Average Bubble Diameter Research Articles

Effect of Fine Bubbles on Removal of Linear Alkyl Benzene Sulfonate Surfactant during the Rinsing Stage of Laundry Washing

AbstractThe use of fine bubbles is a promising approach to remove surfactant efficiently during the rinsing process of clothing, to fulfill a requirement. Therefore, the influence of fine bubbles on the removal performance of surfactant from cloth during the rinse process of pulsator washing machine (top loading type) was investigated. The test apparatus was assembled by connecting a microbubble generation tank and a small washing machine with tubes and circulating fine bubble water to a small washing machine. Swatches of cloth with a specified amount of linear alkylbenzene sulfonate (LAS) adsorbed from aqueous solution, were rinsed with tap water, and the LAS concentration in the rinse water was examined with an HPLC system equipped with a high‐precision fluorescence detector. The average bubble diameter of the fine bubble water used was 0.13–1.4 μm. In the rinsing experiment, no difference was found in the final LAS removal efficiency between water with and without bubbles; but the former increased the LAS removal rate during the initial stage of rinsing. This tendency was particularly noticeable when the stirring power of the washing machine was weak. Therefore, it was concluded that the fine bubble effect on the removal of the surfactant is mainly a kinetic effect rather than an equilibrium effect.

Numerical Simulation of Gas–Liquid Two-Phase Flow Characteristics of Centrifugal Pump Based on the CFD–PBM

This work seeks to apply the computational fluid dynamics–population balance model (CFD–PBM) to investigate the gas distribution and flow mechanism in the gas–liquid two-phase flow of a centrifugal pump. The findings show that the numerical simulation accurately captures the bubble distribution characteristics in the process of coalescence and breakage evolution. In addition, comparing the CFD–PBM with the Double Euler, the hydraulic head of the pump are similar, but the efficiency using the Double Euler is much higher—even close to single-phase. This is in contrast to previous experimental research. Then, the unsteady flow usually led to the formation of bubbles with larger diameters especially where vortices existed. In addition, the rotor–stator interaction was a main reason for bubble formation. Generally, it was observed that the coalescence rate was greater than the breakage rate; thus, the coalescence rate decreased until it equaled the breakage rate. Thereafter, the average diameter of the bubble in each part tended to be stable during the process of bubble evolution. Finally, the average diameter of bubbles seemed to increase from inlet to outlet. The results of this study may not only enhance the gas–liquid two-phase internal flow theory of centrifugal pumps, but also can serve as a benchmark for optimizations of reliable operation of hydraulic pumps under gas–liquid two-phase flow conditions.

Effect of size variation on microbubble mass transfer coefficient in flotation and aeration processes

Microbubble technology dramatically raises the efficiency of the flotation and aeration processes of water treatment plants (WTPs), which see extensive use in developed countries. A local institution, Indonesia Water Institute, has tried to investigate microbubble technology intended for lab-scale WTP. However, the current reactor system does not yet meet the microbubble criteria, especially as it has had few investigations of its abilities in flotation and aeration. This study aims to analyze the effect of size variations that affect the rising velocity and mass transfer coefficient (kLa) of aeration contact time. Three local spargers were used to produce microbubbles. Bubble diameters were measured optically and analyzed using ImageJ software. The dissolved oxygen (DO) concentration was measured every minute using an automated sensor so that the kLa could be determined. Of the three spargers, the smallest bubble size was produced by the vortex type with an average bubble diameter of 89 μm and the slowest rising velocity of 17.67 m/h. It also yielded the highest kLa of 0.297/min, which gave an aeration contact time of 3.64 minutes. The experimental uses of three local spargers revealed that the smaller the microbubble diameter, the higher the mass transfer coefficient in flotation and aeration processes. This research can be the basis for developing microbubble technology for WTP in Indonesia.

