The Bubble Shape in Contaminated Bubbly Flows: Results for Different NaCl Concentrations in Purified Water

Abstract

Abstract:The bubble shape influences the transfer of momentum and heat/mass between the bubble and the surrounding fluid as well as the flow field around the bubble. The shape is determined by the interaction of the fluid field in the bubble, the physics on the surface, and the surrounding flow field. It is well known that contaminations can disturb the surface physics so that the bubble shape can be influenced. Indeed, an influence of sodium chloride (NaCl) on the hydrodynamics of bubbly flows was shown for air/water systems in previous studies. The aim of the present work is to investigate if, and to what extent, the NaCl concentration affects the bubble shape in bubble columns. For this purpose, several experiments at the Helmholtz-Zentrum Dresden-Rossendorf and at the pilot-scale bubble column at the Politecnico di Milano are evaluated. The experiments were executed independently from each other and were evaluated with different methods. All experiments show that the bubble shape is not distinctly affected in the examined concentration range from 0 to 1 M NaCl, which is in contrast to a previous study on single bubbles. Therefore, the effect of NaCl on the hydrodynamics of bubbly flows is not induced by the bubble shape.

A study of bubble size/shape evolution in microbubble countercurrent contacting flotation column

“…Figure 11 shows the predicted values of Equations () and () for each set of aspect ratio data. It can be seen from the figure that the two equations had good predictions for aspect ratio data of Liu et al, 12 Besagni and Inzoli., 24 Ziegenhein and Lucas, 33 and Ziegenhein et al, 34 which were in line with the current 20% error range. By adding GE609 to change the air–liquid surface properties, Work 2–5 recorded the bubble aspect ratios at 0, 0.0118, 0.0353, 0.0471, and 0.0588 mol/m 3 , respectively.…”

“…Many attempts have been made in the papers to correlate the aspect ratio as a function of dimensionless parameters 23,24,33–38 . These works included the single bubble and group bubbles in the multiple systems of the pure water system.…”

The Effect of Hydraulic Conditions in Barbotage Reactors on Aeration Efficiency

“…In view of the free inflow of water into the airlift, the inlet was mounted 22 cm above the tank bottom. The airlift was fed by two membrane blowers (1) arranged in a serial connection and equipped with a release valve (3) and a valve regulating the intensity of air inflow supplied to the installation (2). The amount of supplied air Q p was measured using a cone-and-float rotameter (4) and determined at the required level using valves (2,3).…”

“…The airlift was fed by two membrane blowers (1) arranged in a serial connection and equipped with a release valve (3) and a valve regulating the intensity of air inflow supplied to the installation (2). The amount of supplied air Q p was measured using a cone-and-float rotameter (4) and determined at the required level using valves (2,3). The water level in the tank was measured using an analog measuring rod (5) and a hydrostatic liquid level probe coupled with a microcontroller (10).…”

“…Various factors influence water aeration processes, both directly and indirectly. Oxygen solubility in water depends mainly on water temperature and the intensity of mixing, rather than atmospheric pressure and salinity [1][2][3]. An increase in water temperature causes a significant decrease in the amount of oxygen dissolved in water.…”