Experimental study of the formation and diffusion of soap bubbles for wrapping and transporting indoor airborne pollution

Abstract

A novel soap-bubble-assisted local exhaust ventilation (SBA–LEV) system is proposed in this study, which uses soap bubbles to separate centralized released airborne pollutants from ambient air and prevents mixing and dilution in the pollutant diffusion process. Four SBA-LEV system modes were proposed, and the formation and free diffusion of the soap bubbles in Mode A were studied by using a single-nozzle air-supply experimental setup. The velocity range of the soap bubble formation was determined, and the relationship between the maximum bubble-forming flow velocity and nozzle diameter was obtained. For a given nozzle diameter, the diameters of the generated soap bubbles were essentially the same and independent of the blowing velocity. Moreover, the soap bubble diameter increased linearly with an increase in nozzle diameter. In the soap bubble diffusion process, it showed that the moving trajectory of a soap bubble is similar to a parabola, and the error between the theoretical and experimental values was less than 20%. Moreover, it indicated that the diffusion range of a soap bubble group expanded with an increase in diffusion height. When the blowing velocity was near the minimum critical airflow velocity, the diffusion range of soap bubbles is the smallest and suitable for capture. Finally, a general design and efficiency evaluation method of the SBA–LEV system was discussed. The SBA-LEV system can effectively reduce the difficulty of pollutant capture by exhaust airflow and the required exhaust air volume, and finally improve the pollutant-removal and energy-saving efficiency of LEV system.