Single-phase Liquid Research Articles

Research on the Performance of a Liquid–Solid Triboelectric Nanogenerator Prototype Based on Multiphase Liquid

In recent years, liquid–solid triboelectric nanogenerators (L-S TENGs) have been rapidly developed in the field of liquid energy harvesting and self-powered sensing. This is due to a number of advantages inherent in the technology, including the low cost of fabricated materials, structural diversity, high charge-energy conversion efficiency, environmental friendliness, and a wide range of applications. As liquid phase dielectric materials typically used in L-S TENG, a variety of organic and inorganic single-phase liquids, including distilled water, acidic solutions, sodium chloride solutions, acetone, dimethyl sulfoxide, and acetonitrile, as well as paraffinic oils, have been used in experiments. However, it is noteworthy that the function of multiphase liquids as dielectric materials is still understudied. The “Multiphase Liquid Triboelectric Nanogenerator Prototype (ML-TENG Pro)” presented in this paper takes a single-electrode solid–liquid triboelectric nanogenerator as the basic model and uses lubricating oil and deionized water as dielectric materials. After verifying the stability of single-phase liquid materials (e.g., DI water, seawater, ethanol, etc.) for power generation, the power generation performances of oil–water two-phase, gas–oil–water three-phase (with a small number of bubbles), and gas–oil–water three-phase (with many bubbles) in open space are further investigated. COMSOL Multiphysics 6.0 software was used to investigate the material transport mechanism and formation of oil–water two-phase and gas–oil–water three-phase. Finally, this study presents the power generation performance of ML-TENG Pro in the extreme state of gas–oil–water three-phase “emulsification”. This paper outlines the limitations of the ML-TENG, named PRO, and suggests avenues for future improvement. The research presented in this paper provides a theoretical basis for evaluating the quality of lubricants for mechanical power equipment.

Investigation of the Arrangement of Aluminum Fins on the Thermal Behavior of Lauric Acid as a Phase Change Material in a Two-pipe Heat Exchanger by CFD Simulation

BackgroundPhase change material (PCM) thermal storage systems store more thermal energy per unit volume than sensible heat storage systems. PCMs offer a potential solution to reduce energy consumption in various thermal engineering applications. This study aimed to examine how fin arrangement affected the thermal efficiency and melting time of PCMs. MethodsA two-dimensional numerical analysis of the melting process of lauric acid in a heat exchanger featuring two pipelines and fins was conducted using CFD simulation. In most previous investigations, the heat transfer fluid was a single-phase liquid. An enthalpy-porosity technique was used to model the solid and liquid phases of PCM. The governing equations were solved using the commercial software ANSYS Fluent 2021, and the pressure and velocity equations were coupled using the SIMPLE algorithm. Significant FindingsThe best model among the 13 tested was Model 5, which featured 6 fins and a consistent angle of 60 degrees. For Model 5, the melting time was 1818.3 seconds. Due to sensible heating, the fin's temperature (Temp) rose gradually from 300 K to 318 K. Temp then gradually increased as the PCM melted in the phase transition zone between 316.5 K and 321.2 K. Once the phase transition was complete, the PCM's Temp steadily rose from 324 K to 340 K. In Model 5, the inner wall Temp and the maximum Temp of the PCM were closest, at 327.34 K and 333.55 K, respectively. The thermal shock between the PCM and the ambient Temp caused a peak heat flux at the beginning of the PCM loading process.

Green liquid supra molecular solvent (SUPRA) phase for fast and selective liquid-liquid micro-extraction of Co2+ ions from aqueous samples

