Conductivity Of Fluid Research Articles

Measurement of a radial flow profile with eddy current flow meters and deep neural networks *

Eddy current flow meters (ECFMs) measure flows of conductive fluids. Recent interest in ECFMs has increased due to applications in advanced nuclear reactors. ECFMs are well suited for such applications, as they can provide non-invasive measurements of flow in fluids that are often difficult to measure. Traditionally, ECFMs are operated using an alternating current at a single frequency, limiting ECFMs to measure average fluid velocities, blockages, or voids. We expand the capabilities of ECFMs by measuring the fluid radial velocity profile of liquid mercury. To accomplish this, we made several ECFM sensitivity measurements at a range of frequencies. Different frequencies vary the electromagnetic skin depth of the device. By adjusting frequencies, we probed the fluid velocity at various radial locations and constructed a flow-velocity profile. The relationship between the ECFM measurements and velocity profile is nonlinear and requires solving an inverse problem. Using electromagnetic finite-element simulations to train a deep neural network (DNN), we created a model that provides a stable general relationship between the sensitivity measurements of an ECFM and the fluid velocity profile. Using ECFM measurements of liquid mercury, our DNN model calculates a flow profile that agrees well with computational fluid dynamics (CFD) simulations. This technique has potential to improve flow monitoring for optimization, safe operation of conductive fluid loops, and/or validating complex CFD models.

Irreversibility Marangoni Tri-Hybrid Nanoflow Analysis for Thermal Enhancement Applications.

Increasing heat transfer is an important part of industrial, mechanical, electrical, thermal, and biological sciences. The aim of this study is to increase the thermal competency of a conventional fluid by using a ternary hybrid nanofluid. A magnetic field and thermal radiation are used to further improve the thermal conductivity of the base fluid. Irreversibility is analyzed under the influence of the embedded parameters. The basic equations for the ternary hybrid nanofluids are transformed from Partial Differential Equations (PDEs) to Ordinary Differential Equations (ODEs) using the similarity concept. The Marangoni convection idea is used in the mathematical model for the temperature difference between the two media: the surface and fluid. The achieved results are provided and discussed. The results show that ternary hybrid nanofluids are more suitable as heat-transmitted conductors than conventional fluids.

A Review on Non-Invasive Magnetic and Electric Field Excited Methods for Flow Characterisation of Incompressible Newtonian Low Conductive Liquids

Monitoring the flow rate of low conductive fluid is critical in sectors such as waste, culinary, chemical, pharmaceutical, oil and gas, and power. The flow meter can be used to measure several parameters like flow rate range, fluid electrical conductivity, cost and the scenario of desired monitoring. The existing invasive flow sensors for monitoring the velocity of conductive fluid are often associated with undesirable attributes of being obstructive, prone to interference effects, corrosion, significant pressure reduction, and energy loss in pipe systems causing severe and long-term damage to pipes during installation. This paper presents a comprehensive survey of various non-invasive methods for characterizing low conductive fluid flow based on the sources of strong magnetic and electric fields. This review discusses fundamental insights for understanding the physical phenomenon in the generation of eddy currents, Lorentz force, and the formation of the electric double layer with pertinent illustrations and discussions. The review presented in this paper concludes that each non-invasive measurement technique has limitations based on the excitation source of either magnetic or electric fields. Different values of low conductivity of fluid flow and flow velocity have been considered in various studies to get an in-depth understanding of the capability of selected techniques so that their scope and versatility can be researched further. This paper also highlights that emerging technologies like cryostats with superconducting magnet systems, which unquestionably exceed the mass limitation, have become viable in applications such as Lorentz force velocimetry.

Electrochemical Properties and Local Structure of the TEMPO/TEMPO+ Redox Pair in Ionic Liquids.

Redox-active organic species play an important role in catalysis, energy storage, and biotechnology. One of the representatives is the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical, used as a mediator in organic synthesis and considered a safe alternative to heavy metals. In order to develop a TEMPO-based system with well-controlled electrochemical and catalytic properties, a reaction medium should be carefully chosen. Being highly conductive, stable, and low flammability fluids, ionic liquids (ILs) seem to be promising solvents with easily adjustable physical and solvation properties. In this work, we give an insight into the local structure of ILs around TEMPO and its oxidized form, TEMPO+, underlining striking differences in the solvation of these two species. The analysis is coupled with a study of thermodynamics and kinetics of oxidation in the frame of Marcus theory. Our systematic investigation includes imidazolium, pyrrolydinium, and phosphonium families combined with anions of different size, polarity, and flexibility, opting to provide a clear and comprehensive picture of the impact of the nature of IL ions on the behavior of radical/cation redox pairs. The obtained results will help to explain experimentally observed effects and to rationalize the design of TEMPO/IL systems.

