This experimental study describes the effect of the oscillating grid on hydrodynamics and mass transfer in an aquarium. The contribution of the two driving elements CO2 and oscillating grid is identified. Depending on the operating conditions, either these two effects add up and promote the circulation and transport of the liquid, or these effects are opposite, the liquid velocity is then reduced. On the other hand, with regard to gas-liquid mass transfer, the use of the grid is beneficial since, under certain operating conditions; the mass transfer coefficient is increased compared to that obtained without the grid. Analysis of the various energy contributions in the unit shows that the presence of the grid is justified only in cases where the CO2 flow rate must remain low. Flow characterization was performed using Particle Image Velocimetry (PIV) technique. The results were compared with previous studies. In order to perform the concentration field measurements by planar laser induced fluorescence (PLIF) technique and simultaneous PIV and PLIF measurements, the test bench was modified. The observations of velocity and concentration fields are in adequacy with the previous studies and allow to validate the bench. The necessary tools have been put in place, the study of mass transfer can continue.

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Bubble flows consist a liquid phase and a gaseous phase dispersed as bubbles. They occur in nature and in many industrial applications, such as oil transportation in pipelines and steam generators for power generation. Due to large difference in density between gas and liquid, the flottability force causes bubbles to rise, which in turn can generate overall motion and agitation in liquid. This use of gravity as a flow driver, which is specific to disperse phase systems, is used in process engineering (bubble columns and gasosiphon) to sparingly promote mixing and exchange between gas and liquid. In many applications, bubbles are used to agitate a liquid in order to promote mixing and transfers. This work is devoted to study of hydrodynamics of a bubble column. Experimentally, we have determined properties fluctuations of velocities inside the aquarium of rising homogeneous bubbles for different bubble sizes and vacuum rates. The interfacial area between gas and liquid phase is a crucial factor for mass transfer in bubble columns. The molecular exchange between a given volume of gas and water can be enhanced by formation of smaller bubbles, leading to a larger gas-liquid interface. This work presents the various physical phenomena that apply to bubbles, as well as associated dimensionless numbers. A state art of Micro-Bubble Generators (MBG) is then presented, presenting systems using various phenomena such as cavitation, electrolysis, or shear.