct testing of soy-based biodiesel fuels in diesel-powered electric generators (gensets). Neat biodiesel was blended with regular and premium commercial low-sulfur petroleum diesel fuel. B20 and B85 were chosen as test fuels. Two primary NOx control techniques were tested in laboratory tests: charge-air cooling and a cetane number improving fuel additive. For particulate matter, CO, and hydrocarbon reduction, a diesel oxidation catalyst was evaluated. A 276-kW Cummins model ISM was selected to be the laboratory test engine. Screening tests using a NOx reducing fuel additive and biodiesel blends were conducted to see if the fuel additive could offset the increase in NOx emissions that normally occur using biodiesel. The fuel additive was not effective at reducing NOx in the biodiesel blends. Full emissions tests of the biodiesel blends with charge-air cooling demonstrated that significant particulate, CO and gaseous HC reductions can be achieved using B20 or B85 while lowering emissions of NOx. Particulate emis(23) Rothermal, J. G. Investigation of Transesterification Reaction Rates and Engine Exhaust Emissions of Biodiesel Fuels, M.Sc. Thesis, Iowa State University, Mechanical Engineering Department, Ames, IA, 2003.

test method ASTM D 2709 ASTM D 5453 ASTM D 482

EN 14214-2003 biodiesel standard 500 10 0.02

AOCS Ce 1-62

calculation AOCS Ce 1-62

1.0 848.8 3.5 82 -9 9 -16

0.5 839 3.27 79 -9 6 -16

0.023 No. 1 42.5 45.33

0.017 No. 1 42.7 45.55

USP glycerin RS AOCS Cc 7-25 AOCS Te 1a-64 AOCS Tg 1-64 AOCS Cd 8-53 ASTM D 1500 ASTM D 1298 ASTM D 445 ASTM D 93 ASTM D 97 ASTM D 2500 ASTM D 6371 ref 26 ASTM D 189-01 ASTM D 130 ASTM D 4868 ASTM D 4868

12 0.25 0.5 120 860-900 3.5-5.0 120 see Table 2 51 0.3 No. 1

sions were reduced by up to 30%, while NOx reductions of up to 19% were observed. The use of a catalytic convertor increased particulate emissions using B20, but reduced particulate emissions when used with B85. No significant change in generator performance was observed.24 Experimental Section Materials and Methods. Refined used cooking oil originated biodiesel used in diesel-engine and diesel-generator performance tests was produced under the following conditions; oil/alcohol molar ratio, 1:5; catalyst amount, 2% by the weight of oil; temperature, 55 ( 2 °C; pressure, atmospheric; mixing speed, 40 rpm; reaction time, 1 h according to C¸ etinkaya and Karaosmanogˇlu’s study.25 The determined base-catalyzed transesterification reaction conditions were applied in a pressurized, 100 L with a D/L ratio of 1, stainless steel, cone bottom reactor equipped with 0.5-kW explosion-proof mixer, which has a fixed speed of 80 rpm and an internal water heating jacket. Fuel properties of used cooking oil originated biodiesel (B100), B20 (20 (v/v)% biodiesel + 80 (v/v)% No. 2 diesel fuel), and No. 2 diesel fuel are presented in Table 1 and will be discussed further in the study. The engine and generator performance tests were conducted at Anadolu Motor, Istanbul, Turkey. The test engine was a (24) Bickel, K.; Norris, M. Presented at the 95th AOCS Annual Meeting and Expo; Cincinnati, OH, May 9-12, 2004. (25) C¸ etinkaya, M.; Karaosmanogˇlu, F. Energy Fuels 2004, 18 (6), 1888-1895. (26) Krisnangkura, K. J. Am. Oil Chem. Soc. 1986, 63 (4), 552553.

