Differences analysis of water molecular diffusion behaviors in vegetable oil and mineral oil under temperature field

The existence of water will greatly affecf the insulation performance of transformer insulation system. In order to research the difference of diffusion behavior of water molecules in mineral oil and vegetable oil, the diffusion behavior of water molecules in two oil media was studied by using molecular simulation method. The results show that the diffusion motion of water molecules in two oil media was gradually intensified with the increase of temperature. By comparing the diffusion behavior of water molecules in vegetable oil and mineral oil, it is found that the hydrogen bond formed between vegetable oil and water can limit the diffusion motion of water molecules in vegetable oil. Moreover, the interaction energy between water molecules and vegetable oil is greater than that with mineral oil. In addition, the FFV of water molecules in mineral oil is greater than that in vegetable oil, which indicates vegetable oil provides less free space for the diffusion of water molecules. This provides a basis for understanding the difference of diffusion behavior of water molecules in two oil media from a micro perspective. •The hydrogen bond between vegetable oil and water molecules restricts the movement of water molecules in vegetable oil.•Strong electrostatic force can be formed between vegetable oil and water molecules.•The viscosity of vegetable oil is higher, which leads to its smaller free volume.