含内热源球床通道内过冷流动沸腾汽泡行为特性研究

Bubble Behaviors in the Subcooled Flow Boiling Heat Transfer in the Volumetrically Heated Packed Bed

为加深对含内热源球床通道内流动过冷沸腾换热机理的研究,采用高速摄像仪对通道内流动过冷沸腾时的汽泡行为进行了可视化实验研究。结果表明:汽泡在通道内很容易受到球体的阻碍而附着于球面上,受到阻碍的汽泡将沿球面进行滑移运动;汽泡存在大量的"重生现象",即生成的汽泡在生存阶段可能出现多次生长的情况;在球与球接触的角区,会产生稳定的汽化核心点。角区的结构形式对汽泡的脱离直径及脱离频率产生较大的影响。

To profoundly understand subcooled flow boiling heat transfer mechanisms in volumetrically heated packed bed,a visual method was used to study the bubble behaviors in the subcooled flow boiling.The results suggested that the bubbles is easy to attach on the ball surface duo to the block of balls,then the bubbles will slide along the ball surface.The 're-grow up' phenomenon is present in the packed bed,namely,the bubbles can grow many times.The steady nucleate sites usual appear in the contact corner firstly.The contact corner structures have great impacts on the bubble departure diameter and frequency.