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Table 2. Required CFPP Limits Depending on Temperature and Arctic Climates in EN 14214-2003 Temperature Climate Limit (CFPP, max) (°C) grade A

grade B

grade C

grade D

grade E

grade F

+5

0

-5

-10

-15

-20

Arctic Climate Limit (CFPP, max) (°C) class 0

class 1

class 2

class 3

class 4

-20

-26

-32

-38

-44

Table 3. Conditions for the Engine Preparation Stage interval (min)

speed (rpm)

power (kW)

0-5 5-10 10-15 15-20 20-25 25-30

1200 1500 2000 2500 2800 3000

0.45 0.75 2 4 5.2 7.3-8.1 (full speed)

product of Anadolu Motor, 3 LD 510 coded diesel engine. The test engine was a 90-mm stroke, 1-cylinder diesel engine with 510-cm3 displacement and had a power capacity of 9 kW and maximum rotation speed of 3000 rpm. The power generation, torque, fuel consumption, exhaust temperature, oil pressure, and temperature were measured with “Borghi & Saveri s.r.l.” dynamometer. Smoke values were measured with “Bosch Dieselrauch Tester EFAW 65A” apparatus. The engine performance test set was prepared according to “Anadolu Motor Final Control Test Instruction K.K.P.01.T.14” and “Anadolu Motor Instruction for Dynamometer Usage MJ.P.01.T.28”. According to the above instructions, tests were carried out in following manner: At the engine preparation stage, the engine was kept working at given conditions in Table 3 for 30 min to reach the steady state until the engine temperature rose to 80-90 °C. After this stage, determined idle maximum speeds were controlled. The engine was allowed to reach the steady state at 90 °C and 3000 rpm with maximum load and maximum power between 7.3 and 8.1 kW for 1 h. After 1 h, performance parameters, which are power production, fuel consumption, emissions, exhaust temperature, oil temperature and pressure, and medium temperature, were measured for loads between speeds of 3000 and 1800 rpm for diesel fuel, B100, and B20, and the results were recorded. The accuracy of the results can be explained by the working principle of the dynamometer system. The dynamometer measures the torque values by the help of a load cell. These equipments work with an accuracy of (0.005. Other mechanical and electronical parts of the system work with (0.003 accuracy so that in general dynamometer system measures results with (0.005 accuracy. Generator performance tests were conducted according to “Anadolu Motor Instruction for Resistance Load Test Apparatus MJ.P.02.T.03”. The experimental set consisted of two units. The first unit was a resistance load test apparatus, Hilkar-Adapazari, Turkey, with 36 kW, 380 V, and 54 A. The second unit of the experimental set was one of the products of Anadolu Motor, A 100 LB diesel generator set. The generator set consisted of a rotating field three-phases AC generator driven by a 4 LD 640, 1-cylinder diesel engine. The engine has a displacement of 638 cm3 with a 95-mm bore and a 90-mm stroke. The engine is naturally aspirated with a compression ratio of 17:1 and is electronically governed to 3000 rpm. The AC generator unit had a maximum output of 10 kVA with a frequency of 50 Hz. The generator set had a noise level of 88 dB(A) at 7 m. The generator was run with diesel fuel, B100, and B20, respectively. Frequency output, voltage, and current outputs for three phases, R, S, and T, were recorded at three different kW values around 3.5, 7.5, and 8.5 kW.

