Adhesion behavior of oil droplets on solid surface with different wettability and inclined angle in water

Plate separators are widely used for oil-water separation in the petrochemical industry. The microscopic adhesion behavior of oil droplets at the solid surface is the key to understanding the oil-water separation mechanism in the plate separator. However, published microscopic experiments and mechanism research is insufficient. This study experimentally investigates the process of oil droplets impacting solid surfaces of Polytetrafluoroethylene (PTFE), 304 stainless steel, and Polyvinyl chloride using a high-speed camera. The influences of solid surfaces with different wettability and inclined angles from 0 degrees to 45 degrees are studied. The results show that oil droplets have the shortest drainage time and the greatest spreading speed on PTFE plates. The drainage time on an inclined surface is significantly longer than on a horizontal plate, and increases as the angle increases. The maximum spreading length occurs at an inclined angle of 15 degrees, and is less affected by the angle as the Weber number (We) decreases. This study facilitates the understanding of oil droplet adhesion on a coalescing material surface in a plate separator from a microscopic view.