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A. Serdari K. Fragioudakis S. Kalligeros S. Stournas E. Lois e-mail: [email protected] Laboratory of Fuel Technology and Lubricants, Department of Chemical Engineering, National Technical University of Athens, Iroon Polytechniou 9, Zografou Campus 15700, Athens, Greece

Impact of Using Biodiesels of Different Origin and Additives on the Performance of a Stationary Diesel Engine With the exception of rape seed oil which is the principal raw material for biodiesel Fatty Acid Methyl Esters, (FAME) production, sunflower oil, corn oil, and olive oil, which are abundant in Southern Europe, along with some wastes, such as used frying oils, appear to be attractive candidates for biodiesel production. In this paper fuel consumption and exhaust emission measurements from a single cylinder, stationary diesel engine are described. The engine was fueled with fuel blends containing four different types of biodiesel, at proportions up to 100 percent; the further impact of the usage of two specific additives was also investigated. The four types of biodiesel appeared to have equal performance and irrespective of the raw material used for their production, their addition to the traditional diesel fuel improved the particulate matter emissions. The results improve further when specific additive combinations are used. 关S0742-4795共00兲00604-9兴

Introduction The necessity to cope with environmental pollution problems, the changes in petroleum distillate demands, and the strict requirements of modern diesel engines lead to the need to improve diesel fuel quality. The development of biomass derived substitutes for diesel fuel is a possible attractive outlet, as it could help improve diesel fuel quality. The substitution of conventional diesel fuel with rape seed oil methylesters comprises already a commercial activity in many countries of Central Europe 关1兴. However, the use of biodiesel has not expanded into Greece and other Southern European countries, due to the lack of adequate rape seed cultivation. Some other types of vegetable oils, such as sunflower oil, corn oil and olive oil, that are abundant in many Mediterranean areas, along with some wastes, such as used frying oils, appear to be attractive candidates for biodiesel production 关2兴. It must be stressed that the warranty of a product of extra high quality through the application of adequate relevant specifications is of the greatest importance and a key to scientifically proving its performance. It is well known that biodiesel is non-toxic, contains no aromatics, has higher biodegradability than fossil diesel, is less pollutant to water and soil and does not contain sulphur 关3,4兴. It offers safer handling in the neat form and shows reduced oral and dermal toxicity, mutagenic and carcinogenic compounds. It is the most suitable fuel in environmentally sensitive areas 共national parks, lakes, rivers兲 or in confined areas where environmental conditions and worker protection must meet high standards 共underground mines, quarries兲关5–7兴. In this paper exhaust emission and fuel consumption measurements from a single cylinder, stationary diesel engine are described. The engine was fueled with fuel blends containing four different types of biodiesel, at proportions up to 100 percent. For two types of biodiesel, the further impact of the addition of two specific additives was investigated. In general, according to our results, the substitution of mineral diesel with biodiesels produced from sunflower oil, corn oil, olive oil and used frying oils leads to a combination of positive and negative outcomes; the four types

of biodiesel tested performed in a similar way; they decreased exhaust emission of particulate matter, resulted in a limited change of nitrogen oxide emissions and in slightly increasing the volumetric fuel consumption. The strong advantage of the use of fatty acid methyl esters 共biodiesel兲 is the fact that independently on the raw material used for their production, the addition of biodiesel in the traditional diesel fuel improves the emissions of particulate matter 关8兴 which comprise a serious disadvantage of the diesel engine, especially in seriously polluted areas like Athens.

Experimental Procedure For this study, a stationary diesel powered Petter engine, model AV1-LAB was employed. The engine characteristics are cited in Table 1. The engine was fueled with four types of pure biodiesels, pure traditional road diesel and mixtures containing 10 percent, 30 percent, and 50 percent of each type of biodiesel. The four types of biodiesel were methyl esters produced from sunflower oil, corn oil, olive oil and used frying oil. The emission tests included HC, CO, CO2, NOx and particulate matter emission measurements under various loads up to 5 HP, the load being measured by shaft output. Volumetric fuel consumption was checked as well. Similar tests on the stationary diesel engine investigated the effect of using a combination of two specific additives, on exhaust emissions from fuel mixtures containing corn oil and used frying

Table 1 Stationary, Petter AV1-LAB engine

Contributed by the Internal Combustion Engine Division of THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS for publication in the ASME JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received by the ICE Division September 20, 1999; final revision received by the ASME Headquarters May 8, 2000. Technical Editor: D. Assanis.

