Bubble Pressure Research Articles

Influence of Sb additions on surface tension and density of Sn–Sb, Sn–Ag–Sb and Sn–Ag–Cu–Sb alloys: Experiment vs. modeling

Abstract Surface tension and density measurements by maximum bubble pressure and dilatometric techniques were carried out in an extensive range of temperature on liquid alloys close to the ternary eutectic Sn3.3Ag0.76Cu with different Sb content. It has been found that the addition of Sb to Sn, Sn–Sb, to binary eutectic Sn–Ag and to Sn3.3Ag0.76Cu decreases the surface tension and density. The values of the surface tension calculated by the Butler model and by the method based on the binary alloys surface tension data with the ternary and quaternary correction factors were compared with the experimental results. The best agreement between the measured and the calculated values was observed for the model comprising the binary data with the correction factors.

Measurements of Liquid AISI 304L Steel Density and Surface Tension, and Influence of Surface‐Active Elements at High Temperatures

Within the framework of the welding of steel components in pressurized water reactors, the optimization of the weld pool penetration is a major issue. The thermal‐hydraulics of the molten steel pool can be driven by Marangoni flows at the free surface. To compute these flows, liquid steel's thermophysical properties such as density ρ and surface tension σ are required. Such properties for austenitic vessel steel AISI 304L at liquid state are scarce, and even not available above 1800 °C, due to technological issues. The viscometer temperature installation (VITI) is designed to implement sessile droplet (SD) and maximum bubble pressure (MBP) techniques. These techniques allow to determine original ρ and σ data for two grades of AISI 304L steel, namely 304LP1 and 304LP4—low and high sulfur content, at various temperatures. In particular, thanks to the innovative design of MBP configuration, original surface tension data are obtained from the melting point up to 2100 °C. For the first time, experimental evidence of the Sahoo et al.'s (1988) model at high temperature is provided, emphasizing the decisive role played by surface‐active elements such as sulfur and oxygen on surface tension, whose content evolution is assessed by dedicated chemical analyses.

Super-quadric CFD-DEM simulation of chip-like particles flow in a fluidized bed

Chip-like particles may be practised in fluidized beds in some emerging industries, but its fluidization is not well understood. In this work, the computational fluid dynamics-discrete element method (CFD-DEM) is extended to integrate with a super-quadric model to study the fluidization behaviours of chip-like particles in a three-dimensional bubbling fluidized bed (BFB). After model validation, the typical fluidization behaviours of chip-like particles in the BFB are described in terms of bubble dynamics, pressure signals, particle orientation, particle mixing, and particle dispersion. Particularly, the ordered arrangement of chip-like particles appears at the near-wall region while random arrangement occurs in other regions. The effects of superficial gas velocity and aspect ratio on the mixing and dispersion characteristics of chip-like particles are discussed. The results show that increasing aspect ratio induces a higher mean pressure drop and promotes the initial mixing state. Particle dispersion coefficients range from 10-3 m2/s to 10-2 m2/s, whose vertical component is one order of magnitude larger than the horizontal components. Larger aspect ratios and superficial gas velocities lead to larger particle dispersion coefficients. The fundamental study sheds light on the design and optimization of fluidized beds of chip-like particles including solar panel waste recycling.

A transient analysis of slug flow in a horizontal pipe using slug tracking model: Void and pressure wave

In the oil and gas industry, the transient flow arises in daily situations, such as the start-up and shutdown of lines, pigging, artificial lifting, and drilling operations. These disturbances affect the temporal behavior of pressure and void fraction, which could cause separator flooding, system vibration, and production line facilities damage. Nevertheless, there are few numerical studies to describe this phenomenon. In this article, the transient slug flow is studied using the slug tracking model, which predicts the transient behavior and the evolution of slug flow properties. This study demonstrates the slug tracking model's capability to reproduce the transient flow as well as the pressure and void fraction wave's behavior and velocity. Experimental data presented by Maria and Rosa, 2016 were used to assess the model performance. The experimental data show a 6.0 s time delay between the two steady states. This time delay does not influence the void fraction wave, and its numerical maximum deviation is 9.0%. On the other hand, the numerical performance for the pressure wave velocity depends on the time delay. Using the experimental time delay, the maximum deviation for the pressure wave velocity is 6.8%. The slug tracking model is combined with a mass–dashpot–spring analogy to avoid the experimental time delay dependency. Using this methodology, the maximum deviation for pressure wave velocity is 8.2%. Some slug flow properties, such as the bubble nose translational velocity, the bubble and liquid slug lengths, are also compared to experimental data. The comparison is for averaged values and statistical distribution. The bubble nose velocities and pressure deviations are less than 1.5%, while the bubble and liquid slug lengths deviations are 4.1% and 5.3%, respectively. Most slug flow parameters have normal statistical distribution, but slug length follows a close to log-normal distribution. The model reproduces this behavior.

