核动力航天器管壳式换热器换热特性分析

Heat transfer characteristics of shell and tube heat exchangers for nuclear-powered spacecraft

为了研究核动力航天器所需碱金属管壳式换热器的换热特性,本文设计一种换热结构,通过流固耦合传热方法对该换热结构的换热和流动特性进行仿真分析,研究了不同冷、热流体管道布置方式下的换热特性。利用结构化和非结构化网格的网格组装方法,实现不同流体域的耦合换热。对K、Na和NaK流体通道进行对比分析,得出当换热器功率为兆瓦级时,适合选择Na工质作为冷却剂。对流体管道进行优化设计,得出在不改变冷、热流体换热空间体积的情况下,优化设计后的管道布置结构换热能力更强。研究表明当低温流体速度较慢且高温流体速度较快时,冷却效率更高。本文可为核动力航天器的换热器设计和开发提供参考依据。

To study the heat transfer characteristics of alkali metal shell and tube heat exchangers required for nu-clear-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 trans-fer 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-tem-perature fluid velocities were lower and higher,respectively.This study provides a scientific reference for designing and developing heat exchangers for nuclear-powered spacecraft.