Biodiesel Mixtures Research Articles

Droplet combustion of blended fuels with alcohol and biodiesel/diesel in microgravity condition

Based on a drop tower built in the lab space, an environment of reduced gravity was employed to study the droplet combustion of multi-component fuels, specifically of diesel mixed with alcohol (methanol, ethanol, and 2-propanol) and biodiesel. The falling duration was about 0.68s and was sufficient for complete burning of a droplet with a diameter as small as 0.5mm that was suspended at the crossing point of two ultra-thin fibers with a diameter of 2.5μm. The fibers were made of ceramics with low heat conductivity and imposed negligible interference on the droplet that was less subject to deformation as compared to large droplets that were usually tested. In the study, biodiesel was not added merely as an alternative fuel to diesel, but also to provide an interface for the mixing of alcohol and diesel. In the lack of asymmetric convection that was generically rendered by buoyancy or external flow, the burning characteristics were investigated with alleviated complexity while a soot shell could be formed under the flame surface with spherical symmetry. The work can hence be adopted for qualitative understanding of soot formation at the first place, for which quantitative measurement may not be directly performed on the spot, for different fuel mixtures. It was found that the addition of alcohol in a diesel–biodiesel mixture could enhance the burning rate, reduce the preheating delay, and mitigate pollution of soot particles as well as the tendency to form rigid layers. Furthermore, the introduction of microexplosion through the mixing with alcohol of much higher volatility may lead to substantial disintegration and faster combustion of fuel droplets.

Liquid–liquid and vapor–liquid equilibrium data for biodiesel reaction–separation systems

This work reports experimental vapor–liquid and liquid–liquid equilibrium data for binary and ternary systems comprised of various mixtures of biodiesel (from soybean oil), methanol, ethanol, glycerol and soybean oil. The binodal curves for biodiesel+methanol+glycerol, biodiesel+ethanol+glycerol, biodiesel+methanol+soybean oil and biodiesel+ethanol+soybean oil systems were obtained at two different temperatures by titration. An Othmer-type ebulliometer was used for vapor–liquid equilibrium measurements at pressures ranging from 14.0kPa to 92.0kPa. Binodals curves (LLE) indicated that the temperature range used in this study has no effect on the immiscibility region for the biodiesel+methanol+soybean oil system. By contrast, for the biodiesel+ethanol+soybean oil system, the immiscibility region was larger at the lower temperature. For the vapor–liquid equilibrium data, the results showed that the addition of glycerol to the biodiesel+ethanol binary system does not significantly affect the boiling temperature of the system while with the addition of methanol to the biodiesel+soybean oil system the boiling temperatures of the ternary mixture are reduced. These results can be used to enhance the reaction conversion and the purification processes associated with biodiesel production.

Evaluating antioxidants efficiency during storage of ethylic and methylic biodiesel by low pressurized DSC and Rancimat methods

Efficiencies of four commercial antioxidants used during the storage of two biodiesel, BS-ethyl and BS-methyl, respectively obtained from soybean oil by ethylic and methylic routes, were evaluated by measuring their oxidative stability using a low pressurized DSC (low P-DSC) method developed by the authors and by Rancimat method, which is specified by the American ASTM D6751 and European EN 14214 standard methods. The operating temperature of the low P-DSC method was the same as that used in the Rancimat procedure (110 °C). The antioxidants, used in 500 mg kg−1 content, have the following active components: phenol, biphenol, phenol + amine mixture, and a hydroquinone + organic acid mixture. Samples of each biodiesel–antioxidant mixture were evaluated simultaneously by the two methods, right after their preparation and 30, 60, 90, and 120 days of storage at 23 ± 1 °C. A non-dimensional oxidative induction time parameter, defined as the ratio between the oxidation induction time (OIT) or induction time (IT) values at a storage time t and at t = 0, was used to evaluate the antioxidant activity. For the same mixture, changes of this non-dimensional parameter calculated from OIT or IT show a similar trend with storage time, indicating that it can be determined either from low P-DSC or Rancimat method data. As the efficiency of the studied antioxidants depends on their composition, their interaction with each biodiesel, and on the storage time, this parameter can be used to indicate the best storage time for each antioxidant–biodiesel mixture.