Improvement of unresolved CFD-DEM by velocity field reconstruction on unstructured grids

For conventional unresolved CFD-DEM, the accurate Lagrangian tracking of the dispersed particles requires the interpolation of cell-centered fluid velocity to the particle position instead of equally treating every particle in the same cell. However, the interpolation on unstructured grids and the systematic investigations about the influence of interpolation on the simulation results are rarely reported. This study adopted gradient-based interpolation to reconstruct the velocity field on unstructured grids considering efficiency and precision. Three gradient limit strategies were introduced into the unresolved CFD-DEM to constrain the gradient determined by the weighted least-square method because gradient-based interpolation may bring about unwanted extrema that will distort the results. The influence of gradient-based interpolation, as well as three gradient limit strategies on the simulation results, were estimated by comparing the simulation results with experimental measurements in a spouted bed with a conical base. The bubble behaviors demonstrated that the reconstruction of the velocity field was of crucial significance to the improvement of unresolved CFD-DEM. Besides, the pressure drops of experiments coincided with that of simulations except for the case using the limit strategy that constrained the extrema at face centroids. Considering the bubble behaviors and pressure drops, the limit strategy that constrained the extrema at grid vertices was the most recommended.

On studying the mechanisms and assessing the safety of Nd:YAG laser irradiation of the posterior lens capsule (experimental and clinical study)

To study the mechanisms of laser destruction in exposing the posterior lens capsule (PLC) tissue to Nd:YAG laser irradiation, and to evaluate its side effects on the cornea. The experiment involved 6 autopsy samples of human posterior lens capsule with different optical and mechanical properties, which were exposed to laser irradiation. We used the Nd:YAG ophthalmic laser LPULSA SYL-9000 Premio manufactured by «LightMed» (Taiwan/USA) and an experimental Nd:YAG laser system (1.064 μm). The following parameters were compared: the power of the incident radiation and radiation transmitted through the PLC, the mechanical stresses in the PLC tissue, the kinetic energy of the laser ablation products, and the pressure of gas bubbles during laser exposure in capsule samples of different densities. In the clinical part of the work, the negative effects of Nd:YAG laser on the cornea at different PLC densities were assessed using the endothelial microscope SP 3000P («Topcon», Japan). The experiment showed that in hard samples of PLC there are star-shaped point perforations with a diameter of 50±20 μm with partial rarefaction around the point defects. Damage to soft PLC samples in the form of large complete perforations was up to 200 µm in size. The temperature of laser irradiation necessary to achieve breakdown in soft PLC samples was 90 °C, in hard samples - 120 °C. The results of the experiment indicate that the final outcome - destruction of the PLC tissue - is safer to achieve not by increasing the energy, but by increasing the number of laser pulses. Clinical study results confirm a significant effect of the density of PLC on the values of laser energy and on the state of the cornea after laser intervention. The experimental data on the mechanisms of laser destruction of the lens capsule should contribute to the development of new and improvement of already known technologies aimed at reducing the risks associated with laser surgeries.

A micro-scale rheometer to study foam texture and flow resistance in planar fractures.