Results and Discussion The properties of B100, B20, and No. 2 diesel fuel are presented in Table 1. The kinematic viscosity of used cooking oil originated biodiesel was measured as 4.79 cSt, when compared to 55 cSt of kinematic viscosity of used cooking oil; as it can be seen, transesterification reaction can easily eliminate one of the obstacles of vegetable oil applications as a diesel engine fuel. Also, the specific gravity of used cooking oil originated biodiesel was measured as 884.4. The minimum biodiesel water content requirement is 500 mg/kg according to EN 14214-2003. As a result of measurements conducted according to ASTM D 6304; water content of 480.07 mg/ kg for used cooking oil originated biodiesel. This composition is acceptable, with 96.5 wt % methyl ester requirement of EN 14214-2003 standard. Fatty acid methyl ester composition is composed of mainly oleic and linoleic acid methyl esters with 26.56 and 55.81 wt %, respectively. Linolenic acid methyl ester content was determined with a GLC analyzer, and it was determined as 0 wt %, which was in accordance with maximum 12 wt % of linolenic acid methyl ester content requirement of EN 14214-2003. According to the USP glycerin RS standard method, as was discussed above, the total glycerin amount was determined as 0.206 wt %, which was lower than the 0.25 wt % requirement of the EN 14214-2003 standard. Also, free glycerin content of the fuel was measured as 0.011 wt % according to AOCS Ca 14056, which was lower than the 0.02 wt % requirement of the EN 14214-2003 standard. Refractive index of biodiesel was determined as 1.4559. Also the acid value, iodine value, and peroxide value of B100 were determined as 0.289 mg KOH/g, 125.34 mg I-/g, and 0.954 mg O-/kg, respectively, by AOCS standard test methods. The acid value of B100 was in accordance with the maximum required limits given in EN 14214-2003 Biodiesel Standard. The iodine value of the neat fuel is slightly higher than that of required EN 14214-2003 iodine value limit. The iodine value is related to the chemical structure of the fuel. It is the indicator of the number of double bonds in the structure, and also the high iodine value has a good influence on cold flow properties of biodiesel. With the combustion mechanism of hydrocarbons, it is required to have an aliphatic structure, where number of double bonds must be low. This requirement is also limited by the standard limits of linolenic acid methyl ester composition for biodiesel. Also as it is mentioned, the iodine value is directly related to cold-flow characteristics of the fuel. The iodine value measured is very close to the announced limit of 120 mg I-/g in the biodiesel standard, and when the measured cloud point is considered, it is expected that there will not be serious effect on the engine performance. Sulfur content is the most important advantage of biodiesel over No. 2 diesel fuel. Environmental

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concerns put certain limitations to sulfur content of petroleum-based diesel fuel products. EN 14214-2003 sulfur content requirement of biodiesel is 0.5 wt %. According to our tests, used cooking oil originated biodiesel sulfur content was determined to be 0.034%. The flash point of biodiesel was determined to be 176 °C. Cold-flow properties of biodiesel are important indicators of commercial applicability of the fuel. As it is mentioned before, R&D studies on commercial coldflow improvers increase every day, and new products are served to fuel market by famous companies. The cloud point of biodiesel was measured as 9 °C. There is no limitation for biodiesel’s cloud point in the EN 142142003 biodiesel standard. The cloud point of biodiesel must be reported to the customers by the producers to make them be prepared for any implications due to weather conditions. Pour points were measured as -3 °C for biodiesel. Cold filter plugging point tests were conducted according to ASTM D 6371 Standard Test Method for Cold Filter Plugging Point of Diesel and Heating Fuels. Also, required CFPP limits depending on temperature and arctic climates in EN 14214-2003 Biodiesel Standard are given in Table 2. For biodiesel, this value was measured to be 6 °C, which can be considered as Grade C according to temperature climate limits. Also, in Turkey, required limits for cold-filter plugging points of Automative Diesel (TS 3082 EN 590) are announced as “Winter Grade” and “Summer Grade”. The required limit for “Winter Grade” is -10 °C, whereas for “Summer Grade”, it is 5 °C. According to our test results, used cooking oil originated biodiesel can be used as a substitute of “Summer Grade” automotive diesel in Turkey. The cetane index of B100 was measured as 66.3 with the help of the Kriskangkuna method for the calculation of cetane index of methyl esters, where the standards limitation for this property is 51. According to the ASTM D 130 Standard Test Method for Detection of Copper Corrosion from Petroleum Products by the Copper Strip Tarnish Test, all three fuels were graded as No. 1. These results match with the required limit of EN 14214-2003 for both B100 and B20. Carbon residues of B100, B20, and diesel fuel were measured according to ASTM D 189 Standard Test Method for Conradson Carbon Residue of Petroleum Products. Required limit for carbon residue is 0.3 wt % in EN 14214-2003 for 10% distillation residues. For biodiesel, it is not possible to distillate the sample so that the carbon residue tests were conducted on 100% distillation residue samples showed that both B100 and B20 were in the accepted range with 0.032 and 0.023%, respectively. High carbon residue measurements can be collected in a region within the injection nozzle where it can limit the range of motion of moving parts. Measurements show that B100 and B20 did not have a tendency to form in-cylinder carbon deposits. Low and high heating values of B100, B20, and diesel fuel were calculated according to ASTM D 4868, which correlates the density, water content, sulfur content, and ash content of a fuel to determine the heat of combustion values. Low and high heating values of B100 and B20 are lower than that of diesel fuel. Low heating value of combustion values for B100, B20, and diesel fuel were measured as 42, 42.5, and 42.7 MJ/kg, respectively. High heating values of B100, B20, and diesel fuel were

