液氮垂直流动沸腾的双流体模型分析

Analysis of the Vertical Boiling Flow of Liquid Nitrogen Using Two-Fluid Model

采用双流体模型计算了液氮在垂直管内的上升流动沸腾过程,考察了壁面热通量和液体流量对流动及传热传质特征的影响.结果表明:垂直上升流动沸腾中重力压降占主导地位;根据截面液体温差的变化可判断沸腾模式的转变;壁面热通量与液相流量的相对大小决定了沸腾过程中的传热传质特征.

The upward boiling flow of liquid nitrogen in a vertical tube was numerically simulated using the two-fluid model of two phase flow. Emphasis was put on the effect of operative parameters including the wall heat flux and the liquid mass flow rate on the characteristics of hydrodynamic, heat and mass transfer processes. The numerical results show that in an upward boiling flow, the gravitational pressure drop is predominant among the three components. The mode of boiling could be judged according to the predicted across-sectional temperature difference along the flow. The ratio of the mass flow rate to wall heat flux is the key factor to decide the characteristic of transfer processes.