Average Bubble Diameter Research Articles

Strengthening H2 gas-liquid mass transfer using superaerophobic cathodes for enhanced methane production from CO2 in H2-mediated microbial electrosynthesis system.

H2-mediated microbial electrosynthesis (MES) could run under a high current density, but the low solubility of H2 limited its performance. Reducing the H2 bubble size facilitates H2 gas-liquid mass transfer and it has been reported to be realized on superaerophobic electrodes. Therefore, we adopted a CoP nanowire-modified nickel foam (CoP-NiF) as the superaerophobic cathode in a H2-mediated MES reactor to enhance the methane production from CO2. The CoP nanowire modification reduced the average diameter of H2 bubbles from∼300 μm to∼100μm, thereby exhibiting a 129% enhancement of the H2 mass transfer coefficient (KLa=0.32min-1). The maximum CH4 production rate with CoP-NiF cathode exhibited a 27% improvement (2.31 L/L/d) at a high current density of 166.67 A/m2. More importantly, a coulombic efficiency higher than 80% was achieved in the reactor. These results demonstrated that using superaerophobic cathodes is an efficient way to enhance the performance of H2-mediated MES reactors.

Влияние сквашенной молочной основы на показатели качества мороженого и кисломолочных взбитых десертов

Fermented ice-cream and dairy desserts are a healthy alternative to traditional sweets. However, the fermented milk base may affect the quality of high-fat ice-cream and frozen or defrosted whipped fermented desserts. In this study, adding 30% yogurt to the traditional ice cream with 12% fat led to a marginal decrease in the dispersion of air phase and ice crystals. In addition, the permissible anisidine value was reached twice as fast as in the control sample. The experimental fermented desserts demonstrated an increase in such consistency indices as dynamic viscosity (50 times), hardness (1.7 times), apparent module (2 times), and stickiness (11.5 times). The defrosted fermented desserts showed a better air-phase dispersion after 6 h of storage. The average diameter of air bubbles in the fermented milk desserts was 1.5 times as small as in milk after 24 h. The fermented milk base proved commercially feasible for ice-cream and ice-cream desserts. However, producers have to consider its effect on the consistency, dispersion, and fat oxidation. Further research will feature the effect of fat mass fraction, acidity, and overrun on the fat-phase oxidation in ice-cream and whipped desserts.

The Influence and Mechanism of Polyvinyl Alcohol Fiber on the Mechanical Properties and Durability of High-Performance Shotcrete

This study investigates the impact of polyvinyl alcohol (PVA) fibers on the mechanical properties and durability of high-performance shotcrete (HPS). Results demonstrate that PVA fibers have a dual impact on the performance of HPS. Positively, PVA fibers enhance the tensile strength and toughness of shotcrete due to their intrinsic high tensile strength and fiber-bridging effect, which significantly improves the material’s splitting tensile strength, deformation resistance, and toughness, and the splitting tensile strength and peak strain have been found to be increased by up to 30.77% and 31.51%, respectively. On the other hand, the random distribution and potential agglomeration of PVA fibers within the HPS matrix can lead to increased air-void formations. This phenomenon raises the volume content of large bubbles and increases the average bubble area and diameter, thereby elevating the pore volume fraction within the 500–1200 μm and >1200 μm ranges. Therefore, these microstructural changes reduce the compactness of the HPS matrix, resulting in a decrease in compressive strength and elastic modulus. The compressive strength exhibited a reduction ranging from 10.44% to 15.11%, while the elastic modulus showed a decrease of between 8.09% and 12.67%. Overall, the PVA-HPS mixtures with different mix proportions demonstrated excellent frost resistance, chloride ion penetration resistance, and carbonation resistance. The electrical charge passed ranged from 133 to 370 C, and the carbonation depth varied between 2.04 and 6.12 mm. Although the incorporation of PVA fibers reduced the permeability and carbonation resistance of shotcrete, it significantly mitigated the loss of tensile strength during freeze–thaw cycles. The findings offer insights into optimizing the use of PVA fibers in HPS applications, balancing enhancements in tensile properties with potential impacts on compressive performance.