Table 4. Results of Engine Tests of B20, B100, and DF n-crank (rpm)

time (s)

exhaust temp (C°)

oil temp (C°)

oil pressure (bar)

3000 2800 2600 2400 2200 2000 1800

86.50 88.20 91.60 95.20 98.30 100.60 110.30

Fuel Type B20 521 507 510 501 515 523 517

119 119 119 119 118 118 118

3.1 2.9 2.8 2.7 2.5 2.3 2.0

3000 2800 2600 2400 2200 2000 1800

81.10 83.30 86.90 89.60 92.40 98.20 105.30

Fuel Type B100 508 472 476 469 484 482 475

122 122 120 119 118 118 116

3.0 2.9 2.8 2.6 2.5 2.3 2.1

3000 2800 2600 2400 2200 2000 1800

88.2 91.9 92.9 97.6 99.0 106.1 115.2

Fuel Type DF 529 521 520 517 531 530 519

120 119 119 119 118 118 118

3.0 2.9 2.8 2.7 2.5 2.3 2.0

measured as 42.89, 45.33, and 45.55 MJ/kg, respectively. The results were close to each other for the three test fuels; therefore it is important to indicate that the reproducibility of ASTM D 4868 method is 0.15 MJ/kg and that the repeatability of the method is 0.05 MJ/kg. Lower heats of combustion of B100 and B20 resulted in higher brake specific fuel consumption values in diesel-engine and diesel-generator performance tests, which will be discussed in the coming sections. In Table 4, exhaust temperature, oil pressure, and temperature measurements of B20, B100, and diesel fuel between speeds of 1800 and 3000 rpm are presented. Also, results of power generation, brake specific fuel consumption, and Bosch smoke number tests for three test fuels between the speeds of 1800 and 3000 rpm are presented in Figures 1, 2, and 3. Oil temperature of three test fuels ranged between 116 and 122 °C. As can be seen from Table 4, oil pressure was measured between 2.0 and 3.1 bar. One of the parameters was exhaust temperature. Exhaust temperatures at full load for changing engine speeds between 3000 and 1800 rpm for B100 and B20 were less than that of diesel fuel. The maximum and minimum exhaust temperatures at 3000 rpm for DF were measured to be 529 and 519 °C, whereas for B100 and B20 it was 521 and 517 and 508 and 475 °C, respectively. Lower exhaust gas temperature is an indicator of earlier combustion and lower heating value of biodiesel blends. Earlier combustion allows more time and crank angle for the expansion process to remove energy from the hot combustion gases. One of the strong factors affecting these temperatures is ignition timing. Early ignition timing has the effect of increasing the combustion temperature while reducing the exhaust gas temperature due to a longer expansion period. Biodiesel has a high cetane index that reduces the ignition delay after injection. The fuel injection pump also begins injecting biodiesel earlier than with diesel fuel in order to make up for the lower heating value of B100 and B20 when running at the same power levels. This results in an

Cooking Oil Originated Biodiesels

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Figure 1. Power generation results for B20, B100, and DF. Figure 3. Bosch smoke numbers for B20, B100, and DF. Table 5. Generator Performances of B20, B100, and DF Voltage (kVA) power (kW)

Figure 2. Brake specific fuel consumption characteristics of B20, B100, and DF.