Evaluation of flow field design effects on proton exchange membrane fuel cell performance

Fluid distribution, conduction, and heat control are important phenomenon in the fuel cell fraternity, therefore it is crucial to develop a state-of-the-art bipolar plate (BP) to attain optimum cell performance. Metal foam (MF) and fine mesh have attracted a lot of attention in mitigating some of the challenges associated with straight, and serpentine channels. In this study, MF, 3D fine mesh, fine wire mesh (FWM) flow fields are compared with triple serpentine flow field to develop an optimum design for improved PEMFC performance. Two different foam designs are studied to attenuate the existing drawback associated with MF, mainly caused by high water retention. The 3D fine mesh is leading in performance under anodic and cathodic stoichiometry of 1 and 3 respectively. On increasing the anodic and cathodic stoichiometry to 1.2 and 3.5 respectively, the FWM took the lead. This is brought by the improved water drainage under high stoichiometry. Because FWM is already in mass production, although for other purposes, it is cost competitive over the other designs. The fine mesh and the MF have the potential to break down large water droplet making them easy to drain. They also showed symmetric fluid flow, compared to the serpentine design.

Fluid-assisted one-step fabrication of fused deposition molding 3D printing parts with conductive networks and gradient functionalities

The steps of preparing fused deposition molding (FDM) 3D printing conductive materials by melt-compounding are cumbersome, and the addition of fillers degrades the bulk properties of the materials, which limits the promotion and application of FDM 3D printing conductive materials. The FDM 3D printing conductive parts can be prepared by embedding conductive fillers on the surface of the printing filaments or parts, but available preparation methods are difficult to accomplish in one step. Herein, we introduce a facile method of one-step preparation of conductive parts by fluid-assisted FDM 3D printing. In this method, a thin tube transports conductive fluid, loads conductive carbon nanotubes (CNTs) onto the surface of molten polycaprolactone (PCL) filaments at the nozzle, and forms the CNT layers to prepare conductive parts in one step. The SEM and Raman results show that the CNTs are embedded on the surface of the PCL filaments. The sample can obtain a conductivity of 4.24 S m−1 loading only 4 mg CNTs. It also revealed that the preparation method has little effect on the mechanical properties of the FDM 3D printed PCL parts. The results exhibited that the as-proposed one-step preparation of conductive parts by fluid-assisted 3D printing could provide a new method for FDM 3D printing and fabricating high-performance parts, which has great potentials in various fields.

Modeling of anomalous gas transport in heterogeneous unconventional reservoirs using a nonlinear generalized diffusivity equation

Exploitation of unconventional reservoirs is enabled by multi-fractured horizontal wells. Hydraulic fractures are created with the purpose of enhancing fluid conductivity in such low permeability formation. These hydraulic fractures, along with the intricate structure of the reservoir, such as the presence of natural fractures, result in a highly heterogeneous system and introduces significant challenges with respect to obtaining a proper description of fluid movement. This paper proposes the use of anomalous transport concept based on fractional-time derivative to model gas flow through highly heterogeneous unconventional reservoirs. A modified Darcy’s law that accounts for non-local temporal effects, i.e. history, is adopted to account for the complex flow mechanisms encountered in such disordered media with a wide range of heterogeneity scales. Studies previously developed on this topic solely focused on slightly-compressible fluid transport without further consideration of the nonlinear dependency of fluid properties to pressure. In this regard, the development of predictive models simultaneously considering reservoir heterogeneity and the nonlinear nature of gas transport is yet to be accomplished. In this work, transient pressure diffusion is modeled by the so-called nonlinear Generalized Diffusivity Equation (nGDE), and an integral solution is derived based on Green’s function method. It is observed that for the cases of higher heterogeneity level, higher pressure drawdown is required to maintain a given specified (constant) rate, significantly increasing the deviation of the system response from its linear (slightly-compressible) behavior. This finding corroborates the importance of properly accounting for the nonlinear behavior of gas properties and highlights that available analytical solutions suffer drawbacks when extrapolated to compressible flow scenarios.

