Relationships derived from physical properties of vegetable oil and biodiesel fuels

The aim of this study was to estimate mathematical relationships between higher heating value (HHV) and viscosity, density or flash point measurements of various biodiesel fuels. The HHV is an important property defining the energy content and thereby efficiency of fuels, such as vegetable oils and biodiesels. The biodiesels were characterized for their physical and main fuel properties including viscosity, density, flash point and higher heating value. The viscosities of biodiesels (2.8–5.1 mm²/s or cSt at 311 K) were much less than those of pure oils (23–53 mm²/s at 311 K), and their HHVs of approximately 41 MJ/kg were 10% less than those of petrodiesel fules (～46 MJ/kg). Compared to No. 2 diesel fuel, all of the vegetable oil methyl esters were slightly viscous. The density and flash point values of vegetable oil methyl esters are highly lower than those of vegetable oils. The HHVs of vegetable oils and their biodiesels were measured and correlated using linear least square regression analysis. There is high regression between viscosity and higher heating value for vegetable oil and biodiesel samples. An increase in density from 848 to 885 g/L for biodiesels increases the viscosity from 2.8 to 5.1 cSt and the increases are highly regular. There is high regression between density and viscosity values vegetable oil methyl esters. The relationships between viscosity and flash point for vegetable oil methyl esters are considerably regular.     

The effect of temperature and pressure on the physicochemical properties of petroleum diesel oil and biodiesel fuel

Three commercial fuels were studied: biodiesel (based mainly of the fatty acids methyl esters of rapeseed oil), diesel oil Ekodiesel Ultra (standard petroleum diesel oil with sulphur content less than 10 mg/kg), and ON BIO 10 (blend of 20 vol.% of biodiesel with 80 vol.% of standard petroleum diesel oil with sulphur content less than 10 mg/kg). The speeds of sound were measured within the temperatures from 293 to 318 K and at pressures from 0.1 to 101 MPa. The densities and heat capacities were measured under atmospheric pressure in the temperature range from 273 to 363 K and 283 to 359 K, respectively. Using the experimental results, the physicochemical properties such as: density, isentropic bulk modulus, heat capacity, and isobaric thermal expansion were calculated in the same temperature and pressure range as the speed of sound was measured. The results obtained show that although the bulk modulus of ON BIO 10 is higher than that of diesel oil Ekodiesel Ultra over the whole pressure range, the difference is rather small and can be compensated by temperature. Isobaric thermal expansivity of biodiesel decreases with pressure slightly less than that of the diesel oil Ekodiesel Ultra. It is approximately independent of temperature and composition of the fuel at pressures 40 ± 5 MPa.     

Analytical study for atomization of biodiesels and their blends in a typical injector: Surface tension and viscosity effects

This study presents analytical comparisons of atomization characteristics of 7 biodiesels and 17 binary and ternary blends with D1 and D2 at 80 °C, using a direct injection injector. The atomization of a genetically modified vegetable oil – Captex 355 – and its corresponding biodiesel were also studied. Results from statistical analysis showed that B100 coconut biodiesel had similar atomization characteristics to D2, because of its similar properties, i.e. density, surface tension and viscosity. No significant difference in drop size was observed for all B5 blends, and B20 blends and B100 biodiesels of palm, soybean, cottonseed, peanut and canola. It implies these stocks of biodiesels and their blends can be used in a DI engine with similar atomization characteristics. Ternary biodiesel blends, with ⩽10 wt.% petroleum diesel, can yield equal drop sizes as some binary blends with large quantities of D1 and D2. The ternary biodiesel blends are likely to reduce pollution from exhaust emissions better than the biodiesel blends with D1 or D2. Captex 355 biodiesel had the best atomization characteristics of all the fuels studied. The Sauter mean diameter (SMD) produced by this fuel was up to 13% and 25% smaller than that of D1 and D2, respectively. The Captex 355 biodiesel may be used as a base in binary or ternary biodiesel blends to achieve better atomization than D1 and D2 in diesel engines.     