On the prediction of gas hold‐up in two‐phase flow systems using an Euler–Euler model

AbstractWe quantify the ability of the two‐fluid Euler–Euler model to predict the overall gas hold‐up during two‐phase flow in vertical columns using a combination of experiments and simulations. Gas hold‐up in a bubble column and gas hold‐up in the less‐frequently studied co‐current flow are investigated. For homogeneous flow characterized by nearly uniform bubble size, Euler–Euler model predictions are within 10% of the experimental values for both modes of operation, if the bubble diameter supplied as input to the model is the average bubble diameter in the physical system. This also holds true for heterogeneous flow in bubble columns despite the presence of a broad distribution of bubble sizes, if turbulence and bubble swarm effects on momentum exchange between phases are properly accounted for. Swarm corrections adequate for bubble columns, are less successful for co‐current heterogeneous flow, for which gas hold‐up predictions are least accurate (average error of 22%).

Using Time-Series Videos to Quantify Methane Bubbles Flux from Natural Cold Seeps in the South China Sea

Natural cold seeps are an important source of methane and other greenhouse gases to the ocean and atmosphere in the marine environment. Accurate quantification of methane bubble fluxes from cold seeps is vital for evaluating their influence on the global methane budget and climate change. We quantified the flux of gas bubbles released from two natural cold seep sites in the South China Sea: one seep vent in the Haima cold seeps (1400 m depth) and three seep vents at Site F (1200 m depth). We determined bubble diameter, size distribution, and bubble release rate using image processing techniques and a semiautomatic bubble-counting algorithm. The bubble size distributions fit well to log-normal distribution, with median bubble diameters between 2.54 mm and 6.17 mm. The average bubble diameters and release rates (4.8–26.1 bubbles s−1) in Site F was lower than that in Haima cold seeps (22.6 bubbles s−1), which may be attributed to a variety of factors such as the nature of the gas reservoir, hydrostatic pressure, migration pathways in the sediments, and pore size. The methane fluxes emitted at Haima cold seeps (12.6 L h−1) and at Site F (4.9 L h−1) indicate that the Haima and Site F cold seeps in the South China Sea may be a source of methane to the ocean. However, temporal variations in the bubble release rate and the geochemical characteristics of the seeps were not constrained in this study due to the short observational time interval.

旋回流式マイクロバブル発生器の性能向上（テーパ型渦流室出口形状による微細化効果）

Recently, the micro bubble with bubble diameter of less than 50μm is paid to attention. As for this micro bubble, various characteristics that bubble with diameter of several mm doesn’t have are possessed. For instance, water purification, oil separating, growth promotion of creature, and reduction of frictional resistance are reported. The swirl type method, the pressurizing dissolution method, and the perforated plate method, etc. are proposed as the method for generation of micro bubble. The swirl type method can comparatively generate the micro bubble even by low-pressure power in simple structure. In this present study, the effect of shape of swirl chamber on bubble diameter was examined by using the three kinds of shape of swirl type micro bubble generators, which were cylindrical type, taper type, and improved taper type. As a result, it was found to be able to reduce the bubble diameter in the order of improved taper type, taper type, and cylindrical type. And it was clarified that radial outflow type generator could make bubble diameter small compared with axial outflow type generator, and the optimum nozzle shape was the nozzle with inlet angle of 45 degrees, outlet angle of 60 degrees, and nozzle diameter of 3mm. Moreover, it was found that the average bubble diameter of 30μm was obtained under pressure condition of 0.22MPaG in the above-mentioned nozzle shape.

Three-dimensional measurement of bubble in gas-liquid flow by light field photography

A three-dimensional measurement method for bubble parameters in gas-liquid two-phase flow was proposed based on the light field photography for solving the problem that bubble parameters could only be measured in two-dimensional problems using conventional photography. The light field camera recorded the light field information of the gas-liquid two-phase flow, and then the total focus image and the refocused images of the bubbles in the two-phase flow field were obtained using a computational imaging technique. The image processing was performed by binarizing the total focus image to obtain the projection of bubbles in the depth direction and evaluating the sharpness of refocused images to obtain the depth of bubbles. Based on the bubble projection and depth information, the three-dimensional reconstruction of the bubbles was achieved, and the parameters, such as size distribution, spatial position and gas void fraction of bubbles were further calculated. The calibration and the experiment were made to evaluate the proposed method. Experimental results show that the cross-sectional void fraction in the depth direction is in agreement with the bubble depth distribution and oscillates periodically in the vertical direction. With the increase of gas flow rates from 0.5 L/min to 1.1 L/min, the amount of bubbles increases from 28 to 72; the average diameter of bubbles maintains about 1.56 mm before the gas flow rate reaches 0.9 L/min, after increasing sharply; the gas volume fraction rises approximately linearly, and the bubble depth interval increases gradually. The three-dimensional reconstruction results of bubbles are in good agreement with the law of bubble formation and distribution, thus verifying the feasibility of the proposed method.

