Methyl Esters of Different Origin as a Fuel for Compression-Ignition Engines

Methyl Esters of Different Origin as a Fuel for Compression-Ignition Engines S. Kruczynski 1,2, K. Kolodziejczyk 1, P. Orlinski 2, M. Owczuk 1 1 AUTOMOTIVE INDUSTRY INSTITUTE, 55 Jagiellonska Str., 03-301, Warsaw, Poland 2 Institute of Vehicle, WARSAW UNIVERSITY OF TECHNOLOGY, 84 Narbutta Str., 02-524 Warsaw, Poland This chapter presents the physical and chemical properties of methyl esters of Camelina sativa (CME) and palm oils (PME) as well as methyl esters of animal fats (FME), compared to the properties of methyl esters of rapeseed oil (RME), in terms of their suitability for use as a bio-component or biofuel for diesel engines. The test mixtures were prepared with particular attention to the parameters limiting the amount of bio-components in the biodiesel and which can not be improved by using additives. Prepared mixtures meet the quality requirements of PN EN 14214. The results were compared with the results of engine tests with using Perkins 1104C-44 engine. They specified the influence of each methyl esters to the most important parameters characterizing the combustion process and the emission of toxic gases. These results were compared to the standard diesel oil and methyl esters of rapeseed oil (B100). The results show that it is possible to prepare mixtures of biofuels consisting of methyl esters of various origins, with similar quality to standard diesel oil. However, they require some changes in the engine fuel supply system, which are described in this chapter. Keywords: Camelina sativa; methyl esters; bio-component; biofuel; engine tests 1. Introduction In Europe, rapeseed oil methyl esters are an essential component of biofuel for supplying of compression ignition engines [1, 7]. Due to the fact that the amount of rapeseed yields depends on the climatic conditions and the quality of the soil, its supply to the market are sometimes uneven causing large fluctuations in its price. It is also important to reduce the impact of production technology development of bodies on food production. Therefore, other alternative raw materials of vegetable and animal origin are sought [2, 3, 8, 9 and 10]. In this paper, some tests results of mixtures containing methyl esters of various origins: vegetable: rapeseed oil (RME), palm oil (PME) and Camellia sativa oil (CME) and animal: pork fats (FME). were presented. All test mixtures were prepared in appropriate proportions to meet the requirements of PN-EN 14214. Test results of low-temperature properties and oxidative stability were presented as well as test results with using stationary engines on selected parameters of the combustion process. 2. Mixtures preparation The most important criterion for the optimal composition of biofuel samples was to meet the quality requirements for FAME according to PN-EN 14214. Thus, the following two parameters of each test component were performed before the mixing: iodine value, content of linolenic acid methyl esters, Table 1 Physical and chemical parameters of test components, that can be modified only by composition modification [5, 6]. Iodine value (PN-EN 14214 - max 120) Linolenic acid methyl esters (C 18:3) (PN-EN 14214 - max 12,0) Unit Components RME PME FME CME gj 2 /100g 111,0 51,2 53,5 156,0 %(m/m) 8,71 0,18 0,59 36,54 i.e. parameters which can not be improved by using additives but only by changes in composition. The detailed procedure for selection of mixtures with optimal composition is described in paper [4]. FORMATEX 2013 289

