Review of Condensation Mass Flux in the Presence of Non-condensable Gas

Film-wise condensation on the wall at the presence of non-condensable gas (NCG) such as air is of great importance in advanced passive nuclear power plant, in particular, in passive containment cooling system. Several condensation models have been suggested by several authors, and among them Collier's model is most sophisticate. His approach is based on the thermodynamic property profile in the boundary layer, which can be said 'diffusion layer' because the property variation is driven by gas species diffusion. Through strict and intensive review and derivation the exact formula of steam condensation mass flux was obtained. In Collier et al.'s derivation unrealistic assumption of the constant mixture molar concentration in the diffusion layer was used. And p_g which is not explicitly explained in their final result is believed steam density plus molar ratio weighted air density as shown in Eq.. If the actual mixture molar profile is considered, somewhat different form of equation was derived. Fundamentally, if Fick's law is expressed as the gradient of concentration rather than fraction, the analytic form seem very hard as shown in Eq.