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Development, implementation and assessment of specific closure laws for inverted-annular film-boiling in a two-fluid model

Technical Report:

Abstract

Inverted-annular film-boiling (IAFB) is one of the post-burnout heat transfer modes taking place, in particular, during the reflooding phase of the loss-of-coolant accident, when the liquid at the quench front is subcooled. Under IAFB conditions, a continuous liquid core is separated from the wall by a superheated vapour film. The heat transfer rate in IAFB is influenced by the flooding rate, liquid subcooling, pressure, and the wall geometry and temperature. These influences can be accounted by a two-fluid model with physically sound closure laws for mass, momentum and heat transfer between the wall, the vapour film, the vapour-liquid interface, and the liquid core. The applicability of existing IAFB two-fluid models is limited. This is attributed to shortcomings in the description of heat transfer within the liquid core, to use of certain correlations outside their validity range, and to a limited use of experimental information on IAFB. The usual approach has been to develop models employing generally applicable closure laws including, however, adjustable parameters, and to adjust these using global experimental results. The present approach has been to develop IAFB-specific closure laws in such a form that they could be adjusted separately using detailed, IAFB-relevant, experimental result. Steady-state results, including heat  More>>
Authors:
Cachard, F de [1] 
  1. Paul Scherrer Inst. (PSI), Villigen (Switzerland)
Publication Date:
Oct 01, 1994
Product Type:
Technical Report
Report Number:
PSI-94-16
Reference Number:
SCA: 420400; PA: AIX-26:008350; EDB-95:009268; SN: 95001301235
Resource Relation:
Other Information: PBD: Oct 1994
Subject:
42 ENGINEERING; FILM BOILING; COMPUTERIZED SIMULATION; MATHEMATICAL MODELS; VERIFICATION; WATER VAPOR; FILMS; EXPERIMENTAL DATA; STEADY-STATE CONDITIONS; THEORETICAL DATA; TRANSIENTS; 420400; HEAT TRANSFER AND FLUID FLOW
OSTI ID:
10103950
Research Organizations:
Paul Scherrer Inst. (PSI), Villigen (Switzerland)
Country of Origin:
Switzerland
Language:
English
Other Identifying Numbers:
Other: ON: DE95611091; TRN: CH9400369008350
Availability:
OSTI; NTIS; INIS
Submitting Site:
CHN
Size:
96 p.
Announcement Date:
Jun 30, 2005

Technical Report:

Citation Formats

Cachard, F de. Development, implementation and assessment of specific closure laws for inverted-annular film-boiling in a two-fluid model. Switzerland: N. p., 1994. Web.
Cachard, F de. Development, implementation and assessment of specific closure laws for inverted-annular film-boiling in a two-fluid model. Switzerland.
Cachard, F de. 1994. "Development, implementation and assessment of specific closure laws for inverted-annular film-boiling in a two-fluid model." Switzerland.
@misc{etde_10103950,
title = {Development, implementation and assessment of specific closure laws for inverted-annular film-boiling in a two-fluid model}
author = {Cachard, F de}
abstractNote = {Inverted-annular film-boiling (IAFB) is one of the post-burnout heat transfer modes taking place, in particular, during the reflooding phase of the loss-of-coolant accident, when the liquid at the quench front is subcooled. Under IAFB conditions, a continuous liquid core is separated from the wall by a superheated vapour film. The heat transfer rate in IAFB is influenced by the flooding rate, liquid subcooling, pressure, and the wall geometry and temperature. These influences can be accounted by a two-fluid model with physically sound closure laws for mass, momentum and heat transfer between the wall, the vapour film, the vapour-liquid interface, and the liquid core. The applicability of existing IAFB two-fluid models is limited. This is attributed to shortcomings in the description of heat transfer within the liquid core, to use of certain correlations outside their validity range, and to a limited use of experimental information on IAFB. The usual approach has been to develop models employing generally applicable closure laws including, however, adjustable parameters, and to adjust these using global experimental results. The present approach has been to develop IAFB-specific closure laws in such a form that they could be adjusted separately using detailed, IAFB-relevant, experimental result. Steady-state results, including heat flux, wall temperature and void fraction data have been used for the adjustment. A key issue in IAFB modeling is to predict how the heat flux reaching the vapour-liquid interface is split into a liquid heating term and a vaporization term. In the model proposed, convective liquid heating is related to the liquid velocity relative to the interface, and not to the absolute liquid velocity, as in previous models. This relative velocity is deduced from the interfacial shear stress, using the liquid-interface friction law. With this modification, the prediction of the experimental trends is greatly improved. (author) figs., tabs., refs.}
place = {Switzerland}
year = {1994}
month = {Oct}
}