Comparisons of Biodiesel Produced from Unrefined Oils of Different Peanut Cultivars

Biodiesels were prepared according to standard procedures from unrefined oils of eight commercially available peanut cultivars and compared for differences in physical properties important to fuel performance. Dynamic viscosity, kinematic viscosity and density were measured from 100 to 15 °C, and differences (p < 0.05) in these physical properties occurred more frequently at lower temperatures when comparing the different cultivars. Unlike data for the oil feedstocks, no meaningful correlations among biodiesel fatty acid profiles and either fuel viscosity or density were observed. Low temperature crystallization of the peanut biodiesels was measured via differential scanning calorimetry. Increased concentrations of long chain saturated fatty acid methyl esters (FAME) were associated with an increased propensity for low temperature crystallization, and the single FAME category most associated with low temperature crystallization was C:24. Tempering at 10 °C followed by analysis of the soluble fractions (winterization), improved crystallization properties and confirmed the importance that long chain saturated FAMEs play in the final functionality of peanut biodiesel. Peanut data is also compared to data for canola and soy biodiesels, as these feedstocks are more common worldwide for biodiesel production. Overall, this work suggests that minimizing the concentration of long chain saturated FAMEs within peanut biodiesel, either through processing and/or breeding efforts would improve the low temperature performance of peanut biodiesel.     

Ethanolysis of used frying oil. Biodiesel preparation and characterization

The transesterification reaction of used frying oil by means of ethanol, using sodium hydroxide, potassium hydroxide, sodium methoxide, and potassium methoxide as catalysts, was studied. The objective of the work was to characterize the ethyl esters for its use as biodiesels in compression ignition motors. The operation variables used were ethanol/oil molar ratio (6:1–12:1), catalyst concentration (0.1–1.5 wt.%), temperature (35–78 °C), and catalyst type. The evolution of the process was followed by gas chromatography, determining the concentration of the ethyl esters at different reaction times. The biodiesel was characterized by its density, viscosity, flash point, combustion point, cold filter plugging point, cloud and pour points, Conradson carbon residue, characteristics of distillation, cetane index and high heating value according to ISO norms. The biodiesel with the best properties was obtained using an ethanol/oil molar ratio of 12:1, potassium hydroxide as catalyst (1%), and 78 °C temperature. The density, viscosity, cetane index, Conradson carbon residue and calorific power of the biodiesel obtained had values close to those of a no. 2 diesel. On the contrary, the cold filter plugging point, and cloud and pour points are higher than the conventional diesel fuel. Although higher, flash and combustion points fulfil the norms for ethyl esters derived from vegetable oils. In consequence, the final product obtained had very similar characteristics to a no. 2 diesel oil, and therefore, these ethyl esters might be used as an alternative to fossil fuels. The two-stage transesterification was better than the one-stage process, and the yields of ethyl esters were improved 30% in relation with the one-stage transesterification.     

Ignition delay in a palm oil and rapeseed oil biodiesel fuelled engine and predictive correlations for the ignition delay period

This paper presents the results of engine tests of biodiesels obtained by transesterification of palm oil and rapeseed oil and with fossil diesel fuel as a reference. The analysis is focused on the determination of the ignition delay and on obtaining a predictive correlation for it. The experiments show no significant difference in in-cylinder pressures at injection timing for each fuel. With biodiesel slightly lower peak cylinder pressures were observed for most engine conditions. Palm oil and rapeseed oil biodiesel gave shorter ignition delay than fossil diesel fuel due to the higher cetane number for the biodiesels. The ignition delay data were correlated as a function of the equivalence ratio, the mean cylinder pressure and mean temperature over the ignition delay interval. A comparison is made with other available correlations. The ignition delay values estimated by the new correlations are in good agreement with the experiments.     