Experimental investigations of ignition delay period and performance of a diesel engine operated with Jatropha oil biodiesel

Jatropha-curcas as a non-edible methyl ester biodiesel fuel source is used to run single cylinder, variable compression ratio, and four-stroke diesel engine. Combustion characteristics as well as engine performance are measured for different biodiesel – diesel blends. It has been shown that B50 (50% of biodiesel in a mixture of biodiesel and diesel fuel) gives the highest peak pressure at 1750rpm, while B10 gives the highest peak pressure at low speed, 1000rpm. B50 shows upper brake torque, while B0 shows the highest volumetric efficiency. B50 shows also, the highest BSFC by about (12.5–25%) compared with diesel fuel. B10 gives the highest brake thermal efficiency. B50 to B30 show nearly the lowest CO concentration, besides CO concentration is the highest at both idle and high running speeds. Exhaust temperature and NOx are maximum for B50. Delay period is measured and correlated for different blends. Modified empirical formulae are obtained for each blend. The delay period is found to be decreased with the increase of cylinder pressure, temperature and equivalence ratio.

Infl uence of castor oil mix composition on the production of biofuel

Castor oil trans esterifi cation has been evaluated as a source of alternative biodiesel. Three mixtures of biofuel (B5% B10% and B20%) were tested in a diesel engine. Power, fuel consumption, temperature and exhaust emissions were measured. Also, densities, viscosities, refractive indexes and combustion heats of the mixtures were determined. The use of biodiesel mixtures produces an increase of viscosity and fuel consumption, decreasing the heating and engine power, reducing the combustion gases like CO, CO2, sulfur oxides, hydrocarbons, and lowering the opacity of exhaust emissions. Additionally, a balance in the observed diesel engine performance was evidenced by the engine temperatures.

Acceleration of biodiesel–glycerol decantation through NaCl-assisted gravitational settling: A strategy to economize biodiesel production

When making biodiesel, slow separation of glycerol; the main by-product of the transesterification reaction, could lead to longer operating times, bigger equipment and larger amount of steel and consequently increased production cost. Therefore, acceleration of glycerol/biodiesel decantation could play an important role in the overall biodiesel refinery process. In this work, NaCl-assisted gravitational settling was considered as an economizing strategy. The results obtained indicated that the addition of conventional NaCl salt decreased the glycerol settling time significantly up to more than five times. However, NaCl inclusion rates of more than 3g to the mixture (i.e. 5 and 10g) resulted in significantly less methyl ester purity due to the occurrence of miniemulsion phenomenon. Overall, addition of 1g NaCl/100ml glycerol–biodiesel mixture was found as optimal by accelerating the decantation process by 100% while maintaining the methyl ester purity as high as the control (0g NaCl).

Screening Analysis of Biodiesel Mixture Feedstock Using near Infrared Spectrometry

Germano Veras, Gean B. Costa, Jessika Pequeno de Freitas, Ana Claudia Dantas de Medeiros, Adriano Araujo Gomes and David Douglas de Sousa Fernandes Departamento de Quimica, Centro de Ciencias e Tecnologia, Universidade Estadual da Paraiba, 58.429–500 Campina Grande—PB, Brazil. E-mail: germano.veras@pq.cnpq.br Programa de Pos-Graduacao em Ciencias Farmaceuticas, Universidade Estadual da Paraiba, 58.429–500 Campina Grande—PB, Brazil Departamento de Quimica, Universidade Federal da Paraiba, 58.051–970, Joao Pessoa—PB, Brazil Programa de Pos-Graduacao em Ciencias Agrarias, Universidade Estadual da Paraiba, 58.429–500 Campina Grande—PB, Brazil

Evaluation of the Oxidative Stability of Biodiesel Blends from Soybean, Tallow and Castor Bean using Experimental Mixture Design

This study proposes an experimental design of biodiesel constrained mixtures to evaluate and optimize the oxidative stability of soybean biodiesel mixed with different amounts of tallow and castor bean biodiesels. To prepare the biodiesel blends, the proportions of each type of biodiesel were varied, producing mixtures that contained 80-86% (v/v) soybean, 5-15% (v/v) tallow, and 1-10% (v/v) castor bean biodiesel. The induction period of pure soybean biodiesel served as the baseline for comparing the stability of the mixtures. The experimental design strategy was capable of producing the best oxidative stability for biodiesel mixtures. The quadratic model obtained in the optimization stage fits the experimental data well. The higher induction period occurred at the following composition: 82.5% (v/v) soybean, 7.5% (v/v) tallow and 10.0% (v/v) castor bean.

Modelo basado en redes neuronales para predecir las emisiones en un motor diésel que opera con mezclas de biodiésel de higuerilla

En este documento se explican algunos métodos de identificación de sistemasno lineales mediante el uso de redes neuronales artificiales. También se planteaun modelo basado en redes neuronales Feed Forward supervisadas, desarrolladopara identificar y predecir el comportamiento de las emisiones volumétricas dela combustión de un motor diésel estacionario en función de dos variables deentrada: la carga del motor y la mezcla de biodiésel de higuerilla. El entrenamientode la red neuronal y la validación del modelo se realizaron mediante elprograma NNModel.