Relation between bubble behaviors in spray sheet and bubbly flow inside an air-induction fan nozzle: A visualization study

The present study aims to elucidate the relationship between bubble behaviors in the spray sheet and internal bubbly flow of the air-induction nozzle. An experimental work was performed using the visualization technique. Effects of the air inlet position and spray pressure were investigated. The results show that compared with the bubbles inside the air-induction nozzle, bubbles in the spray sheet have smaller volume but larger average diameter. Disturbance propagates in the horizontal air-inlet segment. When the air inlet position shifts toward the nozzle outlet, overall bubble volume inside the nozzle decreases by about 56%, while in the spray sheet, the bubble volume decreases by about 77%. Bubble breakup causes a decrease in overall bubble volume as bubbles travel from the inner flow passage of the nozzle to the environment. The coalescence and compression of bubbles induce the increase in average bubble diameter. When the spray pressure increases from 0.1 to 0.3 MPa, both the total bubble volume and average bubble diameter increase.

Carbon dioxide stripping from acidic wastewater through a vortex venturi tubular microbubble generator

Carbon dioxide stripping from acidic wastewater through a vortex venturi tubular microbubble generator

Evolution and stability of bubbles in cement-based materials under low air pressure: A Theoretical and experimental Study

Evolution and stability of bubbles in cement-based materials under low air pressure: A Theoretical and experimental Study

Effects of non-isothermal annealing on the microstructure of pure and potassium-doped tungsten sheets

Effects of non-isothermal annealing on the microstructure of pure and potassium-doped tungsten sheets

Mass transfer enhancement and flow field simulations for a Venturi bubble generator with multiple inlet tubes

Mass transfer enhancement and flow field simulations for a Venturi bubble generator with multiple inlet tubes

Adsorption Layer Properties and Foam Behavior of Aqueous Solutions of Whey Protein Isolate (WPI) Modified by Vacuum Cold Plasma (VCP)

For years, cold plasma processing has been used as a non-thermal technology in industries such as food. As interfacial properties of protein play a remarkable role in many processes, this study investigates the effect of cold plasma on the foaming and interfacial behavior of WPI. The objective of this study is to evaluate the effect of different gases (air, 1:1 argon–air mixture, and sulfur hexafluoride (SF6)) used in low-pressure cold plasma (VCP) treatments of whey protein isolate (WPI) on the surface and foaming behavior of aqueous WPI solutions. Dynamic surface dilational elasticity, surface tension isotherms, surface layer thickness, and the foamability and foam stability were investigated in this study. VCP treatment did not significantly affect the adsorption layer thickness. However, an increase in induction time, surface pressure equilibrium value, and aggregated size is observed after SF6VCP treatment, which can be attributed to the reaction of WPI with the reactive SF6 species of the cold plasma. The surface dilational elastic modulus increased after VCP treatment, which can be related to the increased mechanical strength of the protein layer via sulfonation and aggregate formation. VCP treatment of WPI increases the foam stability, while the average diameter of foam bubbles and liquid drainage in the foam depends on the gas used for the cold plasma.

Quantifying the chemical activity of cavitation bubbles in a cluster.

Acoustic cavitation bubbles drive chemical processes through their dynamic lifecycle in liquids. These bubbles are abundant within sonoreactors, where their behavior becomes complex within clusters. This study quantifies their chemical effects within well-defined clusters using a new laser-based method. We focus a laser beam into water, inducing a breakdown that generates a single cavitation bubble. This bubble undergoes multiple collapses, releasing several shockwaves. These shockwaves propagate into the surrounding medium, leading to the formation of secondary bubbles near a reflector, separated from the input laser beam. We evaluate the chemical activity of these bubble clusters of various sizes by KI dosimetry, and to gain insights into their dynamics, we employ high-speed imaging. Hydrophone measurements show that conversion from focused shockwave energy to chemical reactions increases to a maximum of 16.5%. Additional increases in shockwave energy result in denser bubble clusters and a slightly decreased conversion rate, falling to 14.9%, highlighting the key role of bubble dynamics in the transformation of mechanical to chemical energy and as a result in the efficiency of the sonoreactors. The size and frequency of bubble collapses influence the cluster's chemical reactivity. We introduce a correlation for predicting the conversion rate of cluster energy to chemical energy, based on the cluster's energy density. The maximum conversion rate occurs at a cluster energy density of 2500 J/L, linked to a cluster with an average bubble diameter of 91 m, a bubble density of 3500 bubbles/ml, and a bubble-to-bubble distance ratio of 8.