Comparison of particle emissions from an engine operating on biodiesel and petroleum diesel

Biodiesel is an alternative fuel with growing usage in the transportation sector. To compare biodiesel and petroleum diesel effects on particle emissions, engine dynamometer tests were performed on a Euro II engine with three test fuels: petroleum diesel (D), biodiesel made from soy bean oil (BS) and biodiesel made from waste cooking oil (BW). PM_2.5 samples were collected on Teflon and quartz filters with a Model 130 High-Flow Impactor (MSP Corp). Organic (OC) and elemental (EC) carbon fractions of PM_2.5 were quantified by a thermal-optical reflectance analysis method and particle size distributions were measured with an electrical low pressure impactor (ELPI). In addition, the gaseous pollutants were measured by an AMA4000 (AVL Corp). The biodiesels were found to produce 19-37% less and 23-133% more PM_2.5 compared to the petroleum diesel at higher and lower engine loads respectively. On the basis of the carbon analysis results, the biodiesel application increased the PM_2.5 OC emissions by 12-190% and decreased the PM_2.5 EC emissions by 53-80%, depending on the fuel and engine operation parameters. Therefore OC/EC was increased by three to eight times with biodiesel application. The geometrical mean diameter of particles from biodiesels and petroleum diesel had consistent trends with load and speed transition. In all the conditions, there is a shift of the particles towards smaller geometric mean diameter for the biodiesel made from waste oil.     

Comparative study of performance and emissions of a diesel engine using Chinese pistache and jatropha biodiesel

An experimental study of the performances and emissions of a diesel engine is carried out using two different biodiesels derived from Chinese pistache oil and jatropha oil compared with pure diesel. The results show that the diesel engine works well and the power outputs are stable running with the two selected biodiesels at different loads and speeds. The brake thermal efficiencies of the engine run by the biodiesels are comparable to that run by pure diesel, with some increases of fuel consumptions. It is found that the emissions are reduced to some extent when using the biodiesels. Carbon monoxide (CO) emissions are reduced when the engine run at engine high loads, so are the hydrocarbon (HC) emissions. Nitrogen oxides (NOx) emissions are also reduced at different engine loads. Smoke emissions from the engine fuelled by the biodiesels are lowered significantly than that fuelled by diesel. It is also found that the engine performance and emissions run by Chinese pistache are very similar to that run by jatropha biodiesel.     

Biodiesel production via peanut oil extraction using diesel-based reverse-micellar microemulsions

Vegetable oils have been studied as a feasible substitute for diesel fuel, and short term tests using neat vegetable oils have shown results comparable to those of diesel fuel. However, engine problems arise due to the high oil viscosity after long-term usage. Vegetable oil/diesel blending as biodiesel fuel has been shown to be one technique to reduce vegetable oil viscosity. The goal of this research is to demonstrate the feasibility of producing this biodiesel fuel via vegetable oil extraction using diesel-based reverse-micellar microemulsions as an extraction solvent. In this extraction technique, peanut oil is directly extracted into the oil phase of the microemulsion based on the “likes dissolve likes” principle and the product of the extraction process is peanut oil/diesel blend. The results show that diesel-based reverse micellar extract oil from peanuts more effectively than both diesel and hexane alone under the same extraction condition. An extraction efficiency of 95% was achieved at room temperature and short extraction time of 10 min in just a single extraction step. The extracted peanut oil/diesel blend was tested for peanut oil fraction, viscosity, cloud point and pour point, which all meet the requirements for biodiesel fuel.     

Fuel properties of hydroprocessed rapeseed oil

This paper deals with the hydroprocessing of rapeseed oil as a source of hydrocarbon-based biodiesel. Rapeseed oil was hydroprocessed in a laboratory flow reactor under four combinations of reaction conditions at temperatures 310 and 360 °C and under hydrogen pressure of 7 and 15 MPa. A commercial hydrotreating Ni-Mo/alumina catalyst was used. Reaction products contained mostly n-heptadecane and n-octadecane accompanied by low concentrations of other n-alkanes and i-alkanes. Reaction product obtained at 360 °C and 7 MPa was blended into mineral diesel fuel in several concentration levels ranging from 5 to 30 wt.%. It was found, that most of the standard parameters were similar to or better than those of pure mineral diesel. On the other hand, low-temperature properties were worse, even after addition of high concentrations of flow improvers.     

