冷却条件下超临界CO₂在突扩管中流动及其换热的数值模拟

Numerical Simulation on the Flow and Heat Transfer of Supercritical CO₂ in Sudden Expansion Pipe under Cooling Condition

超临界流体在突扩管中的流动换热规律对于新型能源转换系统、废弃物资源化回收利用等工艺与装置的高效设计具有重要意义。本文通过有限体积法数值计算方法,研究了超临界CO2在突扩冷却条件下的流动与传热规律。研究发现,在冷却条件下超临界CO2在突扩管中流动规律与其在加热条件下的流动规律基本上是一致的。但与加热条件下流动换热规律比较,冷却条件下超临界CO2流动更易失稳。且随着冷却热流密度增大,回流区长度变小。这既是与前人研究的对比又是补充,对超临界CO2作为工作流体材料在突扩管中流动换热规律的工程应用有一定的指导意义。

The flow and heat transfer law of supercritical CO2 in sudden expansion duct has important meaning on efficient design of technology and devices of new energy conversion system and recycling of waste resources. In this paper, the numerical method is finite volume method. The flow and heat transfer law of supercritical CO2 in sudden expansion duct under cooling condition is studied in this paper by using numerical method of finite volume method. It is founded that the flow situation of supercritical CO2 in sudden expansion pipe under cool condition is the same as that of under heat condition in this study. Compared with the condition of heating, the bifurcation phenomenon is easier to appear under cooling. And with the increase of wall cooling heat flux, the length of recirculation regions becomes smaller. It is a comparison and supplement to the previous studies, and sheds some light on the application of the law of flow and heat transfer of supercritical CO2 as working fluid material in sudden expansion duct.