Research and Development of Highly Efficient Sequestration System of CO_2 at the Deep Ocean Using Large-Scale Structure of Turbulent Bubbly Flows

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On the basis of experimental and numerical approaches to elucidate large-scale structure and multi-scale structure of the turbulent bubbly flows in a large-diameter pipe, we have obtained the following results on the characteristics of large-scale GLAD System (Gas Lift Advanced Dissolution System for CO_2) as well as its environmental and cost performance:1)ExperimentsWe have elucidated the large-scale structure of the turbulent bubbly flows in a turbulence water vessel using PIV (Particle Image Velocimetry), LDA (Laser Doppler Anemometer) and 4-Tip Optical-fiber Probe newly developed by our research group as follows:a)The turbulent bubbly flows have the large-scale structure by superimpose the buoyancy flow induced by the bubble swarms onto the large-scale structure of the liquid-phase single phase flow.b)The coupling mechanism between the interface motion of a member bubble of the swarms and the motion of its surrounding liquid have been elucidated form a viewpoint of the local-scale … More structure.c)The coupling mechanism between mass transfer and the interface motion of a CO_2 bubble have been elucidated.2)ModelingWe have established a model of the bubble swarm motipn considered the large-scale structure of the turbulent bubbly flows:a)The region of a surrounding liquid flow induced, by the buoyancy of an individual single bubble is of about two times of the bubble diameter.b)The flow of the upper side of the bubble swarm is well approximated by the surrounding liquid flow induced by the buoyancy of an individual single bubble.c)Characteristic frequency components is caused mainly by the interface motion of the bubble and the center-of-gravity motion of the bubble.3)Numerical simulationWe have analyzed the large-scale structure of the turbulent bubbly flows using both DNS and LES methods. On the basis of the numerical analysis, we have grasped characteristics of the GLAD system using improved DEM.4)Prototype systemWe have developed prototype GLAD system of 149 mm in pipe diameter and 40 m in height. We have confirmed the system performance, environmental acceptability and the cost. Furthermore, we demonstrated its pumping performance using the 200-m scale test facility of the GLAD system. Less