Expermental Investigation of Single Bubble Characteristics in a Cold Model of a Hall-Héroult Electrolytic Cell

Understanding the characteristics of the bubbles generated within a Hall-Héroult electrolytic cells, can assist greatly in the optimization and the operation of the process. One of the significant factors that greatly influence the bubbles formation is the vertical walls formed by the anodes. In this paper we used a high speed camera to investigate the effect of vertical walls on the shape of a single bubble rising in two liquids of high and low viscosity namely glycerol and water respectively under various offsets of the vertical wall and gas injection rates. The images of the bubble rising were recorded at the speed of 5000 frames per second and subsequently processed using the classical image-processing algorithms incorporated with MATLAB. The data related to various parameters such as aspect ratio, equivalent diameter of the bubble and bubble distance from the vertical wall are presented and discussed for various flow rate regimes. The findings showed that the presence of a vertical wall on one side of the bubble has a significant effect on the bubble shape, orientations and the trajectory path. In addition, it was found that as the bubble moved away from the wall, the velocity of the fluid between the bubble and the wall increased relative to the surrounding fluid, which created an asymmetric flow field around the bubble. Still the aspect ratios of the bubbles were found to be a function of the rate of gas injection as well as wall offset.