Evaporation Characteristic Study On Aqueous Nano-film Under Electric Field

Many microelectronics and nanotechnology fields use external electric fields as the driving force,such as electrostatic spraying,inkjet printing,nanomanufacturing,and electrostatic spinning.In these technical applications,the droplet or film evaporation under the action of an electric field is the key basic physics.One of the processes,a higher evaporation rate is crucial.The application of an electric field does not need to form a closed loop,is easy to operate,and has low operating costs,and the applied electric field can significantly enhance evaporation,so it has attracted much attention.The current research is not clear about the micro-mechanism of electric field enhanced liquid evaporation,and the effects of different electric field forms on evaporation have not been discussed in detail.In this paper,molecular dynamics method is used to simulate the evaporation behavior of nano-water liquid film under the action of electric field.The micro-mechanism of electric field to enhance the evaporation of water liquid film is revealed from the molecular perspective.The influence of evaporation rate supplies persuasive theory for the advancement and development of high-tech.The results of the evaporation of the dissolved salt liquid film under the effect of the DC electric field show that the application of the Ex(electric field parallel to the surface of the liquid film)electric field significantly increases the evaporation rate of the liquid film;the effects of the electric field Ex=0.2 V nm-1 and Ex=0.3 V nm-1 The evaporation rate of the insoluble salt liquid film(containing 2240 water molecules)is 2.86 and 5.72 times compared with the aqueous film at Ex=0 V nm-1,respectively.From a molecular perspective,it is found that free ions in the salt solution film accelerate under the action of a high-voltage electric field.Because the ions have hydration,the water molecules in the hydration clusters and the ions accelerate together,which weakens the interaction between water molecules.This makes it easier for water molecules to escape the liquid membrane.There is a solid-liquid interface and a gas-liquid interface in the direction of the vertical liquid film surface.The applied Ey(the electric field is perpendicular to the liquid film surface direction)ions cannot continue to accelerate,and the evaporation rate of the dissolved salt liquid film is lower than the applied electric field.Under the effect of Ex electric field,there are differences in evaporation rates of different concentrations and different types of salt liquid films.Within a certain range of salt ion concentration,as the ion concentration increases,the liquid film evaporation rate increases;when the same ion molar concentration is dissolved,the solvent With NaCI liquid film evaporation is the fastest,followed by KCl and LiCl,and CaCl2 is the slowest.When an alternating electric field with different frequencies is applied,the evaporation rates of pure water and dissolved salt film increase(Ex and Ey are applied).When the applied frequency is 500 GHz alternating electric field(Ex=0.03 V nm-1)3 the evaporation rate of pure water liquid film,NaCl 75 and NaCl 150 dissolved salt liquid film(containing 3360 water molecules)is the evaporation of liquid film without electric field 1.71,1.69 and 1.66 times.Under the action of a time-varying electric field,both the rotational kinetic energy and the kinetic energy of water molecules increase.Therefore,the application of an alternating electric field will accelerate the temperature rise of the water-liquid film,thereby increasing its evaporation rate.In addition,the potential energy of water molecule interaction weakens,which makes it easier for water molecules to break free from the water liquid film.When the alternating electric field Ex is applied,the evaporation rate of the liquid film is higher than that when the alternating electric field Ey is applied.