Exploration of a new type of biodiesel

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Exploration of a New Type of Biodiesel 1 Overview Abstract: A new type of biodiesel, namely ethylene glycol ether soybean oil monoester, was synthesized using ethylene glycol ether and refined soybean oil. A single-cylinder engine was used to study the effects of this new biodiesel on the engine’s power output, fuel efficiency, and emission performance. The results showed that when this new biodiesel was used, the power output of the diesel engine remained almost unchanged, while the fuel consumption increased； Emission levels of exhaust soot, CO, and HC were significantly reduced, while N₂O emissions increased slightly. Keywords: internal combustion engine ； Biodiesel ； Ethylene glycol ethyl ether soybean oil ester ； Emissions Key words: IC engine ； biodiesel ； ethylene glycol monoethyl ether soyate ； exhaust em lSS10 n Chinese Library Classification Number: TK464 Document Code: A Vegetable oil is a potential alternative fuel for cleaning diesel; its main components are fatty acid glycerides. However, due to its high viscosity, poor atomization properties, and tendency to clog, it is difficult to use directly in diesel engines. Converting vegetable oil into vegetable oil monoesters yields biodiesel. It can overcome the inherent defects of vegetable oils; after ester exchange with monohydric alcohols, the molecular chains become shorter and the molecular weight decreases. The viscosity is reduced, and the key technical parameters are close to those of diesel. Biodiesel possesses excellent environmental benefits; it is a renewable, oxygen-containing clean fuel that has become one of the hot topics of research. The biodiesel that has been developed is mainly fatty acid monostearates obtained through transesterification reactions using animal and plant oils along with common monoalcohols (methanol, ethanol, propanol, and butanol). Due to its low oxygen content, it makes it difficult to significantly improve the emission performance of diesel engines. In this paper, ethylene glycol ether was used in place of monohydric alcohols to synthesize the ethylene glycol ether soybean oil monoester through an ester exchange reaction with refined edible soybean oil. This monoester contains one more ether group than traditional biodiesel, which increases its oxygen content and thus improves its emission properties. In addition, its cetane number is higher, giving it better ignition performance. 2 Synthesis and structural analysis of novel biodiesel: Synthesis was carried out using an alkaline-catalyzed transesterification reaction. The basic process involves using sodium as a catalyst to replace the glycerol in soybean oil triglycerides through diethylene glycol ether, thereby converting one fatty acid glyceride molecule into three long-chain fatty acid monostearates. The main reactions are as follows. Date of receipt: 2005-09-06. Author’s profile: Zhang Hongyun (born 1979), female, master’s degree; her main research area is novel biodiesel. E-mail: zhy200l200l5l8@sohu.com. VIP Information http://www.cqvip.com Issue 5, 2006 Internal Combustion Engine Engineering · 17 · R R R 2HOCH2CH2()CH2CH +2Na—2Na()CH2CH2()CH2CH +H + C0()CH COOCH COOCH + 3NaOCH2 CH2 OCH2 CH. Soybean oil ester, sodium alcoholate: Prepare ethylene glycol ether soybean oil monoester as shown in Figure 1. Figure 1: Process flow diagram for the production of novel biodiesel Rl COOCH2 CH2 OCH2 CH. R COOCH CH2 OCH CH + R. COOCH2CH2OICH2CH biodiesel: The infrared spectroscopy of the product was analyzed using an EQUIN[X]55 Fourier transform infrared spectrophotometer, with a testing frequency range of 4,000.31–399.26 cm⁻¹. KBr pellets were used for sample preparation, and the obtained infrared spectroscopic data along with their interpretations are shown in Table 1. As can be seen from the table, the product contains groups such as methyl, methylene, carbonyl, C–( )–C, and C–C. Table 1 Infrared spectroscopy data and interpretation: Absorption wavenumber/era, Group assignment, Type of vibration, Absorption intensity. 