Molten salt reactors, one of the important types of fourth-generation advanced reactors, use high-boiling-point molten salt as a nuclear fuel carrier after melting, hence have the characteristics of high-temperature output and normal-pressure operation. A heat-pipe molten salt reactor based on thermoelectric power generation has the advantages of its components, that is, high output temperature, high thermoelectric conversion efficiency, simple structure, safety, and reliability. Therefore, the reactor of heat-pipe molten salt has significant advantages in the field of energy systems as it is an ideal energy source for outer space and deep-sea exploration missions. However, because of the low thermal conductivity of the molten salt in the core, the dense arrangement of heat pipes complicates the heat transfer design of the thermal power generator in the condensing section of the heat pipes.

This study aims to design a heat-pipe–thermal power generation coupling system structure suitable for molten salt reactors, and analyze its heat transfer characteristics on the basis of design requirements of the reactor.

Firstly, the condensing section of the core heat pipe was designed using a tower thermoelectric power generation system. A thermoelectric generator was placed between the outer wall of the hot-side tower and the inner wall of the cold-side tower, and the gap between the generators was made of an insulating material to reduce heat leakage. Then, a heat transfer simulation of a four-layer tower thermoelectric power generation system suitable for a heat-pipe molten salt reactor was performed using the ANSYS Workbench. Finally, temperature distribution and variation under different power values at each layer of the thermoelectric generator and every thermoelectric generator, etc., were analyzed.

The analysis results reveal that, when the system is running with maximum heat-pipe temperature of 696 ℃, the temperature distribution in the overall tower is uniform, the effective heat utilization rate is >96%, the system leakage heat is <4%, and the temperature difference between the two sides of the generator is >490 ℃, which is conducive for improving the thermoelectric conversion efficiency.

The structural design of this study is feasible and conducive for promoting the application of thermoelectric power generation in a heat-pipe molten salt reactor.