A correlation of conductivity medium and bioparticle viability on dielectrophoresis-based biomedical applications.

Dielectrophoresis (DEP) bioparticle research has progressed from micro to nano levels. It has proven to be a promising and powerful cell manipulation method with an accurate, quick, inexpensive, and label-free technique for therapeutic purposes. DEP, an electrokinetic phenomenon, induces particle movement as a result of polarization effects in a nonuniform electrical field. This review focuses on current research in the biomedical field that demonstrates a practical approach to DEP in terms of cell separation, trapping, discrimination, and enrichment under the influence of the conductive medium in correlation with bioparticle viability. The current review aims to provide readers with an in-depth knowledge of the fundamental theory and principles of the DEP technique, which is influenced by conductive medium and to identify and demonstrate the biomedical application areas. The high conductivity of physiological fluids presents obstacles and opportunities, followed by bioparticle viability in an electric field elaborated in detail. Finally, the drawbacks of DEP-based systems and the outlook for the future are addressed. This article will aid in advancing technology by bridging the gap between bioscience and engineering. We hope the insights presented in this review will improve cell suspension medium and promote DEP-viable bioparticle manipulation for health-care diagnostics and therapeutics.

A three-dimensional thermal-hydro-mechanical coupling model for simulation of fracturing driven by multiphysics

Geothermal mining, nuclear waste disposal, and other projects involve rock fracturing under the multiphysics effect. There is an urgent need for a numerical analysis tool that can consider both thermal-hydro-mechanical coupling (THM) effects and rock fracturing to analyze such projects. This paper presents a three-dimensional thermal-hydro-mechanical coupling model that can consider rock fracturing, which incorporates the advantages of the combined finite discrete element method (FDEM) for simulating fracture and fragmentation. The 3D thermal-hydro-mechanical coupling model includes three parts: fracture-pore mixed seepage model, heat transfer model (including heat conduction in solid and fluid, heat advection, heat exchange between solid and fluid), and FDEM fracture mechanics calculation model. Some examples with the analytical solution for seepage, hydromechanical, thermal–mechanical, hydrothermal, and thermal-hydro-mechanical coupling problems are used to verify the correctness of the FDEM based 3D THM model in detail. In addition, an example of rock fracturing caused by the thermal-hydro-mechanical coupling effect is also given. The simulation results show that the FDEM based 3D thermal-hydro-mechanical coupling model can simulate the complex fractures initiation, propagation, and extension caused by multiphysics effects, such as heat, fluid, and mechanics.

THERMAL CONDUCTIVITY, RHEOLOGY AND ELECTRICAL CONDUCTIVITY OF WATER AND ETHYLENE GLYCOL BASED NANOFLUIDS WITH COPPER AND ALUMINUM PARTICLES

Nanoparticles are mesoobjects that occupy an intermediate position in size between ordinary molecules and macroscopic particles. Suspensions with nanoparticles, called nanofluids, are also specific mesoscopic suspensions. Today it is known that their thermophysical and mechanical properties are not described by classical theories. The unusual properties of these dispersed fluids make them extremely popular in a wide variety of applications. However, successful use of nanofluids involves the prediction of their properties, which in turn requires systematic studies. This paper presents an experimental study on the thermophysical properties of water and ethylene glycol based nanofluids with aluminum and copper particles. The thermal conductivity, rheology and electrical conductivity of nanofluids were systematically studied. The weight concentration of nanoparticles varied from 2.5 to 20%. It was shown that the thermal conductivity of these nanofluids significantly exceeds that of nanofluids with oxide particles. Its higher values are determined by the size of the nanoparticles and the thermal conductivity of the base fluid. The nanofluids studied are either pseudoplastic or viscoplastic. Their rheology is determined by the concentration and size of nanoparticles. The smaller the size of nanoparticles and the higher their concentration, the more likely the change in rheology is. Correlation curves were constructed for the rheological parameters of nanofluids versus the concentration and size of nanoparticles. It was found that the electrical conductivity of nanofluids increases almost linearly with increasing nanoparticle concentration and strongly depends on the nanoparticle size. The electrical conductivity mechanisms of nanofluids were discussed. The speed of sound in a nanofluid and its dependence on particle size were measured.

