Modification Strategy for High-Performance Coalescing Filters with a Patterned Surface and Its Application to Cartridges

Abstract

Gas–liquid coalescence filters are extensively applied in industrial fields, mainly to separate oil mist droplets that are carried in gases. The traditional wettability treatment on the filter surface can improve the filtration efficiency but usually also increases the pressure drop. In this study, a surface modification method based on tip patterns was proposed. Nonuniform wettability filter surfaces with tip patterns were prepared by combining star-shaped molds and spraying modification to explore the influence of key pattern parameters on the performance of filters. In this way, industrial cartridges were prepared based on the optimal modification parameters and their filtration performance was analyzed and verified. The results showed that liquid collection by the modified filters improved significantly under the combined effect of the wettability driving force and Laplace force produced by the shape gradient, while the steady-state pressure drop decreased by 34.2–47.4% compared to the substrate filter. The modifications facilitated an increase in the effective fiber surface area and strengthened the droplet capture effect by diffusion. When the tip angle was 50°, all of the modified filters achieved the highest droplet filtration efficiency across different droplet size intervals. When there were nine patterns at a 50° tip angle, the modified filters achieved the optimal comprehensive filtration performance, and the steady-state quality factor increased 3.1- and 3.4-fold for submicrometer and micrometer droplets, respectively, compared to the substrate filter. Industrial cartridges were prepared based on the optimal filters. Under different liquid-loading rates, the modified cartridges had significantly higher efficiency and lower resistance compared to the unmodified cartridge. The proposed pattern modification method provides a direction for the design and development of new high-performance coalescence components.