A new visual method for quantitative measurement of frothers effect and flotation efficiency was presented. A self-designed electrolytic cell was chosen as the reaction environment with sodium chloride (NaCl) as the e...A new visual method for quantitative measurement of frothers effect and flotation efficiency was presented. A self-designed electrolytic cell was chosen as the reaction environment with sodium chloride (NaCl) as the electrolyte. Constant current, supplied by a self-designed power supplier and fixed cathode and anode equipment, guaranteed the constant bubble volume per unit time. Even aperture of the cathode material guaranteed the original bubbles size to be uniform. Bubble generating equipment was connected with a microscopical camera. Statistic data collected by high speed charge-coupled device (CCD) and processed by software Sigmascan and Matlab could reflect bubble characteristics. The efficiency of dipropylene glycol monomethyl ether (DPM) and tripropylene glycol n-butyl ethel (TPnB) were measured at the same condition, and 2×10-4 mol/L and 5×10-2 mol/L were found to be the inflexions of bubble size changes.展开更多
The turbulence behavior of gas-liquid two-phase flow plays an important role in heat transfer and mass transfer in many chemical processes. In this work, a 2D particle image velocimetry (PIV) was used to investigate t...The turbulence behavior of gas-liquid two-phase flow plays an important role in heat transfer and mass transfer in many chemical processes. In this work, a 2D particle image velocimetry (PIV) was used to investigate the turbulent characteristic of fluid induced by a chain of bubbles rising in Newtonian and non-Newtonian fluids. The instantaneous flow field, turbulent kinetic energy (TKE) and TKE dissipation rate were measured. The results demonstrated that the TKE profiles were almost symmetrical along the column center and showed higher values in the central region of the column. The TKE was enhanced with the increase of gas flow and decrease of liquid viscosity. The maximum TKE dissipation rate appeared on both sides of the bubble chain, and increased with the increase of gas flow rate or liquid viscosity. These results provide an understanding for gas-liquid mass transfer in non-Newtonian fluids.展开更多
An experimental study was conducted to investigate the 2 D bubbly flow downstream of a cylinder. Sparsely distributed bubbles were produced using the ventilation method. The carrier flow was measured using the particl...An experimental study was conducted to investigate the 2 D bubbly flow downstream of a cylinder. Sparsely distributed bubbles were produced using the ventilation method. The carrier flow was measured using the particle image velocimetry(PIV) technique. The shadow imaging technique was used to capture instantaneous bubbly flow images. An image-processing code was compiled to identify bubbles in acquired image, calculate the bubble equivalent diameter and the bubble velocity. The effects of Reynolds number and the flow rate of the injected air were considered. The result indicates that the carrier flow is featured by distinct flow structures and the wake region is suppressed as the upstream velocity increases. Regarding the bubbles trapped in the wake flow, the number of small bubbles increases with the upstream velocity. On the whole, the bubble velocity is slightly lower than that of the carrier flow. The consistency between small bubbles and the carrier flow is high in terms of velocity magnitude, which is justified near the wake edge. The difference between the bubble velocity and the carrier flow velocity is remarkable near the wake centerline. For certain Reynolds number, with the increase in the air flow rate, the bubble equivalent diameter increases and the bubble void fraction is elevated.展开更多
基金Project(50834006) supported by National Natural of Science Foundation of China
文摘A new visual method for quantitative measurement of frothers effect and flotation efficiency was presented. A self-designed electrolytic cell was chosen as the reaction environment with sodium chloride (NaCl) as the electrolyte. Constant current, supplied by a self-designed power supplier and fixed cathode and anode equipment, guaranteed the constant bubble volume per unit time. Even aperture of the cathode material guaranteed the original bubbles size to be uniform. Bubble generating equipment was connected with a microscopical camera. Statistic data collected by high speed charge-coupled device (CCD) and processed by software Sigmascan and Matlab could reflect bubble characteristics. The efficiency of dipropylene glycol monomethyl ether (DPM) and tripropylene glycol n-butyl ethel (TPnB) were measured at the same condition, and 2×10-4 mol/L and 5×10-2 mol/L were found to be the inflexions of bubble size changes.
基金Supported by the National Natural Science Foundation of China (21076139)the Opening Project of State Key Laboratory of Chemical Engineering (SKL-ChE-08B03)the Program of Introducing Talents of Discipline to Universities (B06006)
文摘The turbulence behavior of gas-liquid two-phase flow plays an important role in heat transfer and mass transfer in many chemical processes. In this work, a 2D particle image velocimetry (PIV) was used to investigate the turbulent characteristic of fluid induced by a chain of bubbles rising in Newtonian and non-Newtonian fluids. The instantaneous flow field, turbulent kinetic energy (TKE) and TKE dissipation rate were measured. The results demonstrated that the TKE profiles were almost symmetrical along the column center and showed higher values in the central region of the column. The TKE was enhanced with the increase of gas flow and decrease of liquid viscosity. The maximum TKE dissipation rate appeared on both sides of the bubble chain, and increased with the increase of gas flow rate or liquid viscosity. These results provide an understanding for gas-liquid mass transfer in non-Newtonian fluids.
基金Supported by the National Natural Science Foundation of China(51676087)
文摘An experimental study was conducted to investigate the 2 D bubbly flow downstream of a cylinder. Sparsely distributed bubbles were produced using the ventilation method. The carrier flow was measured using the particle image velocimetry(PIV) technique. The shadow imaging technique was used to capture instantaneous bubbly flow images. An image-processing code was compiled to identify bubbles in acquired image, calculate the bubble equivalent diameter and the bubble velocity. The effects of Reynolds number and the flow rate of the injected air were considered. The result indicates that the carrier flow is featured by distinct flow structures and the wake region is suppressed as the upstream velocity increases. Regarding the bubbles trapped in the wake flow, the number of small bubbles increases with the upstream velocity. On the whole, the bubble velocity is slightly lower than that of the carrier flow. The consistency between small bubbles and the carrier flow is high in terms of velocity magnitude, which is justified near the wake edge. The difference between the bubble velocity and the carrier flow velocity is remarkable near the wake centerline. For certain Reynolds number, with the increase in the air flow rate, the bubble equivalent diameter increases and the bubble void fraction is elevated.
