1,720,986 research outputs found
H2020 NanoDome Project: A Unified Approach for Gas-Phase Nanoparticles Synthesis Modelling
No full textA novel approach for the estimation of nanoparticle evaporation through the Method of Moments
Full text linkIn this article the results of the application of two numerical approaches - the Method of Moments and the nodal method - for the prediction of the evaporation phenomena in the synthesis of nanoparticles are presented and compared, in order to evaluate the limits of the moment methods and to determine the usability of the method in plasma environments (i.e. high temperatures and steep gradients). Furthermore, a new closure term is introduced in the Method of Moments, in order to consider the disappearance of the particles due to the evaporation process. The Nodal Method is used as a benchmark for the Method of Moments
Analysis of thermal stratification phenomena in the CIRCE-HERO facility
Full text linkIn the present paper, CFD simulations related to the operating conditions considered during the experimental campaign on CIRCE-HERO facility are presented, with the aim of investigating the observed temperature stratification phenomena. Calculations are performed using the commercial codes STAR-CCM+ and ANSYS Fluent adopting a RANS approach; the numerical results and the experimental data are compared. Four distinct experimental tests are investigated also performing sensitivity analyses regarding the boundary conditions. In particular, assumptions concerning the heat losses distribution and the shape of the pool inlet were taken into account. The numerical results provide support for further understanding of the involved phenomena, suggesting the possible causes of the thermal stratification observed experimentally inside the pool. Similar trends for the predicted and experimental data were obtained and – even from a quantitative point of view - the observed discrepancies can be considered acceptable, assuming the uncertainties in the experimental boundary conditions and measurement
Analysis of the temperature distribution in the pin bundle of the CIRCE facility
Full text linkIn this paper, a CFD analysis of the Fuel Pin Simulator (FPS) of the CIRCE-HERO facility built at the ENEA research centre in Brasimone was performed. STAR-CCM + code was used with the purpose of reproducing steady-state and transient experimental conditions adopting LBE as working fluid. RANS and URANS simulations were performed comparing the calculated temperature trends with the experimental data. In particular, the FPS average outlet temperature was monitored for the transient case and an exhaustive study of the heat transfer between the FPS and the pool during the transient was carried out. The impact of the involved heat transfer phenomena on the FPS energy balance was studied from a quantitative point of view and the relevant difference in terms of thermal inertia between pool and FPS component was pointed out
NACIE-UP post-test simulations by CFD codes
Full text linkThe paper concerns about CFD calculations of LBE flowing in the wire-wrapped hexagonal array electrical pin bundle of NACIE-UP facility. Pressure drop and friction factor analyses are performed in order to find possible matching between CFD results and available correlations to be used in the frame of forthcoming applications involving CFD/System Codes (STH) coupling calculations. The Fuel Pin Simulator of the NACIE-UP facility is presently considered for calculations; post-test analyses are performed as well in order to understand capabilities and uncertainties of available CFD codes and techniques in the liquid metal thermal hydraulics field. Calculations were performed using the commercial codes STAR-CCM+ and ANSYS FLUENT and promising results were provided. In particular, good matching between CFD results and predictions from the Cheng and Todreas (1986) correlation is observed in the frame of the pressure drop analysis. Post-test analyses aiming at comparing the measured and calculated temperature values for three selected operating conditions were performed; the adopted CFD tool reported good capabilities in reproducing the experimental results. Sensitivity analyses considering anomalous power distributions were also performed. The lesson drawn provided further comprehension of the involved phenomena and interesting information for future applications involving CFD/STH codes in coupling calculations
STH/CFD coupled calculations of postulated transients from mixed to natural circulation conditions in the NACIE-UP facility
No full textIn the present paper, coupled STH/CFD calculations are performed addressing two operating conditions in the frame of the NACIE-UP experimental campaign. In order to simulate mixed and natural circulation phenomena related to liquid metals thermal hydraulics, the RELAP5/Mod3.3 STH code and the CFD code ANSYS Fluent are adopted in an integrated manner. The combined use of STH and CFD codes aims to help the user overcoming the limits of the individual techniques and thus achieving a better predicting capability with respect to each stand-alone application. Measured values and calculated results are compared. In particular, the coupled application provides the best results in terms of predicted mass flow rate and comprehensiveness of information giving the possibility to analyse the local and cross-sectional distributions. Furthermore, as an additional beneficial aspect, CFD results can be used as a tuning tool for some of the STH code parameters. The aim of the present work is highlighting the advantages and drawbacks of the adopted techniques, also reporting the margins of error that may presently be expected from these applications. Though perfectly matching results were not obtained, coupled STH/CFD application report promising modelling capabilities and may be consequently considered as a sound candidate for addressing liquid metal thermal hydraulics in complex geometries and large systems
Liquid-Metal Thermal-Hydraulic Numerical Analyses in Support of the Upcoming CIRCE-THETIS Experimental Campaign
No full textLiquid metal cooled reactors are among the design proposals accepted by the Generation IV International Forum for the fourth generation of nuclear power plants. During the last decade, many European Union (EU) projects started with the goal to pave the way for the development of this type of reactor. The present research work is performed in the framework of the EU Partitioning And Transmuter Research Initiative in a Collaborative Innovation Action (PATRICIA) project, supporting the development of the Multi-purpose hYbrid Research Reactor for High-tech Applications (MYRRHA). Among the cornerstones of the project are experimental and numerical analyses involving the CIRColazione Eutettico (CIRCE) facility set at the ENEA Brasimone Research Centre. The upcoming experimental campaign will address the new CIRCE-THETIS configuration, including a new kind of heat exchanger named THETIS: a helical coil steam generator (SG) whose heat transfer capabilities and impact on pool thermal hydraulics are to be investigated. The main goal of the present work is to provide numerical support to experimentalists to help them set up the CIRCE-THETIS experimental facility, the operating conditions test matrix, and postulated transients, providing information about potential needed updates or dangerous conditions. This paper reports on pretest computational fluid dynamics and system thermal-hydraulic analyses performed at the University of Pisa in the frame of the PATRICIA project. The new SG was first addressed assessing its heat transfer capabilities. Sensitivity analyses were performed; among the outcomes, the excellent heat transfer capabilities of the SG were highlighted. The pool and the reactor vessel auxiliary cooling system component were later investigated reporting valuable information concerning both postulated steady-state and transient conditions. The performed analyses had a relevant impact on the design of the facility, suggesting updates based on numerical calculations. After the experimental campaign, posttest analyses will be performed to draw lessons from the observed phenomena. This will also provide room for improvement of the adopted numerical tools
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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