Liquid Conditions Research Articles

Hydrodynamic Effects of Static Liquid Height in the Thermolysis Reactor for Cu-Cl Cycle Hydrogen Production

Hydrodynamic Effects of Static Liquid Height in the Thermolysis Reactor for Cu-Cl Cycle Hydrogen Production

INFLUENCE OF TEMPERATURE GRADIENTS AND FLUID VIBRATIONS ON THE THERMOCAPILLARY DROPLET BEHAVIOR IN A ROTATING CYLINDER

In this paper, a computational fluid dynamics (CFD) approach is used to analyze and numerically present the droplet movement in both stagnant and vibrated liquid in a rotating cylinder. The Ansys Fluent commercial software package is used to solve the governing continuum conservation equations for two-phase flow. The volume of fluid (VOF) method is used to track the liquid/liquid interface. The inherent velocity of droplets decreases with increasing Marangoni number, in agreement with previous space onboard experimental findings that have been documented in literature. Complex behaviors of droplets in zero gravity were observed due to small host fluid vibration and rotational motion, which are neglected in the presence of gravity. Therefore, the impact of varying vibration amplitude as well as angular velocity on bubble migration is presented. It has been found that thermocapillary migration slows down with high vibration amplitude (A), when the fluid is vibrating. For a static liquid inside a rotating cylinder, the velocity of thermocapillary droplet migration decreases with the angular velocity increase. Temperature gradient (∇T) increment also increases the droplet's migration speed inside the vibrating fluid and a rotating cylinder of different Marangoni numbers (Ma<sub>T</sub>). A flow pattern figure that illustrates the actual flow behind each modification is included with every result.

The shape of an axisymmetric meniscus in a static liquid pool: effective implementation of the Euler transformation

Abstract We examine the classical problem of the height of a static liquid interface that forms on the outside of a solid vertical cylinder in an unbounded stagnant pool exposed to air. Gravitational and surface tension forces compete to affect the interface shape as characterized by the Bond number. Here, we provide a convergent power series solution for interface shapes that rise above or fall below the horizontal pool as a function of contact angle and Bond number. We find that the power series solution expressed in terms of the radial distance from the wall is divergent, and thus rewrite the divergent series as a new power series expressed as powers of an Euler transformed variable; this series is modified to match the large distance asymptotic behaviour of the meniscus. The Euler transformation maps non-physical singularities to locations that do not restrict series convergence in the physical domain, while the asymptotic modification increases the rate of convergence of the series overall. We demonstrate that when the divergent series coefficients are used to implement the Euler transformation, finite precision errors are incurred, even for a relatively small number of terms. To avoid such errors, the independent variable in the governing differential equation is changed to that of the Euler transform, and the power series is developed directly without using the divergent series. The resulting power series solution is validated by comparison with a numerical solution of the interface shape and the small Bond number matched asymptotic solution for the height of the interface along the cylinder developed by Lo (1983, J. Fluid Mech., 132, p.65-78). The convergent power series expansion has the ability to exceed the accuracy of the matched asymptotic solution for any Bond number given enough terms, and the recursive nature of the solution makes it straightforward to implement.

Comparison of System Constants of Thermostable Polysiloxane Stationary Liquid Phases of Different Origins

Comparison of System Constants of Thermostable Polysiloxane Stationary Liquid Phases of Different Origins

Breakup regimes of the long-time dynamics of a finite-size air filament in a dense fluid

The long-time dynamics of a quiescent finite-size three-dimensional air filament in a static liquid is studied using three-dimensional numerical simulations. The two ends of the air filament retract under the effect of surface tension and form bulges. A long filament with the aspect ratio Γ = 30 is considered to trigger the end-pinching regime of the filament rupture. The study focuses on the effect of the Ohnesorge number, which relates viscous forces to inertia and surface tension forces. Depending on the value of the Ohnesorge number, two or three successive ruptures of the filament are observed. Wavy structures form at the interface of the air filament after the first rupture and lead to a subsequent breakup in the middle of the filament or in several places depending on the corresponding Ohnesorge number. The size distribution of the bubbles generated is provided and shows an average diameter twice as large as the initial diameter of the air filament. Microbubbles are generated, and their number is shown to increase when the Ohnesorge number decreases.