The results presented in Table 1 indicate that, in the case of CME, values of both parameters are significantly exceeded standard limits, so that in the test mixtures should be used a limited content of this component. Taking account this fact, the 43 mixtures were prepared consisting of methyl esters of: rapeseed oil (RME), palm oil (PME), Camelina sativa oil (CME) and animal fats (FME) in various proportions, each having 2 or 3 above mentioned ingredients. So prepared mixtures were tested in short-term storage test. All samples were stored in sealed glass containers, with absence of light, under atmospheric pressure at room temperature (set 1) and at 7 C (set 2). Observations were carried out: immediately after preparation the mixtures, after 24 hours, after 2 weeks and after 4 weeks. This test allowed excluding unstable mixtures, i.e. those in which visual changes have occurred, for example: phase delaminating, deposits precipitation, changes in clarity or physical state. The effect of the changes is shown in Figure 1. a) b) Fig. 1 The visual effects of changes in test mixtures after the short-term storage test. a) samples number 29-31 were consisted of a high content of PME; b) samples number 1-4 were consisted of a high content of FME [5]. As shown in Figure 1, deposits precipitation (in the whole volume in some cases) can be observed in samples with a high content of PME and FME. Based on the results of: iodine value, content of linolenic acid methyl esters and, short-term storage test, four samples were selected for the next stage of tests [4]. Their compositions are shown in Table 2. Table 2 Compositions of selected mixtures [5, 6]. Mixtures Compositions RME PME FME CME P1 90 - - 10 P2 85-5 10 P3 50 30-20 P4 75 10-15 It can be noticed that in all selected mixtures the RME is the main component. The other components may only be used in limited contents. However, in the case of a large volume of biodiesel production, the sold volumes of these components may be significant. Additionally, they can be used interchangeably depending on the price and availability in the market. 3. Low-temperature properties and oxidative stability 3.1 Low-temperature properties The effectiveness of the additives was assessed with using four different types of additives: Infineum R 408 (mixture of polymers), Keroflux 9213 (mixture of olefin polymers and amines in organic solvents), Viscoplex 10-171 (oil solution of an acrylic polymer), Viscoplex 10-310 (oil solution of a polymer on the basis of long-chain methacrylic acid esters). Cold filter plugging point (CFPP) tests for sets of each mixture with: 0, 500, 1000, 1500 and 2000 ppm of depressant additive were performed. The results are shown in Figure 2. 290 FORMATEX 2013

a) b) c) d) Fig. 2 CFPP tests results of selected mixtures with additives [5]: a) Infineum R 408; b) Keroflux 9213; c) Viscoplex 10-171; d) Viscoplex 10-310. Based on the CFPP test results with using depressant additives it can be concluded that: Infineum R 408 in the amount of 2000 ppm was the most effective in mixtures P1 and P2, Keroflux 9213 was ineffective, Viscoplex 10-171 already at the content of 500 ppm significantly improved CFPP of mixture P1, CFPP for larger amounts of additive remain unchanged in this mixture, Viscoplex 10-310 in the amount of 2000 ppm was effective in mixture P1. It can be seen that the additives were the most effective in mixtures with a high content of RME. Test depressants worked selective, therefore, for each mixture, both type of additive and sufficient quantity have to be selected individually. 3.2 Oxidation stability In order to assess and verify the suitability of test mixtures for long-term storage, the oxidative stability tests were performed. Tests were conducted by Rancimat method according to PN-EN 14112. The test samples were stored for a period of three years, in closed containers, protected from light, at room temperature. Test samples were not protected against aging by antioxidant additives. The results are summarized in Figure 3. Test results for long-term storing mixtures clearly indicated that: fresh samples were characterized by a good stable ability (values of oxidative stability were placed near the limit according to the quality standard PN-EN 14214 min. 6 hours), after a three-year store, values of oxidative stability decreased to about 2 hours for all mixtures, that means the oxidation processes occurred in advanced level, it should be noted that all mixtures were not protected by the addition of antioxidant. FORMATEX 2013 291

Fig. 3 Oxidation stability of test mixtures during long-term storage [5]. To assess the possibility of improving the oxidation stability of the test mixtures, two commercial additives phenolic type were selected: Kerobit TP26 and Irganox L135. The oxidation stability tests (PN-EN 14112 Rancimat method) for sets of each mixture with: 0, 250, 500, 1000 and 1500 of antioxidants additives were performed. The results are shown in Figure 4. Fig. 4 Oxidation stability of test mixtures with antioxidant additives [5]: a) Kerobit TP26; b) Irganox L135. a) b) It was observed that Kerobit TP26 was more effective additive than Irganox L135 for all test mixtures. This additive increased oxidative stability of all mixtures over 6 hours (minimum value specified for this parameter in the PN-EN ISO 14214) at 1500 ppm. It should be also noted that both two additives were used in blends with low oxidation stability. 4. Analysis of combustion process parameters 4.1 Combustion processes Engine tests of four test mixtures and commercial diesel fuel (Diesel) as well as commercial rapeseed oil methyl ester (RME, B100) was performed with using the engine Perkins 1104C-44 Tier II low-charged (with direct fuel injection and mechanically controlled fuel pump). The test engine was steered by Schenck desktop and quick-parameter measurements were made with using AVL IndiSmart equipment (dedicated to this engine) [1]. All engine tests were carried out in the same speed-load conditions during engine working cycle and at two characteristic rotational speeds of the engine crankshaft. The first speed corresponding to the maximum of its power (2200 rpm) and the second speed to maximum torque generated by the engine (1400 rpm). The engine was working according to the original factory settings i.e. angle of fuel injection advance and the fuel doses have not been modified. Therefore settings of the engine were prepared to supply it only by conventional fuels. Test results were presented in Figures 5-8. Figures 5 and 6 show pressure records in the combustion chamber, averaged from 50 engine working cycles. Figures 7 and 8 illustrate the pressure increases in the combustion chamber and finally the Figures 9 and 10 present heating values appearing during the combustion process. 292 FORMATEX 2013

