低温输运管道预冷过程的气液两相数值分析

Numerical analysis of cryogenic two-phase precooling flow in a mini pipe

低温流体在输运管道中预冷时会出现复杂的气液两相流现象。本研究的数值仿真主要针对液氮在管道内沸腾过程中的传热特性、气泡的生成规律、临界热通量等进行分析。通过改变管道直径、入口液氮流量,讨论了不同时刻计算域内部的温度、热通量以及两相分布规律,最终得到研究范围内的临界热通量(CHF)特性。研究发现,流体温度突变时间随着管径的减小而提前,随着流量的增大而后延;壁面温度变化幅度随着管径的增大而增大;CHF值随着管径的减小而增加,随着入口流量的增加而减小。

There are many applications about cryogenic multiphase flow in various industry situations.In this paper,the precooling flow of liquid nitrogen in a mini pipe was discussed with numerical simulation,some characteristics were displayed such as,bubbles formation,critical heat flux,and temperature profiles,etc.The employed mathematical and physical methods were verified with some experimental data in the previous literature.According to simulation results about precooling processes,the temperature drop of internal fluid happened early with the pipe diameter decreasing,and the temperature drop happened lately with the liquid nitrogen mass flow increasing.The amplitude of the wall temperature drop decreased with the pipe diameter decreasing.In the range of calculation conditions,the higher CHF values occurred with less inner diameter tubes and higher mass flow rate.