Comparison of System Constants of Thermostable Polysiloxane Stationary Liquid Phases of Different Origins

The expansion of possible areas of use of modern gas chromatography is largely determined by the thermal stability of stationary liquid phases (SLP), which allows the separation of complex mixtures of high-boiling compounds. A way to increase the thermal stability of nonpolar and weakly polar polysiloxane SLPs is to introduce rigid fragments into the polysiloxane chain. Currently, there is an extensive set of columns with thermostable SLPs, which, in some cases, have the index “ms”. However, in most cases, the nature of these phases and the methods for preparing the columns are not disclosed. In this work, using the linear free energy relationship (LFER) model, we compared the selectivity of a number of proprietary columns with in-house columns in which the siloxane–silarylene phase and the column preparation methods themselves are known. Various types of intermolecular interactions are considered within the framework of the LFER model.

Numerical simulation of the motion and interaction of bubble pair rising in a quiescent liquid

In the present study, the motion and interaction of a bubble pair rising in a stationary liquid are simulated in two dimensions using the volume of fluid method (VOF) in the open-source CFD package OpenFOAM. For validation, the single bubble rising for different regimes was simulated. Comparing the present study results and previous numerical and experimental results showed that the results have a good agreement. In the present study, the bubble pair is arranged along a horizontal line, and results showed that in 2D domain four different interactions happen between the bubble pair rising based on the Bond (Bo) and Morton (Mo) numbers which are: coalescence, bouncing, zigzagging, and breakup. The simulations are done at three different slopes of the line connecting the center of two bubbles (θ=[0°, 45°, and 90°]), which shows the different arrangements of bubble pairs. At θ=90°, due to the attraction created by the wake of the leading bubble, the trailing bubble gets a significant acceleration in its motion, and will coalesce in the absence of surfactants. The results showed that the value of the trailing bubble velocity increases with decreasing the separation distance between the bubbles. Also, the rising velocity of the trailing bubble is always greater than the velocity of a single bubble due to the attraction effect of the leading bubble’s wake. The drag force of a trailing bubble decreases with decreasing the separation distance between the bubbles. Finally, a general criterion based on dimensionless numbers of Bo and Mo is presented to determine the type of interaction between bubble pair.

On Liouville-type theorems for the stationary nematic liquid crystal equations

On Liouville-type theorems for the stationary nematic liquid crystal equations

Inertial capture of aerosol particles using liquid bridges in cross flow

We investigate the inertial capture of aerosol particles, suspended in a laminar cross flow between parallel plates, by stationary cylindrical liquid bridges. We track the motion and fate of individual aerosol droplets (3–9 μm diameter) suspended in a flow moving across a single liquid bridge or two-bridge systems, using high-speed imaging under a microscope. First, we measure the capture efficiency by inertial impaction of an isolated liquid bridge collector as a function of the aerosol particles Stokes number and show that it agrees with the efficiency calculated for rigid particles moving in a potential flow past a solid cylinder. We then consider two-bridge systems, that is two parallel cylindrical collectors oriented perpendicular to the flow, but offset from each other. We investigate the effect that the upstream collector has on the effective capture efficiency of the downstream test collector, depending on the transverse offset and Stokes number. The offset is the relative displacement of the downstream collector normal to its axis and in the direction perpendicular to the freestream flow. For small values of the transverse offset, smaller than the radius of the collector, small (zero) effective efficiencies are measured for the test collector, due to a partial (complete) shielding effect by the upstream collector. The effective efficiency thus increases from zero with increasing transverse offset, above a threshold value for complete shielding. As the transverse offset increases further, effective efficiencies larger than the efficiency of an isolated bridge are measured for the test collector, showing enhanced capture due to the redistribution of particles moving past the upstream collector. The relative increase in the inertial capture efficiency is significant for Stokes numbers around (but below) unity, 0.45≲St≲0.9, with relative gains as large as approximately 50%. There is an optimum offset displaying maximum effective efficiency and larger offset values lead to a slight decrease in measured efficiencies. These results demonstrate the importance of the relative arrangement of individual collectors on the overall inertial capture efficiency of aerosol particles and suggest that an array of bridges in a slanted configuration (with optimal transverse offsets) could be used as a high-performance filtration system for aerosol particles.

