Molecular Simulation Of Leidenfrost Effect During Droplet Impingement On High Temperature Copper Wall With Different Wettability

With the increase of temperature in industrial applications,the temperature resistance of materials has been greatly challenged,and water spray temperature reduction as a common form of cooling is widely used in various industrial applications,including seawater desalination and the impact of brine droplets on the heat transfer tube of falling film evaporator in refrigeration;water droplet impact on turbine blades;Spray cooling in quenched metal castings and extrusions as well as fire extinguishing and electronic cooling systems.However,the existing Leidenfrost phenomenon significantly reduces its cooling efficiency,and the current research mostly focuses on the Leidenfrost effect of fixed droplets,so it is of great significance to study the Leidenfrost effect under the impact of droplets to improve the cooling efficiency of water spray.In this paper,the Leidenfrost effect of droplets hitting different wetting high-temperature copper walls was studied by molecular dynamics simulation method,and the characteristics of Leidenfrost phenomenon under the microscopic level were defined by kinetic energy stability test,and the molecular dynamics simulation results showed that the hydrophilic surface determined by atomic potential energy had a lower dynamic Leidenfrost temperature(LFP)than the hydrophobic surface.And at different surface temperatures,there is a critical contact angle that triggers the Leidenfrost phenomenon,and the critical contact angle is measured and error analyzed by tangential method and it is found that the critical contact angle increases with the increase of surface temperature.In addition,the influence of different structural surfaces and velocity on the dynamic Leidenfrost effect was also studied,and the simulation found that the increase of bubble nucleation sites can activate the Leidenfrost phenomenon and significantly reduce the Leidenfrost temperature point,and through the analysis of the dynamic characteristics of droplets hitting the wall at different speeds,it is found that the influence of velocity on the Leidenfrost effect is diametrically opposite on hydrophilic surfaces and hydrophobic surfaces.Hitting the hydrophilic surface with a large velocity droplet inhibits the Leidenfrost phenomenon,and hitting the hydrophobic surface activates the Leidenfrost phenomenon.The work in this paper is of great significance for focusing on the prediction of the Leidenfrost temperature of new high-temperature insulation materials and for the development of industrial application surfaces with lower critical contact angles.