The gravity-driven drainage behavior of coalesced oil has been extensively characterized in fine porous coalescence materials, showing that oil drains in a (partially) closed film at the rear side, whereas intraporous drainage is negligible in such materials. In industrial applications, a structural support structure and a drainage layer (a.k.a. entrainment barrier) are often placed behind the coalescence material.

These components introduce additional interfaces that can alter drainage behavior, potentially leading to interfacial drainage paths along the gaps of the interface. Furthermore, contrary to fine-porous coalescers, the open porous structure of the drainage material can present an intraporous drainage path. This research aims to obtain a fundamental understanding of the drainage behavior of coalescing filters in real applications.

A novel filter chamber will be designed with partitions to distinguish between and measure the intraporous, interfacial film, and rear-side surface film drainage streams. The filter chamber requires oil outlets at different and precise positions to measure the various drainage rates. This study will investigate how the drainage behavior is influenced by the properties of the drainage material (e.g., mean pore size, thickness) and the support structure, along with process parameters (e.g., face velocities, oil delivery rate)...