Improved numerical model of high temperature variable conductance heat pipe based on network method: Application in residual heat removal system for marine heat pipe reactor

Abstract

The Variable Conductance Heat Pipe, containing non-condensable gas for regulating heat transfer capability, have great application potential in passive heat transfer and residual heat removal processes of nuclear reactors. However, complex phenomena such as two-phase boiling flow and the coupling of non-condensable gas cavity compression/release pose significant challenges for numerical simulation of Variable Conductance Heat Pipe. Because the existing numerical models for variable-conductance heat pipes is limited and the demand for transient computation in engineering is growing., this study proposes a new efficient Variable Conductance Heat Pipe model. This model integrates the network method, the flow pressure drop calculation for vapor space, and a Variable Conductance Heat Pipe plane interface theory. This model enables efficient transient simulation of Variable Conductance Heat Pipe by treating the physical processes as purely solid-state heat conduction. The accuracy is validated and compared to other Variable Conductance Heat Pipe models, achieving accelerated computation without sacrificing accuracy. Effects of heating power, charge quantity, and non-uniform heating conditions on heat pipe temperature and non-condensable gas behavior are analyzed. Applied to the heat-pipe reactor residual heat removal system, the model reveals the dynamic response of temperature following reactor shutdown, confirming the feasibility of using Variable Conductance Heat Pipe as thermal switches in such systems.