Development of Non-chemical Micro-bubble Washing Technology Using a Venturi Tube

Abstract

Chemical solvents used for industrial washing process have a negative impact on the environment and the health of their users, and they are high-cost cleaning. In order to reduce the amount of chemical solvent used in the washing process, the non-chemical washing technology with micro-bubble is expected. In the present study, we focus on the microbubble generator with a venturi tube. This generator can generate the bubbles of several-hundred-micrometer diameter in high void fraction. And it is maintenance-free because of its simple structure. The object of the present study is to develop the washing technology with micro-bubbles generated by using a venturi tube. First, the mechanism of washing technology is clarified. The generations of micro-bubbles from bubble collapses were observed in the venturi tube through a high speed video camera. Also, separating dirt from a washing target by a micro-bubble could be observed. The behavior of bubbles separating from the washing target with oil was observed. Furthermore, the pressure on a washing surface, the pressure fluctuations with high amplitude were measured in the flow condition with the bubble collapse phenomena. In washing experiments with oil paint, it was confirmed that washing effect was improved in the condition with the bubble collapse and the pressure fluctuation. Consequently, it is proposed that bubbly jet flow, micro-bubbles and the pressure fluctuation are the advantage of this washing technology.