Numerical simulation of heat transfer deterioration phenomenon to supercritical water in annular channel

As there is no phase change, the risk of boiling crisis can be excluded in Super Critical Water-cooled Reactor (SCWR). The heat transfer deterioration (HTD) phenomena, which result in an abnormal increase of wall temperature, however, may occur under some conditions. Therefore, it is important to understand the mechanism of HTD for keeping the temperature integrity of the fuel cladding. In this study, mechanisms of the influence of turbulence structure and fluid properties on HTD phenomena in annular channels at low mass flux and high mass flux were both investigated. The results showed that HTD at low mass flux is mainly caused by buoyancy effect and the variations of fluid properties, while at high mass flux HTD is due to the acceleration effect and the variations of fluid properties. Heat flux and the operating pressure also play important parts in HTD both at low mass flux and high mass flux.

► Numerical simulation was carried out on heat transfer deterioration in annular channel.
► Mechanisms of the influence of turbulence structure on heat transfer deterioration were investigated.
► Influence of heat flux on heat transfer deterioration was studied.
► Influence of operating pressure on heat transfer deterioration was studied.
► Influence of fluid properties on heat transfer deterioration was studied.