الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Two-Phase channel flow with condensation is a common phenomenon in heating and retiigeration systems, and occurs in a number of nuclear reactor accident scenarios. It also ’pJays an important role during the operation of the safety coolant injection systems in advanced nuclear reactors. Semi-empirical correlations and simple models based on the (,
.~, analogy between heat and mass transfer processes have been previously applied. Rigorous
\ models, compatible with the state-of-the-art numerical algorithms used in thermal-hydraulic , t
. computer codes, are scare, and are of great interest. The objective of this research is to
develop a method for modeling condensation, with and without noncondensable gases, compatible with the state-of-the-art numerical methods for the solution of multi-phase field equations.
The important, state-of-the art, numerical algorithms for the solution of multi-phase conservation equations are reviewed. A two-dimensional condensation model. based on the stagnant film theory, and compatible with the reviewed numerical algorithms. is proposed. The developed methodology rigorously treats the coupling between the heat and mass transfer processes, and allows for an implicit treatment of the mass and momentum exchange tenns at the gas-liquid interphase. without iterations. The methodology is incorporated in, and is demonstrated to be fully compatible with, the robust and efficient RELAP5 mathematical representation and numerical solution schemes. The modified model is validated against available experimental data.
The model is used to study the phenomena of condensation in the presence of noncondensable gases. Model predictions were compared with experimental data relevant to downward, cocurrent flow in vel1ical channels. It is shown that the model can correctly predict all the important data over a wide range of parameters. This model is applied to degraded steam condensation in a vertical tube due to the presence of a noncondensable gas. Such a phenomenon could occur in a loss of residual heat removal accident in a pressurized water reactor. The steam condensation in the presence of air. nitrogen and helium has been calculated .
According to this model, the void fraction-quality relation depends on the tube size. the .Reynolds number. the saturation-to-wall temperature difference and the How direction; .. vertical upward or downward flows are studied.
investigation includes the heat transfer coefficient variation and the gas temperature 4Jatribution along inverted U-tube length for steam condensation in the presence of a DOnCOndensable gas.
Lastly, the developed model was Llsed in the application of loss of coolant in pressurized Water reactor accidents .