The limitation of Liquid-liquid micro-extraction (LLME) procedures can be the need for the use of a dispersive solvent which should be soluble in both of aqueous and organic phases. In this research, a new method named SUPRA-based LLME, is introduced which uses supra molecular solvent (SUPRA), as an environmentally friendly solvent, for quantitative and selective extraction of Co2+ ions from its aqueous solution via liquid-liquid micro-extraction process. The aqueous immiscible SUPRA phase, composed of vesicles of decanoic acid was synthesized via ex-situ procedure and used as a single liquid phase. In order to make the SUPRA phase selective, N, Nʹ-disalicylidene-3, 4-diaminotoluene (H2dst) was synthesized and completely dissolved in the SUPRA phase. Then the lipophilic and selective prepared liquid sorbent, as liquid SUPRA phase, was used for the facile and selective LLME of Cobalt (II) ions from aqueous samples. Experimental studies showed that there was not any need of dispersing solvent and so liquid SUPRA phase could easily dispersed in the aqueous phase and then separated by centrifugation as the supernatant phase. Then the effects of some important variables on the extraction efficiency were also investigated and optimized. The results showed that under optimal conditions, efficient extraction of Cobalt (II) ions was achieved, about 99 % ± 2.7 (n = 10), in a short time of extraction (10 min), and the linear range of calibration curve was from 500 to 2500 μg L−1 of Cobalt(II) with correlation coefficient of 0.999. Also detection limit and pre-concentration factor were 150 μg L−1 and 35.2, respectively. Although the experimental conditions were optimized for extraction of only Co2+ ions, the selectivity study showed a high tendency of selective liquid SUPRA phase toward extraction of both of Co2+ and Ni2+ ions. The matrix effects on the SUPRA-based LLME of Co2+ ions from matrix samples, factory wastewater and sea-water, were studied and least matrix effects were observed.

Streamline rotodynamic pump model for two-phase flow simulation

Abstract This study is concerned with the simulation of water-vapor two-phase flows in pressurized water reactors (PWR) primary pumps. The correct modeling of such flows is essential to predict the consequences of a Loss Of Coolant Accident (LOCA), an accident scenario involving a rupture in the reactor primary circuit. During such accidents, pressure loss leads to important coolant vaporization in the circuits, pumps and other system components. A review of turbomachinery streamline models, used to represent pumps in system codes, is presented. Particular attention is paid to the model used in the CATHARE-3 system code, as its development is the motivation for the present work. Numerical simulations were then performed using CATHARE-3 streamline pump model, currently validated for single-phase liquid flows. These simulations included test cases for pure liquid and vapor conditions, as well as one two-phase flow case, with inlet void fraction of approximately 10 %. For pure liquid water, the agreement is good for discharge between 75% and 150% of nominal discharge. Results are satisfying up to 300% of nominal discharge for the single-phase vapor case. The two-phase results are close to experimental values around 75 and 130 % of nominal discharge. Further work is required in order to consolidate the physical analysis and to improve and validate CATHARE-3 streamline pump model for two-phase flow conditions.

A unifying bubble-layer-based theoretical model for flow boiling and application to a rod bundle

Current analyses of flow boiling primarily utilize two−/three-dimensional numerical simulations or one-dimensional empirical correlations/models. To develop a quasi-two-dimensional theoretical model, a unifying bubble-layer-based theoretical model is proposed, which can be applicable to the entire flow boiling process, from the single-phase liquid flow to the dryout point. This model considers bubble behaviors in each region and heat and mass transfer at the interfaces of two regions, consisting of conservation equations of mass, momentum, and energy, supplemented by a few empirical correlations. A sensitivity analysis of these correlations is conducted, revealing that the slip ratio correlation and bubble condensation rate correlation have the most significant impacts. Using experimental data on void fraction, the most accurate combination of empirical correlations is identified, with a total absolute error of 27.9 %. The verification ranges are 0.1-8Mpa for pressure, 182-1700 kW/m2 for heat flux, 240-2200 kg/m2s for mass flux, 0.83–1.76 for Prandtl number, and 4.4e3–2.98e5 for Reynold number. Finally, this model is applied to the analysis of the NHR200-II rod bundle, revealing the variations of several two-phase parameters under micro-boiling conditions and the influence of operating conditions on the length proportion of different flow sections, serving as important references for analyzing the impact of boiling on reactor reactivity.

Water/oil interfacial photocatalysis of amphiphilic CdS/Bi2WO6 S-scheme heterojunctions for efficient production and spontaneous separation of H2O2 and value-added organics