Recent advances in thermal conductivity and thermal applications of graphene and its derivatives nanofluids

• Seven factors should be considered in the study of graphene thermal conductivity. • Significant research gap exists in factors of graphene thermal conductivity. • Positive and negative effects both exist when graphene nanofluids are applied. • Economics and environment must be considered in application of graphene nanofluids. • More thermal studies on the graphene nanofluids are warranted. With the rapid development of industrial technology, more and more high-power-consumption devices are utilized, resulting in significant challenges to the durability, reliability, and efficiency of devices, facilities, and systems. Developing efficient thermal management systems for high power consumption application scenarios has evolved as a prominent research topic. Graphene nanomaterials are suitable candidates for nanofluids because of their excellent physical properties and high thermal conductivity. Although there are many studies on graphene nanofluids, there is no comprehensive review article about the influencing factors of thermal conductivity and the applications of graphene nanofluids, especially in economic and environmental analysis. This paper reviews the influencing factors of the graphene nanofluid thermal conductivity, including temperature, nanoparticle size and shape, base fluid, concentration, pH, surface modification, and ultrasonication. Moreover, the applications of graphene nanofluids in heat pipes, heat exchangers, solar collectors, and pool boiling devices are presented. Their applications are also discussed in terms of economics and the environment. In addition, the findings of thermal research on graphene nanofluids are summarized, and available opportunities and challenges are demonstrated. It is concluded that graphene nanomaterials significantly improve the thermal conductivity of the base fluid by 1.2% to 83.4%. Graphene nanofluids significantly improved the performance of thermal management devices. This comprehensive review is necessary to promote the research and effective application of graphene nanofluids in the context of sustainable development and carbon neutrality.

Competing effects of buoyancy-driven and electrothermal flows for Joule heating-induced transport in microchannels

Ionic fluids subjected to externally applied electric fields experience Joule heating, which increases with the increased electric field and ionic conductivity of the medium. Temperature gradients induced by Joule heating can create buoyancy-driven flows produced by local density changes, as well as electrothermal transport due to the temperature-dependent variations in fluid permittivity and conductivity. This manuscript considers Joule heating-induced transport in microchannels by a pair of electrodes under alternating current electric fields. Resulting buoyancy-driven and alternating current electrothermal (ACET) flows are investigated theoretically, numerically and experimentally. Proper normalizations of the governing equations led to the ratio of the electrothermal and buoyancy velocities, as a new non-dimensional parameter, which enabled the construction of a phase diagram that can predict the dominance of ACET and buoyancy-driven flows as a function of the channel size and electric field. Numerical results were used to verify the phase diagram in various height microchannels for different ionic conductivity fluids and electric fields, while the numerical results were validated using the micro-particle-image velocimetry technique. The results show that ACET flow prevails when the channel dimensions are small, and the electric potentials are high, whereas buoyancy-driven flow becomes dominant for larger channel heights. The present study brings insights into Joule heating-induced transport phenomena in microfluidic devices and provides a pathway for the design and utilization of ACET-based devices by properly considering the co-occurring buoyancy-driven flow.

Topological nature of the Parker magnetostatic theorem

The two-plate initial boundary-value problem of Parker is reviewed, treating the relaxation of a 3D magnetic field prescribed with an arbitrary topology to a terminal force-free field in a cold, viscous, electrically perfect fluid conductor. Anchored by their foot-points at the perfectly conducting rigid plates, the relaxing field preserves its topology. The Parker magnetostatic theorem states that for most prescribed field topologies, the terminal field must embed current sheets. The elements of this theorem are reviewed and analyzed to relate this initial boundary-value problem to (i) the variational problem for a force-free field of a given topology and (ii) the direct construction of a force-free field in terms of its pair of Euler flux functions. New insights and understanding are presented on the theorem as the compelling basis of the Parker theory of solar coronal heating.

ТЕЧЕНИЕ ГАРТМАНА В СЛОЕ ЖИДКОСТИ С ПРОСТРАНСТВЕННО НЕОДНОРОДНЫМИ СВОЙСТВАМИ

In this study we consider the flow of a spatially-inhomogeneous electrically conductive fluid between parallel planes in a transverse magnetic field. The distributions of electrical conductivity and viscosity of the fluid are given by linear functions. The slopes of these distributions characterize the maximum deviation of the fluid properties from their mean values. We show that inhomogeneity of the fluid properties leads to distortion of the velocity profiles. The resulting profiles are asymmetric and have inflection points. We use a quantity equal to the ratio of flow rates in the upper and lower halves of the layer as a quantitative measure of asymmetry. We determine the relationship between this quantity, the average Hartmann number, and the parameters of the distributions of inhomogeneous properties. We show that starting from a relatively small mean Hartmann number, the inflection points in the velocity profiles appear for any values of the distribution parameters. We provide estimates of characteristic temperatures and concentrations of non-conducting impurity for liquid sodium, at which the described effects appear.