artificially advanced timing and earlier ignition. All of these factors have the tendency to increase the combustion temperature of B100 and B20, while decreasing the exhaust gas temperatures as obtained in our experiments. In Figure 1, generated powers at given loads for three types of fuels are given. As it can be seen from Figure 1, as the load decreases, generated power by all fuels decreases. For B20 and B100, the maximum generated power was 7.45 kW, and minimum generated power values were 5.9 and 5.7 kW, respectively. A small decrease in power generation was observed as a result of B100 and B20 applications when compared to No. 2 diesel fuel in the range of 0.8% and 0.66%, respectively. The same power values were obtained as a result of B20 application. This observation shows that 20% biodiesel addition to No. 2 diesel fuel does not affect the fuel performance. The consumption time for 50 g of fuel sample was recorded in order to determine the brake specific fuel consumption (BSFC) of three types of fuel. The measurements are presented in units of g kW-1 h-1 unit, whereas the generated power amount and the fuel consumption times were combined. The results of BSFC calculations are presented in Figure 2. As it can be seen from Figure 2, specific fuel consumption values for B100 and B20 are higher than that of diesel fuel in the range of 10% and 4%, respectively. The lower heats of combustion for B100 and B20 require that a larger amount of fuel be injected into the engine to produce the same power. This results in the higher BSFC often noted for B100 and B20. The results of smoke tests are presented in Figure 3. The results show that, as a result of B100 and B20 usage in the engine, especially B100, significant deductions in the emission production were achieved. For B20 and B100, the maximum smoke values were 3.5 and 5.0 Bosch smoke numbers and minimum smoke values were 1.2 and 2.1 Bosch smoke numbers, respectively, whereas for DF, these values were measured to be 3.0 and 7.7

R

S

T

Current (A) R

S

T

frequency (Hz)

3.6 7.5 8.6

Fuel Type B20 244 243 246 4.8 5.1 5.2 243 240 242 10.0 10.0 10.3 238 232 236 9.6 9.8 11.3

52.40 51.01 49.61

3.6 7.3 8.3

Fuel Type B100 246 245 246 4.8 5.1 5.2 241 238 241 9.9 9.9 10.2 233 230 225 9.4 9.5 11.0

52.37 51.00 49.00

3.7 7.5 8.8

Fuel Type DF 247 245 247 4.7 5.1 5.2 243 240 243 10.1 10.0 10.2 241 238 231 9.6 9.7 11.4

52.47 51.00 50.00

Bosch. The smoke reduction was in the range of 60% for B100 and ∼25% for B20. These reductions are significant when the low carbon residue and sulfur content measurements are considered. Generator test results are presented in Table 5. Performances of three test fuels were measured at three different power values: ∼3.5, 7.5, and 8.5 kW. Voltage and current produced by the generator were measured for three different phases R, S, and T. The frequency of electricity production for three different kW values were also measured. Frequency measurements for diesel fuel, B20, and B100 gave similar results. As a result of diesel fuel, B20, and B100 application at ∼3.5 kW, frequencies of 52.57, 52.40, and 52.37 Hz were obtained, respectively. The results are close enough that B20 and B100 can be considered to have similar performance results when compared to diesel fuel. Although small decreases in voltage, current, and frequency of B20 and B100 were measured, these drops were in the range of 1% at most, which was considered to be negligible by the company authorities. The performance of generators generally decreases as the working time increases. Therefore, the decreasing trend in frequency was explained as a general trend for generator applications. Guo et al.11 showed that utilization of biodiesel produced reduced smoke and HC emissions while the NOx emissions changed slightly. An unnoticeable drop in the maximum engine power output was observed even at 100% biodiesel where the same results were obtained according to our studies. Dorado et al.12 characterized emissions with biodiesel from used olive oil and No. 2 diesel fuel. The use of biodiesel resulted in lower emissions of CO, CO2, NO, and SO2 with an increase in emissions of NO2. Biodiesel also presented a slight increase in BSFC. Combustion efficiency re-

