An Experimental Study Of Frost Formation On The Surface With Different Material Properties

Frost phenomenon wingspread exists in some areas such as aerospace,transportation, and air conditioning heat pump. Frosting problem will cause differentdegrees of damage to the equipment, the lighter will reduce the operation efficiency ofequipment or even reduce to paralyze the equipment. In recent years, related scholarshave carried out a large number of experimental researches, involving the observationof frosting process, the research of the rule of frost growth and the mechanism of frost,and exploration of frost prevention, etc. A large amount of research not only can clearunderstanding the frost layer growth process, but also provide the theoretical basisand experimental base study of frost prevention/frost suppression method, and theyhas a very important practical significance.If you want to solve the problem of frost damage, the frosting process must befully recognized. Therefore, this paper have taken some microscopic observation ofthe different cold frost formation process on the surface, recognized the cold surfacefrosting process, analyzed the growth rules of frost layer; And frost experiment wascarried out on the surface hydrophobicity of biological and artificial hydrophobiccoating based on the microscopic observation, and analyzed the frost suppressionmechanism of hydrophobic surface. The specific contents are as follows:(1) In this paper, frost formation on the surface of the arched brass is observed byusing the microscopic observation. And the frost formation process on the coldsurface have three stages: the generation of droplet, the initial frost of frost growthstage and layer of the late growth stage; by adopting the combination of experimentalobservation and theoretical analysis method, we have analyzed the frost growthphenomenon and the frost layer growth rule.(2) In this paper, it found that the scales on the wing are imbricate scales alongthe vein and rules of arrangement, the micro/nano-structures have much approximateparallel longitudinal rib spacing equal and special cross rib by using microscopicobservation to observe the biological hydrophobic surface. Some observation testsabout frosting on biological hydrophobic surface have been performed and havefounded that the frosting process also experienced drops condensed phase, the frostlayer growth stage and full growth stage of frost layer. The difference is the beginningof the cold frost on the surface of the water is more noticeable in the form of generation grew up, and merge. After repeated frost/slow cream test the biologicalhydrophobic surface that the suppression of frost resistance, and experimentalverification that the wing scales can obviously delay the freezing time of droplet.(3) In this paper, the super hydrophobic coating was prepared on the glasssubstrates, and the comparison and analysis the hydrophilic and hydrophobic coatingon the surface of the glass surface frosting process. the test have found that largerdroplets size, delayed the freezing of droplet, delayed the appearance of frost crystalin the early stage, and reduced the density of the frost layer growth on the surface ofhydrophobic coating. And in the same conditions, the different temperature ofhydrophilic surface of glass frosting experiment observation, found that the dropletoccurs time, the occurrence time of freezing droplets, the size of the freezing waterand frost branch of time has obvious difference. The morphology of frost layer hasobvious differences in the different stage.