Development of a Condensation Model for Realistic Analysis of Heat Removal Behavior by Passive Heat Sinks within a Containment

Abstract

The Colburn-Hougen condensation model, proposed in 1934 based on gas kinetics, assumes that the gas mixture around the condensation surface is in a static state. Therefore, it does not reflect the turbulent effects that occur when a strong flow field is formed around the condensation surface. In this study, we developed a new condensation model by introducing the turbulence diffusion coefficient to account for turbulent effects by convective flow of steam mixed with a non-condensable gas. In the original Colburn-Hougen model, turbulent effects were merely considered in the Sherwood number correlation used for calculating the mass transfer coefficient. The developed condensation model adopted the Cebeci-Smith model to calculate a turbulent diffusion coefficient, which is added to the molecular diffusivity. For application to the basic form of the Colburn-Hougen model, we derived a modified Sherwood number correlation by calculating the mass transfer coefficient from the condensation rate measured in the flat plate condensation experiments. The developed model has been validated against the COPAIN, CONAN, and SETCOM experiments, in which local heat fluxes were measured under forced convection conditions. In most cases, the results of the developed model closely predicted the experimental heat fluxes, and the average standard deviation of the relative error was 24.1%. Furthermore, the developed model better predicted the local heat flux along the condensation surface compared to the original model.