CFD simulation on the flow and heat transfer characteristics of mist flow in wire-wrapped rod bundle

•A phase change model of liquid droplet during mist flow is proposed.•The numerical result agrees well with the experimental result in mist flow.•Flow and heat transfer in the complex wire-wrapped rod bundle is discussed. The heat transfer characteristics of post-CHF (critical heat flux) is very important and complicated, which has aroused wide attention in the topic of nuclear reactor safety. In this paper, a phase change model of liquid droplet during mist flow is proposed to consider the heat transfer of mist flow. Couple with this phase change model, three dimensional CFD simulation has been carried out to study the flow and heat transfer characteristics of mist flow in a wire-wrapped rod bundle. The discussion and analysis focus on the turbulent flow behavior and the heat transfer performance of post-CHF mist flow in the rod bundle. The effect of vapor properties such as density, heat capacity, thermal conductivity and viscosity on heat transfer are considered in the CFD simulation, and those properties are dependent on temperature. According to the CFD simulation result, the pressure distribution, temperature distribution, velocity distribution and phase distribution in the wire-wrapped rod bundle are analyzed in detail.