Preparation Of Superhydrophobic Surface And Research On Its Condensation Characteristics

The superhydrophobic,which have unique water repulsion,are widely used in daily life,building antifouling,pipeline transportation and even defense aviation.It is significant that study the condensation characteristics of superhydrophobic surfaces droplet for optimizing airconditioning system and reduce the adverse effects of liquid film and dust during the operation of heat exchanger.In previous studies,there have been few studies on low-temperature condensation and on the effect of bank angle on condensation.In this paper,superhydrophobic surfaces were prepared on copper substrates by the method of chemical etching followed by silica sol modification,and then studying related condensation characteristics and analyzing the effect factors.Firstly,In order to study the innfluence of temperature and humidity on the condensation of air on superhydrophobic surface,the SHS placed horizontally on a cooling-stage for condensation experiments.The results show that the droplet coverage and average radius increase with the temperature of condensation decreasing,and the surface coverage experiences a sharp increase with temperature decreasing when the temperature is less than the specified value.The average radius of condensate droplets at high humidity compared with the condensate droplets at medium and low humidity decreases significantly and the droplet coverage rate is obviously more extensive.The difference of droplet coverage is small between medium and low humidity.The nucleation and growth of droplet of the SHS at high humidity conditions is faster than medium and low humidity,which hve the advantages of rapid droplet renewal rate and small droplet size,although it has the disadvantage of high droplet converge.Secondly,there are two aspects to evaluate the excellent performance of SHS.On the one hand,it is the nature hydrophobic properties of SHS at the condensation condition.On the other hand,other extrinsic factors that can affect its hydrophobic properties.The results of experiments found that the state of condensed droplets on the SHS affected by the inclination angle of the sample,and the larger the inclination angle is,the smaller the volume of the condensed droplets is.For copper-based superhydrophobic surfaces,the condensation characteristics of water droplets when placed vertically are significantly better than the condensation characteristics of water droplets when placed horizontally.The droplets on the SHS achieved periodic nucleation,growth,and bounce off in a continuous condensation experiment for two hours when the sample was placed vertically in the center of a cold stand.Finally,study the dust process of SHS at the condensation condition and the infactors affecting the dust removal when the SHS was dust spread.The factors that affect the dust removal such as the particle size,dust coverage and air humidity were analyzed,and the three priorities of dust particles leaving were explained.The studies show that the condensation droplets can carried away the dust,but the removal time and the dust removal effect are different.In this paper,the surface condensation droplet coverage and size distribution were quantitative analysed,which indicaded that the influence of common variables such as temperature and humidity,surface angle of inclination and surface cleanliness on the condensation characteristics of superhydrophobic surfaces,which provides a theoretical reference for the application of superhydrophobic surfaces.