The Modelling of Wall Condensation with Noncondensable Gases for the Containment Codes PDF Download
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ISBN:
Category :
Languages : en
Pages : 21
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Book Description
This paper presents several approaches in the modelling of wall condensation in the presence of noncondensable gases for containment codes. The lumped-parameter modelling and the local modelling by 3-D codes are discussed. Containment analysis codes should be able to predict the spatial distributions of steam, air, and hydrogen as well as the efficiency of cooling by wall condensation in both natural convection and forced convection situations. 3-D calculations with a turbulent diffusion modelling are necessary since the diffusion controls the local condensation whereas the wall condensation may redistribute the air and hydrogen mass in the containment. A fine mesh modelling of film condensation in forced convection has been in the developed taking into account the influence of the suction velocity at the liquid-gas interface. It is associated with the 3-D model of the TRIO code for the gas mixture where a k-[xi] turbulence model is used. The predictions are compared to the Huhtiniemi`s experimental data. The modelling of condensation in natural convection or mixed convection is more complex. As no universal velocity and temperature profile exist for such boundary layers, a very fine nodalization is necessary. More simple models integrate equations over the boundary layer thickness, using the heat and mass transfer analogy. The model predictions are compared with a MIT experiment. For the containment compartments a two node model is proposed using the lumped parameter approach. Heat and mass transfer coefficients are tested on separate effect tests and containment experiments. The CATHARE code has been adapted to perform such calculations and shows a reasonable agreement with data.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 21
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Book Description
This paper presents several approaches in the modelling of wall condensation in the presence of noncondensable gases for containment codes. The lumped-parameter modelling and the local modelling by 3-D codes are discussed. Containment analysis codes should be able to predict the spatial distributions of steam, air, and hydrogen as well as the efficiency of cooling by wall condensation in both natural convection and forced convection situations. 3-D calculations with a turbulent diffusion modelling are necessary since the diffusion controls the local condensation whereas the wall condensation may redistribute the air and hydrogen mass in the containment. A fine mesh modelling of film condensation in forced convection has been in the developed taking into account the influence of the suction velocity at the liquid-gas interface. It is associated with the 3-D model of the TRIO code for the gas mixture where a k-[xi] turbulence model is used. The predictions are compared to the Huhtiniemi`s experimental data. The modelling of condensation in natural convection or mixed convection is more complex. As no universal velocity and temperature profile exist for such boundary layers, a very fine nodalization is necessary. More simple models integrate equations over the boundary layer thickness, using the heat and mass transfer analogy. The model predictions are compared with a MIT experiment. For the containment compartments a two node model is proposed using the lumped parameter approach. Heat and mass transfer coefficients are tested on separate effect tests and containment experiments. The CATHARE code has been adapted to perform such calculations and shows a reasonable agreement with data.
Author:
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Category :
Languages : en
Pages : 13
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Book Description
This paper reports part of a study of possible severe pressurized water reactor (PWR) accidents. The need for containment modeling, and in particular for a hydrogen risk study, was reinforced in France after 1990, with the requirement that severe accidents must be taken into account in the design of future plants. This new need of assessing the transient local hydrogen concentration led to the development, in the Mechanical Engineering and Technology Department of the French Atomic Energy Commission (CEA/DMT), of the multidimensional code GEYSER/TONUS for containment analysis. A detailed example of the use of this code is presented. The mixture consisted of noncondensable gases (air or air plus hydrogen) and water vapor and liquid water. This is described by a compressible homogeneous two-phase flow model and wall condensation is based on the Chilton-Colburn formula and the analogy between heat and mass transfer. Results are given for a transient two-dimensional axially-symmetric computation for the first hour of a simplified accident sequence. In this there was an initial injection of a large amount of water vapor followed by a smaller amount and by hydrogen injection.
