ABSTRACT Pool scrubbing codes combining bubble dynamics and aerosol transport models are used to determine the pool scrubbing efficiency. However, the effect of bubble parameters, diameter and bubble rising velocity (v b), on retention efficiency was not yet analysed much in detail. In this experimental study, the effects of air content, S/P temperature, submergence, and downcomer diameter on bubble parameters at the pool surface are evaluated under wetwell venting conditions applying the backlit shadowgraphy technique. With increasing air content in the carrier gas, v b decreased while no significant effect was observed on Sauter mean diameter (SMD). Under the deeper submergence, the results of SMD and v b were less scattered. With increasing pool temperature, SMD and v b decreased. The thermal stratification of pool water did not affect bubble parameters. Downcomer diameter did not affect SMD, while slight increase in v b was observed. Measured SMD and the corresponding v b SMD have a fair agreement with the values adopted in the pool scrubbing codes; thus, the deposition velocities of gravitational sedimentation, inertial impaction, and Brownian diffusion demonstrate fair agreement with those based on the measured data. Steam condensation is the dominant retention mechanism except for low subcooling conditions. Therefore, modelling of steam condensation retention mechanism should be further carefully examined.

中文翻译：

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湿井排气条件下水池洗涤模型气泡参数的实验研究

摘要 结合气泡动力学和气溶胶传输模型的池洗涤代码用于确定池洗涤效率。然而，气泡参数、直径和气泡上升速度 (vb) 对保留效率的影响尚未详细分析。在这项实验研究中，在湿井通风条件下，应用背光阴影成像技术评估了空气含量、S/P 温度、淹没和降液管直径对水池表面气泡参数的影响。随着载气中空气含量的增加，vb 降低，而对 Sauter 平均直径 (SMD) 没有观察到显着影响。在较深的淹没下，SMD 和 vb 的结果较不分散。随着池温升高，SMD 和 vb 降低。池水的热分层不影响气泡参数。降液管直径不影响 SMD，而观察到 vb 略有增加。测量的 SMD 和相应的 vb SMD 与池清理代码中采用的值具有相当的一致性；因此，重力沉降、惯性撞击和布朗扩散的沉积速度与基于测量数据的沉积速度相当吻合。除了低过冷度条件外，蒸汽冷凝是主要的滞留机制。因此，应进一步仔细研究蒸汽冷凝滞留机制的建模。重力沉降、惯性撞击和布朗扩散的沉积速度与基于测量数据的沉积速度相当吻合。除了低过冷度条件外，蒸汽冷凝是主要的滞留机制。因此，应进一步仔细研究蒸汽冷凝滞留机制的建模。重力沉降、惯性撞击和布朗扩散的沉积速度与基于测量数据的沉积速度相当吻合。除了低过冷度条件外，蒸汽冷凝是主要的滞留机制。因此，应进一步仔细研究蒸汽冷凝滞留机制的建模。