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Table 2 Specifications of the exhaust emission analyzers

ments. For every fuel change, the fuel lines were cleaned, and the engine was left to run for at least 60 minutes to stabilize on the new conditions. No fuel filter was used.

Test Fuels The conventional diesel fuel was supplied by Hellenic Aspropyrgos Refinery and the values of its fuel properties are presented in Table 3. All types of biodiesel used in the currently described tests were supplied by the Italian company Florys Spa and their properties were in complete accordance with the Italian specifications for biodiesel 共CUNA specifications兲. The fuel properties of the four types of biodiesel are given in Table 4.

Discussion and Results oil biodiesel at various proportions. The two additives 共additive H1 and H2兲 are commercially available; H1 is a common diesel cetane improver 共iso-octyl nitrate兲, while H2 is a combustion improver. The additive H1 was used in a concentration of 200 ppm in the fuel mixture and the additive H2 was used in a concentration of 500 ppm. These two additives have already been used in previous experiments in our Laboratory; the two additives were used in various concentrations for diesel evaluation, and the combination of 200 ppm H1 and 500 ppm H2 seems to be a very good proportion, since it resulted in the reduction of both particulate and nitrogen oxide emissions 关9兴. Two exhaust emission analyzers were used: a Horiba instrument 共type MEXA 574-GE, that gauges HC, CO and CO2 exhaust emissions兲 and a NOx analyzer 共42C NO-NO2-NOx Analyzer High Level, Thermo Environmental Instruments Inc.兲. The specifications of the emissions analyzers are cited in Table 2. The above analyzers were supported by Exhaust Gases Transportation Heated Lines, 共Signal Instruments Co, model 530/540兲, and a Prefilter 共Signal Instruments Co, Prefilter Unit 333兲 that restrains the emitted particulates from entering the Horiba and Thermo Environmental analyzers. To measure particulate matter emitted from the stationary diesel Petter engine, equipment recommended by the Western Precipitation Division Joy Manufacturing Company was used. According to this method, exhaust gases pass through a fiber glass filter, while the flue gas volume is recorded by using a gas meter. Particulate matter weight results were obtained by subtracting the weight of the clean fiberglass filter from its weight at the end of the experiment, after drying. The procedure followed is depicted in Fig. 1. The filters used were glass microfiber by Whatman, Grade 934-AH. The filter face velocity of the exhaust gases was measured to be 1.3 m/sec, whereas, at the filter face, the average temperature was 150°C and the pressure drop 4⫻103 N/m2. Fuel was supplied to the Petter engine by an outside tank of about three-liter capacity, which could easily be drained for fuel changes; a glass burette of known volume was also attached in parallel to this tank and was used for fuel consumption measure-

The experiments in the stationary Petter engine included emission and consumption measurements, under various loads. The engine was fueled with five different fuels containing biodiesels, at various proportions. The fuels tested were low sulphur typical Greek road diesel and mixtures of the typical Greek road diesel containing 10 percent, 30 percent, and 50 percent by volume sunflower oil, corn oil, olive oil and used frying oil biodiesel. The pure 共100 percent兲 biodiesels were also examined. Also, the impact of the additive combination 共200 ppm of the additive H1 and 500 ppm of the additive H2兲 on the performance of fuel mixtures containing corn oil and used frying oil biodiesel at various proportions was examined. The use of biodiesel fuels results in the reduction of unburned hydrocarbons and carbon monoxide 关10–12兴. However, in the course of our experiments, both of these pollutants were practically unaffected by the addition of every type of biodiesel; their emission levels were very low even when mineral diesel fuel was used. Moreover, their emission levels were much lower than the measuring accuracy of the Horiba Analyzer. The same performance was observed when the additive combination was examined. This behavior is attributed to the technology of the specific engine. The emission levels of the base fuel without and with the addition of additives are cited in Table 5; the mean values of 4 indiTable 3 Greek road diesel properties

Fig. 1 The sampling procedure for measuring particulate matter „PM…

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Table 4 Characteristic properties of the pure „100 percent… biodiesels

