Volumetric properties at high pressure of waste oil methyl ester compared with diesel oil

In this paper, the isothermal compressibility coefficient, the cubic expansion coefficient and the propagation speed of pressure waves of waste oil methyl ester (WOME) and diesel oil (DO) are presented. These properties can be derived mathematically from the specific volume, the only property measured in this work (from 288.15 to 328.15 K and from atmospheric pressure to 350 MPa). The modified Tait–Tammann Equation has been adjusted to the experimental data with a high correlation coefficient and confidence level. Because of their different physical properties, the use of WOME instead of DO can affect the behaviour of some diesel equipments and, for instance, the economic efficiency and the behaviour of heat engines.     

生物柴油特性及作为混合燃料添加剂的研究

论述了生物柴油优越的理化特性,可作为柴油的替代燃料,并讨论了生物柴油作为乙醇（甲醇）与柴油或汽油混合燃料的添加剂情况.通过溶解度测定及三相图实验数据表明生物柴油作为乙醇与柴油添加剂,促溶效果较好;对于生物柴油-汽油-乙醇体系来讲,三者可以任意比例混合,可改善汽油的燃烧性能;对于生物柴油-柴油-甲醇体系,效果不理想.     

柴油低温粘温特性和流变性研究

考察了柴油加入低温流动改进剂前后的低温粘温特性和流变特性。结果表明,随着温度降低,柴油的表观粘度和粘流活化能增大,稠度系数增大．流动特性指数减小,柴油的流变特性越来越偏离牛顿流体,非牛顿性越来越强,柴油在低温下为假塑性非牛顿型流体。加入低温流动性改进剂T1804 后,柴油的低温表现粘度和粘流活化能显著降低,柴油的流动特性指数值增大,稠度系数值减小,与未加剂柴油相比,更接近于牛顿流体。     

Exhaust emissions and fuel properties of partially hydrogenated soybean oil methyl esters blended with ultra low sulfur diesel fuel

Important fuel properties and emission characteristics of blends (20 vol.%) of soybean oil methyl esters (SME) and partially hydrogenated SME (PHSME) in ultra low sulfur diesel fuel (ULSD) were determined and compared with neat ULSD. The following changes were observed for B20 blends of SME and PHSME versus neat ULSD: improved lubricity, higher kinematic viscosity and cetane number, lower sulfur content, and inferior low-temperature properties and oxidative stability. With respect to exhaust emissions, B20 blends of PHSME and SME exhibited lower PM and CO emissions in comparison to those of neat ULSD. The PHSME blend also showed a significant reduction in THC emissions. Both SME and PHSME B20 blends yielded small increases in NO_x emissions. The reduction in double bond content of PHSME did not result in a statistically significant difference in NO_x emissions versus SME at the B20 blend level. The test engine consumed a greater amount of fuel operating on the SME and PHSME blends than on neat ULSD, but the increase was smaller for the PHSME blend.     

Transesterification of vegetable oil to biodiesel fuel using alkaline catalyst

Biodiesel is gaining more and more importance as an attractive fuel due to the depleting fossil fuel resources. Chemically biodiesel is monoalkyl esters of long chain fatty acids derived from renewable feed stock like vegetable oils and animal fats. It is produced by transesterification in which, oil or fat is reacted with a monohydric alcohol in presence of a catalyst to give the corresponding monoalkyl esters. This article reports experimental data on the production of fatty acid methyl esters from vegetable oils, soybean and cottonseed oils using sodium hydroxide as alkaline catalyst. The variables affecting the yield and characteristics of the biodiesel produced from these vegetable oils were studied. The variables investigated were reaction time (1-3 h), catalyst concentration (0.5-1.5 w/wt%), and oil-to-methanol molar ratio (1:3-1:9). From the obtained results, the best yield percentage was obtained using a methanol/oil molar ratio of 6:1, sodium hydroxide as catalyst (1%) and 60 ± 1 °C temperature for 1 h. The yield of the fatty acid methyl ester (FAME) was determined according to HPLC. The composition of the FAME was determined according to gas chromatography. The biodiesel samples were physicochemically characterized. From the results it was clear that the produced biodiesel fuel was within the recommended standards of biodiesel fuel.     

Hydrocracking of petroleum vacuum distillate containing rapeseed oil: Evaluation of diesel fuel

Hydrocracking of pure petroleum vacuum distillate and the same fraction containing 5 wt.% of rapeseed oil was carried out at 400 and 420 °C and under a hydrogen pressure of 18 MPa over commercial Ni-Mo catalyst. Reaction products were separated by distillation into kerosene, gas oil and the residue. Fuel properties of fractions suitable for diesel production were evaluated (gas oils and remixed blends of kerosene and gas oil). Gas oils obtained from co-processing showed very good fuel properties as the remixed distillates did. Gas oil obtained from co-processing at 420 °C showed also reasonable key low-temperature properties (cloud point: −23 °C, CFPP: −24 °C) similar to those of gas oil obtained from pure petroleum raw material processing.     