The Surface Shape of Static Liquids between Double Vertical Plates in Different Gravity Environments

Liquid surface tension is produced at interfaces between liquid and air, due to the different molecular attractions on both sides. If the adhesion between a liquid and a solid wall is greater than the cohesion of the liquid itself, the liquid surface rises in a concave form due to the action of the surface tension, and the liquid near the surface produces a suction head. Conversely, if the liquid-solid adhesion is less than the cohesion of the liquid, the surface drops down in a convex form and the liquid has a pressure head. This paper systematically investigates the surface shape and tension distributions of static liquids near solid walls. The scenarios investigated the walls of double vertical plates. For the plane-based problems, an analytical method is used to extract exact solutions. For a double plates, fitting formulae are presented. All of the quantities required for these results can be easily measured in different gravity environments.

Research and development of gas electrode potential oxygen sensors in saturated oxygen liquid LBE

Oxygen sensors play a crucial role in the effective operation of the Active Oxygen Control System (OCS) in liquid LBE systems. In this study, the performance of LSCF/air, LSM/air and Pt/air reference electrode sensors with yttrium stabilized zirconia (YSZ) as the solid electrolyte in the static oxygen saturated liquid lead bismuth eutectic alloy (LBE) was evaluated with varying temperature range by measuring the electromotive force. Compared with the activation temperature of Pt electrode sensor (420 °C), the activation temperature of LSCF electrode and LSM electrode sensor is as low as 320 °C. The LSCF/air and LSM/air sensors show good performance in the high and low temperature tests. However, the electrochemical balance of the Pt/air reference sensor has an irreversible effect at the lowest temperature, leading to the sensor malfunction. During the temperature transient process, the electromotive force (EMF) measured by the sensor shows a deviation from the theoretical value. Besides, the LSCF/air reference sensor has the smallest deviation and the Pt/air reference sensor has the largest deviation. Therefore, the LSCF electrode sensor exhibits best performance in the low operating temperature region.

Corrosion behaviors of ODS-FeCrAl in oxygen-saturated lead-bismuth eutectic at 550°C: Effects of grain boundaries and minor elements

Long-term corrosion behavior of ODS-FeCrAl tube was investigated in oxygen-saturated static liquid lead-bismuth eutectic (LBE) at 550 °C. Different densities of sub-grain boundaries (sub-GBs) lead to different corrosion behaviors on the inside and outside surfaces of the tube. The oxide film formed on the inside surface consists of Fe3O4, Fe-Cr-Al spinel and Al2O3, and on the outside surface consists of Fe-Cr-Al spinel rich in Cr&Al and Al2O3. Excessively high density of sub-GBs accelerates the oxidation rate. The precipitation of W&Ti promotes the formation of Cr-rich and Al-rich oxides. The corrosion mechanism of ODS-FeCrAl in liquid LBE is discussed.

Approximate Method for Calculating the Velocity Profile of a Two-Dimensional Stationary Turbulent Liquid Flow

Approximate Method for Calculating the Velocity Profile of a Two-Dimensional Stationary Turbulent Liquid Flow

Plastron restoration for underwater superhydrophobic surface by porous material and gas injection