We designed and fabricated a new microfluidic device to better enable study of foam microstructure and rheology in planar fractures. The design phase included stress-strain finite element analysis to enhance the pressure tolerance of the device. The optimized design is a 2 cm wide by 7.75 cm long rough fracture that includes 25 posts to anchor the glass cover plate. The posts simulate asperities and provide structural support during bonding of a glass cover plate to the device. Importantly, the new design illustrates improved ability to sustain large differential pressure compared to previous designs in the literature. The rheometer permits study of the relationship among foam bubble morphology, pressure drop, and flow rates. Our findings validated the previous, sparse microvisual studies mentioned in the literature and confirmed that small quality foam, ranging from 20 to 50% gas by volume, contains dispersed bubbles separated by liquid lenses. In this range, the distribution of bubble sizes was roughly 80-90% small uniform bubbles and only 10-20% of larger and more elongated bubbles. Additionally, our studies reveal that foam apparent viscosity is a strong function of foam quality, velocity, and texture (i.e., bubble size). Apparent viscosity of foam ranged from 100 to 600 cP for the conditions studied. High quality foams in fractures are independent of gas flow rates but very sensitive to liquid flow rates. On the other hand, low quality foams are sensitive to gas flow rates but independent of liquid flow rates.

Numerical Investigation of Turbulence Production Under Two-Phase Flow in a Simulation of Electrical Submersible Pump Performance

Abstract Investigating the characteristics of gas–liquid two-phase flow in a centrifugal pump is critical for evaluating pump performance. In this study, a numerical simulation was performed to understand the effects of gas–liquid turbulence formation in the impeller channels on the performance of a single-stage centrifugal pump. The focus was on the inlet gas volume fraction (IGVF) at constant flowrate and constant impeller speed on the flow structure in the impeller and the pressure surging characteristics. The correlation between Reynolds shear stress and turbulent kinetic energy on pump performance is shown by examining pressure, velocity, turbulent kinetic energy, and gas volume fraction (GVF). The model verification is verified using the theoretical pump pressure head determined by the manufacturer, which demonstrated adequate uncertainty (μ<5%) for a flowrate of 250 L/min. The results show a 9.41% decrease in wall shear stresses when the in-situ GVF varies between 1% and 10%. Wall shear stresses combined with circulation resulted in a 3.76% decrease in turbulent kinetic energy, while the contribution of turbulence to pump performance degradation is minimal. Other factors such as gas entrapment, impeller inlet blockage due to bubble coalescence, pressure gradient, and bubble size had a much greater impact on performance. The performance decreased dramatically by 26.53% when the GVF increased from 1% to 10%. The proposed flow structure can be further investigated together with the wall shear stress and circulation phenomena, such as vorticity and shear layers in the context of two-phase flow.

ESTIMATION OF NUCLEAR FUSION REQUIREMENTS IN BUBBLES DURING ULTRA-HIGH-PRESSURE, ULTRA-HIGH-TEMPERATURE CAVITATION PROMOTED BY MAGNETIC FIELD

In the present work, a strong magnetic field was applied near the outlet of the water jet nozzle to promote the generation of multifunction cavitation bubbles. Because these bubbles contained charged species, the bubbles experienced a Lorentz force due to the magnetic field and collided with greater force. As such, the internal bubble pressure exceeded the threshold value required for fusion to occur. The expansion of these charged bubbles in response to ultrasonic irradiation affected adjacent charged bubbles so that the energy density of the atoms in the bubbles was greater than the fusion threshold. The results of this work strongly suggest that the formation of bubbles via the UTPC process in conjunction with a strong magnetic field may result in bubble fusion.

High-Pressure Phase Equilibria Measurements of the Carbon Dioxide + Cycloheptane Binary System

The phase behavior of the carbon dioxide + cycloheptane binary system for which no literature data are available has been examined at temperatures ranging from 292.6 to 372.8 K. Saturation pressures, ranging from 23.9 to 154.8 bar, were acquired by a synthetic and visual method. In concrete terms, an adjustable-volume high-pressure cell was utilized to measure bubble and dew point pressures by visual detection of phase transitions at constant overall composition. A total of 11 different mixtures with mole fractions of carbon dioxide ranging from 0.20 to 0.96 were prepared, and a total of 99 experimental points were reported. The experimental results obtained in this work reveal the absence of liquid–liquid immiscibility in the studied temperature range and make it possible to conclude that the vapor–liquid critical line of the binary system is continuous and uninterrupted between the two pure compounds. Experimental data were correlated with the Peng–Robinson equation of state and classical van der Waals mixing rules with temperature-dependent binary interaction parameters. They were also compared to the PPR78 model, an entirely predictive group contribution method in which the kij depends on temperature.

