Experimental analysis of heat transfer within the AP600 containment under postulated accident conditions

Publisher Summary Condensation plays a significant role in the heat rejection parts of the rankine power generation cycle and the vapor compression refrigeration cycle, which generally involve single components. Condensation is initiated by a nucleation process either in a bulk vapor or on a solid surface. Condensation heat transfer can be studied from either the macroscopic or the microscopic point of view. The macroscopic viewpoint considers matter as a continuum and requires the introduction of certain phenomenological laws, the macroscopic transport equations, in addition to the conservation equations of mass, energy, and momentum, in order to deal with rate processes. The microscopic viewpoint deals with molecules, atoms, and subatomic particles.

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Condensation Heat Transfer

Much of the early work on problems involving liquid-solid phase change was confined essentially to the cases in which the liquid melt is stagnant or the motion of the liquid is due entirely to the phase-change process itself. In these transient (conduction) phase-change problems, the un­ knowns are the interface that separates the regions of liquid and solid and the temperature distributions in both regions. The interface motion is expressed implicitly in an equation for the conservation of thermal energy at the interface. This introduces a nonlinear character to the problem that has intrigued and challenged engineers and mathematicians since Stefan's (1891) pioneering study of the growth of sea ice. Many powerful analytic and numerical techniques have been reported for dealing with heat-diffusion-controlled freezing or melting problems, and references to the mathematical studies on this subject may be found in several previous surveys by Bankoff (1964), Muehlbauer & Sunderland (1965), Rubinshtein (1967), Ockendon & Hodgkins (1975), and Wilson et al. (1978). In contrast to the earlier studies of phase change in stagnant media, problems in which the melt· material is in motion have recived detailed attention only during the past two decades. The stimulus was provided to a large extent by requirements in the nuclear and "alternate" energy

Complex Freezing-Melting Interfaces in Fluid Flow

A model is presented for the prediction of the corrosion rate by carbon dioxide (CO2) under dewing conditions. A mecha- nistic approach is developed that takes into consideration the hydrodynamics, thermodynamics, heat and mass transfer, chemistry, and electrochemistry during the phenomenon of top-of-the line corrosion. This model is validated by experi- mental data. It offers a better insight into the role played by primary parameters such as temperature, total pressure, par- tial pressure of CO2, gas velocity, and condensation rate.

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Joseph Gerstmann

Papers

Laminar film condensation on the underside of horizontal and inclined surfaces