Restoring and maintaining the gas layer (plastron) on underwater superhydrophobic surface (SHS) is critical for the real-world application of SHS, such as reducing friction drag in high-Reynolds number turbulent flows. In this work, we experimentally investigated the capability of a technology based on porous material and gas injection to restore the plastron on an underwater SHS from a fully wetted state. The SHS was created by sprayed coating a commercial superhydrophobic coating on a porous steel plate. In the experiments, the SHS was immersed in stationary liquid, the gas injection pressure and gas injection duration were independently controlled. The status of gas layer on SHS was examined by a high-speed camera. We found that the surface area being restored with a plastron increased with increasing gas injection pressure and gas injection duration, and that the plastron restoration process involved bubble formation, merging and detachment. A layer of gas was left on the surface after bubble detachment. The size of the detached bubble increased with time due to bubble merging, and became stable when there was no more bubble merging. Increasing gas injection pressure led to higher gas flow rates, larger detached bubble sizes and faster plastron restorations. A plastron restoration within 0.3 s was achieved at the highest pressure, faster than the in-situ gas generation methods. Furthermore, we found that the gas flow rate through the underwater SHS can be described by a modified Darcy’s law. Our results highlighted the potential of using porous material and gas injection to restore the plastron and made possible the real-world implementation of SHS.

Multicapillary columns with ionic liquids as stationary liquid phase

The study demonstrates the possibility of using ionic liquids (IL) as a stationary liquid phase (SLP) for gas chromatographic (GC) multicapillary columns (MCC). Three types of IL of three classes were employed as SLP: Imidazolium, Pyridinium and Quinolinium. Dependences of the MCCs efficiency on the carrier gas flow rate were obtained. Highest efficiency was achieved on the column with 1,2-Dimethyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide (DiMPrIm). For this column, dependence of the efficiency on the sample volume has been investigated. Also the loading capacity of the MCC with DiMPrIm was determined. Separation of fatty acid esters and phenols served as an example to demonstrate that using ionic liquids as SLP for МСС make it possible to combine fast separations with high selectivity.

Prediction of bubble shape deformation in aqueous solutions of short-chain alcohols

The behaviour of bubbles in aqueous solutions of short-chain alcohols depends significantly on the alcohol concentration. At low concentrations, alcohols act as surfactants and slow the rising velocity of the bubble, whereas at higher concentrations, primarily due to the internal arrangement at the molecular level, the desorption of molecules from the bubble surface is facilitated and the mobility of the bubble surface is increased. These factors significantly affect both bubble velocity and deformation. On the basis of experimental data (aqueous solutions of ethanol and propanol in the entire concentration range), two relations were proposed for the estimation of bubble deformation depending on the dimensionless Weber number. The model was successfully verified on an independent data set of the velocity and deformation of bubbles that rise in a stationary liquid.

Research on Single Crystal Preparation via Dynamic Liquid Phase Method

Traditional liquid phase methods for growing single crystals are static growth methods, which include seed crystal sedimentation growth and seed crystal clamping growth using seed crystal holders. Single crystals grown via seed crystal sedimentation often have a flat and elongated shape, and the region in contact with the bottom of the container is restricted during growth, resulting in significant defects. Similarly, the seed crystal clamping growth method cannot avoid contact with external objects, leading to abnormal growth at the contact points and along the direction of the seed crystal holder, also resulting in certain defects. Both of these growth methods require processes, such as cutting and grinding, to remove defects, resulting in resource waste. To address the shortcomings of the static liquid phase single-crystal preparation mentioned above, this study successfully designed a dynamic liquid phase method for single crystal growth, which achieved the successful suspension of seed crystals in the mother solution and the growth of high-quality, large-sized single crystals, avoiding contact with the walls and the bottom of the container during the crystal growth process. Based on the dynamic liquid phase single crystal growth apparatus mentioned above, stable and dynamic liquid phase preparation was successfully achieved, ranging from seed crystals with a diameter of approximately 5 mm to single crystals with a diameter of approximately 20 mm, by controlling the cooling rate and adjusting the solution flow rate.