Sensitivity of Diesel Particulate Material Emissions and Composition to Blends of Petroleum Diesel and Biodiesel Fuel

A number of investigations have examined the impact of the use of biodiesel on the emissions of carbon dioxide and regulated emissions, but limited information exists on the chemical composition of particulate matter from diesel engines burning biodiesel blends. This study examines the composition of diesel particulate matter (DPM) emissions from a commercial agriculture tractor burning a range of biodiesel blends operating under a load that is controlled by a power take off (PTO) dynamometer. Ultra-low sulfur diesel (ULSD) fuel was blended with soybean and beef tallow based biodiesel to examine fuels containing 0% (B0), 25% (B25), 50% (B50), 75% (B75), and 100% (B100) biodiesel. Samples were then collected using a dilution source sampler to simulate atmospheric dilution. Diluted and aged exhaust was analyzed for particle mass and size distribution, PM2.5 particle mass, PM2.5 organic and elemental carbon, and speciated organic compounds. PM2.5 mass emissions rates for the B25, B50, and B75 soybean oil biodiesel mixtures had 20%–30% lower emissions than the petroleum diesel, but B100 emissions were about 40% higher than the petroleum diesel. The trends in mass emission rates with the increasing biodiesel content can be explained by a significant decrease in elemental carbon (EC) emissions across all blending ranges and increasing organic carbon (OC) emissions with pure biodiesel. Beef tallow biodiesel blends showed similar trends. Nevertheless, it is important to note that the study measurements are based on low dilution rates and the OC emissions changes may be affected by ambient temperature and different dilution conditions spanning micro-environments and atmospheric conditions. The results show that the use of biodiesel fuel for economic or climate change mitigation purposes can lead to reductions in PM emissions and a co-benefit of EC emission reductions. Detailed speciation of the OC emissions were also examined and are presented to understand the sensitivity of OC emissions with respect to biodiesel fuel blends. Copyright 2012 American Association for Aerosol Research

High Temperature Density, Viscosity, and Interfacial Tension Measurements of Bitumen–Pentane–Biodiesel and Process Water Mixtures

As an alternative to solvent addition to the steam-assisted gravity drainage process for bitumen recovery, coinjection of biodiesel with steam as a surfactant additive to reduce bitumen–water interfacial tension was considered. The density and viscosity of bitumen and bitumen–pentane mixtures up to 15 % pentane concentrations by mass were measured at a 1 MPa pressure and up to 448 K temperature. The interfacial tension between bitumen, bitumen–pentane mixtures up to 15 % pentane concentrations, bitumen–biodiesel mixtures up to 0.3 % and water, and process water was also measured at a 1 MPa pressure and up to 423 K temperature. Laboratory tests showed that the density of bitumen–pentane mixtures decreased linearly with an increase in pentane content, and their viscosity decreased exponentially with the increase in temperature. A decrease in bitumen viscosity with an increase in pentane content was dramatic at low temperatures and became less sensitive at temperatures above 373 K. Interfacial tension measur...

Effect of blends of Diesel and Palm-Castor biodiesels on viscosity, cloud point and flash point

Many countries are promoting the use of biodiesel as a direct replacement for, or blend stock component with petroleum based diesel fuel using policy instruments that aim to gradually increase the use of vegetable oil biodiesel–diesel ratio from the current (or inexistent) blend to values among 15–20% by an specific upcoming year. For the particular use of palm oil as biomass raw material in the diesel–palm oil biodiesel (Diesel–POB) blend that goal could bring some difficulties because the high content of saturated fatty acids in POB could confer a problematic high cloud point to the fuel mixtures. On the other hand, the use of castor oil biodiesel in the blends could lower the cloud point value but, simultaneously, increase the viscosity of the diesel–biodiesel blends. In this article there were evaluated three properties (viscosity, cloud point and flash point) of binary mixtures castor oil biodiesel (COB), palm oil biodiesel (POB) and diesel fuel. It was also measured the cloud point for some ternary bends of Diesel/POB/COB. It was found that diesel–castor oil biodiesel (DieselCOB) blends showed appropriate and approximately the same cloud point temperatures when the biodiesel concentration in those mixtures was under 40% in volume. The use of palm oil biodiesel–castor oil biodiesel (POBCOB) blends to obtain a type of pure biodiesel with both low cloud point and viscosity was not a practical option. Experimental data were also compared with the predictions of different published models for diesel–biodiesel mixtures. The general thermodynamic expressions used for estimation of viscosity and cloud point for liquid mixtures showed lower deviations from experimental values properties predictions from other proposed empirical models.

