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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.
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Category :
Languages : en
Pages : 21
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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: Lee
Publisher: CRC Press
ISBN: 9781560327974
Category : Science
Languages : en
Pages : 696
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This year's set of papers includes 23 Keynote Papers and 537 refereed General Papers, in seven volumes. Experts from around the world have combined to address the leading edge of research and practical innovations in convection, combustion, heat exchangers, two-phase flow, and much more. Whether one is involved in mechanical, chemical, nuclear, or energy engineering the quantity, international scope, and high quality of the contents make access to these volumes essential.
Author: Atam S. Rao
Publisher:
ISBN: 9780791812266
Category : Nuclear energy
Languages : en
Pages : 602
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Author:
Publisher:
ISBN:
Category : Nuclear engineering
Languages : en
Pages : 604
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Author: Joseph Patrick Reyes
Publisher:
ISBN:
Category :
Languages : en
Pages : 234
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Author:
Publisher:
ISBN:
Category : Nuclear engineering
Languages : en
Pages : 1060
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Author: Richard John Fox
Publisher:
ISBN:
Category :
Languages : en
Pages : 412
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Author: Ilpo K. Huhtiniemi
Publisher:
ISBN:
Category :
Languages : en
Pages : 362
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Author: Arthur P. Pernsteiner
Publisher:
ISBN:
Category :
Languages : en
Pages : 194
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