Ultralow-Pressure-Drop Multiplexed Coalescence Inertial Filters

Multiphase flows containing small droplets are ubiquitous in engineering applications and often pose a significant challenge to the efficient and reliable design of thermofluidic systems. This work describes multiplexed coalescence inertial filters composed of parallel helical pathways, designed to capture fine droplets (< 40 µm) through inertial separation. These filters have a large number of flow passages, resulting in an ultralow pressure drop (< 400 Pa). Filtration efficiencies for streams of air laden with 7 µm and 30 µm droplets were characterized under varying flow conditions, with complete capture observed above a threshold flowrate. Models for filtration efficiency and pressure drop were developed and validated against experimental results to allow system design and optimization, enabled by the tunable additive manufacturing approach used to fabricate the filters. Furthermore, additive manufacturing methods were modified to create porous multiplexed coalescence inertial filters that may be continuously drained. This multiplexed coalescence inertial filtration approach could find use in HVAC systems, fog harvesting, chemical reactors, and microgravity droplet capture.