Measurements of Static and Dynamic Bubble Surface Tension Using a Deformation-Based Microfluidic Tensiometer.

The surface tension of bubbles is critical for processes involving mixed liquid-gas systems, from sea spray aerosol generation to firefighting foam aspiration. In particular, the size- and surfactant-dependent time scales of dynamic surface tension decay due to adsorption of surface-active chemicals at the curved interface significantly dictate the multiphase system dynamics. While size-dependent surfactant adsorption and interfacial dynamics have been well characterized for liquid-liquid systems using microfluidic platforms, application of microfluidic methods to liquid-gas systems has received less attention. This work uses a high-throughput microfluidic tensiometer to measure the static and dynamic surface tension of microscale bubbles compared with millimeter bubbles characterized by pendant drop. It is shown that the static surface tension measurements for surfactant-free interfaces with microfluidics show good agreement with pendant drop for most systems. At the same time, its accuracy can be affected by bubble pressure, inertia force at high Re, drag force, bubble expansion, and image processing limitation. In the presence of surfactants, the dynamic surface tension measurements show that both smaller bubbles and higher surfactant concentrations can lead to a much shorter time to reach equilibrium compared with pendant drop, similar to the observation for liquid-liquid interfaces. This work shows the potential of a microfluidic tensiometer to capture early time surface tension decay and accurately measure surface tension even in the presence of Marangoni stress tangential to the interface.

Tensiometry as a Simple Analytical Method for Quantification of Solubility and Release of Aroma Molecules in Aqueous Media.

Dynamic tensiometry is shown to be a high-potential analytical tool in assessing physico-chemical characteristics of fragrance molecules, such as solubility limit, volatility as well as much rarely assessed interfacial activity of these amphiphilic molecules. Surface tension of aqueous solutions of selected essential oils has been measured as a function of time and fragrance concentration using maximum bubble pressure method. The effect of the temperature and saline solution on the rate of dissolution in water was assessed. Dynamic surface tension turned to be sensitive to the composition of fragrances, as demonstrated on examples of natural and synthetic mixtures. Furthermore, presented work reveals the possibility of maximum bubble pressure tensiometry method to quantify the amount of fragrance compositions in flavored salts, including the artificially aged carrier samples. Suggested here analytical approach can be used for the detection of the purity of essential oils, for the optimization of compositions and of the manufacturing processes of fragrances-containing products, as well as for the assessment of the release/evaporation of fragrances from carrier systems.

Investigation of laser-induced bubble dynamics in water at high hydrostatic pressures

Hydrostatic pressure is a key factor that influences laser-induced bubble dynamics in water. In this work, we investigated laser-induced bubble dynamics at high hydrostatic pressures up to 53.2 MPa, by using a high-pressure chamber combined with the shadowgraph imaging technique. It was shown that at the atmosphere pressure, the bubble evolution agrees well with the Keller-Miksis model during the free expansion and collapse phase. As the ambient pressure increases, both the size and the oscillation period of the bubble decreases dramatically as a consequence of faster dynamics. The maximum bubble radius, as well as the collapse time, decrease nonlinearly with the increasing pressure; while the pressurization effect on bubble expansion before 100 ns is negligible due to the high internal bubble pressure in the early stage. Time-resolved plasma emission images were also taken with an ICCD camera to illustrate the plasma evolution at high hydrostatic pressures. It was demonstrated that at a high pressure above 40 MPa, the plasma can gain energy from the bubble collapse, while the bubble will lose its energy, which may lead to a shorter collapse time than that obtained from the numerical calculation. This work provides insight into laser-induced bubble dynamics and the plasma-bubble interaction at high hydrostatic pressures.

Visualization and Sound Measurements of Vibration Plate in a Boiling Bubble Resonator

We developed a boiling bubble resonator (BBR) as a new heat transfer enhancement method aided by boiling bubbles. The BBR is a passive device that operates under its own bubble pressure and therefore does not require an electrical source. In the present study, high-speed visualization of the flow motion of the microbubbles spouted from a vibration plate and the plate motion in the BBR was carried out using high-speed LED lighting and high-speed cameras; the sounds in the boiling chamber were simultaneously captured using a hydrophone. The peak point in the spectrum of the motion of the vibration plate and the peak point in the spectrum of the boiling sound were found to be matched near a critical heat-flux state. Therefore, we found that it is important to match the BBR vibration frequency to the condensation cycle of the boiling bubble as its own design specification for the BBR.

