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核态沸腾换热是一种高效的换热形式,沸腾机理的研究对强化传热的研究很重要。实验采用微尺度96加热片阵列,通过独立的控制电路,加热独立的各个加热片,使其维持在恒定温度120℃上。利用高速摄像技术分别从汽泡的底部和侧面对汽泡生长及运动现象进行可视化观测,并用高速数据采集系统同步记录汽泡一个生长期间不同阶段的热流密度。实验首先单独加热每个独立的区域,产生单个汽泡,并分析汽泡脱离频率、脱离直径和热流密度;然后通过加热两个相隔一定位置的加热片区域,使得汽泡长到一定大小后能够碰撞、合并为一个新汽泡并最终脱离。这种汽泡交互作用伴随着汽泡的变形、滑移,显著增加了沸腾换热的热流密度和汽泡脱离频率。通过分析每个加热片的热流密度,得出瞬态导热是沸腾换热的主要机理。
Nucleate boiling heat transfer is an efficient form of heat transfer. The study of boiling mechanism is very important for the study of enhanced heat transfer. Experiments using micro-scale 96 heating chip array, through an independent control circuit, the heating of each individual heating chip, it is maintained at a constant temperature of 120 ℃. The high-speed camera technique was used to visualize the bubble growth and movement from the bottom and the side of the bubble. The high-speed data acquisition system was used to synchronously record the heat flux at different stages during the growth of the bubble. In the experiment, each independent region was heated separately to generate a single bubble, and the bubble departure frequency was analyzed to get rid of the diameter and the heat flux. Then, by heating two heated regions separated by a certain distance, the bubble could grow up to a certain size Collide, merge into a new bubble and finally disengage. This bubble interaction is accompanied by the deformation and slippage of the bubble, which significantly increases the heat flux density and bubble breakaway frequency of boiling heat transfer. By analyzing the heat flux density of each heater, the transient heat transfer is the main mechanism of boiling heat transfer.