• Energy Research

The thermal behavior and oxidative stability of Jatropha curcas oils and their derived fatty acid ethyl esters (FAEE) obtained from two different Cuban regions and varieties are evaluated. A decrease in acid value is found for the FAEE compared to the oils from both natural sources. Primary and secondary oxidation products are significantly different among samples. Thermogravimetry and the derivate thermogravimetry were applied to the oils and FAEE samples using air and nitrogen atmospheres. The main differences between oil and FAEE derived from Jatropha oil are the number of decomposition steps that are lower in FAEE samples. Concerning the onset temperature in the mass loss process, no pattern is observed when oils and the derived FAEE are compared. A comparison among biofuels obtained from the different regions shows that the biofuels obtained from one of both plantations are less thermally stable and they also have more oxidation activity. The obtained results can influence the engine performance and exhaust emissions when these biofuels are used as fuels.

AbstractThis work deals with obtaining models for predicting the cetane number and ignition delay using artificial neural networks. Models for the estimation of the cetane number of biodiesel from their methyl ester composition and ignition delay of palm oil and rapeseed biodiesel using artificial neural networks were obtained. For the prediction of the cetane number model, 38 biodiesel fuels and 10 pure fatty acid methyl esters from the available literature were given as inputs. The best neural network for predicting the cetane number was a conjugate gradient descend (11:4:1) showing 96.3% of correlation for the validation data and a mean absolute error of 1.6. The proposed network is useful for prediction of the cetane number of biodiesel in a wide range of composition but keeping the percent of total unsaturations lower than 80%. The model for prediction of the ignition delay was developed from 5 inputs: cetane number, engine speed, equivalence ratio, mean pressure and temperature. The results showed that the neural network corresponding to a topology (5:2:1) with a back propagation algorithm gave the best prediction of the ignition delay. The correlation coefficient and the mean absolute error were 97.2% and 0.03 respectively. The models developed to predict cetane number and ignition delay using artificial neural networks showed higher accuracy than 95%. Hence, the ANN models developed can be used for the prediction of cetane number and ignition delay of biodiesel.

Data in this paper covers in-cylinder pressure and volume, crank angle degrees as time magnitude, first derivate of in-cylinder pressure, admission pressure and injection pressure in a diesel engine fuelled with biodiesel. This data brings additional information such as ignition delay and rate of heat released. As condensed information, some graphs were obtained and are into the database such as in-cylinder vs. CAD, first derivate of in-cylinder pressure vs. CAD and ROHR vs. CAD. The data shows the measurements of the cylinder pressure behaviour of biodiesel from two different sources, which are both of interest of bioenergy industry at local scenarios (Jatropha curcas and Fatty Acid Distillates). Data in the paper are shown in Tables and Graphs. Through this data, a more accurate approach to engines performance and combustion can be reach, enhancing combustion efficiency and understanding of differences with standard diesel fuel.

The production and use of terpene-based fuels represents a renewable source of energy in the transportation sector, especially in the aviation sector. The literature on the conversion of terpenes into valuable compounds is not new but has been based on the production of products for cosmetics and pharmaceutics. Several established chemical routes are also a way to develop drop-in fuels. The present work explores all the main chemical processes that can transform terpenes into more valuable fuels or additives, focusing on the use of heterogeneous catalysis, catalyst type, operating conditions, and reaction performance. α-pinene is the most studied catalyst, since it is the main component of turpentine. Isomerization is the most frequently applied chemical pathway used to enhance fuel properties, and a wide group of heterogeneous catalysts have been reported, with sulphonic acid resin catalysts, transition metals, alumina, and silicates being the most used. This work also explores the current production and commercialization of terpenes, as well as the challenges for their use as fuels at a commercial scale. The future challenge is to discover new catalysts or to improve the performance of the current products and reduce production costs. The feasibility of the production and commercialization of terpene-derived fuels is also linked to oil prices.

The scope of this work is to evaluate some properties of the oils and derived fatty acid ethyl esters (FAEE) from two different Jatropha Curcas species planted in Cuba. The properties that were determined include the acid value, peroxide value, p-anisidine value and fatty acid ethyl esters composition. In order to study the influence of the genus species and geographic conditions on the fuel properties, the oils from Jatropha Curcas planted in two regions of Cuba and their derived FAEE were analyzed and compared. The two plantations were in San Jose (SJ) and Guantanamo (Gt) representing respectively the western and eastern part of the island. The analyses indicated that the FAEE obtained from Guantanamo has a higher acid value and peroxide value compared with the FAEE from San Jose. The p-anisidine values did not show a clear trend and the results of gas chromatography-mass spectrometry indicated a similar FAEE composition. The results obtained by gas chromatography are in good agreements with previous reports. (C) 2011 Elsevier Ltd. All rights reserved.

Abstract Due to the scarcity of fossil fuels and the future stringent emission limits, there is an increasing interest for the use of renewable biofuels in compression ignition engines. However, these fuels have different physical, chemical and thermodynamic properties affecting atomization, spray development and combustion processes. The results reported in this paper have been obtained by experimentation with a constant volume combustion chamber. The influences of physical fuel properties on injections under non-evaporating conditions are studied, using a pump-line-nozzle system from a medium speed diesel engine with injection pressures up to 1200 bar, by changing the fuel type and temperature. Experiments were conducted for diesel, biodiesel, straight vegetable oils and animal fats. Injection pressure and needle lift measurements were analyzed. A high speed camera was used to visualize the spray, which enabled us to study the spray penetration and spray angle. Our results show that the fuel temperature is an important parameter to control because it significantly affects the fuel properties. Both the injection timing and injection duration are affected by the fuel properties. The influences of these properties on the spray development were less pronounced. At low temperatures, a strongly deteriorated atomization of oils and fats was observed.

The scope of this paper is to analyze the possibility and feasibility of the use of emulsification method applied to waste cooking oils and fatty acid distillates as diesel engine fuels, compared with other commonly used methods. These waste products are obtained from the refining oil industry, food industry and service sector, mainly. They are rarely used as feedstock to produce biofuels and other things, in spite of constitute a potential source of environmental contamination. From the review of the state of arts, significant decreases in exhaust emissions of nitrogen oxides, cylinder pressure as well as increases of the ignition delay, brake specific fuel consumption, hydrocarbon, smoke opacity, carbon monoxide, particulate matters to emulsified waste cooking oils and fatty acid distillates compared with diesel fuel are reported. In some experiments the emulsified waste cooking oils achieved better performance than neat fatty acid distillates, neat waste cooking oils and their derivatives methyl esters. International Journal of Sustainable Energy Planning and Management, Vol 9 (2016)