Improved Numerical Model of Variable Conductance Heat Pipe based on Network Method: Application in Residual Heat Removal System for Marine Heat Pipe Reactor

摘要: The Variable Conductance Heat Pipe (VCHP), containing non-condensable gas (NCG) for regulating heat transfer capability, is widely used in reactor applications, enabling simultaneous heat transfer, control, and related functions. However, complex phenomena such as two-phase boiling flow and the coupling of NCG cavity compression/release pose significant challenges for numerical simulation. This study proposes a numerical method to efficiently simulate VCHP, tailored to the computational demands of emergency residual heat removal system using VCHP. The approach integrates the network model, the flow pressure drop calculation for vapor space, and a VCHP plane interface theory. Heat conduction in heat pipe is treated as highly efficient, with transient behavior resolved through iterations of node temperatures and NCG length. The accuracy is validated and compared to traditional VCHP models, demonstrating a balanced improvement in computational speed and precision without compromising either. Effects of heating power, charge quantity, and non-uniform heating conditions on heat pipe temperature and NCG behavior are analyzed. Applied to the residual heat removal system, the model reveals the dynamic response of temperature and NCG behavior following reactor shutdown, confirming the feasibility of using VCHP as switches in such systems.