Separation characteristics of gases from water including small-sized unused gases through power-free mixing

Abstract

Dissolved oxygen can be used for underwater respiration. By injecting prepared mixed gases with the characteristics of exhalation into water and then separating the dissolved gasses through hollow fiber membranes, the separation amount of gases with oxygen can be increased. In this study, we propose a method of increasing the separation amounts of gases dissolved in water through a separator with hollow fibers by injecting prepared mixed gases with the characteristics of exhalation into water, and then separating the dissolved gases from the fluid passing through a passive mixer composed of multiple plates with evenly spaced small holes in the radial direction. After the prepared mixed gases were injected into the water, the mixed gases in the form of large bubbles were transformed into fine bubbles while passing through the fine-holed plates in multiple stages. The separation amount of gases through membranes was increased by enlarging the gas-liquid contact area by decreasing the bubble size. These results are expected to be beneficial for the development of portable underwater breathing devices owing to the high separation amount of dissolved gases in water by supplying mixed gases with fine bubbles through power-free mixing.