3 008.23 = [H] stretching vibration, Weak; 2 926.37 –CH3 stretching vibration, Strong; 2 856.15 –[H]–CH3 stretching vibration, Strong; 1 739.88 –[O–H] stretching vibration, Strong; 1 460.18 [H] shear vibration, Weak; 1 382.75 –[H] bending vibration, Weak; 1 126.58 [O–H] antisymmetric stretching vibration, etc.; 1 174.89 [O–H] symmetric stretching vibration, etc.; 722.03 [H]. Planar rocking vibration: weak. Nuclear magnetic resonance spectroscopic analysis was carried out using an lN()VA-type superconducting NMR spectrometer; the solvent used was CDCI, with TMS as the internal standard, and the observation frequency was 400 MHz. In the nuclear magnetic resonance spectroscopic data of the obtained product, the peak with a chemical shift of 5.40×10 (with an area of 1.28) corresponds to the protons attached to the C–C bond in the fatty acid alkyl group (R); the peaks with chemical shifts lower than 3.()(]×10 (except for 2.04×10) correspond to the protons attached to the saturated carbon atoms of R. The data for the other proton peaks in the spectrum are shown in Table 2, and they correspond to the protons on the ethylene glycol ether group. According to the literature, the chemical structure of the synthetic product is RC()()CH CH:()CH. CH H H H ()N )Na ()N Sodium glycerate Table 2 Interpretation of proton nuclear magnetic resonance spectra Chemical shift /×10 3.63 4.23 3.53 2.04 Proton peak splitting (multiplicity) 3 3 4 3 Peak area 0.82 0.89 0.82 1.46 Corresponding number of protons 2 2 2 3 3 Results and discussion of diesel engine tests The tests were conducted on a single-cylinder, four-stroke, water-cooled direct-injection diesel engine test bench. The main technical parameters of the engine are: cylinder diameter of 100 mm, stroke of 115 mm, displacement of 0.903 l, compression ratio of 18, ∞-type combustion chamber, and rated power of 11 kW at 2,300 r/min. Maximum oil flow limit for the gear rack of the diesel engine’s high-pressure fuel pump, with spring adjustment. Comparative tests were conducted using three types of fuel in the engine: 0# diesel, B50 (50% bio-diesel), and pure bio-diesel. The exhaust smoke density of the engine is measured online using an opaque smoke meter, the AVI Dismoke4000; the smoke density value is expressed in terms of the extinction coefficient ； An online measurement of the concentrations of harmful gases NO—c() and HC is carried out using the five-gas analyzer produced by Foshan Analysis Instrument Factory. 3.1 Effect of fuel on engine power and energy consumption. Figure 2 shows a comparison of the effects of using 0# diesel and a new type of biodiesel on the torque of diesel engines. It also displays a comparison of their effects on the energy consumption rate. Figure 2 presents the test results regarding the impact of these two fuels on engine torque and energy consumption at 1,800 revolutions per minute. Source: VIP Information http://www.cqvip.com; Engine Technology, Issue 5, 2006. As can be seen from Figure 2a, the output torque of the fuel remains essentially constant. The calorific value of the new type of biodiesel (38.65 MJ/kg) is lower than that of 0# diesel (42.50 MJ/kg); therefore, the power output of diesel engines when using this biodiesel should decrease. However, the higher oxygen content in biodiesel compensates for this loss in power due to its lower heat value. As can be seen from Figure 2b, the energy consumption rate increases significantly after burning the new type of biodiesel. Since biodiesel has a higher specific gravity than 0# diesel, and its calorific value is lower than that of 0# diesel, when the same volume of fuel is supplied, more biodiesel is required. With the engine’s rated power remaining essentially unchanged, more biodiesel must be burned to generate the same amount of power per unit of time; as a result, the energy consumption rate is higher. 3.2 Effect of fuel on engine emissions Figure 3 shows the emission characteristics of the engine when using three different fuels at 1,800 r/min and 2,300 r/min. Figure 3 shows the effect of fuel on engine emissions: (1) smoke density. As can be seen from the graph, after burning B50, the smoke density of the diesel engine decreased by 37.5–71.2 at 1,800 r/min, and by 48.9–75.0 at 2,300 r/min. After burning pure bio-diesel, the emission effects were more pronounced: the soot level decreased by 59.8–78.8 at 1,800 r/min, and by 62.9 Pe at 2,300 r/min; MPa(b) was between 2,300 r/min and 83.3. There are mainly two reasons for this: First, biodiesel does not contain aromatic hydrocarbons, and it has a high content of saturated alkanes. Since the carbon-to-hydrogen ratio (C/H) of aromatic hydrocarbons is much higher than that of alkanes, biodiesel results in lower smoke emissions compared to pure diesel ； Secondly, biodiesel is an oxygen-containing fuel (with an oxygen content of over 10%), and the oxygen atoms play a role in facilitating combustion, especially in areas with high fuel concentrations. VIP Information: http://www.cqvip.com, Issue 5, 2006; Internal Combustion Engines. The oxygen content in the fuel reduces incomplete combustion, allowing the fuel to burn more completely and thereby lowering smoke emissions. (2)CO。 