Dynamic thermal characteristics analysis of integrated space nuclear reactor with core and Stirling power conversion components

The Autonomous Circulation Miniature Integrated nuclear Reactor (ACMIR) integrates a nuclear reactor and a Stirling power system, which is of great importance for solving the electrical power demand in space. In the present work, 3D computational fluid dynamics simulations are performed on the new design of ACMIR. The dynamic mesh method is used to simulate the cyclic motion of the Stirling power system. The heat transfer effects are evaluated by analyzing the coolant flow characteristics and dynamic thermal characteristics. The results show that the coolant velocity in the same channel varies cyclically with the piston motion in the range of 0–35 m/s, which causes the temperature of the fuel, cladding and gas gap to rise and fall in the same cycle as that of the piston. The heat flux and heat transfer coefficients between the cladding surfaces and the coolant at different locations are also affected, which rise and fall with the piston in the same cycle, with a variation range of about 2500–7500 W/m2‧K. It indicates that the coolant has the ability to remove the heat from the core effectively. These phenomena provide numerical references for the safe design and development of the integrated space reactor.