Analisis Sifat Fisik dan Daya Terima Bubble (Tapioca Pearl) dengan Penambahan Puree Bit (Beta Vulgaris)

The innovation of making bubble with the addition of beet puree can be one way to improve the quality of texture, taste and nutrition of bubble. To get a chewy bubble texture, it require a long boiling time to cook through inside. One way to reduce this weakness is to use beetroot as the raw material for bubble. Beetroot have a high starch content which causes increased elasticity in the dough. The starch contained in beets really helps the starch gelatinization process. The method used is an experimental method with three types of treatment, which bubble with the addition of 60%, 80% and 100% beet puree. The validity test conducted using organoleptic tests on five expert panelists with six aspects, that is color, chocolate aroma, beet aroma, sweetness, beet taste and texture. Based on the results of the analysis, bubble with the addition of 60% beet puree is superior in various aspects of assessment so it is concluded that bubble with the addition of 60% beet puree is the product with the best organoleptic quality. Physical test is done by measuring the weight and diameter of the bubble before and after boiling with 3 repetitions. The analysis results showed that the average bubble weight is 457.3 mg, while the average bubble diameter is 8.74 mm. Consumer acceptence test was conducted using hedonic test (favorability test) on 30 panelists. The results of the favorability test showed that bubble with the addition of 100% beet puree was most liked. Analysis result show that the addition of beet puree to bubble has no real effect or difference.

MASS TRANSFER IN THE BIOREACTOR DURING GAS DISPERSION FROM THE STIRRER VORTEX CAVITY

Gas-liquid bioreactors in which the introduction of the gas substrate in the culture liquid is carried out from the vortex cavity formed by the rotation of the stirrer. In order to simplify the design and intensify mass transfer a new method of dispersing the gas substrate from the vortex cavity is proposed and studied. It consists in maintaining local zones with reduced pressure in the liquid behind the rotating paddles and creating the necessary conditions for the introduction of the gas substrate. On the basis of numerical simulation the pressure is calculated and the zones of low pressure in liquid behind the stirrer paddles are determined. The value of differential pressure necessary for gas dispersion has been estimated. The angular velocity of liquid rotation depending on the number of partitions on the apparatus wall and the number of mixer revolutions is presented. The gas content in the liquid during the implementation of the investigated method has been determined. The average surface diameter of gas bubbles and interfacial surface of gas-liquid medium were calculated from experimental data. The power spent on stirring in the apparatus has been established and the power criterion with regard to gas content has been determined. Mass transfer at intensive gas dispersion from gas vortex cavity into liquid has been investigated. Criterion dependence for calculation of mass transfer coefficient is presented, taking into account energy dissipation spent on mixing and interfacial surface. The fields of application of bioreactor with new method of gas dispersion are shown.

Effect of micro-bubble size and dynamic characteristics on oil removal efficiency of the flotation

Effect of micro-bubble size and dynamic characteristics on oil removal efficiency of the flotation

Numerical and experimental analysis of oxygen transfer in bubble columns: Assessment of predicting the oxygen-transfer rate in clean water and with surfactant solutions

Numerical and experimental analysis of oxygen transfer in bubble columns: Assessment of predicting the oxygen-transfer rate in clean water and with surfactant solutions

Study on the Mechanism of Gas Intrusion and Its Transportation in a Wellbore under Shut-in Conditions

This paper presents a comprehensive study based on multiphase-seepage and wellbore multiphase-flow theories. It establishes a model for calculating the rate of gas intrusion that considers various factors, including formation pore permeability, bottomhole pressure difference, rheology of the drilling fluid, and surface tension. Experiments were conducted to investigate the mechanism of gas intrusion under shut-in conditions, and the experimental results were employed to validate the reliability of the proposed method for calculating the gas intrusion rate. Furthermore, this research explores the transportation rates of single bubbles and bubble clusters in drilling fluid under shut-in conditions. Additionally, empirical expressions were derived for the drag coefficient for single bubbles and bubble clusters in the wellbore. These expressions can be used to calculate gas transportation rates for various equivalent radii of single bubbles and bubble clusters. The initial bubble size of intrusive gas, the transportation speed of intrusive gas in the wellbore, the rate of gas intrusion, and variations in the wellbore pressure after gas intrusion were analyzed. Additionally, a method was developed to calculate the rising velocity of bubble clusters in water based on experimental results. The study reveals that the average bubble size in the bubble cluster is significantly smaller than the size of single bubbles generated from the orifice. When the viscosity of the drilling fluid is low, the transportation velocity of the bubble cluster exhibits a positive correlation with the average bubble diameter. When the average bubble diameter exceeds 1 mm, the bubble velocity no longer varies with changes in the bubble-cluster diameter. The research results provide theoretical support for wellbore pressure prediction and pressure control under shutdown conditions.

