Abdelmagid Ghassan, Yilbas Bekir Sami, Al-Sharafi Abdullah, Al-Qahtani H, Al-Aqeeli Nasser
Mechanical Engineering Department, King Fahd University of Petroleum & Minerals Dhahran Saudi Arabia
Center of Excellence in Renewable Energy, King Fahd University of Petroleum & Minerals Dhahran Saudi Arabia.
RSC Adv. 2019 Jan 28;9(7):3582-3596. doi: 10.1039/c8ra10092f. eCollection 2019 Jan 25.
A water droplet's behavior on an inclined hydrophobic surface in the presence of environmental dust particles is considered and the droplet's dynamics are analyzed pertinent to self-cleaning applications. A polycarbonate wafer is crystallized using the solution-crystallization method to generate hierarchically distributed micro/nano-sized spherules and pillars on the surface. To improve the wetting state and lower the contact angle hysteresis, functionalized silica particles are synthesized and, later, deposited on the crystallized surface. Environmental dust particles are collected and characterized in terms of elemental composition, size and shape. A high-speed camera is used to monitor a water droplet's behavior on the inclined hydrophobic surface with and without the presence of dust particles. The influence of droplet volume on the dust particle removal rate from the inclined hydrophobic surface is assessed. It is found that the functionalized silica particles deposited on the surface result in a droplet contact angle in the order of 158 ± 2° and contact angle hysteresis of 2 ± 1°. The water droplet mainly rolls on the inclined hydrophobic surface and the sliding velocity remains almost 13% of the transverse velocity of the droplet. Droplet wobbling is influenced by the dust particles and the droplet size; in which case, increasing the droplet volume enhances the droplet puddle thickness on the hydrophobic surface. The cloaking of the droplet fluid onto the dust particles causes mixing of the dust particles with the droplet fluid while enhancing the particle removal from the hydrophobic surface. Increasing the droplet volume slightly enhances the size of the area of the cleaned surface.
研究了环境尘埃颗粒存在下，水滴在倾斜疏水表面上的行为，并分析了与自清洁应用相关的水滴动力学。采用溶液结晶法使聚碳酸酯晶片结晶，在其表面生成分层分布的微米/纳米级小球和柱状结构。为改善润湿状态并降低接触角滞后，合成了功能化二氧化硅颗粒，随后将其沉积在结晶表面上。收集环境尘埃颗粒并对其元素组成、尺寸和形状进行表征。使用高速摄像机监测有无尘埃颗粒时水滴在倾斜疏水表面上的行为。评估了液滴体积对倾斜疏水表面尘埃颗粒去除率的影响。结果发现，沉积在表面的功能化二氧化硅颗粒使水滴接触角约为158±2°，接触角滞后为2±1°。水滴主要在倾斜疏水表面上滚动，滑动速度几乎保持在水滴横向速度的13%。水滴摆动受尘埃颗粒和液滴尺寸的影响；在这种情况下，增加液滴体积会增加疏水表面上的液滴水坑厚度。液滴流体包裹在尘埃颗粒上会导致尘埃颗粒与液滴流体混合，同时增强颗粒从疏水表面的去除。增加液滴体积会略微增大清洁表面的面积。
