The Effect of Humidity on the Removal of Fine Particles on a Solid Surface Using a High-Speed Air-Jet

The effect of operating conditions on the removal efficiency of deposited particles using a high-speed air jet was studied with particular attention to the humidity of air surrounding at particle deposition and the air-jet removal. The experimental results showed that the removal efficiency of particles deposited in a low-humidity atmosphere decreased with increasing drying time after the deposition. In the case of deposition under high humidity, the removal efficiency increased at the beginning of drying and decreased rapidly after achieving maximum efficiency. For drying over 80 hrs, however, the humidity of surrounding air at the particle deposition did not affect the removal efficiency. The efficiency also depended on the humidity at the air-jet removal, and achieved maximum value at 67 % relative humidity. Such a variation in removal efficiency has been well explained by the change of Hamaker's constant with the adsorbed layerthickness of water molecules and the variation of liquid surface tension with the thickness of liquid bridge.