Interfacial Dynamics of Dissolving Bubbly Turbulent Flow in Carbon Dioxide Sequestration Process

本研究的主要目标是：(A)阐明气泡动力学与气液传质之间的关系，(B)可视化溶解组分的弥散动力学(S)。在可能控制界面传质速率方面取得了以下成果/发现：(1)通过连续监测液体中的气泡向下流动，研究了气体从含CO_2气泡溶解成液体的动态过程，这是GREAD系统中普遍存在的溶解泡状湍流的本质。基于建立的这些可视化技术，发现起伏表面可以看作是一个具有传播波的表面，这种起伏起伏可以通过降低表面…的机制来提高溶解速度(3)设计了一个气泡尺寸分布可控的气体分散系统来模拟气泡流动，其中还设计了光纤探头测量技术来获得气泡相互作用下气泡分散的统计信息，从而从机理上理解了相干结构的气泡流动。(4)设计了另一种(传输)型光纤探头技术，通过在pH敏感的介质中应用激光诱导荧光来测量气泡或液滴周围的溶解浓度。将上述高速成像和探头技术相结合，现在有可能深入研究在湍流液体流动中上升的相互作用的气泡中溶解成分的弥散动力学。这个项目是朝着界面流动的动力学和传质之间的耦合迈出的第一步(但也是关键的)，并为更好地控制和理解这些复杂的现象提供了非常重要的发现。较少

With the two main objectives addressed in the present research project - (A) to clarify the relationship between bubble dynamics and gas-liquid mass transfer, and (B) to visualize the dispersive dynamics of dissolved component(s) the following achievements/findings have been made toward possible control of the interfacial mass transfer rate :(1) The dynamic process of gas dissolution from a CO_2-containing bubble into liquid, which represents an essential of the dissolving bubbly turbulent flow prevailing in the GLAD system, has been studied by continuously monitoring the bubble held in the liquid flowing downward. This visual study has been coupled with high-speed imaging for detailed observation of the bubble-surface motion.(2) Based on these visualization techniques established, it has been found that the fluctuating surface is viewed as a surface with propagating waves, and that the dissolution rate can be enhanced by such wavy fluctuations via the mechanism of reducing the surface … More renewal time.(3) A gas-dispersed system of controlled bubble size distribution has been devised to simulate the GLAD flow, in which a fiber-optic probes measurement technique also devised has been utilized to obtain statistic information on bubble dispersion under bubble-bubble interactions, toward mechanistic understanding of the coherently structured GLAD bubbly flow.(4) Another (transmitting) type of fiber-optic probe technique has been devised to measure the dissolved concentration around bubbles or droplets by applying laser-induced fluorescence with pH-sensitive agents.By combining the above high-speed imaging and probe techniques, it is now possible to investigate in depth the dispersive dynamics of the dissolved component from mutually interacting bubbles rising in turbulent liquid flow. This project has been an initiation (yet critical) step toward the coupling between these dynamics of interfacial flow and mass transfer, and has provided very important findings toward better control as well as under standing of such complex phenomena. Less