Hydrodynamics and Mass Transfer at the Vortex Stage and during Bubbling

Vortex contact devices for gas introduction have been developed and studied. The devices make it possible to increase the gas and liquid loading on stages compared with valve and cap devices, to reduce the fluctuations of the gas–liquid medium on the liquid surface, and to increase the separation efficiency. Based on the experimental studies and numerical modeling, a scheme of liquid and gas motion at the stage was developed, and the velocity profiles during bubbling were calculated. The stage parameters were determined: hydraulic resistance, gas content, average surface diameter of bubbles, interphase surface area, efficiency, and mass transfer coefficients. The dependences for their calculation were presented. A vortex stage for the exhausting distillation column was designed, which provides a 1.5-fold reduction of metal consumption and increased efficiency at a velocity factor of up to 3 Pa0.5 and spray rate of 78 m3/(h m2) compared with the standard cap plate.

Gas-liquid flow characteristics variation along inclined flat channel

The results of an experimental study of bubble diameters variation with distance from the point of gas injection in an upward bubble flow in an inclined flat channel are presented. The measurements were carried out for a superficial fluid velocity of 0.51 m/s (Re=12400) and at various values of the gas flow rate ratio. It is shown that at small values of the gas flow rate ratio (β <2%), the coalescence of bubbles is practically absent, therefore the angle of inclination of the channel and the distance from the point of introduction of gas into the liquid flow do not affect the average diameter of gas bubbles.

Investigation of particle agglomeration with in-situ generation of oxygen bubble during the tungsten chemical mechanical polishing (CMP) process

This research investigates abrasive particles agglomeration via interaction between O2 bubbles and slurry abrasives during the tungsten chemical mechanical polishing (W CMP) process. The abrasive particles in slurry were highly agglomerated due to higher volumes of O2 bubbles produced in the reaction between the catalyst Fe(NO3)3 and the oxidizer H2O2. Results obtained from a gas pressure sensor confirmed the generation of higher O2 volume via the decomposition of H2O2 at a high catalyst concentration and an increase in reaction temperature. The decomposed O2 volume rate at 80 °C was reported at the maximum value of 2.0 × 10−2 L/s at 120 ppm as compared to the moderate and minimum rates of 3.5 × 10−3 and 3.2 × 10−4 L/s for catalyst concentrations of 60 and 30 ppm, respectively. Images of O2 bubbles, captured using a high-speed camera, exhibited subsequent enhancement in average O2 bubble diameters of 91, 427, and 503 μm at 25, 60, and 80 °C, respectively. Analysis of surface scans confirmed large abrasive particles contamination on the TEOS wafer with an increase in the O2 bubble flow rate and bubbling time. Also, large abrasive particles agglomeration was observed in the presence of O2 bubbles as compared to no bubbles, as measured by dynamic light scattering DLS. It is believed that higher hydrophilicity of abrasive particles with O2 bubbles increased the adhesive force between the abrasive particles and the in-situ generated O2 bubbles. The high drag force generated during the collapse of O2 bubbles is essentially attributed a strong attractive force between the abrasive particles and the TEOS wafer which strongly binds with the abrasive particles and intensifies the defect level as particle agglomeration.