The photocatalytic co-production of H2O2 and value-added organics in a suitable water/oil biphasic system offers an intriguing strategy to address the challenges encountered in a single liquid-phase solution, including the efficient separation of H2O2 and organic products as well as the mitigation of undesirable secondary reactions. For this, exploring amphiphilic photocatalysts with high performance is highly required. Herein, an amphiphilic CdS/Bi2WO6 S-scheme heterojunction photocatalyst is designedly synthesized through a two-step solvothermal process, aiming to achieve efficient interfacial photocatalytic reactions at the water/oil interface for simultaneous generation and selective separation of H2O2 and organic products. The CdS/Bi2WO6 heterojunction photocatalyst exhibits enhanced light absorption in UV–visible region, increased electron-hole separation efficiency, and powerful charge carriers with high redox abilities. Moreover, the formation of S-scheme heterojunction improves the catalyst stability by preventing CdS from photocorrosion. As a result, the production rate of H2O2 reaches up to 216.76 mmol g−1 h−1, accompanied by the generation of organic products (benzaldehyde: 104.91 mmol g−1 h−1, benzoic acid: 49.88 mmol g−1 h−1, and benzyl benzoate: 38.01 mmol g−1 h−1), in a water/benzyl-alcohol biphasic system under simulated sunlight irradiation. The photocatalytic mechanism is elucidated based on the results of comprehensive experiments and characterizations. This study highlights a rational construction of amphiphilic photocatalysts and their application in organic/water interfacial photocatalytic reactions.

Pressure wave propagation in high viscous magma containing crystals and bubbles

The presence of bubbles and crystals in highly viscous liquid (e.g., glass, magma) has been important for the purpose of both basic and practical viewpoints. In this presentation, especially, we focus on a magma, and investigate theoretically P-wave (i.e., pressure wave) propagation in the magma containing many bubbles. Based on an averaged theory of dispersed multiphase flow, we can regard the mixture of crystals (i.e., solid phase) and melt (i.e., liquid phase) as a single liquid phase, i.e., single non-Newtonian liquid, which is approximated to a Newtonian liquid by using the concept of an effective viscosity composed of various parameters (especially crystals). The system of basic equations for multiphase flow containing the effective viscosity, can be reduced to the KdV-Burgers equation as a nonlinear evolution equation via theoretical approximation based on singular perturbation method. As a result, the effect of fraction of crystals and bubbles on the acoustic characteristics (e.g., waveform evolution, nonlinearity, attenuation) is discussed.

Enhanced Solubility and Miscibility of CO2-Oil Mixture in the Presence of Propane under Reservoir Conditions to Improve Recovery Efficiency

The existence of propane (C3H8) in a CO2-oil mixture has great potential for increasing CO2 solubility and decreasing minimum miscibility pressure (MMP). In this study, the enhanced solubility, reduced viscosity, and lowered MMP of CO2-saturated crude oil in the presence of various amounts of C3H8 have been systematically examined at the reservoir conditions. Experimentally, a piston-equipped pressure/volume/temperature (PVT) cell is first validated by accurately reproducing the bubble-point pressures of the pure component of C3H8 at temperatures of 30, 40, and 50 °C with both continuous and stepwise depressurization methods. The validated cell is well utilized to measure the saturation pressures of the CO2-C3H8-oil systems by identifying the turning point on a P-V diagram at a given temperature. Accordingly, the gas solubilities of a CO2, C3H8, and CO2-C3H8 mixture in crude oil at pressures up to 1600 psi and a temperature range of 25–50 °C are measured. In addition, the viscosity of gas-saturated crude oil in a single liquid phase is measured using an in-line viscometer, where the pressure is maintained to be higher than its saturation pressure. Theoretically, a modified Peng–Robinson equation of state (PR EOS) is utilized as the primary thermodynamic model in this work. The crude oil is characterized as both a single and multiple pseudo-component(s). An exponential distribution function, together with a logarithm-type lumping method, is applied to characterize the crude oil. Two linear binary interaction parameters (BIP) correlations have been developed for CO2-oil binaries and C3H8-oil binaries to accurately reproduce the measured saturation pressures. Moreover, the MMPs of the CO2-oil mixture in the presence and absence of C3H8 have been determined with the assistance of the tie-line method. It has been found that the developed mathematical model can accurately calculate the saturation pressures of C3H8 and/or CO2-oil systems with an absolute average relative deviation (AARD) of 2.39% for 12 feed experiments. Compared to CO2, it is demonstrated that C3H8 is more soluble in the crude oil at the given pressure and temperature. The viscosity of gas-saturated crude oil can decrease from 9.50 cP to 1.89 cP and the averaged MMP from 1490 psi to 1160 psi at 50 °C with the addition of an average 16.02 mol% C3H8 in the CO2-oil mixture.