Table 6 Emission measurements of total nitrogen oxide „ppm… due to the addition of biodiesels and additives

vidual measurements along with their standard deviations at the 95 percent confidence level are included. In Tables 6 and 7 the effect, on the NOx emissions and the particulate matter 共PM兲, respectively, of adding the four investigated types of biodiesel and the additives to mineral diesel fuel, at various proportions and under various loads up to 5 HP 共full load兲, are presented along with their standard deviations at the 95 percent confidence. More specifically, 1 Regarding the impact of the four biodiesel containing fuels on total nitrogen oxide emissions, it seems that at low concentrations of biodiesel 共10 percent and 30 percent兲, total nitrogen oxide emissions are reduced in most cases, Table 6 and Figures 2–5. At high concentrations of biodiesel 共50 percent and 100 percent兲, in most of the cases total nitrogen oxide emissions are increased. This becomes more apparent at high loads 共75 percent and 100 Table 5 Emission measurements from the stationary Petter engine, when Greek diesel fuel was used „base fuel measurements…

percent兲, almost in all mixtures and for every type of biodiesel. These results are in agreement with the relevant literature 关13–16兴 which shows, in most of the cases, a trend to increase NO and NOx emissions. This increase is due to the oxygen content of the biodiesel, which leads to better oxidation of the nitrogen available, thus increasing the nitrogeneous emissions, although engine technology also plays an important role 关17兴. 2 As for the impact on particulate matter emissions of adding 626 Õ Vol. 122, OCTOBER 2000


Table 7 Emission measurements of particulate matter „mgÕm3… due to the addition of biodiesels and additives

Fig. 2 Percentage change of the total nitrogen oxide emissions „ppm…, due to the addition of sunflower oil biodiesel

Fig. 3 Percentage change of the total nitrogen oxide emissions „ppm… due to the addition of corn oil biodiesel

different types of biodiesel to mineral diesel fuel, the literature review 关16–19兴 shows that particulate matter emissions are generally reduced by the addition of biodiesel in the traditional diesel fuel, due to the oxygen contained in the biodiesel molecules and the abscence of sulphur. Some studies however, showed a big increase in particulate emissions in transient cycles 关17兴. In this study biodiesel appears to reduce particulate emissions almost in Journal of Engineering for Gas Turbines and Power

Fig. 4 Percentage change of the total nitrogen oxide emissions „ppm… due to the addition of olive oil biodiesel

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Fig. 5 Percentage change of the total nitrogen oxide emissions „ppm… due to the addition of used frying oil biodiesel

Fig. 7 Percentage change of particulate matter emissions „mgÕm3… due to the addition of corn oil biodiesel

all cases, Table 7 and Figs. 6–9. At low concentrations and loads the reduction is marginal, especially at 10 percent mixtures, whereas the most beneficial reductions appear at higher concentrations and loads. Although it is an important aspect of the particulate matter emitted from compression ignition engines, no further treatment was carried out to establish the soluble organic fraction 共SOF兲. The study of the impact of adding the specific combination of H1 and H2 additives 共200 ppm H1 and 500 ppm H2兲 to some of the above fuel blends included emissions 共NOx, particulates兲 and volumetric fuel consumption measurements in the same engine. For these experiments, fuel blends with corn oil biodiesel and used frying oil biodiesel were used. Table 5 shows the effect of the additives on the base fuel. It can be seen that for all loads there is a systematic decrease of the NOx emitted from the engine. This is to be expected, since the iso-octyl nitrate 共H1兲 is a Cetane Number improver which, at the concentration used, increases the base fuel Cetane Number by 1 unit. However, any increase in Cetane Number usually leads to lower NOx emissions 关17兴. The additive H2 is a combustion improver and, being an organometallic compound, it has a catalytic effect on the combustion process in the diesel engine 关17兴. Addition of 10 percent corn oil biodiesel into the base fuel plus additives, initially reduces NOx emissions for all loads, but this tendency is reversed for higher concentrations, the exceptions being at 30 per-

Fig. 6 Percentage change of particulate matter emissions „mgÕm3… due to the addition of sunflower oil biodiesel

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Fig. 8 Percentage change of particulate matter emissions „mgÕm3… due to the addition of olive oil biodiesel

