Study On The Influence Of Temperature And Electric Field On The Diffusion Of Water Molecules In SiO₂ Modified Insulating Oil

As the most widely used insulating oil,naphthenic mineral insulating oil plays an irreplaceable role in the insulation system.Relevant experiments have proved that nano-SiO₂ particles can improve the breakdown voltage of insulating oil.Moisture is the biggest"enemy"of insulating oil except temperature,however,there is little research on the influence of nano-SiO₂ particles on the microscopic mechanism of insulating oil.Therefore,this paper discusses the microscopic mechanism of nano-SiO₂ particles on the diffusion behavior of water molecules in insulating oil,which has important academic value and practical significance for the further study of nano-modified insulating oil.First based on the molecular simulation technology,the diffusion behavior of water molecules in the insulating oil model with and without nano-SiO₂ particles is compared.Secondly,the influence of nano-SiO₂ particles on the diffusion of water molecules was studied under the five temperature conditions of 303K,323K,343K,363K and 383K.Finally,under the action of electric field and temperature,the diffusion behavior of water molecules in nano-SiO₂ insulating oil was studied,the conclusions are as follows:?1?Nano-SiO₂ particles can effectively bind the diffusion behavior of water molecules in insulating oil.Because nano-SiO₂ particles can reduce the free volume in the model,the activity space of water molecules is reduced,and the interaction energy between water molecules and oil molecules is increased,so the diffusion coefficient of water molecules in the model is reduced.But with the increase of water content,the binding effect will gradually weaken.?2?Nano-SiO₂ particles can effectively reduce the influence of temperature on the diffusion behavior of water molecules in insulating oil.The increase of temperature will increase the free volume of the model and provide more space for the diffusion of water molecules,However,the volume fraction of the model without nano-SiO₂ particles increased by 9.4%,while the free volume fraction of the model with nano-SiO₂ particles increased only by 5.3%.In addition,the chemical bond and hydrogen bond between atoms will also weaken with the increase of temperature,resulting in the decrease of the interaction energy between water molecules and oil molecules,and the restraint of oil molecules on water molecules.Similarly,the interaction energy of the model without nano-SiO₂ particles decreased by 16.3%,while that of the model with nano-SiO₂ particles decreased by 9.5%,which shows that nano-SiO₂ particles can effectively slow down the effect of temperature on the diffusion behavior of water molecules in insulating oil.?3?Compared with temperature,electric field is the main factor affecting the diffusion behavior of water molecules in nano SiO₂ insulating oil.The electric field will polarize the water molecules,from the original disorderly arrangement to the orderly arrangement along the direction of the electric field and the Brownian motion will be weakened,and the free volume fraction in the model will be sharply less because of the electric field,and the free volume fraction in the model will be sharply less because of the electric field,so the diffusion ability of the water molecules will be greatly weakened,and the electric field will increase the electrostatic force between the water molecules and the oil molecules,which is the main reason for the increase of the interaction energy.However,the increase of temperature can only slightly affect the diffusion ability of water molecules in the model,so the electric field is the main factor affecting the diffusion behavior of water molecules in insulating oil.