Experimental study on the influence of initial state parameters on the start-up and heat transfer characteristics of separated heat pipe system

As a specialized form of heat pipe, the separated heat pipe shows great potential in passive residual heat removal due to its high efficiency in transferring heat and flexible arrangement. A separated heat pipe system has been designed for the Swimming Pool-type Low-Temperature Heating Reactor (SPLTHR), and its heat transfer ability is crucial to ensure the safety of SPLTHR. To investigate the heat transfer performance of this system under various conditions, a large-scale thermal hydraulic test-bed applicable to SPLTHR has been established, utilizing water as its heat transfer medium and operating at sub-atmospheric pressures. The effect of filling ratio and initial vacuum degree on the start-up and heat transfer characteristics of the system is studied. The results show that the filling ratio has little effect on the heat transfer rate of the separated heat pipe within a certain range. The heat transfer is not optimized at either low or high filling ratios. The initial vacuum degree significantly impacts the system's start-up and heat transfer rate. Furthermore, the start-up and heat transfer characteristics of the system below the working temperature have been analyzed. This study has analyzed the influence of the initial parameters on the separated heat pipe, which provides data support for SPLTHR to use the separated heat pipe to export the residual heat.