Fuel consumption and emissions from a diesel power generator fuelled with castor oil and soybean biodiesel

This work investigates the impacts on fuel consumption and exhaust emissions of a diesel power generator operating with biodiesel. Fuel blends with 5%, 20%, 35%, 50%, and 85% of soybean biodiesel in diesel oil, and fuel blends containing 5%, 20%, and 35% of castor oil biodiesel in diesel oil were tested, varying engine load from 9.6 to 35.7 kW. Specific fuel consumption (SFC) and the exhaust concentrations of carbon dioxide (CO₂), carbon monoxide (CO), and hydrocarbons (HC) were evaluated. The engine was kept with its original settings for diesel oil operation. The results showed increased fuel consumption with higher biodiesel concentration in the fuel. Soybean biodiesel blends showed lower fuel consumption than castor biodiesel blends at a given concentration. At low and moderate loads, CO emission was increased by nearly 40% and over 80% when fuel blends containing 35% of castor oil biodiesel or soybean biodiesel were used, respectively, in comparison with diesel oil. With the load power of 9.6 kW, the use of fuel blends containing 20% of castor oil biodiesel or soybean biodiesel increased HC emissions by 16% and 18%, respectively, in comparison with diesel oil. Exhaust CO₂ concentration did not change significantly, showing differences lower than ±3% of the values recorded for diesel oil operation, irrespective of biodiesel type, concentration and the load applied. The results demonstrate that optimization of fuel injection system is required for proper engine operation with biodiesel.     

Cetane number effect on the energetic and exergetic efficiency of a diesel engine fuelled with biodiesel

This study presents the energy, exergy and heat release analysis of a John Deere 4045 T 4.5 L, four-stroke, four-cylinder, turbocharged diesel engine. The engine was run with four different types of fuel: yellow grease methyl ester (YGME); soybean oil methyl ester (SME); and soybean oil methyl ester containing either 0.75 or 1.5 w/w % of the cetane improver 2-ethylhexyl nitrate (SME-0.75%EHN and SME-1.5%EHN, respectively). The engine was tested at 1400 1/min under a full load of 352 Nm. For reliability, the fuels were tested three times, and the mean values were compared using different statistical techniques. The objective in this study was to determine the effect of cetane number and ignition delay on the energy and exergy efficiencies of an internal combustion engine and to compare the results for the types of fuel stated earlier. The average thermal efficiency was approximately 40.5%, and the exergetic efficiency was approximately 37.3%. The mean exergetic efficiencies of the fuels were in the order ψ_SME > ψ_SME-0.75%EHN > ψ_SME-1.5%EHN > ψ_YGME. There were significant differences among the mean values according to Student's t-tests. It is concluded that a lower cetane number, a longer ignition delay period and a higher level of premixed combustion may increase the exergetic efficiency of a diesel engine.     

Insights into the physicochemical properties of coffee oil

The lipid fraction of roasted coffee is an interesting ingredient that could be used in a large number of food formulations. Coffee oil has peculiar flavouring as well as nutraceutical characteristics. The feasibility of the use of coffee oil as ingredient greatly depends not only on its chemical characteristics but also on its physical properties. The crystallisation and melting properties of the coffee oil extracted from Arabica roasted coffee powder were determined by using synchrotron X‐ray diffraction coupled with differential scanning calorimetry. The fatty acid composition and the flavour profile were also assessed by using GC and GC‐MS analyses, respectively. The main fatty acids found in coffee oil are linoleic and palmitic acid. Significant amounts of stearic and oleic acid are also present. These chemical characteristics are linked to the phase transition behaviour. The crystallisation of coffee oil occurs at 6.5 ± 0.3 °C, independently of the cooling rate applied (from 0.5 to 10 °C/min). A unique crystalline structure was identified: a double chain length (2L) β' structure (55.29 Å). The sole formation of the β' form indicates that this metastable crystal is the only one that one should expect in foods containing coffee oil stored below 7 °C.     

