核动力航天器管壳式换热器换热特性分析

To study the heat transfer characteristics of alkali metal shell and tube heat exchangers required for nuclear-powered spacecraft, we designed a heat exchange structure and simulated and analyzed its heat transfer and flow characteristics using the fluid-structure coupled heat transfer method. The heat transfer characteristics under different cold and hot fluid pipeline layouts were also investigated. Coupled heat transfer by different fluid domains is realized using the mesh assembly method of structured and unstructured grids. The comparative analysis of K, Na, and NaK fluid channels showed that when the heat exchanger power was megawatt class, the selection of the Na working fluid as the coolant was suitable. The optimized design of the fluid pipeline showed that the heat transfer capacity of the optimized pipeline layout structure was higher without changing the volume of the cold and hot fluid heat exchange space. Furthermore, the cooling efficiency was higher when the low-temperature and high-temperature fluid velocities were lower and higher, respectively. This study provides a scientific reference for designing and developing heat exchangers for nuclear-powered spacecraft.