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mained constant using either biodiesel or No. 2 diesel fuel; the results of this study are in accordance with Dorado et al.’s work. Dorado et al.13 also worked to determine the feasibility of running a 10% waste vegetable oil-90% diesel fuel blend during a 500-h period in a three-cylinder direct-injection, 2500 cm3 Diter diesel engine. Approximately 12% power loss, slight fuel consumption increase, and normal smoke emissions were observed, which are similar to our results. Gomez et al.14 investigated the exhaust emissions and performance characteristics of the Toyota van, powered by a 2l IDI naturally aspirated diesel engine, operating on vegetable-based waste cooking oil methyl ester. Waste cooking oil methyl ester developed a significantly lower smoke opacity level and reduced CO, CO2, and SO2 values, whereas O2, NO2, and NO levels were higher when compared to No. 2 diesel fuel. Power values were comparable for the two fuels, which can be considered as similar with our results. Al-Widyan et al.17 tested with several ester/diesel blends including 100% No. 2 diesel fuel and biodiesel as a baseline fuel. The experiments were conducted on a standard test rig of a single-cylinder, direct-injection diesel engine. As a result, it was investigated that the blends were burnt more efficiently with less specific fuel consumption and resulted in higher engine thermal efficiency and less CO and unburned HC emissions. The best results were obtained with 100% biodiesel and 75:25 ester/diesel blends, whereas the best results were obtained with 50: 50 blend for emission amounts at all speed ranges tested. As a part of the M.Sc. study conducted by Rothermal,23 emission level comparisons between No. 2 Diesel fuels and methyl esters were investigated. Exhaust emissions comparisons between biodiesel and No. 2 diesel fuels showed an average 10% increase in NOx for biodiesel-based fuels at 80% of maximum engine power but an 11% decrease in NOx emissions at 100% of maximum engine power. Smoke tests showed significantly reduced particulate emissions for biodiesel at all operating conditions with an average 27% reduction at 80% of maximum engine power and a 54% reduction at 100% of maximum engine power. Exhaust gas temperatures were reduced under all operating conditions for the biodiesel-based fuels as compared to the No. 2 diesel fuels, where the similar results were obtained in our studies.

Conclusion Diesel engine and generator performance tests of B100 and B20 gave similar results with diesel fuel. A small reduction of around 1% in power generation was observed as a result of B100 and B20 applications; these amounts were considered to be negligible, and its effect on generator performance was neglected. B100 reduced exhaust gas temperatures around 5% in average. The exhaust gas temperatures at all operating conditions for B20 and B100 were lower than for diesel fuel. The BSFC values of biodiesel blends (B20 and B100), especially for B100, were higher than that of diesel fuel. This increase in the BSFC for the neat fuel can be attributed to its lower heating value, which is 12% lower than that of No. 2 diesel fuel in average for B100. Generator performances of B20 and B100 were similar to that of DF. Frequency, voltage, and current measurements for three different phases of the AC generator gave acceptable results. Bosch smoke analysis was conducted after biodiesel application on generator engine. Results showed that B100 and B20 utilization ended in a reasonable reduction in smoke values. The reduction at maximum speed (3000 rpm) and minimum speed (1800 rpm) were at the range of 40 and 55%, respectively, for the neat fuel and 10 and 36% for B20. Further, the reduction in Bosch smoke number increases substantially with increased engine load. As a result, used cooking oil originated biodiesel is presented as an environmentally friendly alternative generator fuel candidate, in both forms which are neat fuel and blend component, as it is shown in this paper directly through the smoke number. Further investigation must contain the engine noise test and the measurements of specific emission types (NOx, SOx, CO, etc.). Acknowledgment. The authors would like to thank chemical engineer Serdar Kahyaogˇlu for his support and hard work during engine and generator tests. The authors would like to extend their gratitude to Anadolu Motor for their support. This study has been awarded with an “Industrial Oil Products Division Student Excellence Award” by the American Oil Chemists’ Society in May 2004 and with a “Rudolf Diesel Research Award” by MAN Turkey A.S. in October 2004. EF049890K