Analysis And Research On The Rolling Dust-carrying Process Of Super-hydrophobic Surface Droplets

Dust deposition will reduce the power generation efficiency and even endanger the life of solar photovoltaic panel.Traditional cleaning methods generally have problems such as large water consumption,high cost and low cleaning efficiency.However,the superhydrophobic surface had self-cleaning properties,and the application of superhydrophobic surface to solar photovoltaic panel is expected to achieve self-cleaning of solar photovoltaic panels.Although studies have shown that the rolling of superhydrophobic surface droplets can adsorb dust particles at the trailing edge,but the dynamics of droplets and particles is no clear during the dust-carrying process of droplets on superhydrophobic surfaces.In order to solve the air flow field problem of super-hydrophobic surface,a numerical model of air flowing through super-hydrophobic surfaces was established.The drag reduction characteristics of super-hydrophobic surfaces were analyzed by CFD method.The simulation results showed that super-hydrophobic surfaces have a certain drag reduction effect on air flow.But the drag reduction rate was affected by parameters such as mass flow rate,groove sizes and types.When the dimensionless spacing s⁺of the V-shaped groove was between 5and 45,the superhydrophobic surface had a drag reduction effect.The maximum drag reduction rate appears when s⁺was 20,and the maximum drag reduction rate reaches 5.33%.By comparing the drag reduction effects in four different types of groove structures,it was found that the circular groove structure had the largest drag reduction range and a higher drag reduction rate,with the maximum drag reduction rate reaching 9.66%;The effect of the superhydrophobic surface structure on the starting process of particles was analyzed by coupled EDEM software.The simulation results showed that the starting wind speed of the particles on the superhydrophobic surface increases slightly,and the change rate was within2%,compared with the hydrophilic smooth surface.Therefore,dust particles wound still stay on the superhydrophobic surface under the action of wind.In order to study dynamic characteristics in the process of droplet rolling and carrying dust,the force that particles might be subjected to during the droplet rolling and carrying dust was theoretically analyzed,The liquid-gas interface force received by the particles is the main force for the droplets to carry the particles,and the wall contact angle will affect the size of the liquid-gas interface force,thereby affecting the cleaning efficiency of the particles.Subsequently,a four-stage mechanical model was established in which dust particles are in contact with the leading edge of the droplet,the particle is immersed in the droplet,the particle contacts the trailing edge of the droplet,and the particle moves with the droplet.The research results show that at the leading edge of the droplet It can also adsorb particles.The calculation formulas R_fc and R_bc of the critical radius of dust particles carried by the leading edge and trailing edge of the droplet are deduced.At the same time,a rolling dust-carrying experiment of super-hydrophobic surface droplets was carried out to verify the theoretical analysis.The experimental research is in good agreement with the theoretical analysis.The particles exceeding the critical radius cannot be absorbed by the rolling droplets and be taken away.The experimental results also found that particles with a radius less than 37μm are adsorbed when they are in contact with the leading edge of the droplet.