During steady-state operation of a mist filter, captured aerosol is driven by the airflow toward the rear surface of the media, where it drains as a thin film through which the air has to break through. Maintaining this steady-state flow of coalesced liquid requires an additional “wet ∆p” above and beyond the “dry ∆p” of the media, which is composed of an internal contribution (“channel-Δp”) required to “pump” liquid through the media – typically in distinct channel-like structures – plus a final steep “jump-Δp” required to overcome capillary retention forces and maintain the liquid drainage film on the surface.
While the jump-∆p is determined mostly by the structural properties of the filter media (Kampa, 2015; Kolb et al., 2015), the channel-Δp shows an additional strong dependence on operating parameters such as air flow velocity v, aerosol concentration c, and liquid loading rate c*v. Understanding and optimizing these parameters is key to minimizing the wet ∆p.
The paper concentrates on the effects of aerosol concentration c and oil loading rate on Δp for flow velocities ranging from 10 cm/s to 70 cm/s. Numerous experiments were carried out with multiple layers of wettable glass fiber media, which were loaded with submicron oil aerosol until well past steady-state. At the end of each experiment the global saturation per layer was measured. Also the individual layers were photographed and the local oil distribution (i.e. number and diameter of oil channels) was determined as a function operation conditions. The results show a significant effect of flow velocity on ...
Session: G3 - Mist and Droplet Separation I
Day: 11 October 2016
Time: 14:45 - 16:00 h