Fig. 5 The mean pressures in combustion chamber as a function of crank angle recorded at rotational speed of engine crank corresponding to maximum torque (1400 rpm) and maximum dose of fuel. Fig. 6 The mean pressures in combustion chamber as a function of crank angle recorded at rotational speed of engine crank corresponding to maximum torque (2200 rpm) and maximum dose of fuel. Fig. 7 Increase of pressure in combustion chamber as a function of crank angle recorded at rotational speed of engine crank corresponding to maximum torque (1400 rpm) and maximum dose of fuel. FORMATEX 2013 293

Fig. 8 Increase of pressure in combustion chamber as a function of crank angle recorded at rotational speed of engine crank corresponding to maximum torque (2200 rpm) and maximum dose of fuel. Fig. 9 Mean values of released heat Q as a function of crank angle recorded at rotational speed of engine crank corresponding to maximum torque (1400 rpm) and maximum dose of fuel. Fig. 10 Mean values of released heat Q as a function of crank angle recorded at rotational speed of engine crank corresponding to maximum torque (2200 rpm) and maximum dose of fuel. 294 FORMATEX 2013

4.2 Emissions in the cycle C1 in accordance with ISO 8178 Set of tests were carried out with using engine which was qualified for Stage II G category, according to 8-phase cycle C1 ISO 8178 [1]. The engine ran under load characteristics of three constant rotational speeds: 1400 rpm rotational speed of max torque of the crankshaft, 2200 rpm rotational speed of max power of the engine, idle. Based on the recorded results and calculations of fuel consumption per hour, fuel supply and exhaust gas flow, individual toxic exhaust emissions with using the coefficient for the various phases in the whole test in accordance with ISO 8178 for the six test fuels were determined. Fig. 11 Toxic exhaust emissions for six test fuels in cycle C1 according to ISO 8178. 5. Summary The laboratory analyses for mixtures contained of methyl esters different origin show that: To meet requirements of PN-EN 14214, RME has to be the main component of such type of mixtures: CME has to high level of iodine value and linolenic acid methyl esters content and PME and FME have poor lowtemperature properties. Test results of low-temperature properties (CFPP) show that all test mixtures could be used not only during summer but also during spring and autumn (below 0 C) in temperate climate. Test depressants worked selective, therefore, for each mixture consisted of methyl esters different origin, both type of additive and sufficient quantity have to be selected individually. It could be observed that the test additives were the most effective in mixtures with a high content of RME. All test mixtures lost their stability properties slightly after 2-year-storing that means they have ability for long-term storing. Despite the fact that antioxidant additives were used in mixtures with low oxidation stability, they were very effective. Engine test also demonstrate usefulness biofuels consisted of methyl esters different origin: It can be seen, in averaging indicator diagrams, that for Diesel ignition initiating occurs after about 3 CA than for P1, P3, P4 and RME at two characteristic rotational speeds of crankshaft, while in the case of P2 only about 1-2 CA. This is mainly effect of different physical and chemical properties of the test mixtures (density, viscosity and lubricity). For mixtures of esters the max pressures in the combustion chamber are higher than for Diesel. The highest pressure in the tests was recorded for P3. This result can be explained by the fact that the methyl esters of vegetable oils have in its internal structure to 10% of oxygen and because of its higher density. These are the reasons that such type of fuel is previously injected into the cylinder (in the case of a mechanically controlled, conventional engine fuel supply system as in Perkins 1104C-44 engine). The highest increases in pressure in the combustion chamber were recorded for P4 (at 2200 rpm) and for Diesel (at 1400 rpm). More maximum amount of heat released in the premix combustion area for Diesel. This can be explained by the smaller size of Diesel droplets (compared to the esters) which contributes to the faster increases of pressure FORMATEX 2013 295