Influence of Newtonian and non-Newtonian fluid behaviour on void fraction and bubble size for a gas-liquid flow of sub-millimeter bubbles at low void fractions

This study compares the effect of Newtonian and non-Newtonian blood-mimicking test liquids on void fraction and bubble size distribution (BSD) for the case of gas–liquid bubbly flow. Along with this comparison, the novelty of the present work is extended to the examined conditions, which combine low void fractions (<10−1) with bubbles smaller than 1 mm, resembling bubbly flow in human bloodstream during Decompression Sickness. Such conditions, however, can be also found in common two-phase applications such as subcooled flow boiling in macro-channels. Experiments are performed in co-current upward bubbly flow. Void fraction and BSD are determined by a non-intrusive electrical impedance technique and by image analysis of bubbly flow images, respectively. Xanthan gum is employed (0, 150 and 1000 ppm) to impart non-Newtonian (shear-thinning) behaviour to the baseline aqueous glycerol/NaCl test liquid. The role of surface tension (by adding Triton X-100) and gas/liquid superficial velocities (Usg, Usl) on acquired data is studied as well. Results demonstrate that increase of bubble size and decrease of void fraction is primarily due to the non-Newtonian liquid character rather than the increase of dynamic viscosity caused by the addition of high Xanthan gum concentration. The addition of surfactant (Triton X-100) decreases bubble size and increases void fraction. Furthermore, bubble size and void fraction increase with Usg and decrease with Usl. Void fraction signal fluctuations show a strong dependence on bubble size. Furthermore, the performance of an empirical equation that predicts average bubble diameter from void fraction statistical quantities is tested and seems to be unaffected by the Newtonian/non-Newtonian liquid behaviour. Of particular interest are the intense peaks noticed in void fraction signals for the highest examined Xanthan gum concentration (1000 ppm) and the lowest examined liquid superficial velocity (2.89 cm/s). These peaks correspond to voluminous bubbles clusters rising among isolated bubbles, which do not appear at higher liquid velocities.

Dimensional Analysis of Average Bubble Diameter in Desulfurization of Hot Metal

Dimensional Analysis of Average Bubble Diameter in Desulfurization of Hot Metal

The importance of pore throats in controlling the permeability of magmatic foams

Vesiculation of hydrous melts at 1 atm was studied in situ by synchrotron X-ray tomographic microscopy at the TOMCAT beamline of the Swiss Light Source (Villigen, Switzerland). Water-undersaturated basaltic, andesitic, trachyandesitic, and dacitic glasses were synthesized at high pressures and then laser heated at 1 atm. on the beamline, causing vesiculation. The porosity, bubble number density, size distributions of bubbles, and pore throats, as well as their tortuosity and connectivity, were measured in three-dimensional tomographic reconstructions of sample volumes, which were also used for lattice Boltzmann simulations of viscous permeabilities. Connectivity of bubbles by pore throats varied from ~ 100 to 105 mm−3, and for each sample correlated with porosity and permeability. Consideration of the results of this and previous studies of the viscous permeabilities of aphyric and crystal-poor magmatic samples demonstrated that at similar porosities permeability can vary by orders of magnitude, even for similar compositions. Comparison of the permeability relationships from this study with previous models (Degruyter et al., Bull Vulcanol 72:63–74, 2010; Burgisser et al., Earth Planet Sci Lett 470:37–47, 2017) relating porosity, characteristic pore-throat diameters, and tortuosity demonstrated good agreement. Modifying the Burgisser et al. model by using the maximum pore-throat diameter, instead of the average diameter, as the characteristic diameter reproduced the lattice Boltzmann permeabilities to within 1 order of magnitude. Correlations between average bubble diameters and maximum pore-throat diameters, and between porosity and tortuosity, in our experiments produced relationships that allow application of the modified Burgisser et al. model to predict permeability based only upon the average bubble diameter and porosity. These experimental results are consistent with previous studies suggesting that increasing bubble growth rates result in decreasing permeability of equivalent porosity foams. This effect of growth rate substantially contributes to the multiple orders of magnitude variations in the permeabilities of vesicular magmas at similar porosities.

