Freezing propagation of condensate droplets at early stage of frosting on vertical hydrophobic surface
Freezing propagation of condensate droplets at early stage of frosting on vertical hydrophobic surface
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DOI：
10.1016/j.csite.2022.102617
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发表时间：
2023-01
影响因子：
6.8
通讯作者：
F. Wang;Fei Dai;Caihua Liang;Xiaosong Zhang
中科院分区：
文献类型：
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作者：
F. Wang;Fei Dai;Caihua Liang;Xiaosong Zhang
由于结霜初期形成的凝结液滴是霜层生长的基础，因此研究凝结液滴的冻结传播对于了解结霜过程具有重要意义。本文通过可视化实验，讨论了霜晶横向扩展的影响因素和凝结液滴的冻结传播方式，并结合理论分析揭示了其传播机理。结果表明，凝结液滴依靠霜晶的横向扩散实现冻结传播，霜晶借助冻结液滴向冷面中心扩散。结霜晶体的横向扩散是实现凝析液滴冻结传播的关键，伴随着小尺寸液滴的蒸发。凝结液滴的冻结传播受霜晶横向扩展速率和液滴间距的影响。增加冷面接触角，可降低冻结扩展速率，延缓结霜。有趣的是，当霜晶与过冷液滴接触时，观察到两种冻结传播模式，即“接触-冻结”和“吸收-冻结”。增大表面接触角或减小接触角滞后可以增加“吸收-冻结”模式的频率，从而有助于降低凝析液滴的冻结传播速度。
As condensate droplets formed at the early stage of frosting are the foundation of frost layer growth, to study the freezing propagation of condensate droplets is of great significance to understand the frosting process. In this paper, the influencing factors of lateral spreading of frost crystals and freezing propagation modes of condensation droplets were discussed by visualization experiments, and the propagation mechanism was revealed combined with theoretical analysis. It is observed that condensate droplets relies on the lateral spreading of frost crystals to realize the freezing propagation and frost crystals diffuse to the center of the cold surface with the help of freezing droplets. The lateral spreading of frost crystals is the key to achieve freezing propagation of condensate droplets, which is accompanied by the evaporation of droplets with small size. The freezing propagation of condensate droplets is affected by the lateral spreading rate of frost crystals and the droplet spacing. Increasing the contact angle of the cold surface reduces the freezing propagation rate and delay frost formation. Interestingly, two freezing propagation modes, “contact-freeze” and “absorption-freeze”, are observed when the frost crystals contact the subcooled droplets. Increasing the surface contact angle or reducing the contact angle hysteresis can increase the frequency of the “absorption-freeze” mode, which helps to reduce the freezing propagation rate of condensate droplets.