Nucleation-assisted microthermometry: A novel application to fluid inclusions in halite

Halite deposits have long been utilized for interrogating past climate conditions. Microthermometry on halite fluid inclusions has been used to determine ancient water temperatures. One notable obstacle in performing microthermometric measurements, however, is the lack of a vapor bubble in the single-phase liquid inclusions at room temperature. (Pseudo-) isochoric cooling of the inclusions to high negative pressures, far below the homogenization temperature, has commonly been needed to provoke spontaneous vapor bubble nucleation in the liquid. High internal tensile stress in soft host minerals like halite, however, may induce plastic deformation of the inclusion walls, resulting in a wide scatter of measured homogenization temperatures. Nucleation-assisted (NA) microthermometry, in contrast, employs single ultra-short laser pulses provided by a femtosecond laser to stimulate vapor bubble nucleation in metastable liquid inclusions slightly below the expected homogenization temperature. This technique allows for repeated vapor bubble nucleation in selected fluid inclusions without affecting the volumetric properties of the inclusions, and yields highly precise and accurate homogenization temperatures.In this study, we apply, for the first time, NA microthermometry to fluid inclusions in halite and we evaluate the precision and accuracy of this thermometer utilizing (i) synthetic halite crystals precipitated under controlled laboratory conditions, (ii) modern natural halite that precipitated in the 1980s in the Dead Sea, and (iii) Late Pleistocene halite samples from a sediment core from Death Valley, CA. Our results demonstrate an unprecedented accuracy and precision of the method that provides a new opportunity to reconstruct reliable quantitative temperature records from evaporite archives.

Best-estimate water hammer simulations to avoid the calculation of unrealistically high loads or unphysical pressure and force peaks

For safety-related systems fluid loads due to fluid transients have to be quantified for subsequent structural analyses to ensure their integrity or function, as required. Usually transient fluid loads in pipe systems are determined with one-dimensional water hammer software. For single-phase liquid flow, the method of characteristics (MOC) is often used that gives in this case appropriate results. For the consideration of local vapor bubbles, the MOC is combined with the discrete vapor cavity model (DVC). The DVC model may generate unrealistic pressure spikes due to the calculation of the collapse of multi-cavities in scenarios, where only one vapor bubble should actually occur. The application of a two-phase code may improve the calculation results. One requirement for the latter codes is the ability to calculate the propagation of steep gradients without suffering from numerical diffusion to exclude the underestimation of fluid loads. This is commonly attained by applying higher-order numerical schemes. However, the application of a numerical method of pure 2nd order leads to the calculation of unphysical oscillations at steep gradients causing severe problems during the solution. To exclude this, numerical methods with flux limiters can be used. With their application, the calculation of unrealistically high loads due to numerical deficiencies can be minimized. In addition, the consideration of further physical effects, that lead to the reduction of loads during transient flow processes, allows for a more realistic calculation of the loads. These are unsteady friction, widening of the pipe caused by pressure increase, fluid-structure interaction at junctions and due to friction, degassing of gas that is initially dissolved physically in a liquid and thermodynamic non-equilibrium during vapor bubble collapse. The in-house code DYVRO applies a second-order accurate scheme with flux limiters based on the Godunov method and can account for the above-described physical phenomena. It is shown by comparison of calculation results obtained by DYVRO with experimental data from literature that with modeling of these physical effects the loads can be calculated more realistically. Generally, these loads are lower than the results calculated by simplified models, which do not account for these effects. Considering that these loads are applied in subsequent structural analyses, cost-intensive oversizing of pipes and their supports can be avoided, by ensuring the necessary safety.

Phase equilibria of CaO–Al2O3–CaO·TiO2 system at 1500 °C in hydrogen atmosphere

The phase diagram of CaO–Al2O3-TiOx system is of great importance in guiding the design of metallurgical slag systems for Al–Ti alloy steel, controlling Ti-bearing inclusions in molten steel, and regulating the mineral phase of vanadium-titanium magnetite. In the present work, the high temperature equilibration-quench technique was adopted, and the types and compositions of equilibrium phases were identified by Electron Probe Micro Analysis (EPMA) and X-ray diffraction (XRD). The isothermal section of CaO–Al2O3–CaO·TiO2 system at 1500 °C in H2 atmosphere was constructed for the first time. There are 7 three-phase fields, 10 two-phase fields, and a single liquid phase field. On this basis, according to the theoretical analysis of the crystal structure, the formation energy analysis based on first-principles calculations, and the related theories of defect chemistry, the formation mechanisms of CaTiO3 and Ca3Ti2O7 solid solution with were determined, respectively. Additionally, the experimental phase diagram was utilized to discuss the dissolution type and the equilibrium solubility of typical inclusions (Al2O3, Ti3O5, and CaO·TiO2) in Al–Ti alloy steel.