Viscosities and viscosity deviations of binary mixtures of biodiesel + petrodiesel (or n-hexadecane) at different temperatures

Viscosities of four binaries mixtures [soybean biodiesel + diesel oil (or n-hexadecane) and coconut biodiesel + diesel oil (or n-hexadecane)] have been determined at T = (293.15, 313.15, 333.15, 353.15, 373.15) K and atmospheric pressure over the entire composition range. Experimental data were fitted to the Andrade equation and the adjustable parameters and the standard deviations between experimental and calculated values were estimated. From the experimental data, the viscosity deviations, , were calculated by using the Redlich - Kister polynomial equation. The comparison between experimental data determined in this work and four predictive methods used for the estimation of viscosities of biodiesel fuels (based on their fatty acid composition) is discussed.

Pure silica nanoparticles for liposome/lipase system encapsulation: Application in biodiesel production

In this work we report the synthesis of organic–inorganic solid with spherical morphology where enzyme, as active compounds, is encapsulated. The organic phase of nanospheres is composed of l-α-phosphatidylcholine, as liposome, and lipase from Rhizomucor miehei, as enzyme. The organic phase is covered with porous inorganic silica shell that could stabilize the internal liposomal phase and, consequently, isolate and protect the bioactive molecules. The liposome and silica amount used during the immobilization procedure have been optimized in order to obtain active and stable heterogeneous biocatalyst. Hybrid-nanospheres containing the enzyme were used to catalyze the transesterification reaction of triolein with methanol to methyl esters, typical biodiesel mixture compounds. The encapsulated enzyme retains its activity after 5 reaction cycles. The total productivity of the best catalyst obtained is higher than that of the free enzyme.

Experimental and kinetic modeling study of 1-hexanol combustion in an opposed-flow diffusion flame

Biofuels are of particular interest as they have the potential to reduce our dependence on petroleum-derived fuels and the levels of greenhouse gas emissions from transportation. 1-Hexanol is a promising renewable long chain alcohol that can be used in conventional fuel blends or as a cosolvent for biodiesel mixtures. However, the fundamental combustion properties of 1-hexanol have not been fully characterized in the literature. Thus, new experimental results, consisting of temperature and concentration profiles of stable species were obtained for the oxidation of 1-hexanol generated in an opposed-flow diffusion flame at 0.101MPa. This experimental data were compared to the predicted values of a detailed chemical kinetic mechanism proposed in the literature to study the combustion of 1-hexanol.This mechanism consists of 361 chemical species and 2687 chemical reactions (most of them reversible). Reaction pathway and sensitivity analyses were performed to interpret the results. In addition, improvements were investigated to optimize the proposed mechanism.

Simulation of biodiesel combustion in a light-duty diesel engine using integrated compact biodiesel–diesel reaction mechanism

This computational fluid dynamics (CFD) study is performed to investigate the combustion characteristics and emissions formation processes of biodiesel fuels in a light-duty diesel engine. A compact reaction mechanism with 80 species and 303 reactions is used to account for the effects of chemical kinetics. Here, the mechanism is capable of emulating biodiesel–diesel mixture of different blending levels and biodiesel produced from different feedstock. The integrated CFD-kinetic model was validated against a test matrix which covers the entire saturated–unsaturated methyl ester range typical of biodiesel fuels, as well as the biodiesel–diesel blending levels. The simulated cases were then validated for in-cylinder pressure profiles and peak pressure values/timings. Errors in the peak pressure values did not exceed 1%, while the variations in peak pressure timings were kept within 1.5 crank angle degree (CAD). For this reported work, in-cylinder formation mechanisms of nitrogen monoxide (NO) and soot from the combustion of biodiesel fuels such as coconut methyl ester (CME), palm methyl ester (PME) and soybean methyl ester (SME) were simulated and compared against that of the baseline diesel fuel. It is established here that an increase in the degree of unsaturation in biodiesel fuels can have detrimental effects on engine-out NO and soot concentrations. Biodiesel fuel with greater unsaturation level such as SME has the predisposition to produce greater thermal NO due to larger regions of high temperature achieved during combustion. Besides, the highly unsaturated SME has greater tendencies to produce acetylene which are precursors for prompt NO and soot, leading to higher engine-out emissions of these pollutants. In all, this study has demonstrated the feasibility of integrating a compact multi-component surrogate fuel mechanism with CFD to elucidate the in-cylinder combustion and emissions characteristics of biodiesel fuels. The knowledge acquired here is useful for the development of biodiesel usage strategies in light-duty diesel engines for mass adoption.