Mathematical modeling of the effect of SEN outport shape on the bubble size distribution in a wide slab caster mold

Herein, the effects of outport shapes of the submerged entry nozzle (SEN) on the size distribution of argon bubbles were studied in a wide slab caster mold by the mathematical modeling. The Eulerian–Eulerian model coupled with Multiple-Size-Group (MUSIG) approach were used to solve equations of the two phase flow and polydispersed bubbly flow in the mold, respectively. The effect of the SEN outport angle and shape on the distribution of the molten steel flow, argon gas volume fraction, and argon bubble size were investigated. The outport shapes of the SEN included large rectangular, small rectangular, square, trapezoid, and runway. Results showed that the speed of molten steel increased within the range of 260 mm from the SEN, and decreased within the range of 550 mm from the narrow face with the outport angle of SEN increased from 20° to 45°. The bubble diameter was 5.7 mm at 255 mm distance from the SEN along the mold width at different outport angles. The average speed of molten steel at the outport of SEN decreased from 0.91 to 0.72 m/s with the outport shape changed from small rectangular to runway, trapezoid, square and large rectangular. The average diameter of bubbles was approximate 5.2 mm at the outport for the five types of nozzles, and increased from 3.2 to 3.45 mm inside the mold with the outport shape changed from the runway to square, trapezoid, large rectangular and small rectangular, indicating the rate of bubble breakup was larger with the runway and square SEN casting.

The effect of baffles on the hydrodynamics of a gas-solid fluidized bed studied using real-time magnetic resonance imaging

The effect of baffles on the hydrodynamics of a gas-solid fluidized bed studied using real-time magnetic resonance imaging

Two-phase flow evolution and bubble transport characteristics in flow field of proton exchange membrane water electrolyzer based on volume of fluid-coupled electrochemical method

Two-phase flow evolution and bubble transport characteristics in flow field of proton exchange membrane water electrolyzer based on volume of fluid-coupled electrochemical method

Bubble breakage and aggregation characteristics in a vortex pump under bubble inflow

The behaviors of bubbles in a vortex pump play a crucial role in its performance when handling gas–liquid flows. However, not much research has been done on the distribution of the gas–liquid phases and the characteristics of bubble breakage and aggregation in vortex pumps. This lack of understanding hinders the improvement of pump performance in gas–liquid flow transport. This study aims to investigate the bubble characteristics in a vortex pump using the population balance model, focusing on the variation of bubble size and the influence of the inlet gas volume fraction (IGVF) on bubble breakage and aggregation. The results show that as the IGVF increases, the gas volume fraction in the impeller becomes larger than that in the bladeless chamber. The majority of bubbles in the impeller are concentrated near the hub, while they also remain in the circulating-flow zone of the bladeless chamber. Under low IGVF conditions, the average diameter of bubbles decreases from the pump inlet to the outlet. The bladeless chamber has a larger average bubble diameter and a higher percentage of large bubbles compared to other parts of the pump. Moreover, the bubble number density at the pump outlet increases with the IGVF, indicating the production of more bubbles, while the increase in IGVF also results in an increase in the percentage of large bubbles. The study also discusses the mechanism of bubble breakage and aggregation in vortex pumps. It suggests that the effective breakage frequency and effective aggregation frequency are responsible for bubble breakage and aggregation in the vortex pump. The gas volume fraction and turbulent dissipation rate are identified as important parameters affecting the effective breakage and aggregation frequency. These findings provide new insights into understanding the characteristics of bubble breakage and aggregation in vortex pumps.

Regulation role of calcium lignosulfonate on the entrainment behavior of serpentine during brucite recycling: A new perspective

Regulation role of calcium lignosulfonate on the entrainment behavior of serpentine during brucite recycling: A new perspective