What Phenomena Happen During Pyrolysis of Plastic? FTIR AND GC-MS Analysis of Pyrolyzed Low Linear Density Polyethylene (LLDPE) Polymer Particles Completed with Bibliometric Research Trend and Pyrolysis Chemical Reaction Mechanism

This research aims to determine the compounds produced from the pyrolyzed Low Linear Density Polyethylene (LLDPE) using Fourier Transform Infrared (FTIR) and Gas Chromatography-Mass Spectroscopy (GC MS). We used pyrolysis of 985 g of 2-mm diameter LLDPE plastic ore at a temperature between 192-194°C for 135 min using a batch reactor (length x width x height = 35 cm x 24 cm x 44 cm) equipped with an outlet connected to two condensers (24°C). To ensure the chemical results, the reactor was connected in series to condensers 1 and 2. The results obtained in condenser 1 were 3 mL of 2-phase liquid with a strong odor. The upper fluid is yellow, and the lower fluid is brown. In condenser 2 (connected directly to condenser 1), 4 mL of yellow single-phase liquid was produced with a strong odor. The liquid obtained from the pyrolysis process was then analyzed by FTIR and GC-MS. FTIR results on both samples showed that the samples contained the functional groups O-H, CH₂, and C=O. The GC-MS results on condenser sample 2 showed that the pyrolysis product contained acetone compounds. This confirmed that pyrolysis caused chemical structural changes in LLDPE due to LLDPE chain bond-breaking reactions, producing many smaller chemical compounds. Additionally, some oxidation happens, which is due to the oxygen content in the reactor. This study provides new insights into the LLDPE pyrolysis mechanism and the physical and chemical properties of the liquid resulting from the pyrolysis process.

Localized oxygen evolution and transport analysis in PEM water electrolysis on local static pressure, temperature and current density

With the escalating severity of the global climate crisis and the strengthening global demand for carbon neutrality, hydrogen produced from renewable energy offers a pathway towards achieving carbon neutrality. To reduce the cost of eco-friendly hydrogen production, we need to increase the current density in proton exchange membrane water electrolysis for green hydrogen production, a promising technology. One problem arising from an increase in current density is that it leads to a significant generation of oxygen, resulting in mass transfer losses. However, there have been few studies on oxygen transport near the anode catalyst layer, with most studies only measuring current density. In this study, local static pressure and temperature were measured in real-time to elucidate the relationship between voltage and current. At 2.1 V (corrected voltage = 2.03 V), the static pressure amplitude is approximately −5 to 5 kPa. At 2.55 V (correction voltage = 2.41 V), it decreased by about 50 % to about −2.5 to 2.5 kPa, and the frequency became faster. With increasing voltage, the decrease in static pressure amplitude and the increase in frequency occur because oxygen rapidly increases in the catalyst layer, resulting in a reduction in residence time. At 1.65 V (corrected voltage = 1.63 V), there is little change in local static pressure, indicating the dominance of the liquid single phase. At 3.6 V (corrected voltage = 3.05 V), there is little change in local static pressure. This is due to the rapid detachment of oxygen bubbles, leading to the dominance of the gas single phase. This elucidates how oxygen bubbles are influenced by fluctuations in local static pressure, leading to the conclusion that efficient design patterns for future anode flow fields can be achieved.

Study of the energy calibration of the DEAP-3600 detector using Na-22 source data and simulations

DEAP-3600 is a single-phase liquid argon (LAr) direct-detection dark matter experiment, operating 2 km underground at SNOLAB (Sudbury, Canada). The detector consists of 3.3 tons of LAr contained in a spherical acrylic vessel. At WIMP mass of 100 GeV, DEAP-3600 has a projected sensitivity of 10-46 cm2 for the spin independent elastic scattering cross section of WIMPs. Radioactive sources have been used for the energy calibration and to test the detector performance. One of the most effective calibration run has been taken with a 22Na source deployed in a tube located around the DEAP-3600 steel shell. The simultaneous emission of three γs by the source provides an excellent tagging for the 22Na decay. The results concerning the energy response of the detector and the agreement between data and Monte Carlo simulations in DEAP-3600 are investigated in this study.