Phase-field simulations of fission gas bubbles in high burnup UO2 during steady-state and LOCA transient conditions

To improve the economics of commercial light water reactors, increased understanding of UO2 nuclear fuel with the high burnup structure (HBS) is required in both steady-state and transient conditions. Here, a phase-field model of the fission gas bubble microstructure in nuclear fuel is developed based on the Kim-Kim-Suzuki (KKS) formulation and implemented in Idaho National Laboratory’s Marmot application for phase-field simulation of nuclear materials. The model includes the effects of gas pressure and the surface tension of the bubble-fuel matrix interface for arbitrary interfacial curvature. Simulations of bubble growth in the HBS region during steady-state conditions showed that initially overpressurized bubbles decreased in pressure during growth, but still remained above equilibrium pressure. During a loss-of-coolant accident (LOCA) transient, simulations of bubbles in the HBS region showed that bubble size did not change significantly. The bubble pressure in response to the LOCA transient was calculated for a variety of bubble sizes, initial pressures, and external restraint pressures.

Multiple-relaxation-time lattice Boltzmann method for three dimensional free-surface flows with multi-bubble model

Flow with bubbles is a commonly occurring phenomenon in nature and industrial applications. This study provides a multi-bubble model for the free surface lattice Boltzmann method (FSLBM) which can be used to simulate fluid flow with bubbles as well as their splitting and merging processes. FSLBM neglects the flow of gas and considers only the gas pressure, and thus simplifies the gas-liquid two-phase flow to a single-phase free surface. The compression of the bubble will influence its pressure and lead to movement, splitting, or merging processes within the bubble flow. The multi-bubble model considers the evolution of bubble's pressure by enhancing the model for free surface which simulates the behavior of gas-liquid interface inside the liquid. The Smagorinsky subgrid-scale model (SGS) and the more advanced multiple-relaxation-time (MRT) collision model is used for high Reynolds number. In this study, a bubble algorithm to handle the bubble splitting and merging without incurring significant computational costs is provided. The verification and analysis of this model are given by a comparison between both analytical solution and an experiment. Therefore, the multi-bubble as an extension of FSLBM can be used to solve a wider range of two-phase flow problems more efficiently, such as bubble formation, metal foaming process, and development in chemical reactors.

Experimental and theoretical analysis of detonation products state on bubble dynamics and energy distribution in underwater explosion

The initial states and pressure of detonation products in a bubble have a great impact on bubble pulsation in underwater explosions; particularly, the initial accelerated expansion of a bubble can determine the energy distribution. The energy output and distribution of explosives were obtained on the basis of the underwater explosion experiment in this paper. To study the process of bubble pulsation and energy output, we proposed a gas equation of state (EOS) combining the pvk form, Jones–Wilkins–Lee (JWL) EOS, and the initial states of a bubble to take the effects of the initial bubble pressure and detonation products state transformation into account; furthermore, the bubble radius, velocity, and acceleration vs time were obtained through the Rayleigh–Plesset equation under our experimental condition. The differences of bubble behaviors were compared by adopting the JWL EOS and a polytropic EOS with k = 3. The results showed that the initial bubble pressure and detonation products state transformation influence the accelerating expansion and the subsequent bubble oscillation, respectively. Subsequently, comparisons of the energy output and distribution for different gas EOSs showed that the initial shock wave energy for the JWL EOS was underestimated in accelerating expansion, and the bubble energy was overestimated using the polytropic EOS for k = 3; the obtained energy output and distribution had a better agreement with experimental data when adopting the improved gas EOS. In addition, the energy distribution was determined before the detonation products turned to the explosion gas state in initial expansion based on the relationship of the accelerating expansion characteristics and the initial shock wave energy generation. The research has a great significance to reveal the mechanism of bubble pulsation in underwater explosions.