Convective Bubbly Flow of Water in an Annular Pipe: Role of Total Dissolved Solids on Heat Transfer Characteristics and Bubble Formation

Formation of bubbles in water inside an annulus pipe in a flow boiling regime was experimentally investigated. The effect of various variables, such as total dissolved solid materials (TDS) in terms of mass fraction, flow rate of water, and applied heat flux (HF) on the heat transfer coefficient (HTC) and bubble behavior of water, was experimentally investigated. A regression formula was fitted to estimate the average bubble diameter at various TDS values, with accuracy of &lt;4.1% up to heat flux of 90 kW/m2. Results show that the presence of TDS materials can increase the contact angle of bubble and bubble diameter, and also promotes the HTC value of the system. However, flow rate of water suppressed bubble generation, and increased the heat transfer coefficient due to the renewal of the thermal boundary layer around the boiling surface. Likewise, it was identified that forced convective and nucleate boiling heat transfer mechanisms contribute to the flow of boiling water, and heat flux is a key parameter in determining the mechanism of heat transfer. In the present study, heat flux of 15 kW/m2 at 50 °C was the heat flux in which onset of nucleate boiling was identified inside the annulus pipe. The contact angle of water at TDS values of 300 mg/L and 1200 mg/L was 74° and 124°, respectively, showing the improvement in heat transfer characteristics of water due to the presence of TDS materials.

A novel jet-aerated tangential swirling-flow plate photobioreactor generates microbubbles that enhance mass transfer and improve microalgal growth

To reduce bubble diameter and enhance mass transfer, a novel jet-aerated tangential swirling-flow plate photobioreactor was developed that improves the growth rate of microalgae. In this system, the circulating microalgal solution enters a jet aerator that takes up 15% CO2 by vacuum suction and then injects into a plate photobioreactor through four centrally symmetric nozzles. Each jetflow is tangent to a tangential circle, driving vertical vortex movement of the surrounding microalgal solution, which markedly reduced the bubble diameter and enhanced mass transfer. The mass transfer coefficient was enhanced by decreasing the nozzle number (n) and increasing the ratio of tangential circle diameter to plate photobioreactor equivalent diameter (d/D). The average bubble diameter decreased by 80.2% to 0.37 mm and the mass transfer coefficient increased 4.6 times to 48.9 h−1 when n was 4 and d/D was 0.34. Finally, the optimized system increased the biomass dry weight of microalgae by 49.4%.

Experimental study on the microscopic characteristics of foams stabilized by viscoelastic surfactant and nanoparticles

Viscoelastic surfactant and nanoparticles have gained significant attention in the development of foamed fracturing fluid. In this article, the microscopic characteristics of foams stabilized by viscoelastic surfactant (EAPB) and nanoparticles (SiO2) at different temperature were investigated. By analyzing the bubble images taken from optical microscope, it is concluded that there was synergistic effect between elongated wormlike micelles and nanoparticles to stabilize foams which was indicated by large bubble number, small average bubble diameter and spherical shape of bubbles over time. Results showed that although temperature played a vital role on the acceleration of drainage rate and Ostwald ripening rate, this acceleration would be weakened by applying viscoelastic surfactant and nanoparticles together. Two calculation methods that are polydispersity based on statistic data and fractal theory based on box counting method were proposed to investigate the bubble size distribution and bubble structure. The small value of polydispersity and fractal dimension of the foams stabilized by 3% EAPB and 1% SiO2 demonstrated the relatively uniform bubble size distribution and regular bubble structure. Lastly, cryo-SEM was applied to observe the bubble morphology at microscopic scale, which showed the intense and compact bubble structure due to the formation of particle-micelle network. This study provides the workflow for the analysis of foams at microscopic scale and broadens the application of foamed fracturing fluid in the development of unconventional resources.

Пенообразующие свойства концентрата белков обезжиренного молока

Aerated products are popular all over the world, especially those with a foam structure. They are widely represented in the range of the global food market, including that of the Russian Federation. Traditionally, milk proteins are added to stabilize various foods. The present research explains how the concentration of skimmed milk proteins affects the foaming properties of concentrates. The experiment featured the influence of various protein concentrations (from 3.4 to 16.0%) on the foaming properties of reduced skim milk (9.2%) and of milk protein concentrates obtained by ultrafiltration. The research established their practical application for aerated products. The quality of protein foam was evaluated by foaming characteristics and foam stability. The distribution of protein foam bubbles by size was modelled using Erlang distribution. According to the simulation, the foams of protein solutions with a concentration of 12% were more stable. Concentrates with the highest protein content (16%) had not only a greater foaming, but also a greater stabilizing property. The protein samples density increased together with protein concentration. Similarly, the foaming characteristics of protein solutions (multiplicity and density of the foam) increased together with protein concentration. The stability of the foam structure was estimated by the half-life of the foam volume and the average diameter of the foam bubbles in the protein solutions. The most stable foams were those with the highest protein content in the concentrate. The protein concentrates from reduced skim milk were inferior in foaming characteristics to concentrates from milk that was not subjected to drying. However, the results suggest that the reduced skim milk and its protein concentrates are ideal for the production of aerated dairy products because they provide both good foaming and stability.