Influence of soybean biodiesel content on basic properties of biodiesel-diesel blends

The world tendency in last years is to restrict the use of fossil fuels and replace them partially or totally by renewable fuels. Accordingly, biodiesel is being studied as one of the main alternatives and the production and consumption of this pure biofuel and its binary blends with fossil diesel have been markedly grown. Thus, the present work evaluated the influence of biodiesel concentration on such blends when mixed to diesel in 5, 15, 25 and 50 volume percentages. For each blend, both methanol and ethanol biodiesels were investigated. The biodiesel samples were physicochemically characterized. Their rheological behavior was analyzed. It was observed that the biodiesel enrichment leads to an acceptable increase in the viscosity and to a decrease in the volatilization of the binary blends. The viscosity was also shown to be temperature-dependent, as well as the fatty acids chain length and unsaturation.     

Flow properties of biodiesel fuel blends at low temperatures

The dynamic viscosities of biodiesel derived from ethyl esters of fish oil, no. 2 diesel fuel, and their blends were measured from 298 K down to their respective pour points. Blends of B80 (80 vol.% biodiesel–20 vol.% no. 2 diesel), B60, B40 and B20 were investigated. All the viscosity measurements were made with a Bohlin VOR Rheometer. Cloud point and pour point measurements were made according to ASTM standards. Arrhenius equations were used to predict the viscosities of the pure Biodiesel (B100), no. 2 diesel fuel (B0) and the biodiesel blends (B80, B60, B40, and B20) as a function of temperature. The predicted viscosities agreed well with measured values. An empirical equation for calculating the dynamic viscosity of these blends as a function of both temperature and blend has been developed. Furthermore, based on the kinematic viscosity and density measurements of B100 up to 573 K by Tate et al. [Tate RE, Watts KC, Allen CAW, Wilkie KI. The viscosities of three biodiesel fuels at temperatures up to 300 °C. Fuel 2006;85:1010–5; Tate RE, Watts KC, Allen CAW, Wilkie KI. The densties of three biodiesel fuels at temperatures up to 300 °C. Fuel 2006;85:1004–9] an empirical equation for predicting the dynamic viscosity of pure biodiesel for temperatures from 277 K to 573 K is given. Empirical equations for predicting the cloud and pour point for a given blend give values in good agreement with experiments. The dynamic viscosity of biodiesel and its blends increases as temperature decreases and show Newtonian behaviour down to the pour point. Dynamic viscosity, cloud point and pour point decreases with an increase in concentration of no. 2 diesel in the blend.     

Fuel properties and nitrogen oxide emission levels of biodiesel produced from animal fats

FAME of lard, beef tallow, and chicken fat were prepared by base-catalyzed transesterification for use as biodiesel fuels. Selected fuel properties of the neat fat-derived methyl esters (B100) were determined and found to meet ASTM specifications. The cold-flow properties, lubricity, and oxidative stability of the B100 fat-derived fuels also were measured. In general, the cold-flow properties of the fat-based fuels were less desirable than those of soy-based biodiesel, but the lubricity and oxidative stability of the fat-based biodiesels were comparable to or better than soy-based biodiesel. Nitrogen oxide (NO_x) emission tests also were conducted with the animal fat-derived esters and compared with soybean oil biodiesel as 20 vol% blends (B20) in petroleum diesel. The data indicated that the three animal fat-based B20 fuels had lower NO_x emission levels (3.2–6.2%) than did the soy-based B20 fuel.     

Preparation and Evaluation of Biodiesel from <Emphasis Type="Italic">Sterculia foetida</Emphasis> Seed Oil

Sterculia foetida oil contains cyclopropene fatty acids namely 8,9-methylene-heptadec-8-enoic acid (malvalic) and 9,10-methylene-octadec-9-enoic acid (sterculic) to an extent of 50–55%. The present study reports the preparation of biodiesel from S. foetida oil using sodium hydroxide as catalyst. The resultant biodiesel was evaluated for physico-chemical properties namely iodine value (72.6), free fatty acids (0.17%), phosphorous content (0 ppm), flash point (179 °C), cloud point (3 °C), pour point (3 °C), viscosity at 40 °C (4.72 cSt), oxidative stability at 110 °C (3.42 h), density (0.850 g/cm³ at 15 °C), and trace metals (Group I metals 0.21 ppm). The properties were compared with that of sunflower, soybean and rapeseed oil-based biodiesels and found to be comparable except for the pour point.     

