沿程加热气泡泵流动沸腾模拟研究

Numerical Simulation Study on Flow Boiling of Bubble Pump along Heating

利用两相流理论建立二维稳态气泡泵两流体模型,以1atm下饱和水为工质,采用CFX19模拟研究沿程加热气泡泵流动沸腾中流态问题,探究热流密度,管径和流量对气泡泵性能影响。结果表明出口液相表观速度和泵送比变化相似,均随热流密度的增加先增大后减少,呈现抛物线变化。随着管径的增大,泵送比最大值反而随之减小。提升管管径增大在气泡泵轴向结合流态分析,得出最佳提升性能下的流态为搅拌流。当热流输入达到最佳热流密度时,液相速度在轴向上表现出先增大后减小的趋势。模拟不同管径和进口质量流量,发现最佳热流密度与进口质量流量存在二次函数关系,与管径成一次函数关系。

The twophase flow theory is used to establish a twofluid model of a twodimensional steadystate bubble pump.Using saturated water at 1 atm as the working medium,CFX19 is used to simulate the flow behavior of the bubble pump along the heating process,and to explore the heat flow density,pipe diameter and flow rate's impact on bubble pump performance.The results show that the apparent velocity of the outlet liquid phase and the pumping ratio change similarly,and both increase first and then decrease with the increase of the heat flux,showing a parabolic change.As the pipe diameter increases,the maximum pumping ratio decreases accordingly.The increase in the pipe diameter of the riser is combined with the flow pattern analysis in the axial direction of the bubble pump,and it is concluded that the flow pattern under the best lifting performance is the stirring flow.When the heat flow input reaches the optimal heat flow density,the velocity of the liquid phase increases first and then decreases in the axial direction.Simulating different pipe diameters and inlet mass flow rates,it is found that there is a quadratic function relationship between the optimal heat flux density and the inlet mass flow rate,and a linear function relationship with the pipe diameter.