A Computational Investigation for Steam Condensation on a Flat Plate in the Presence of Non-condensable Gas Using a CUPID Code

The Passive Containment Cooling System (PCCS) consists of a number of tube banks, such that condensation occurs at the exterior surface of the tubes, and the cooling fluid comes into the tube bank from the heat sink called the Passive Containment Cooling Tank (PCCT) installed at the outside of the containment in such a way that working fluid can circulate the loop between the PCCS cooling device and PCCT in a passive way, relying only on gravitational force. In many nuclear safety applications, steam condensation occurs in the presence of non-condensable gases. For a hypothetical severe accident, hydrogen generated from core damage degrades steam condensation. For nuclear safety analyses, lumped parameter codes have been conventionally used due to less computational burden. However, since most lumped parameter codes use simplified flow models, they often over-predicts or under-predicts the thermal-hydraulic responses. In addition, flow variables are calculated over relatively large cells or lumped parameter volumes, thus, they have inherent limitations in describing flow fields. In this work, a steam condensation model based on a turbulent wall function and the heat and mass transfer analogy was presented and it was implemented to the CUPID code. The validation results showed that the proposed model was overall good agreements with experimental data and other codes in developed flow region. However, in entrance region some deviations were observed. For future work, the proposed condensation model would be further tested for complicated geometry involving 3D phenomena and the adequacy of the resolved boundary approach would be investigated.