Characteristics of polycyclic aromatic hydrocarbons emissions of diesel engine fueled with biodiesel and diesel

With mutagenic and carcinogenic potential, polycyclic aromatic hydrocarbons (PAHs) from mobile source exhaust have contributed to a substantial share of air toxics. In order to characterize the PAHs emissions of diesel engine fueled with diesel, biodiesel (B100) and its blend (B20), an experimental study has been carried out on a direct-injection turbocharged diesel engine. The particle-phase and gas-phase PAHs in engine exhaust were collected by fiberglass filters and “PUF/XAD-2/PUF” cartridges, respectively, then the PAHs were determined by a gas chromatograph/mass spectrometer (GC/MS). The experimental results indicated that comparing with diesel, using B100 and B20 can greatly reduce the total PAHs emissions of diesel engine by 19.4% and 13.1%, respectively. The Benzo[a]Pyrene (BaP) equivalent of PAHs emissions were also decreased by 15.0% with the use of B100. For the three fuels, the gas-phase PAHs emissions were higher than particle-phase PAHs emissions and the most abundant PAH compounds from engine exhaust were naphthalene and phenanthrene. The analysis showed that there was a close correlation between total PAHs emissions and particulate matter (PM) emissions for three fuels. Furthermore, the correlation became more significant when using biodiesel.     

Evaluation of the oxidation stability of diesel/biodiesel blends

Biodiesel is an alternative fuel derived from vegetable oils, animal fats and used frying oils. Due to its chemical structure, it is more susceptible to oxidation or autoxidation during long-term storage compared to petroleum diesel fuel. One of the major technical issues regarding the biodiesel blends with diesel fuel is the oxidation stability of the final blend, which is, nowadays, of particularly high concern due to the introduction of ultra low sulphur diesel, in most parts of the EU. This study examined the factors influencing the stability of several biodiesel blends with low and ultra low sulphur automotive diesel fuels. The aim of this paper was to evaluate the impact of biodiesel source material and biodiesel concentration in diesel fuel, on the stability of the final blend. Moreover, the effects of certain characteristics of the base diesels, such as sulphur content and the presence of cracked stocks, on the oxidation stability are discussed.     

Fuel properties and emissions of soybean oil esters as diesel fuel

The effects of using blends of methyl and isopropyl esters of soybean oil with No. 2 diesel fuel were studied at several steady-state operating conditions in a four-cylinder turbocharged diesel engine. Fuel blends that contained 20, 50, and 70% methyl soyate and 20 and 50% isopropyl soyate were tested. Fuel properties, such as cetane number, also were investigated. Both methyl and isopropyl esters provided significant reductions in particulate emissions compared with No. 2 diesel fuel. A blend of 50% methyl ester and 50% No. 2 diesel fuel provided a reduction of 37% in the carbon portion of the particulates and 25% in the total particulates. The 50% blend of isopropyl ester and 50% No. 2 diesel fuel gave a 55% reduction in carbon and a 28% reduction in total particulate emissions. Emissions of carbon monoxide and unburned hydrocarbons also were reduced significantly. Oxides of nitrogen increased by 12%.     

Effects of biodiesel on a DI diesel engine performance, emission and combustion characteristics

Experimental tests were investigated to evaluate the performance, emission and combustion of a diesel engine using neat rapeseed oil and its blends of 5%, 20% and 70%, and standard diesel fuel separately. The results indicate that the use of biodiesel produces lower smoke opacity (up to 60%), and higher brake specific fuel consumption (BSFC) (up to 11%) compared to diesel fuel. The measured CO emissions of B5 and B100 fuels were found to be 9% and 32% lower than that of the diesel fuel, respectively. The BSFC of biodiesel at the maximum torque and rated power conditions were found to be 8.5% and 8% higher than that of the diesel fuel, respectively. From the combustion analysis, it was found that ignition delay was shorter for neat rapeseed oil and its blends tested compared to that of standard diesel. The combustion characteristics of rapeseed oil and its diesel blends closely followed those of standard diesel.     

The specific gravity of biodiesel and its blends with diesel fuel

The specific gravities of biodiesel and 75, 50, and 20% blends with No. 1 and No. 2 diesel fuels were measured as a function of temperature from the onset of crystallization to 100°C. The results indicate that biodiesel and its blends demonstrate temperature-dependent behavior that is qualitively similar to the diesel fuels. The temperature dependence of the specific gravity for biodiesel and its blends was compared with the ASTM D 1250-80 procedure for the temperature correction of hydrocarbon fuels, and the procedure was found to provide accurate corrections. A blending equation was developed that allows the specific gravity of blends to be calculated from the specific gravities of the biodiesel and diesel fuels.     

The effect of hot surface temperature on diesel fuel deposit formation

The aim of this study is to investigate fuel deposits by using the hot surface deposition test (HSDT). In this test, diesel fuel droplets were repeatedly impinged to the hot surface and deposits were developed on it. The hot surface temperature affected the deposit formation. Different hot surface temperature showed different droplet-surface interaction, evaporation lifetime and wet/dry condition where various deposit development features resulted. The hot surface temperatures that located near MEP (maximum evaporation rate point) temperature have potential to reduce the deposit formation on the hot surface. The deposition within nucleate heat transfer boiling regime (lower than the MEP temperature) caused greater deposit accumulation on the hot surface compared to the deposition within transition heat transfer boiling regime (near the MEP temperature). Less total amount of deposit that was described as slow deposit development, resulted under non-overlapping impingement and dry deposit condition. Under the overlapping impingement and wet deposit condition, it caused the accumulation of greater total amount of deposit compared to the non-overlapping and dry deposit condition.     

