水平三维内微肋管在局部蒸干区的沸腾换热及其关联式

为了得到不同流型下的换热性能 ,以 R1 3 4a为实验工质在一种水平三维内微肋管内进行了流动沸腾换热实验研究 ,通过可视化等措施对得到的主要流型及其转换曲线表示在 G-x图上。对局部蒸干区的沸腾换热特点进行了讨论 ,并根据此区域换热的特点 ,沿周向管壁分成两个部分 ,即 :蒸干部分和非蒸干部分。对于非蒸干部分又分为淹没微肋的底部液体 ,且认为同环状流换热机理相同 ,而另一部分认为液休带领在沟槽中 ,从而得到了此区域的换热实验关联式 ,此换热关联式与实验值的最大偏差在± 1 6%以内

The Boiling Heat Transfer of the Partial Annular Flow in a Horizontal Three-Dimensional Microfin Tube

In\|tube boiling experiments for R134a are carried out in a horizontal three\|dimensional (3\|D) microfin tube and two\|phase flow patterns are observed in the experiment. The curve of the flow pattern criteria of the 3\|D microfin tube is first constructed in G\|x draw. Then the heat transfer characteristics with partial annular flow are disused. And the heat transfer is contributed to the wetted portion of the tube. Thus the wetted portion of tube is divided into the flow liquid film in the underside of the tube and the flow liquid in the groove. Furthermore, the characteristic of the flow liquid film in the underside of the tube is assumed to be the same as that of the annular flow liquid film. The heat transfer of the flow liquid in the groove is only convection. Based on above, the correlation is obtained in the partial annular flow. The calculated data of the correlation is very good agreement with the experimental data. It is showed the capillary action of the liquid in the grooves decreases the inside surface of the partial dryout.