Geology and ore fluids geochemistry of the Hamzeh–Gharanin orogenic gold deposit, NW Iran

The Hamzeh–Gharanin gold deposit (HGD) is located in the Qolqoleh–Kasnazan shear zone in the northwest of Sanandaj–Sirjan Zone (SSZ) and 40 km SW of Saqez. The main rock units are an assemblage of the Precambrian metasedimentary (pelitic) rocks and the Cretaceous phyllite associated with marble interlayers. The post–Cretaceous intrusive granitoids with NW–SE trends intruded within these two units. Mineralization occurs mainly within the NE–SW extensional veines and veinlets in proto–mylonitic, mylonitic and ultra–mylonitic rocks. Hydrothermal alterations consist of sericitization, carbonatization, silicification and chloritization. The main ore minerals include pyrite, chalcopyrite, arsenopyrite, pyrrhotite, sphalerite, galena, gold, magnetite and hematite. The fluid inclusions study from quartz minerals associated with the mineralization shows four different phases: single vapor phase (V; type I), single liquid phase (L; type II), liquid–vapor biphasic (LV; type III) and three phases (LLV; type IV). Microthermometric studies were performed on types III and IV of fluid inclusions. Homogenization temperatures (Th) for Types III and IV inclusions vary between 138 and 310 °C (mean 230 °C) and 250–335 °C (mean 300 °C) and their salinity varies between 0.52 and 13.87 and 4.79 to 9.58 (wt% NaCl), respectively. Moreover, the density of Types III and IV inclusions vary from 0.71 to 0.927 g/cm3 and 0.700–0.870 g/cm3, respectively. The oxygen (in quartz: 4.58–7.80 ‰; mean 5.82 ‰) and δ34S (in pyrite: 5.54–6.28 ‰; mean 5.91‰) isotope compositions of the mineralizing fluids indicate an insignificant meteoric water input during hydrothermal evolution and a magmatic origin of sulfur in the deposit which is broadly similar to those of orogenic gold deposits worldwide.

Liquid-Liquid equilibrium measurements analysis of synthetic multicomponent solvent (n-Pentane, n-Hexane, n-Heptane, Cyclo-Hexane, Toluene)/Bitumen System: Implications for solvent-aided in-situ bitumen extraction

Understanding the Liquid-Liquid Equilibrium (LLE) of multicomponent solvent/bitumen systems is pivotal in optimizing in-situ bitumen extraction. While Vapor-Liquid Equilibria (VLE) of solvent-bitumen systems has been extensively studied, LLE data and predictive models for these mixtures, especially those involving synthetic multicomponent solvents, are scarce. This study provides comprehensive LLE measurements of bitumen and a multicomponent synthetic solvent (n-pentane + n-hexane + n-heptane + cyclo-hexane + toluene) conducted under controlled equilibrium conditions at temperatures of 295 to 352 K, solvent concentrations up to 70 wt% at 1.291 MPa. Application of common correlation used in the construction of solvent-aided process fluid models exhibited average absolute relative deviations (AARDs) of 0.37 % for density and 8.87 % for viscosity. We identified the boundaries marking the shift from homogenous single-phase liquid to two-phase (LLE) states, which occurs within the synthetic multicomponent solvent concentration range of 50 to 60 wt%. We also successfully constructed calibration curves to measure solvent concentrations in both phase regions. The molecular weight distribution and saturates, aromatics, resins, and asphaltene (SARA) fractionation of both liquid phases were determined, highlighting that the heavy liquid phase is primarily asphaltene (∼46 wt%). The insights gained from the measurements and analysis find applications in designing and optimizing solvent-assisted thermal recovery processes for bitumen extraction.

Toward the eco-friendly cosmetic cleansing assisted by the micro-bubbly jet.

While numerous types of chemical cosmetic cleansers have been presented, those with sensitive skin may still experience some irritation while using them. Moreover, the environmental issue of chemical agents has been documented repeatedly. To address these, we suggest the potential application of a micro-sized bubble-laden water jet to cleanse the cosmetics without (or less) using chemical detergents. We devised a venturi-type nozzle with a mesh and air holes capable of generating massive fine bubbles. By testing with the foundation and lip tint (known to be highly adhesive) coated on the synthetic leather and artificial skin surfaces, we measured that the cleansing performance of the bubbly jet is much better (even without the chemical agent) than the single-phase liquid jet. As a mechanism for enhanced removal, it is understood that the greater kinetic energy of the jet due to the acceleration of the effective liquid-air mixture flow and the direct bubble-cosmetic collisions play essential roles. We believe that the present results will spur the development of environment-friendly cleaning methods.

