An efficient strategy to enhance air filtration through the synergistic effects of ultrasonics and seed particles

Abstract

The individual and combined effects of ultrasonic acoustics agglomeration (AA) with the addition of seeding water droplets for particle agglomeration (DA) are demonstrated for their efficiency in manipulating the number concentration of airborne particles as a pre-treatment mechanism in filtration systems. Through a series of experiments in a purpose-built aerosol wind tunnel with particle separation and filtration stages, it is demonstrated that the combined effect of AA and DA can reduce the particle number concentration by up to 30 % as a result of extensive particle agglomeration. This reduction is significantly higher than that achieved either by the individual action of AA or DA and higher than the direct superposition of the reductions achieved individually by these two actions. In addition, the synergistic effects of combining AA and DA can extend filter operating lifespan significantly by up to 57 % due to lower mass deposition in the filter. A theoretical model is developed for the prediction of filters’ pressure drop patterns under various pre-conditioning methods. The current study sheds light on the development of filtration pre-conditioning systems that are capable of enhancing particle removal efficiencies alongside reduced pressure drop increment across filters, leading to both environmental and cost benefits.