As can be seen from the graph, after burning the new type of biodiesel, the CO emission concentration shows little change at low load levels ； As the load increases. The CO emission concentration has decreased significantly. After burning pure novel biodiesel. The CO emission concentration decreased by 47.7%–64.3% at 1,800 r/min, and by 55.69/6–76.79/6 at 2,300 r/min ； After burning B50, the CO emission concentration decreased by 13.9–44.4% at 1,800 r/min, and by 38.1–55.89% at 2,300 r/min. This is because the average effective pressure is low. The engine burns under a lean fuel condition. Due to excessive air volume. The fuel can burn more completely, so CO emissions remain at a stable low level ； When the mean effective pressure is high. The engine is operating in a rich fuel condition. The temperature of the gas inside the cylinder increases. Because biodiesel has a relatively high oxygen content. Oxidation increases. It improved the degree of complete combustion of the fuel. As a result, CO emissions dropped sharply. (3)HC。 As can be seen from the graph, after the diesel engine burns the three types of fuel. HC emissions show a fluctuating pattern. Under light load conditions. The emission differences among the three fuels are minimal ； Under high-load conditions, the HC emissions are significantly reduced after burning pure bio-diesel. This is mainly because biodiesel has a high cetane number. Free of aromatic hydrocarbons. So, it has good fuel ignition performance. The afterburning period is short. Both its unburned hydrocarbons and pyrolyzed hydrocarbons are low ； Furthermore, the higher oxygen content in biodiesel also contributes to HC emissions. Numerous studies have found that the HC emissions from diesel engines increase when oxygen-containing fuels are used in combustion. After burning B50, HC emissions also increase under high-load T conditions; the reason requires further investigation. As can be seen from the graph. Whether burning B50 or pure new-type biodiesel. HC emissions were all significantly reduced. HC emissions decreased by 48.9 to 64.79% when burning pure biodiesel. Emissions from burning B50HC decreased by 30.39/6 to 45.79/6. (4) NO⋯ As can be seen from the graph, the three fuels are essentially similar at low loads, while the NO emissions from burning biodiesel increase slightly at high loads. This is because it applies to diesel engines. At low load, there is sufficient oxygen in the air-fuel mixture. But the temperature in the combustion chamber is low. Therefore, the NO emissions are also low ； As the load increases. The gas temperature in the combustion chamber rises. It increased the rate of N oxidation to N() at high temperatures. So N(), increases. Although biodiesel has a high cetane number. The hold-up time is short. There is a trend toward reducing NO emissions. However, biodiesel is an oxygen-containing fuel, and the oxygen atoms play a role in facilitating combustion during the burning process, without any changes to the structure of the diesel engine. Oxygen enrichment during combustion further increases N() emissions. Therefore, when burning the new type of biodiesel N(】), emissions increase slightly. 4 Conclusions (1) A new type of biodiesel, ethylene glycol ether soybean oil ester, was synthesized. Its structure was confirmed by FTIR and 1H NMR analysis. (2) Compared with the original machine after using pure new-type biodiesel. Soot emissions were reduced by 59.89/6 to 83.39/6. CO emissions decreased by 47.79–76.79/6, HC emissions decreased by 48.9–64.7, while NOx emissions increased slightly. (3) Comparison with the original machine after using B5O. Soot emissions were reduced by 37.5 9/6 to 75.9/5. CO emissions decreased by 13.99/6 to 55.89/6, HC emissions decreased by 30.3 to 45.79/6, while NO emissions increased slightly. (4) Use pure new-type biodiesel. The torque output of the diesel engine remains basically unchanged. And the fuel consumption rate has increased.