Research on water droplet interception mechanism of sheet-type drift eliminator based on three-dimensional transient numerical simulation

A three-dimensional transient numerical study was conducted on the sheet-type drift eliminator single-channel to reveal the droplet interception mechanism, using a mechanical draft wet cooling tower (MDWCT) as a typical operating environment. The droplet-air, droplet-droplet, droplet-film, and film-air interactions were considered comprehensively from the aerodynamics and heat transfer. The results indicate the existence of two distinct types of droplet escape: primary escape and secondary escape. The Stokes number (St) ≤ 1 for the vast majority of primary escaped droplets, whereas the secondary escaped droplets exhibit a considerable range of St. The correlation curves between the escape rate and the Stokes number (Stin) is similar under different inlet velocities (vin). The escape rate first decreases and then increases as Stin increases. There is a safety zone (Stin from 0.83 to 18.62) where the escape rate is near zero. For the studied eliminator, the specific safety zone is 65∼190 μm. The mass flow rate of escaped droplets first decreases and then increases as vin increases. The secondary escape dominates instead of primary escape when vin ≥ 7 m/s. This paper provides theoretical support for improving interception efficiency of eliminator while extending the methods for drift reduction and water savings.