Study of Fast-Start Heat Transfer Characteristics of Potassium Heat Pipe

High-temperature heat pipe is a critical heat transfer element in heat pipe reactor, and the study of its transient characteristics is of great value to the reactor safety. Based on COMSOL Multiphysics, a single heat pipe model was established and the heat pipe start-up transient condition was calculated and analyzed. The effects of convective heat transfer coefficient, the length of evaporation section, the condensation section and the adiabatic section, and input power on heat pipe were all considered. A method that facilitates fast start-up of heat pipes was proposed. The results show that: increasing the input power, decreasing the length of the adiabatic section and condensing section, and decreasing the convective heat transfer coefficient of the condensing section were favorable to improve the start-up speed of the heat pipe; during the process of heat pipe start-up, only the evaporation section was heated and the condensation section was dissipated, which was not conducive to heat pipe start-up; by heating outside the condensing section or heating in the condensing section and the adiabatic section, it is favorable to alleviate the heat pipe start-up failure problem and can greatly accelerate the start-up process and it is favorable to stabilize the axial temperature of heat pipe.