絕緣子超疏水涂層表面水滴凍結過程及其影響因素
本文選題:超疏水涂層 + 過冷卻水滴; 參考:《重慶大學》2014年碩士論文
【摘要】:超疏水表面因具備一定的反彈水滴、延緩凍結及減小與冰的粘接強度的能力,在一定程度上有助于輸電線路導線和絕緣子防冰或延緩覆冰,已成為目前研究的熱點。然而,對超疏水表面是否具有實際防覆冰能力仍存在一定爭論,特別是超疏水表面水滴運動特性與凍結過程等影響超疏水表面覆冰特性的基礎問題尚未見較多深入研究。為了揭示超疏水涂層表面水滴的凍結微觀過程,為研究絕緣子應用超疏水涂層防覆冰提供參考,本文在人工氣候室內對涂覆不同超疏水或疏水涂層的玻璃片表面過冷卻水滴的運動特性、凍結過程以及涂覆不同疏水性涂層的玻璃絕緣子表面覆冰增長進行了試驗研究。取得的主要研究成果如下: 在低溫低氣壓試驗室中,,獲取了連續(xù)噴霧過冷卻水時疏水性表面上水滴運動變化過程,研究了表面水滴的運動特性,并分析了表面的接觸角、接觸角滯后、表面粗糙度、環(huán)境溫度等因素對水滴運動特性的影響。在疏水性涂層表面上,水滴只有在直徑增大到一定的大小才會從表面滾落,接觸角越大、接觸角滯后越小、粗糙度越大、表面傾斜角度越大,表面上水滴滾動所需的直徑就越小,水滴在表面上所能累積的體積越小,停留的時間也就越短,水滴凍結的可能性也就越小。 針對靜置水滴和連續(xù)噴霧過冷卻水情況下的水滴,借助顯微鏡獲得了不同超疏水或疏水涂層表面上水滴結晶成核的動態(tài)過程,并分析了水滴凍結的成核機制及其影響因素。統(tǒng)計分析了不同疏水性涂層表面出現(xiàn)凍結水滴的時間,研究了接觸角、接觸角滯后、表面粗糙度等因素對水滴凍結時間的影響。靜置的水滴無法反映水滴在超疏水表面的運動特性,其凍結時間也難以反映在連續(xù)噴霧時表面延緩覆冰的時長。進行超疏水涂層防覆冰試驗研究時,建議使用對試品連續(xù)噴霧過冷卻水的方法進行試驗,并用表面上出現(xiàn)局部凍結水滴坍塌或是完全凍結水滴的時間或者試品表面完全被冰層覆蓋的時間來表征疏水性涂層延緩覆冰的能力。 在人工氣候室對涂覆不同超疏水或疏水涂層的玻璃絕緣子進行人工覆冰試驗,研究了超疏水涂層對絕緣子表面覆冰增長的影響。結果表明,超疏水涂層能在一定的程度上延緩絕緣子的覆冰,涂層表面的接觸角越大、接觸角滯后越小,水滴滾動特性越好延緩覆冰時間相對越長。超疏水涂層會影響絕緣子表面冰層的形貌,對覆冰密度和冰棱形貌無明顯影響。僅在覆冰初期,對絕緣子表面覆冰的質量、絕緣子表面冰棱的增長有影響。
[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.
【學位授予單位】:重慶大學
【學位級別】:碩士
【學位授予年份】:2014
【分類號】:TM216
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