核态沸腾中汽泡动力学及传热机理分析

Bubble Dynamics and Heat Transfer Under a Single Bubble During Nucleate Pool Boiling

汽泡的传热及生长特性研究对于揭示核态沸腾的机理具有重要作用。本文介绍了利用高速摄像技术对核态沸腾中汽泡生长及运动现象进行实验观测,并用高速数据采集系统记录汽泡一个生长周期不同阶段的热流密度的方法。在不同的过冷度及壁面温度条件下,观测了汽泡的生长、周期性滑移、颈化和脱离现象。计算并绘制出不同条件下一个汽泡生长周期内的热流密度曲线,与汽泡图片相对应,分析并讨论了造成这些现象的机理。

The heat transfer under a single bubble during the nucleate boiling ebullition cycle is analyzed to further understand the nucleate boiling mechanisms.The bubble nucleation,growth and departure cycle during nucleate boiling on a microheater were observed with a high-speed camera while the heat flux during the bubble life cycle under the bubble was recorded with a high-speed data acquisition system.The bubble growth,sliding,necking and departure correspond well with the measured heat flux variations for various wall superheats and liquid subcoolings.The results show that the boiling heat flux varies dramatically during a bubble ebullition cycle.The mechanisms of the phenomena were analyzed.