关键词: 空气, 凝结, 传热, 潜热传热系数, 数值模拟

Abstract: The passive containment cooling system (PCCS) is widely used in the next generation of nuclear reactor systems to maintain the integrity of containment for longer time after utmost accidents such as the loss of coolant and main steam line break. For double concrete containment, the condenser is one of the most essential equipment in the PCCS and its heat transfer capability determines its performance. In the steam condensation process, the presence of large amounts of non-condensable gases will lead to serious deterioration of heat transfer, so further study on steam condensation in the presence of air must be conducted. In this study, condensation processes of steam in the presence of air are modeled by applying a user defined function added to the commercial computational fluid dynamics package. Calculated profiles of temperature, air concentration, velocity components and condensation heat transfer coefficient are compared to experimental results. The simulation results indicate a good agreement between the experimental results and model predictions. It also shows that both the latent and the sensible heat transfer coefficient decrease with the increase of air mass fraction, and the latent heat transfer is a dominant factor in the total condensation heat transfer at air mass fractions less than 50%. Local latent heat coefficient presents an upward tendency along the axial direction of heat transfer tube from the bottom to the top, while the sensible heat transfer coefficient takes an opposite trend.

Key words: air, condensation, heat transfer, latent heat transfer coefficient, numerical simulation