1,721,006 research outputs found
CFD analysis of a tubular heat exchanger for the conditioning of olive paste
No full textThe use of a heat exchanger for the conditioning of the olive paste could enhance the olive oil extraction process. Particularly, paste pre-heating could reduce the malaxation time and, most of all, improve the temperature control during this process (e.g., 27 °C). In this study, a three-dimensional computational fluid dynamics (CFD) analysis of a tubular heat exchanger was carried out to better understand the influence of the inlet conditions of the olive paste on thermal and hydrodynamic behavior within it. CFD analysis was performed with SOLIDWORKS Flow Simulation (ver.2016). The heat exchanger consists of a tube-in-tube module, in which the inner tube was fed with the olive paste, while the jacket was filled of hot water. The main aim was that to predict the heat transfer and pressure drop in paste side of the exchanger. Multiple analyses by varying the mass flow rate and inlet temperature of the paste were carried out, and temperature and pressure drop were estimated. The numerical model has proved very useful in identifying the main factors affecting the optimization of the heat exchanger in order to improve the extraction process of the olive paste
La disfonia infantile nella scuola dell'infanzia e primaria:un progetto operativo dall'indagine alla prevenzione
No full textDevelopment of a Pressure Control System According to Paste Rheology for Ultrasound Processing in Industrial Olive Oil Extraction
Full text linkRecent research has demonstrated how ultrasound can benefit the industrial processing of olive paste before oil extraction. However, the absence of a device for controlling pressure inside the sonication cell is a major hindrance to its application. To address this problem, a pneumatic device with a programmable logic controller was implemented to automatically adjust pressure in the sonication cell according to a preset value: its functionality was tested in industrial oil extraction. An experiment was conducted to compare device performance when applied to olive batches with different solid/liquid ratios and differing rheology. The control system adjusted the flow section of the valve at the outlet of the sonication cell and the mass flow rate of the feed pump in order to maintain the pressure preset by the operator. Results indicate that the pressure was 3.0 ± 0.2 bar, 3.5 ± 0.2 bar, and 4.0 ± 0.2 bar when the set point was 3.0 bar, 3.5 bar, and 4.0 bar, respectively: there was thus no significant difference between controlled and set values. This indicates that the device is able to control pressure inside the sonication cell with a maximum deviation of 0.2 bar. In this case, the sonication intensity was stabilized at 135 W/cm2, 150 W/cm2, and 165 W/cm2 at 3.0 bar, 3.5 bar, and 4.0 bar, respectively. This study presents an advancement in ultrasound applications for industrial olive oil extraction: optimal pressure control in the sonication cell
Das Christentum - eine unmögliche Religion?
No full textIl capitolo analizza alcuni aspetti paradossali della religione cristiana, facendone vedere il valore ambiguo: di sfida e, al tempo stesso, di elemento di difficoltà per il nostro presente
Towards energy efficient scheduling in the olive oil extraction industry: Comparative assessment of energy consumption in two management models
Full text linkAlthough olive oil is one of the most important food products throughout the Mediterranean region, the main consideration in configuring and operating extraction plants is still the quantity of crop that will be brought by the individual growers, who are often of small and medium size. On this basis, the common configuration is the batch processing line (Ba-PL) for small and medium capacities, with malaxers arranged in parallel, or in larger -capacity industrial mills, the arrangement of malaxers in series for simulation of continuous processing (Co-PL). A review of literature to date reveals that there have been no assessments of the energy use and scheduling strategies for these two processes, therefore the current study undertakes such assessment and comparison of the Ba-PL and Co-PL configurations, within a single mill facility. The results show that energy output for Ba-PL was 105,570.00 MJ day-1 based on inputs of 3212.76 MJ day-1, while outputs from Co-PL reached 422,280.00 MJ day -1 from inputs of 6740.38 MJ day -1. Given that the yield of oil is almost the same in the two processes, the Net Energy (NE) for Ba-Pl then results as 10,2357.24 MJ day -1 versus 41,5539.62 MJ day-1 for the Co-PL configuration, and moreover the later process is seen to achieve almost double the Energy Use Efficiency, at 62.65 versus 32.86 in Ba-PL. Finally, the Overall Equipment Effectiveness (OEE) analysis of performance for the two processes shows values of 93.1 % for the Co-PL configuration but only 51.2 % for Ba-PL, due mainly to dead times in throughput on the Ba-PL machinery, resulting in a 44.7 % decrease in the values for the Performance parameter. The conclusion is that to meet the needs of small producers, there must be new management ap-proaches and improvement in the energy use for batch processing. Some strategies could be: - measure the oil content and moisture in input batches using rapid, non-destructive methods, so that homogeneous batches can be pooled before processing; - reduce dead time by developing automated systems for pumping the olive paste from the malaxers to the separation decanter; - even in the case that they are non-homogenous, consider pooling undersized batches so as to avoid mass flows far below the malaxer capacities. Throughout the Mediterranean, olive oil production using batch processing remains very substantial, therefore further studies are required for the identification and evaluation of solutions for optimising this process
Modelling the Rheology of Olive Paste for Oil Extraction Plant Automation: Effects of the Crushing Process on the Rheology of Olive Pastes
No full textIn extra virgin olive oil production, it is essential to obtain a well-prepared olive paste which allows not only the extraction of the oil drops from the olives, but also the achievement of a high-quality oil while maintaining high yields. This work addresses the problem of determining the effect of three crushing machines on the viscosity of the olive paste: a hammer crusher, a disk crusher and a de-stoner were tested. The tests were repeated on both the paste leaving each machine and the paste to which water was added; this was done with the main aim of considering the different dilutions of the paste while entering the decanter. A power law and the Zhang and Evans model were used to analyse the rheological behaviour of the paste. The experimental results allow validation of the two models with a high (more than 0.9) coefficient of determination between experimental and numerical data. The results also show that the pastes obtained with the two classic crushing methods (hammers and disks) are almost identical, with a packing factor of about 17.9% and 18.6%, respectively. Conversely, the paste obtained with the de-stoner entails higher viscosity values and a smaller solid packing factor, of about 2.8%. At 30% dilution with water, the volume of the solid concentration dropped to about 11.6% for the hammer and disc crushers, while for the de-stoner it only reached 1.8%. This behaviour is also reflected in the evaluation of yields, which were 6% lower with the de-stoner. No significant differences regarding the legal parameters of oil quality were found using the three different crushing systems. Finally, this paper establishes some fundamental pillars in the research for an optimal model for identifying the rheological behaviour of the paste as a function of the crusher used. Indeed, since there is an increasing need for automation in the oil extraction process, these models can be of great help in optimizing this process
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
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
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