Fig. 9 Percentage change of particulate matter emissions „mgÕm3… due to the addition of used frying oil biodiesel


cent addition of corn oil and loads up to 3.75 HP, Table 6. When used frying oil is added to the base fuel plus additives, there is a further decrease of NOx emissions at 0.1 HP irrespective of the biodiesel concentration, but this tendency again is reversed for higher loads. The notable result is that the use of the two additives into the mixture of the base fuel plus biodiesel, reduces NOx emissions further, practically for all loads and concentrations, irrespective of the type of the biodiesel used, Table 6 and Figs. 10–11. Table 5 shows that the addition of the additives H1 and H2 into the base fuel, reduces the particulate matter 共PM兲 emitted for all loads. Again, as explained earlier this behavior is expected given the nature of the additives 关17兴. Table 7 and Figs. 12–13 illustrate the impact of the addition of H1 and H2 additives, on particulate matter emissions, into fuel blends containing various concentrations of corn oil and used frying oil biodiesel, under various loads up to 5 HP. This combination, almost under any load, either did not affect or reduced the particulate matter emissions. The influence of the addition of the corn oil and used frying oil into the base fuel at various concentrations up to 100 percent, plus the additives H1 and H2, on the fuel consumption is presented in Figs. 14–17. All mixtures, under any load, resulted in slight in-

Fig. 10 Percentage change of the total nitrogen oxide emissions „ppm… due to the addition of corn oil biodiesel¿additives

Fig. 12 Percentage change of particulate matter emissions „mgÕm3… due to the addition of corn oil biodiesel¿additives

Fig. 13 Percentage change of particulate matter emissions „mgÕm3… due to the addition of used frying oil biodiesel¿additives

creases of fuel consumption. Due to the oxygen content and, consequently, to the lower calorific value of the fuels which contain biodiesel, this behavior was expected. No significant impact was observed owing to the use of the additive combination.

Conclusions

Fig. 11 Percentage change of the total nitrogen oxide emissions „ppm… due to the addition of used frying oil biodiesel¿additives


The substitution of mineral diesel with biodiesels produced from sunflower oil, corn oil, olive oil and used frying oils leads to a combination of positive and negative outcomes. The four types of biodiesel examined performed in a similar way; they clearly decreased particulate matter emissions, and resulted in a limited change of nitrogen oxide emissions and slightly increased the volumetric fuel consumption. The strong advantage of the use of fatty acid methyl esters 共biodiesel兲 seems to be the fact that independently on the raw material used for their production, the addition of biodiesel in the traditional diesel fuel improves the emissions of particulate matter which comprise a serious disadvantage of the diesel engine, especially in polluted areas. The specific combination of two additives does not affect exhaust emissions negatively; however, the additives may act as a drawback in some cases where biodiesel blends had achieved sigOCTOBER 2000, Vol. 122 Õ 629

Fig. 14 Fuel consumption for conventional diesel fuel and fuel blends containing 10 percent biodiesel withÕwithout the combination of H1 and H2 additives



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Fig. 17 Fuel consumption for conventional diesel fuel and 100 percent biodiesel withÕwithout the combination of H1 and H2 additives

nificant reduction in exhaust emissions. It was observed that the combination of the two additives was more effective in the cases when the biodiesel blends had not offered a notable reduction in particulate emissions and in the cases where the biodiesel blends had a negative or neutral effect on NOx emissions.

Acknowledgments Thanks are due to the European Commission, DG XVII, for their financial support in the frame of ALTENER 1995 Program. The authors wish to express their gratitude to Hellenic Aspropyrgos Refinery for supplying typical road diesel and to the Italian company Florys SPA for supplying the sunflower oil, corn oil, olive oil and used frying oil biodiesel.

Nomenclature

关4兴关5兴关6兴关7兴

关8兴关9兴

B10 ⫽ diesel fuel containing 10 percent biodiesel and 90 percent diesel fuel B30 ⫽ diesel fuel containing 30 percent biodiesel and 70 percent diesel fuel B50 ⫽ diesel fuel containing 50 percent biodiesel and 50 percent diesel fuel B100 ⫽ 100 percent biodiesel CO ⫽ carbon monoxide CO2 ⫽ carbon dioxide FAME ⫽ fatty acid methyl esters HC ⫽ hydrocarbons HP ⫽ horse power NDIR ⫽ non-dispersive infra-red NOx ⫽ nitrogen oxides ppm ⫽ parts per million

