The drainage layer strategy is a common method for improving filtration
performance of coalescing filter. In this study, using the commercial
glass fibrous filters, the influence of sub-high efficiency drainage
layers on high efficiency coalescing filters were investigated
experimentally. The efficiency of coalescing filter slight increases,
whereas the total wet pressure drop reduces 0.32 kPa after assembling
drainage layer. In addition, the influence of pore size, thickness and
wettability on performance were evaluated. While the pore size of
drainage layer decrease, the wet pressure drop reduces and quality
factor increase. Likewise, the thickness of drainage layer also has
positive effect on filtration performance. By contrast, the wettability
has a weak affect on the filtration performance. As different coalescing
filter with the same drainage layer, the improvement in the filtration
performance increase with the decrease of pore size difference between
the coalescing and drainage layers.