Experimental and numerical investigation on heat transfer analysis of square slotted pin-fin heat sinks

This paper introduces two novel designs of pin-fin heat sink (PHFS), namely the inline slotted pin-fin (ISP) and the V-shaped slotted pin-fin (VSP), to address rapid heat dissipation for one central/graphics processing unit (CPU/GPU) in a single-phase liquid cooling system. Experimental and numerical investigations are conducted to observe the effect of heat transfer for non-slotted and slotted pin-fin heat sinks under different Reynolds numbers (225-720) and heating powers (90-120 W). Parameters such as average wall temperature, Nusselt number, thermal resistance, pressure drop, and hydrothermal performance factor are evaluated. Comparative analyses show that the slotted pin-fin heat sinks exhibit higher Nusselt numbers (Nu) and lower thermal resistance (Rth) levels than that in the non-slotted pin-fin heat sinks, particularly at lower Reynolds numbers. At the Reynolds number 225 and power of 120 W, the inline and V-shaped slotted pin-fin heat sinks experience a 13.98% and 19.69% increase in Nu and a 12.65% and 15.41% reduction in Rth compared to the non-slotted one, respectively. The V-shaped slotted pin-fin heat sink achieves more than 5 ∘C reduction in the maximum wall temperature than the non-slotted one. The slotted structure reduces pressure drop losses by minimizing dead flow areas on one hand. On the other hand, the inclined slots generate vortices behind the fins, increase shear-induced mixing and thus improve the force convection cooling performance.

Flow transitions and effective properties in multiphase Taylor–Couette flow

The properties of multiphase flows are challenging to measure, and yet effective properties are fundamental to modelling and predicting flow behaviour. The current study is motivated by rheometric measurements of a gas-fluidized bed using a coaxial rheometer in which the fluidization rate and the rotational speed can be varied independently. The measured torque displays a range of rheological states: quasistatic, dense granular flow behaviour at low fluidization rates and low-to-moderate shear rates; turbulent toroidal-vortex flow at high shear rates and moderate-to-high fluidization rates; and viscous-like behaviour with rate-dependent torque at high shear rates and low fluidization or at low shear rates and high fluidization. To understand the solid-like to fluid-like transitions, additional experiments were performed in the same rheometer using single-phase liquid and liquid–solid suspensions. The fluidized bed experiments are modelled as a Bingham plastic for low fluidization rates, and as a shear-thinning Carreau liquid at high fluidization rates. The suspensions are modelled using the Krieger–Dougherty effective viscosity. The results demonstrate that, by using the effective properties, the inverse Bingham number marks the transition from solid-like to viscous-flow behaviour; a modified gap Reynolds number based on the thickness of the shear layer specifies the transition from solid-like to turbulent vortical flow; and a gap Reynolds number distinguishes viscous behaviour from turbulent vortical flow. The results further demonstrate that these different multiphase flows undergo analogous flow transitions at similar Bingham or Reynolds numbers and the corresponding dimensionless torques show comparable scaling in response to annular shear.

Effect of TiO2 addition on microstructure and mechanical properties of Al2O3 ceramic joints brazed with Ag‐CuO fillers

AbstractIn our work, 0.5 mol.% TiO2 was added to Ag‐xCuO (x = 2, 4, 8 mol.%) fillers whose compositions at 1050°C were in the L2 single liquid phase region, the boundary of the miscible phase region, and the L1+L2 miscible phase region, respectively. The role of TiO2 was derived by comparing the quenching microstructure of the fillers on the Al2O3 ceramics and the effect on the interfacial microstructure and shear strength of the joints before and after the addition of TiO2. The results showed that the TiO2 would dissolve into the CuO‐rich L1 liquid phase of the filler, leading it to spread outside the molten droplet. When brazing with Ag‐4CuO‐0.5TiO2 filler, the CuO at the joint interface almost completely disappeared, and the shear strength of the joint was significantly reduced. In contrast, the joint strength showed a small increase when using Ag‐8CuO‐0.5TiO2 filler, as the excess CuO at the interface of the brazed joint was reduced. When the filler composition was in the L2 single liquid phase region, CuO was diffusely distributed throughout the molten droplet. TiO2 was hardly contacted with CuO and its addition had no significant effect on the interfacial microstructure and the shear strength of the joints.