关16兴

References

关17兴

关1兴 Biodiesel, Documentation of the World-Wide Status 1997, 1997, Austrian Biofuels Institute, ABI, Austria. 关2兴 Korizi, A., 1995, ‘‘The Perspectives of Biodiesel Development in Greece,’’ Diploma thesis, Laboratory of Fuel Technology and Lubricants, National Technical University of Athens, Greece. 关3兴 ‘‘Acute Toxicity of Biodiesel to Freshwater and Marine Organisms,’’ 1996, Development of Rapeseed Biodiesel for Use in High-Speed Diesel Engines,


关10兴关11兴关12兴关13兴

关14兴关15兴

关18兴关19兴

Progress Report, University of Idaho, Dept. Biol. Ag. Eng., Moscow, ID, pp. 117–131. ‘‘Biodegradability of Biodiesel in the Aquatic Environment,’’ 1996, Development of Rapeseed Biodiesel for Use in High-Speed Diesel Engines, Progress Report, University of Idaho, Dept. Biol. Ag. Eng., Moscow, ID, pp. 96–116. Howell, S., and Weber, A. J., 1997, ‘‘Biodiesel Use in Underground Metal and Non-Metal Mines,’’ MARC-IV, LLC, Consulting, 具http://www.dieselnet.com/ papers/9705howell.html典. ‘‘Field Trials of Soy Methyl Esters as a Fuel for Diesel Powered Equipment in Underground Mines,’’ 1995, U.S. Bureau Of Mines/Air Quality Division, 具http://www.biodiesel.org/cgi-local/search典. ‘‘Summary results from NBB/USEPA TIER I Health and Environmental Effects Testing for Biodiesel Under the Requirements for USEPA Registration of Fuels and Fuel Additives,’’ 1998, Final Report, NBB/USEPA TIER I, 具http:// www.biodiesel.org/cgi-local/search典. Neeft, J., Makeem, P., and Moulijn, J., 1996, ‘‘Diesel Particulate Emission Control, Review Article,’’ Fuel Process. Technol., 47, pp. 1–69. ‘‘Development of a Double Treatment Package for Automotive Diesel Fuel— Stages I, II,’’ 1995, Final Report, Laboratory of Fuel Technology and Lubricants, National Technical University of Athens, Athens, Greece. Sharp, C., 1998, ‘‘Exhaust Emissions and Performance of Diesel Engines With Biodiesel Blends,’’ Southwest Research Institute, San Antonio, TX, 具http:// www.biodiesel.org/cgi-local/search典. Marshall, W., Schumacher, L., and Howell, S., 1995, ‘‘Engine Exhaust Emissions: Evaluation of a Cummins L10E When Fueled With a Biodiesel Blend,’’ SAE Paper 952363. ‘‘Biodiesel First Alternative Fuel to Meet EPA Health Effects Requirements,’’ 1998, Biodiesel Report, National Biodiesel Board. Serdari, S., Fragioudakis, K., Teas, C., Sakellaropoulos, F., Zannikos, F., Stournas, S., and Lois, E., 1998, ‘‘Adding Biodiesel Corn Oil and Sunflower Oil to Diesel Fuel: The Impact on the Performance of Conventional Road Vehicles,’’ J. Inst. Energy, 71, pp. 126–136. ‘‘Alternative Fuel Transit Buses,’’ First Report, 1995, U.S. Department of Energy, National Renewable Energy Laboratory Vehicle Evaluation Program. Ademe, E. U., 1995, ‘‘The Non-Technical Barriers ‘Liquid Biofuels’ European Network 共Used in Engines and Boilers兲,’’ DG XVII 共Altener Programme兲, Information Leaflet, Ademe, Paris. Akasaka, Y., Suzuki, T., and Sakurai, Y., 1997, ‘‘Exhaust Emissions of a DI Diesel Engine Fueled With Blends of Biodiesel and Low Sulfur Diesel Fuel,’’ SAE Paper 972998. Owen, K., and Coley, T., 1995, Automotive Fuels Reference Book, Society of Automotive Engineers, USA. ‘‘The Biodiesel Industry in the United States: An Industry on the Move. An Update,’’ 1995, American Biofuels Association, Arlington, VA. ‘‘Comprehensive Emissions and Chemical Characterization of Rapeseed OilDerived Biodiesel,’’ 1996, Montana Project, Biodiesel and Biolubricants Project, Bioenergy Program, Pacific Northwest and Alaska Regional Bioenergy Program.

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