Detection of Ethylene Emitted by Diesel-biodiesel Engine Using CO2 Laser Photoacoustic Sensors

The increased use of modern society vehicles is rising the pollutant gas emissions causing several environmental and public health problem in urban centers. Diesel fuel is a major emitter of pollutant gases, especially in Brazil, where the transport is predominantly by land. For this reason, Brazilian government aims to modify the energy matrix with the addition of renewable energy sources, such as biodiesel. In this paper, we studied the emission of ethylene gas from the combustion of binary mixtures, because this gas is directly related to the formation of photochemical smog. The Brazilian government does not have specific regulations for the emission of ethylene yet. Thus, it becomes necessary to monitor and to detect this gas through sensitive and selective methods, such as Photoacoustic Spectroscopy. This method was employed in the analysis of binary mixtures of soybean biodiesel in diesel in the following proportions: B5, B10, B15, B20 and B25, which have been tested for combustion in an engine bench. In all samples, ethylene was found in ppmv concentrations.

Pilot Plant of Biodiesel Production from Waste Cooking Oil

Biodiesel, as an alternative auto fuel for conventional fossil fuel, has drawn wide attention in recent years. In this research, a two-step process for biodiesel production using waste cooking oil as feedstock was studied in a pilot plant with a treatment capacity of 3 ton/d. The results show that: the process exihibited a good conversion ratio and the biodiesel displayed suitable physical-chemical properties in comparison with diesel fuel, such as flash point of 137°C, viscosity of 4.49 mm2/s, acid value of 0.44 mg KOH/g etc. The quality of biodiesel meets the agreement with the European specification defined by EN 14214. Afterwards, the mixture of biodiesel and diesel were test in the engine with a ratio of 50/50（v/v）, 20/80（v/v）, and 0/100（v/v）. It indicates the mixed fuel has a reasonable fuel consumption rates without diesel engine modification, when the biodiesel blended with 0# diesel as fuel. The present results demonstrated that the industrial scale plant would achieve promising objective with waste cooking oils and animal fats as raw material. Also, this biodiesel-based diesel fuel could be applied in Tianjin local public transportation system that improves its sustainable development.

Voltammetric Determination of BHT Antioxidant at Gold Electrode in Biodiesel

AbstractThe voltammetric determination of synthetic antioxidant 2,6‐di‐tert‐butyl‐4‐methylphenole (BHT) was studied using linear‐sweep voltammetry (LSV) and cyclic voltammetry (CV) with a gold electrode and performed in isopropanol media containing either 0.1 mol L−1 H2SO4 or 0.1 mol L−1 LiClO4 as supporting electrolyte. The results obtained have revealed that the most reliable detection was acquired in acidic media (isopropanol–H2SO4) whereas the use of isopropanolLiClO4 solution exhibited poorer reproducibility due to possible passivation of the electrode. Real samples of biodiesel mixture were analyzed without any special sample treatment or separation and results were compared with those obtained by FTIR‐spectroscopy.

Parameter estimation and thermodynamic model fitting for components in mixtures for bio-diesel production

In the search of clean, sustainable and renewable energy sources, at present the use of bio-diesel from vegetable oils is one of the possibilities being considered. The knowledge of phase equilibrium in mixtures found in the bio-diesel production is essential for the correct design and operation of the process. However, there is still a lack of information about the parameter values for the models used to describe the phase equilibrium, which could lead to incorrect design of the reactors and the separation processes, and to low efficiency caused by low mass transfer due to the presence of heterogeneous mixtures. In this study, two algorithms are described for the model fitting and parameter estimation, which were used to estimate the values of the parameters in the UNIQUAC and NRTL model for a mixture of vegetable oils and bio-diesel. One of the algorithms uses the Simulated Annealing (SA) method, to find good initial estimates, without any previous knowledge of the parameters. Another algorithm uses Successive Quadratic Programming, using the estimates calculated in the SA algorithm to refine these estimates. In both algorithms, the criterion for fitting is the minimization of the square of the difference between calculated and experimental values. In both algorithms, the equilibrium is calculated using the direct global minimization of the Gibbs free energy with respect to the number of moles of each component, at constant T and P, for a given set of model parameters. The results obtained were able to correctly reproduce the experimental values of phase equilibrium composition.