Author: Seungmin Oh
Publisher:
ISBN:
Category : Boiling water reactors
Languages : en
Pages : 290
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Book Description
Passive Containment Cooling System (PCCS) of the Simplified Boiling Water Reactor (SBWR) is a passive condenser system which is designed to remove energy from the reactor containment during a postulated reactor accident. The presence of noncondensable gas in the vapor can greatly reduce the performance of condensers. Hence a detailed knowledge of the heat removal performance of the PCCS in the presence of noncondensable gas is crucial for the safety and design optimization of the SBWR. The purpose of the present study is the experimental and theoretical investigation of the effects of noncondensable gas in a passive condenser system. Condensation experiments were performed for a vertical tube submerged in water pool. The present experimental data provide a new database for complete condensation, cyclic venting and through flow modes of the passive condenser. Cyclic venting mode was simulated by a control volume analysis Analysis results showed that venting period decreases with noncondensable gas fraction. It was found that inception of venting can occur before the condenser is fully filled with noncondensable gas. A boundary layer model was developed for the prediction of the film condensation with noncondensable gas in a vertical tube. Full set of the governing equations for the liquid film and vapor-gas mixture regions were solved. A heat and mass analogy model was also developed with a specific purpose for use in the thermal hydraulic system analysis code. In the vapor-gas mixture region, general momentum, heat and mass transport relations derived by analytic method were used with the consideration of surface suction effect. The predictions from the models were compared with the experimental data and the agreement was satisfactory. A mechanistic condensation correlation was developed based on the experimental data and the analysis results. It contains all the heat transfer components in its functional relationships. New correlation can provide accurate estimation of local condensation heat transfer coefficient for wide range of operating parameters. The assessment of wall condensation models in RELAP5 code was performed. Experimental conditions were simulated with RELAP5. Code simulation showed quite different results compared with data. Therefore, the condensation model in RELAP5 needs to be improved.
Author:
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ISBN:
Category : Nuclear reactors
Languages : en
Pages : 746
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Book Description
Author:
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ISBN:
Category : Power resources
Languages : en
Pages : 1284
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Book Description
Author: Francesco D'Auria
Publisher: Elsevier
ISBN: 032385611X
Category : Technology & Engineering
Languages : en
Pages : 1012
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Book Description
Handbook on Thermal Hydraulics of Water-Cooled Nuclear Reactors, Volume 2, Modelling includes all new chapters which delve deeper into the topic, adding context and practical examples to help readers apply learnings to their own setting. Topics covered include experimental thermal-hydraulics and instrumentation, numerics, scaling and containment in thermal-hydraulics, as well as a title dedicated to good practices in verification and validation. This book will be a valuable reference for graduate and undergraduate students of nuclear or thermal engineering, as well as researchers in nuclear thermal-hydraulics and reactor technology, engineers working in simulation and modeling of nuclear reactors, and more. In addition, nuclear operators, code developers and safety engineers will also benefit from the practical guidance provided. Presents a comprehensive analysis on the connection between nuclear power and thermal hydraulics Includes end-of-chapter questions, quizzes and exercises to confirm understanding and provides solutions in an appendix Covers applicable nuclear reactor safety considerations and design technology throughout
Author:
Publisher: ScholarlyEditions
ISBN: 1490110941
Category : Technology & Engineering
Languages : en
Pages : 743
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Book Description
Issues in Water and Power Engineering / 2013 Edition is a ScholarlyEditions™ book that delivers timely, authoritative, and comprehensive information about Fusion Engineering. The editors have built Issues in Water and Power Engineering: 2013 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Fusion Engineering in this book to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Water and Power Engineering: 2013 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Author: Wolfgang E. Nagel
Publisher: Springer
ISBN: 3319108107
Category : Computers
Languages : en
Pages : 682
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Book Description
This book presents the state-of-the-art in supercomputer simulation. It includes the latest findings from leading researchers using systems from the High Performance Computing Center Stuttgart (HLRS). The reports cover all fields of computational science and engineering ranging from CFD to computational physics and from chemistry to computer science with a special emphasis on industrially relevant applications. Presenting findings of one of Europe’s leading systems, this volume covers a wide variety of applications that deliver a high level of sustained performance. The book covers the main methods in high-performance computing. Its outstanding results in achieving the best performance for production codes are of particular interest for both scientists and engineers. The book comes with a wealth of color illustrations and tables of results.
Author: Moo Hwan Kim
Publisher:
ISBN:
Category : Condensation
Languages : en
Pages : 552
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Author:
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ISBN:
Category :
Languages : en
Pages : 18
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This paper presents a simple modelling of mass diffusion effects on condensation. In presence of noncondensable gases, the mass diffusion near the interface is modelled using the heat and mass transfer analogy and requires normally an iterative procedure to calculate the interface temperature. Simplifications of the model and of the solution procedure are used without important degradation of the predictions. The model is assessed on experimental data for both film condensation in vertical tubes and direct contact condensation in horizontal tubes, including air-steam, Nitrogen-steam and Helium-steam data. It is implemented in the Cathare code, a french system code for nuclear reactor thermal hydraulics developed by CEA, EDF, and FRAMATOME.
