1,721,005 research outputs found
Sustainable bio kerosene: Process routes and industrial demonstration activities in aviation biofuels
No full textAnalisi dei processi per la produzione di biojet e del loro stato tecnologico. Review of biojet production processes, and assessment of their statu
Design of a circulating fluidized bed combustor for lignin-Rich residue derived from second-Generation bioethanol production plant
Full text linkThe present paper reports on the design of a pilot circulating fluidized bed combustor (CFB) for the conversion of lignin-rich residue derived from a second-generation bioethanol production plant. The designed combustor aims to improve the combustion efficiency of the lignin-rich residue, therefore increasing the heat recovery to partially cover the biorefinery’s heat consumption. Among the existing technologies, the fluidized bed combustion shows several advantages, in particular the fuel flexibility and the higher combustion efficiency mainly due to the presence of an inert material that uniforms the temperature and enhance the reactants mixing. The CFB differs from the bubbling fluidized bed (BFB) for the higher velocity of the oxidizer in the reactor, resulting in a better gas-solid mixing and higher burning rate (Basu 2015). Hence, by providing enhanced fuel conversion rate is and reduced reaction time, the characteristics of this apparatus meet the requirements for a more efficient combustion of the lignin-rich residue. The CFB combustor is mainly composed by a vertical combustion chamber (riser), a solid gas-particle separator (cyclone) and a solid particles recirculation system (recirculation valve or loop seal valve). The design process followed some consequential steps. The first step involved the theoretical 1D modeling of the reactor. Considering the project constraints of maximum plant capacity (5 kg h-1) and the consequent maximum thermal power, the geometry was chosen correlating some literature data to obtain a riser diameter of DN100 and a riser height of 3500 mm. Besides, energy and mass balances were carried out to obtain air mass flowrate data, which has an impact on the hydrodynamic study of the fluidized bed. After the geometry selection and the stoichiometric calculation, a mono-dimensional empirical model was implemented to estimate the physical behavior of the bed particles (Basu 2015), (Kunii & Levenspiel 1991). The main output of the model is the voidage fraction profile along the riser. Further important outcomes of the model are the pressure drop along the riser and the solid recirculating rate. The latter is the main input parameter for the design of the cyclone and the loop seal valve. The second step was focused on the realization of the Piping and Instrumentation Diagram selecting the measurement instruments (thermocouples, pressure transducers and flowmeters) and the ancillary equipment (blower pumps, valves and pipes). In the third step, a threedimensional CAD model was drawn for the design of the mechanical parts including the choice of the materials and the layout. The last step involved the project of the control logic and the hardware for the data acquisition system. The results of combustion tests on the circulating fluidized bed prototype will be used to gain insights into the combustion process of the lignin-rich residue, in the perspective of an industrial scale up to increase the efficiency of the energy recovery
Experimental and numerical investigations of mixing in raceway ponds for algae cultivation
No full textThe current high interest in the algae sector is leading to the development of several demo/commercial scale projects, either for the food market or bioenergy production. Raceway Ponds (RWPs) are a widely used technology for algae mass cultivation. RWPs were developed long time ago, and thus capital and operating costs are well assessed. Nevertheless, room still exists to further reduce operational costs. A possible route towards energy optimization and therefore operational cost reduction can be identified through a better understanding of the mixing phenomena. The focus of the present work is that vertical mixing, defined as the cyclical movement of the algal cells between surface and bottom layers of the culture, cannot be completely determined by considering only turbulence, and therefore it is not represented by the Re number. A 3D Computational Fluid Dynamic (CFD) analysis of a conventional RWP was carried out based on a multi-phase “Volume of Fluid” model, in order to investigate the flow field of the culture in the pond. The CFD results were compared with experimental measures on a 20 m2 pilot RWP. Once agreement among CFD and experimental results was shown, a statistical evaluation of the trajectories calculated for algae particles in the flow was carried out. The aim of this statistical evaluation was to define the level of vertical mixing in different sections of the pond. The model proposed was then used to scale-up the results to a demo/pre-commercial size RWP (500 m2). The standard deviation of the actual trajectory was calculated with respect to the undisturbed trajectory for each section modeled. The results of the simulation showed that a limited mixing is to be expected in RWPs. In the long straight parts of the pond vertical mixing is poor and algae tend to settle to the bottom. Only in the bends the vortexes produced by flow separation move part of the culture from the bottom to the top and vice-versa. This result does not fit with the practice, typically observed in large scale ponds, of reducing vortexes around the bends by placing baffles. The method described can be applied to different pond designs operated at different culture velocities
Oilseed pressing and vegetable oil properties and upgrading in decentralised small scale plants for biofuel production
No full textInvestigation on cold pressing of oilseed: oil quality vs use as biofue
Review and experimental study on pyrolysis and hydrothermal liquefaction of microalgae for biofuel production
No full textReview and experimental study on pyrolysis and hydrothermal liquefaction of microalgae for biofuel productio
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Bio-hydrocarbons through catalytic pyrolysis of used cooking oils and fatty acids for sustainable jet and road fuel production
No full textThe article addressed a literature and experimental investigation on residual lipids and fatty acids conversion into hydrocarbons through catalytic pyrolysi
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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