Hydrodynamic characteristics of the microbubble dissolution in liquid using orifice type microbubble generator

The aim of this work was to investigate the characteristics of oxygen dissolution into water in aeration using an orifice type microbubble generator (MBG). The analysis was conducted using dimensional analysis by taking into account bubble diameter distribution and oxygen mass transfer rate. The characteristics of microbubbles produced by MBG were affected by the combination of air and water flow rates through the MBG. In this study, the ranges of air and water flow rates were set at 0.1–1.0l/min and 30.0–80.0l/min, respectively. The microbubbles were captured by a high-speed camera using shadow photographic technique to obtain the bubbles size distribution as well as the average diameter of the bubbles. The volumetric mass transfer coefficient of oxygen was measured using dynamic physical absorption model.The results verified that the size of microbubble depend on air and water flow rates. The increase of the gas flow rate increased the average bubble diameter. On the other hand, the increase of the water flow rate decreased the average bubble diameter. Furthermore, the increase of water flow rate increased the oxygen volumetric mass transfer coefficient. Finally, by using dimensional analysis, the empirical correlation of volumetric mass transfer coefficient, average bubble diameter, and bubble diameter distribution, was proposed. The correlation showed that liquid Reynolds number played most important role in average bubble diameter and oxygen mass transfer rate obtained in MBG aeration.

Promoting Photochemical Efficiency of Chlorella PY-ZU1 with Enhanced Velocity Field and Turbulent Kinetics in a Novel Tangential Spiral-Flow Column Photobioreactor

A novel tangential spiral-flow column photobioreactor (TSCP) was developed to strengthen the velocity field and turbulent kinetics for improving CO2 fixation with microalgae. Microalgal solution was injected into a column photobioreactor from four symmetrically arranged nozzles, whose central axes had 10°-included angles with the radius. The injection solution streamline formed a tangential swirling circle, thereby driving the surrounding solution to spirally flow upward. This flow pattern was determined via computational fluid dynamics simulation and a miniature Doppler velocimeter. The optimal structural and operational parameters were determined as follows: relative diameter of imaginary tangential circle = 0.3, nozzles number = 4, and injection solution velocity = 1.33 m/s. The average turbulent kinetic energy, bubble diameter, and actual photochemical efficiency in TSCP were 15% higher, 47% lower, and 19% higher than those in the bubble column photobioreactor (BCP), respectively. Therefore, the micro...

Effect of surfactant concentration on foam texture and flow characteristics in porous media

Foam has been widely used for profile control, water plugging, and gas channeling control in enhanced oil recovery (EOR). Because of absorption, the surfactant concentration in foam decreases along the flow direction. In this study, the effects of surfactant concentration on the foam texture, foam seepage characteristics, and gas saturation were evaluated by core-flow experiments using a high-pressure visualization device. The results show that the surface tension of gas and liquid decreases, the flow resistance in core increases, and the foam takes a longer time to reach stability with the increase in concentration of foaming agent. The blocking capability of foam in porous media is closely related to foam texture. With the increase in surfactant concentration, the average diameter of bubbles in porous media decreases, and the bubbles are more uniform. Moreover, the diameter of bubbles is closer to the average pore diameter of core. Clearly, the diameter matching degree of the maximum distribution frequency of bubbles and the average pore diameter of core increase. Therefore, the blocking capability of foam becomes stronger. With the increase in surfactant concentration, the proportion of trapped gas in porous media increases, the gas saturation in core increases, and the flow resistance of foam increases. However, when the surfactant concentration reaches the critical value, the increasing amplitude of gas saturation decreases. Under an injected foam quality of 50%, the gas saturation is more than 80%. The research results can help to analyze the change along the channel of foam flow in formation and are of great significance to improve the effect of foam application.