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Go to Editorial ManagerThe impact of flow velocity (0-900 rpm) on the corrosion rate of carbon steel in a wide range of sulfuric acid concentrations (0-90% in H2O) at 30 °C and 1 h was studied and discussed. In addition, the efficiency of corrosion inhibitor (dimethyl disulfide, DMD) was evaluated in hardest corrosion conditions for the range of velocity investigated. The results revealed that increasing the flow velocity of H2SO4 solution, increases the corrosion rate depending on the acid concentration. When the flow velocity is increased of H2SO4 solution, the corrosion potential was shifted to more negative. The DMD inhibitors showed significant inhibition efficiency at high velocities, where the highest percentage of inhibitor efficiency reached 98% at 900 rpm.
The hydrodynamics of stirred tanks and bubble breakup are crucial in gas-liquid flows, yet this system has not been well characterized for different operating conditions. In this work, the numerical method was used to investigate the hydrodynamics of six- flat blades impeller (Rushton turbine) and the results were employed to understand the bubble breakup behavior in the stirred tank. Simulation results of predicted flow pattern, power number, and the distribution of turbulence energy generated were performed with COMSOL Multiphysics. Numerical results showed good agreement with the experimental literature. The effect of rotational speed on bubble breakup behavior, such as breakage probability, the average number of daughter bubbles, and the breakage time was investigated using the high-speed imaging method. The main finding is that the breakage process occurs in the high energy area of high turbulence intensity, which is located within a distance equal to the blade width of a radius of (15-35 mm). The breakage probability (Bp) was found to be increased by 12.61 percent for a mother bubble of 4 mm at 340 rpm, with an average fragmentation of up to 22 fragments. Furthermore, the bubble breakage time was found to decrease with increasing impeller rotational speed, with an average value of 19.8 ms.
The breakage rate of liquid drops in the dispersed phase is a key way to improve the heat and mass transfer between the continuous/dispersed phases. This work includes a review of experimental results of liquid drop breakage in an agitated tank. The study highlighted the experimental conditions that were investigated as well as the important findings about the impact of operating conditions on some breakup parameters. The conflicts and discrepancies in the findings of those studies were identified and analyzed. The review found that many experimental parameters affect the drop breakage rate. The breakage probability (BP), number of fragments, and breakage time (BT) are direct functions of power input.