Numerical study of the geometric characteristics and kinetic behavior of single bubble rise processes in different liquids

The characterization of single bubble in gas–liquid two phase flow is a critical yet unresolved issue in both science and industry. In this study, the volume-of-fluid (VOF) method is used to numerically simulate and experimentally investigate the effect of initial bubble diameter, liquid viscosity, and surface tension on bubble deformation and the internal flow field of the bubble in a pool of stationary liquid. The findings indicate that as liquid viscosity increases, the bubble's rising speed decreases, and the bubble tends to oscillate. The variation in bubble deformation ratio and the degree of fluctuation increase with the bubble's initial diameter and decrease with the viscosity of the liquid phase. Additionally, as the surface tension of the liquid decreases, the bubble becomes more prone to rupture, and the number of ruptures increases. The flow field inside the bubble can be classified into three categories: “double main vortex type,” “double main vortex type with separated vortex,” and “double main vortex type with scattered vortex.” The velocity reaches its maximum at the center of each vortex type, and the velocity at the interface varies as the bubble interface shape changes. This work lays the foundation for the study of the flow field inside the bubble and improves the predictability of gas–liquid equipment design.

The effect of short-chain fluorocarbon and electrolyte on simultaneous dedusting and explosion prevention performance when applied to coal particle with high oil-content

The fully mechanized mining faces in underground oil-rich coal mines are exposed to the serious dust pollution and the high risk of dust explosion. Traditional materials cannot effectively realize the removal and inerting of coal particles with high oil content. Thus, this paper innovated new materials to eliminate the occupational disasters and explosion accident in underground coal mines by achieving simultaneous dedusting and explosion prevention of coal particles with high oil content. Compare with traditional materials, the presence of short-chain fluorocarbon surfactants and electrolytes achieved 76.30–84.92% improvement on dedusting rate, a maximum 22 times improvement on MIE, 4.20–8.90% improvement on MIT, and 50% improvement of MEC. Mechanism analysis revealed the better performance is attributed to the optimized wetting and agglomerating behaviour. Kinetic analysis showed that the new materials reduced the heat release and inhibit combustion process. The NaCl outperforms NaHCO3 in achieving better dedusting and explosion suppression performance in most cases for its higher TSI and more efficient explosion prevention mechanisms. Studies also demonstrated that the oil content could moderate the dedusting and explosion prevention performance due to the reduction of static liquid bridge force in terms of the increased proportion of saturated hydrocarbons and aromatic hydrocarbons, the reduced concentration of polar functional group, and the corresponding increased contact angle “θ”. The Findings of this paper provide an efficient and environmental-friendly choice for ensuring occupational health and safe production in underground oil-rich coal mines by achieving simultaneous dedusting and explosion prevention. It will also guide the innovation and development of multiple protective materials for coal mine safety protection.

Kinetics of the complexation reaction of iron with dissolved oxygen in liquid sodium

This work aims to study the kinetics of pure iron corrosion by liquid sodium in the presence of dissolved oxygen. The corrosion rate of pure iron in liquid sodium was estimated from the mass loss in the samples as a function of immersion time. The parameters tested were dissolved oxygen content, temperature and velocity of the liquid sodium. The rate of pure iron dissolution in liquid sodium increases with dissolved oxygen content and follows a power law of order 2 as a function of the initial oxygen content (50−400ppm). The mechanism of iron corrosion by liquid sodium is activated in the temperature range between 525∘C and 600∘C. The experimental activation energy is estimated to be 168±10kJ/mol. The dissolution rate also increases with the liquid sodium agitation rate.Under the same experimental conditions, S. Meddeb et al. in [J. Nucl. Mater. 566 (2022) 153785] demonstrated that the iron dissolution is homogeneous and is explained by the formation of the NaFeO2 complex at the iron/liquid sodium interface. The corrosion kinetics measured is limited by the transfer of this complex through the mass transfer boundary layer. In the case of static sodium, the associated transfer coefficient is equal to (2.2 ± 0.8)·10−8 m/s. The proposed kinetic corrosion model estimates an excellent order of magnitude for our measurements of average iron thickness loss. Based on our experimental measurements, calculations lead to a diffusivity of the NaFeO2 complex in static liquid sodium of (1.6 ± 0.6)·10−9 m2/s. The Stokes-Einstein law can then be used to estimate an equivalent complex molecule radius of 2 · 10−9 m. These data, combined with the Stokes-Einstein equation, can be used in industrial applications to simulate the mechanism of iron corrosion in non-isothermal heat transfer loop systems.