Heat transfer of air turbulent mixed convection in the passive containment air-cooling system of a modular small nuclear reactor

Abstract

Passive containment Air-cooling System (PAS) is an important passive system of the modular small nuclear reactor, ACP100. After a severe accident, the air in the annular gap between the steel shell and the concrete shell of the containment is heated, forming buoyancy-driven mixed convection which removes decay heat. Thus, the heat transfer of mixed convection in PAS is essential for the safety of nuclear reactor. However, there are very less related studies on this phenomenon. In the present study, experiments on the mixed convection of atmospheric air in a parallel-plate channel with one-side heating for PAS were carried out. The regions of Re, Gr and Bo range from 1.7 × 104 to 8.8 × 104, 1.0 × 108 to 1.0 × 1010 and 4 × 10−5 to 90, respectively. Furthermore, the effect of the inclination angle on heat transfer was analyzed for the dome which is an integral part of PAS. A heat transfer correlation was newly proposed, which can more accurately predict the heat transfer of PAS with an error within ±15%. In addition, the predicted values of heat transfer agree well with other experimental data of mixed convection in the rectangular channel. The present research puts forward a new model for the analysis of PAS heat transfer performance, and has the reference significance for the optimal design of PAS.