Potential for reducing emissions in a diesel engine by fuelling with conventional biodiesel and Fischer-Tropsch diesel

A gas-to-liquid (GTL) fuel derived from Low Temperature Fischer-Tropsch process has been tested in an automotive diesel engine fulfilling Euro 4 emissions regulations. Both regulated and non-regulated emissions have been compared with those of a commercial diesel fuel, a commercial biodiesel fuel and a GTL-biodiesel fuel (30% and 70% v/v, respectively) in order to check blending properties, synergistic effects and compatibility between first and second generation production technologies for biofuel consumption in current diesel engines. After presenting a detailed literature review, and confirming that similar efficiencies are attained with the four tested fuels under identical road-like operating conditions (this meaning fuel consumption is inversely proportional to their heating values), significant reductions in smoke opacity, particulate matter emissions and particle number concentration were observed with both GTL and biodiesel fuels, with small changes in NO_x emissions. Compared with the reductions in PM emissions derived from the use of biodiesel fuels, those derived from using GTL fuels were quite similar, despite its lower soot emissions reductions. This can be explained by the lower volatile organic fraction of the PM in the case of GTL. By adequately blending both fuels, a considerable potential to optimise the engine emissions trade-off is foreseen.     

Production of biodiesel fuel from tall oil fatty acids via high temperature methanol reaction

Tall oil fatty acids are a byproduct of the paper industry and consist predominantly of free-fatty acids (FFAs). Although this feedstock is ideal for biodiesel production, there has been relatively little study of its conversion to biodiesel. Thus, the purpose of this study was to investigate the high temperature reaction of methanol with tall oil at subcritical and supercritical pressures to produce fatty acid methyl esters. This study investigates the effects of mixing, pressure, temperature, and methanol to oil molecular ratio in order to determine the potential use of tall oil as a biodiesel feedstock. In this work, tall oil fatty acids were successfully reacted with supercritical and subcritical methanol in a continuous tubular reactor, resulting in a reaction that is primarily temperature dependent. Conversions at subcritical pressures of 4.2 MPa and 6.6 MPa were 81% and 75%, respectively. Pressure seemed to have little correlation to conversion in both regimes, and conversions were comparable between the two. Additionally, it was found that tall oil fatty acids react well with methanol to give comparable conversions at the relatively low molecular flow ratio of 5:1 methanol to tall oil. Both of these observations suggest that hydrolyzed triglycerides or free fatty acid feedstocks would make the primary high temperature biodiesel reaction and the subsequent separation and purification operations less expensive than was previously believed.     

The kinematic viscosity of biodiesel and its blends with diesel fuel

As the use of biodiesel becomes more wide-spread, engine manufacturers have expressed concern about biodiesel’s higher viscosity. In particular, they are concerned that biodiesel may exhibit different viscosity-temperature characteristics that could result in higher fuel injection pressures at low engine operating temperatures. This study presents data for the kinematic viscosity of biodiesel and its blends with No. 1 and No. 2 diesel fuels at 75, 50, and 20% biodiesel, from close to their melting point to 100°C. The results indicate that while their viscosity is higher, biodiesel and its blends demonstrate temperature-dependent behavior similar to that of No. 1 and No. 2 diesel fuels. Equations of the same general form are shown to correlate viscosity data for both biodiesel and diesel fuel, and for their blends. A blending equation is presented that allows the kinematic viscosity to be calculated as a function of the biodiesel fraction.     

Winterisation of waste cooking oil methyl ester to improve cold temperature fuel properties

Waste cooking oil methyl ester (WCOME) was winterised at 1, 0, −1 and −2°C following a 4×2 factorial design with one replication per cell. The process was carried out by filtration and both the filtrate (solid phase) and the liquid phase were analysed by gas chromatography (GC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Cold filter plugging point (CFPP) and calorific values were measured.Temperatures of 0 and −1°C in conjunction with the quickest cooling rate (0.1°C min⁻¹) and 15-24 h of cooling gave the most successful results in terms of fuel properties.Improvements in the low temperature properties of the winterised fuel were reflected by a reduction of saturated fatty acid methyl esters (SFAME) in the composition by 1.5-6%, by a decrease in the CFPP values by 2-4°C and by a shift of the DSC high temperature melting peak (approx. 5°C) towards lower temperatures in comparison to the original fuel. Calorific values of the winterised WCOME did not significantly change and boiling temperatures increased (approx. 26%) in comparison to the non-winterised WCOME.