Geometrical effects on heat transfer mechanisms during pool boiling in Dual Tapered Microgap with HFE7000

Dual tapered microgap configuration provides a simple external device that can be retrofitted on a boiling surface. It has been shown to be very effective for enhancing pool boiling heat transfer coefficient (HTC) and Critical Heat Flux (CHF) with water. Recent testing showed that the same geometry is not effective with refrigerants and dielectric fluids. A systematic experimental and theoretical study is conducted to bring out the underlying mechanisms and identify the effect of geometrical parameters mainly on HTC, as higher values are desired in electronics cooling application. Five different taper angles of 5°, 10°, 15°, 20°, and 25° and two inlet gap heights of 0.8 mm, and 1.27 mm were experimentally evaluated with dielectric liquid HFE7000. Theoretical analysis has identified two mechanisms from bubble squeezing and pressure recovery for inducing flow in the microgap. These mechanisms are influenced by the fluid properties and the geometrical parameters. The best geometrical configuration was able to achieve a 2X enhancement in HTC over a plain copper test surface. Further enhancements are expected with introduction of additional surface features such as microchannels on the heater surface in the microgap region. The theoretical model was able to estimate the pressure drop, mass flux, and the resulting HTC with high accuracy for different geometric configurations.

New mathematical modeling of temperature-based properties of ionic liquids mixture: Comparison between semi-empirical equation and equation of state

Ionic liquids are a significant type of organic salts with attractive and superior physicochemical features for employing in a number of chemical processes. Ionic liquids include one large and asymmetric cationic or anionic functional group. The properties of cationic functional group are almost similar and it is main motivation of this study. In the present investigation, we extended various semi-empirical correlations to predict some temperature-based properties of ionic liquids mixture (IL-mixture). These properties are density, viscosity, surface tension and bubble point pressure. In the case of IL-mixture density, modified Rackett equation and Taylor equation with three scenarios, modified Gardas and Coutinho equation were considered and the obtained results were compared with Peng-Robinson equation of state (EoS), Patel-Teja EoS and perturbed-chain statistical associating fluid theory EoS. In the case of IL-mixture viscosity, two types of activation energy concept models were used and also, Lee-Kesler method and modified Brock and Bird were applied to predict IL-mixture bubble point pressure and IL-mixture surface tension, respectively. A used dataset was collected from reliable literature including 2731 data points of bubble pressure (23 binary system), 4643 data points of density (102 binary system), 1011 data points of viscosity (32 binary system) and 391 data points of surface tension (16 binary system). These data relevant to 12 cation-family and 36 solvents. The all of the data was haphazardly separated in two subsets of train and test with a computer program. The obtained results indicated all used semi-empirical correlations gives the best match with corresponding experimental data and the values of statistical parameters demonstrated this hypothesis.

Degradation of amoxicillin from water by ultrasound-zero-valent iron activated sodium persulfate

• Degradation of amoxicillin by ultrasound-zero valent iron activated persulfate was studied. • The effects of different influencing factors on the degradation rate were discussed. • The degradation mechanism and process are discussed. In this paper, studies were conducted on the degradation of amoxicillin by ultrasound-zero valent iron activated sodium persulfate. The effects of ultrasonic power, sulfate concentration, zero-valent iron dosage, pH value and reaction temperature on the degradation of amoxicillin (AMX) were studied. The intermediate products were measured and the degradation pathway was speculated and the optimal degradation conditions were given. It was found that when the ultrasonic intensity acting in the reaction system exceeded the cavitation threshold sound pressure of the cavitation bubbles, with the increase of power, the activation of persulfate and the reaction process of AMX are promoted and accelerated; With the increase of persulfate concentration, the removal effect of AMX is gradually enhanced. When the concentration reaches the optimal value, AMX is completely removed, and the removal time is shortened; Fe 0 can significantly improve the removal efficiency of AMX by persulfate. When the amount of zero-valent iron is added to the optimal value, AMX can be completely removed within a short time; The pH value in the solution has a large effect on the ultrasound-zero-valent iron activated persulfate system. In general, the best removal effect of AMX is achieved under acidic conditions; With the increase of reaction temperature, the removal effect of AMX is further improved. The results indicate that the ultrasonic-zero-valent iron activated persulfate system is of great potential application value in removal of organic pollution and environmental purification.