and heat release during this phase of the combustion process. Whereas slight benefit for mixtures of methyl esters in the amount of heat released during diffusion controlled combustion was observed. More toxic exhaust emissions of CO, HC, PM for Diesel than for test mixtures during C1 cycle was recorded, except emission of NOx, which was lower about 11% to 27% for diesel than for test mixtures. The highest reduction in emission between Diesel and test mixtures for particulate matter (PM) was observed. The reason of lower content of CO in the exhaust gases for test mixtures is high oxygen content in this type of compounds. Thus, there is greater oxidation of CO during power and exhaust stroke causing reduction its emission. Lower emissions of not combusted HC is mainly due to oxygen in the internal structure of the methyl esters, which results in more efficient combustion and more reduced concentrations of polycyclic aromatic hydrocarbons (PAH) which cause carcinogenic, mutagenic and teratogenic effects. Based on above information it can be said, that despite of the fact that CME, PME and FME may only be used in limited contents but in the case of a large volume of biodiesel production, the sold volumes of these components may be significant. Additionally, they can be used interchangeably depending on the price and availability in the market. To get a similar engine operating parameters for esters of different origin as for mineral diesel fuels (without any modification of the fuel supply system), the changes in the system settings as earlier injection advance angle changing by about 2-3 CA have to be done. All test mixtures could be used not only during summer but also during spring and autumn (below 0 C) in temperate climate. But to avoid problems with engine start-up, the fuel heaters should be applied in engine supply system as in Scandinavia is standard on vehicles equipped with compression ignition engines. According to the authors opinion, it is necessary to continue research works on renewable fuels for economical and ecological reasons. It is appropriate to use new type of plants, which could be grown on poor soil and it could be helpful to eliminate the negative influence of biofuel production on food industry. References [1] Ambrozik A., Kruczyński P., Orliński P., Wpływ zasilania silnika ZS paliwami alternatywnymi na wybrane parametry procesu spalania oraz emisję składników toksycznych spalin (The influence of alternative fuels using in CI engines on selected parameters of the combustion process and toxic exhaust emission), Zeszyty Naukowe Instytutu Pojazdów, 2(78)/2010, 157-163. [2] Fröhlich A., Rice B., Evaluation of Camelina sativa oil as a feedstock for biodiesel production. Industrial Crops and Products, Volume 21, Issue 1, January 2005, 25-31. [3] Jeczmionek L., Olej z lnianki siewnej (Camelina sativa) szansa rozwoju biopaliw II generacji? (Camelina sativa oil - opportunity for development of the second generation biofuels), Nafta-Gaz, 09/2010, 841-848. [4] Kolodziejczyk K, Owczuk M. Camelina sativa as biofuel as an alternative feedstock for the production of biofuels used in diesel engines, Chemik, 2011, 65, 6, 531-536. [5] Kolodziejczyk K, Owczuk M. Development of technology to manufacture biofuels using Camelina sativa oil as new raw material base. E!4018, CAMELINA-BIOFUEL, EUREKA Project, 2012. [6] Kolodziejczyk K., Frydrych J., Kruczynski W. S., Orlinski P., Jakubczyk D., Charakterystyka jakościowa oleju lniankowego pod kątem stosowania jako samoistne biopaliwo lub komponent paliwa do silników z zapłonem samoczynnym (Qualitative analysis of Camelina sativa oil for use as biofuel or bio-component for compression-ignition engines), Zeszyty Naukowe Instytutu Pojazdów, 1(82), 2011, 73-83. [7] Labeckas G, Slavinskas S. The effect of rapeseed oil methyl ester on direct injection diesel engine performance and exhaust emissions, Energy Conversion Manage, 2006, 47(13 14), 1954 67. [8] Mikkonen S., Second-generation renewable diesel offers advantages, Hydrocarbon Processing 2008, 87(2), 63-66. [9] Ozsezen A. N., Canakci M., Determination of performance and combustion characteristics of a diesel engine fueled with canola and waste palm oil methyl esters, Energy Conversion Manage, 2011, 52 (1), 108 116. [10] Shonnard D. R., Williams L., Kalnes., T. N., Camelina-derived jet fuel and diesel: sustainable biofuels, Environmental Progress & Sustainable Energy, 2010, 29, 382-392. 296 FORMATEX 2013