生物柴油氧化安定性的实验室研究

用桐油生物柴油、棕榈油生物柴油和石化柴油以不同的比例混和分别放置在不同的条件下常温贮存3×30 d,对其氧化安定性进行考察,定时取样测其过氧化值、酸值、运动粘度。并对得出的变化规律进行总结分析,以求将双键较多的生物柴油应用的更加广泛。     

Formulation of Canola-Diesel Microemulsion Fuels and Their Selective Diesel Engine Performance

Vegetable oils have been considered as an alternative to diesel fuel due to their comparable properties and performance. However, the high viscosity of vegetable oil causes engine durability problems with long-term usage. Vegetable oil viscosity can be reduced by blending with diesel fuel in thermodynamically stable mixtures using microemulsion fuel formulation techniques. This work focuses on the formulation of microemulsion fuels comprising diesel fuel and canola oil as the oil phase with ethanol and sec-butanol as viscosity reducers as well as 1-octanol and oleyl amine as surfactant/cosurfactant. Selective tests on an instrumented diesel engine were performed for formulated microemulsion fuels and No. 2 diesel fuel for comparison. The results show that formulated microemulsion fuels have fuel properties that meet the ASTM requirements for viscosity, cloud point, and pour point for biodiesel. Even more important, they have phase stability over a wide range of temperatures (−10 to 70 °C). Although all of the microemulsion fuels showed higher fuel consumption than diesel fuel, some of the microemulsion fuels had significantly reduced CO and NO_x emissions as well as reduced particulates when compared to baseline diesel fuel. The research demonstrates the potential of these microemulsion fuels as alternative to neat diesel fuel.     

生物柴油降凝机理的研究进展

生物柴油是可再生清洁燃料,能够减缓人类对石化柴油的依赖,然而生物柴油凝固点和粘度相对较高,低温流动性较差,冬季低温环境下结晶体易堵塞发动机管道和过滤器,使发动机无法正常工作。主要综述了生物柴油的性质、特点、降凝剂的作用机理及其研究方法。并对生物柴油的前景做了展望。     

Physical-chemical properties of waste cooking oil biodiesel and castor oil biodiesel blends

This work presents the physical-chemical properties of fuel blends of waste cooking oil biodiesel or castor oil biodiesel with diesel oil. The properties evaluated were fuel density, kinematic viscosity, cetane index, distillation temperatures, and sulfur content, measured according to standard test methods. The results were analyzed based on present specifications for biodiesel fuel in Brazil, Europe, and USA. Fuel density and viscosity were increased with increasing biodiesel concentration, while fuel sulfur content was reduced. Cetane index is decreased with high biodiesel content in diesel oil. The biodiesel blends distillation temperatures T₁₀ and T₅₀ are higher than those of diesel oil, while the distillation temperature T₉₀ is lower. A brief discussion on the possible effects of fuel property variation with biodiesel concentration on engine performance and exhaust emissions is presented. The maximum biodiesel concentration in diesel oil that meets the required characteristics for internal combustion engine application is evaluated, based on the results obtained.     

Biodiesel production from pomace oil and improvement of its properties with synthetic manganese additive

Renewable energy sources are attracting more attention due to lower cost and lower pollution relative to fossil fuels. The aim of this experimental work is the production of renewable and clean methyl ester from pomace oil as an alternative fuel. This oil was obtained from pomace which is the waste of olive oil plants. Optimum producing conditions were determined experimentally. The maximum yield was obtained at 30% of methanol/oil ratio, 60 °C temperature for 60 min with NaOH catalyst. The properties of the biodiesel thus obtained were compared with diesel fuel requirements. An organic based Manganese additive improved the biodiesel properties. Doping the fuel at a ratio of 12 μmol/l oil methyl ester led to a 20.37% decrease in viscosity, 7 °C fall in the flash point and reduced the pour point from 0 °C to −15 °C. This blend of pomace oil methyl ester-diesel fuel with manganese additive was tested in a direct injection diesel engine. The maximum effect of the new fuel blend and diesel fuel on engine performance was obtained at 1400 rpm.