绝缘子超疏水涂层表面水滴冻结过程及其影响因素

发布时间：2018-04-17 16:38

本文选题：超疏水涂层 + 过冷却水滴　；参考：《重庆大学》2014年硕士论文

【摘要】：超疏水表面因具备一定的反弹水滴、延缓冻结及减小与冰的粘接强度的能力，在一定程度上有助于输电线路导线和绝缘子防冰或延缓覆冰，已成为目前研究的热点。然而，对超疏水表面是否具有实际防覆冰能力仍存在一定争论，特别是超疏水表面水滴运动特性与冻结过程等影响超疏水表面覆冰特性的基础问题尚未见较多深入研究。为了揭示超疏水涂层表面水滴的冻结微观过程，为研究绝缘子应用超疏水涂层防覆冰提供参考，本文在人工气候室内对涂覆不同超疏水或疏水涂层的玻璃片表面过冷却水滴的运动特性、冻结过程以及涂覆不同疏水性涂层的玻璃绝缘子表面覆冰增长进行了试验研究。取得的主要研究成果如下：在低温低气压试验室中，，获取了连续喷雾过冷却水时疏水性表面上水滴运动变化过程，研究了表面水滴的运动特性，并分析了表面的接触角、接触角滞后、表面粗糙度、环境温度等因素对水滴运动特性的影响。在疏水性涂层表面上，水滴只有在直径增大到一定的大小才会从表面滚落，接触角越大、接触角滞后越小、粗糙度越大、表面倾斜角度越大，表面上水滴滚动所需的直径就越小，水滴在表面上所能累积的体积越小，停留的时间也就越短，水滴冻结的可能性也就越小。针对静置水滴和连续喷雾过冷却水情况下的水滴，借助显微镜获得了不同超疏水或疏水涂层表面上水滴结晶成核的动态过程，并分析了水滴冻结的成核机制及其影响因素。统计分析了不同疏水性涂层表面出现冻结水滴的时间，研究了接触角、接触角滞后、表面粗糙度等因素对水滴冻结时间的影响。静置的水滴无法反映水滴在超疏水表面的运动特性，其冻结时间也难以反映在连续喷雾时表面延缓覆冰的时长。进行超疏水涂层防覆冰试验研究时，建议使用对试品连续喷雾过冷却水的方法进行试验，并用表面上出现局部冻结水滴坍塌或是完全冻结水滴的时间或者试品表面完全被冰层覆盖的时间来表征疏水性涂层延缓覆冰的能力。在人工气候室对涂覆不同超疏水或疏水涂层的玻璃绝缘子进行人工覆冰试验，研究了超疏水涂层对绝缘子表面覆冰增长的影响。结果表明，超疏水涂层能在一定的程度上延缓绝缘子的覆冰，涂层表面的接触角越大、接触角滞后越小，水滴滚动特性越好延缓覆冰时间相对越长。超疏水涂层会影响绝缘子表面冰层的形貌，对覆冰密度和冰棱形貌无明显影响。仅在覆冰初期，对绝缘子表面覆冰的质量、绝缘子表面冰棱的增长有影响。
[Abstract]:The superhydrophobic surface has the ability to rebound water droplets, delay freezing and reduce the bonding strength with ice, and to some extent help transmission line conductors and insulators to prevent ice or delay icing, which has become a hot research topic at present.However, there is still some controversy about whether the superhydrophobic surface has the actual anti-icing ability, especially the basic problems such as the droplet motion and the freezing process that affect the icing characteristics of the superhydrophobic surface have not been deeply studied.In order to reveal the freezing microscopic process of water droplets on the surface of superhydrophobic coatings, this paper provides a reference for the study of the application of superhydrophobic coatings to the anti-icing of insulators.In this paper, the motion characteristics, freezing process and ice growth of glass insulators coated with different superhydrophobic or hydrophobic coatings were investigated in artificial climate room.The main findings of the study are as follows:In the low temperature and low pressure chamber, the droplet motion on hydrophobic surface during continuous spray supercooling water was obtained, and the motion characteristics of the surface water droplet were studied, and the contact angle, contact angle lag and surface roughness were analyzed.The influence of environmental temperature and other factors on the motion characteristics of water droplets.On the surface of hydrophobic coating, water droplets will roll off the surface only when the diameter increases to a certain size. The larger the contact angle, the smaller the contact angle, the greater the roughness and the greater the angle of inclination of the surface.The smaller the diameter of the droplet is, the smaller the volume the droplet can accumulate on the surface, the shorter the residence time and the less the possibility of freezing the droplet.The dynamic process of crystallization nucleation of water droplets on the surface of different superhydrophobic or hydrophobic coatings was obtained by microscope in the case of static water droplets and continuous spray supercooling water. The nucleation mechanism of water droplet freezing and its influencing factors were analyzed.The effects of contact angle, contact angle lag and surface roughness on the freezing time of different hydrophobic coatings were studied.The static droplets can not reflect the motion characteristics of the droplets on the superhydrophobic surface, and the freezing time of the droplets can hardly reflect the time of delaying the icing on the surface of continuous spray.In the study of anti-icing of superhydrophobic coating, it is suggested that the method of continuous spray supercooling water should be used to carry out the test.The ability of hydrophobic coating to delay the ice coating was characterized by the time of local collapse or complete freezing of water droplet on the surface or the time when the surface of the sample was completely covered by ice layer.The effect of superhydrophobic coating on the growth of ice on the surface of the insulator was studied by artificial icing test of glass insulators coated with different superhydrophobic or hydrophobic coatings in an artificial climate chamber.The results show that the superhydrophobic coating can delay the icing of insulators to a certain extent. The larger the contact angle of the coating is, the smaller the contact angle is, and the better the rolling property of water droplets is, the longer the ice coating time is.The superhydrophobic coating will affect the morphology of the ice layer on the insulator surface, but has no obvious effect on the ice density and the shape of the ice edge.Only in the early stage of icing, the quality of ice coating on insulator surface and the growth of ice edge on insulator surface are affected.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM216

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