A short & updated review of nanofluids utilization in solar parabolic trough collector

The world is facing a crisis of energy because fossil fuels are depleting day by day. The growth of any country mainly depends upon 3Es namely energy, economy and environment. These are the three pillars of sustainability also. The ejaculation of greenhouse gases is also the ultimatum for the world. The major constituent of greenhouse gas is CO2 and it increased rapidly in the last decade which increases the earth's temperature very rapidly. The problem of the energy crisis as well as greenhouse gas emissions from oil and coal-based energy sources can be overcome by the utilization of renewable sources of energy such as solar, wind, hydro, tidal and many more. The sun is the primary source of energy on earth since it is readily available, cost-free, and has no negative effects on the environment. Without emitting greenhouse gases, solar energy can be transformed directly into thermal energy in the form of heat and then into electrical energy. The main obstacle in the utilization of solar energy is the enhancement of heat transfer rate which can be overcome by utilizing a high thermal conductivity fluid known as nanofluid. In the present study progress of nanofluid utilization in solar parabolic trough collectors are reviewed. The effects of various variables such as volume fraction, the flow rate of mass, thermal conductivity and rate of heat transfer are reviewed. The effects of nanofluid utilization for enhancement of efficiency, exergy and pressure drop in PTC are also reviewed.

Transition of natural convection of liquid metal in an annular enclosure under a magnetic field

Natural convection of a low-Prandtl-number conductive fluid driven by a horizontal temperature gradient in an annular enclosure with a square cross section was investigated. The surface temperatures of the inner and outer cylinders were differentially maintained. A static magnetic field was applied in the azimuthal direction. A three-dimensional (3D) numerical simulation was performed for a part of an annulus divided into 20 or 28 equal parts. The natural convection found changes on the order of a two-dimensional (2D) steady, a 3D steady, a 3D non-half-symmetric simply periodic oscillatory, a 3D indefinite oscillatory, a 3D half-symmetric simply periodic oscillatory, and a 3D aperiodic oscillatory flow as the Hartmann number decreases. This transition pattern is identical to that as the Rayleigh number increases in the same system without a magnetic field. In high Rayleigh numbers, the transition is accompanied by an axisymmetric oscillation. A disturbance causing the transition consists of three modes as a 3D steady, a 3D half-symmetric oscillatory, and a 2D axisymmetric oscillatory mode. The Nusselt numbers in most 3D flows are smaller at low Rayleigh numbers and larger at high Rayleigh numbers than that in 2D flows at a same condition, while the kinetic energy of a 3D flow is necessarily smaller than that of a 2D flow.

Chaotic dynamics of magnetic fields generated by thermomagnetic instability in a nonuniformly rotating electrically conductive fluid

Chaotic dynamics of magnetic fields generated by thermomagnetic instability in a nonuniformly rotating electrically conductive fluid

The Effect of Pseudofrazil Particle Entrainment on Salinity Measurements

AbstractSalinity effects of particles entrained into conductivity cells have previously mainly been studied in the context of suspended sediment. Particles influencing conductivity cells can also be small ice crystals (frazil) that may form in supercooled water. The detection of supercooled water depends on accurate, high precision temperature, salinity and pressure measurements. As it is currently not possible to measure salinity in situ, the standard procedure is to measure conductance over a known volume and calculate salinity. Frazil ice entrained into a conductivity cell changes the volume of conductive fluid in the conductivity cell, thus changing the conductivity, salinity and supercooling measurements. We present results on the effect of entraining microplastic into a Sea‐Bird Electronics conductivity cell to simulate the effect of frazil. We show that particle volumes comparable to frazil volumes observed in the ocean change the measured conductivity and led to changes in calculated supercooling between 0.3 and 10 mK, possibly up to the same order of magnitude as naturally observed supercooling in the ocean. Further, we demonstrate that where supercooling is present, natural frazil ice concentrations can have an appreciable effect on parameters calculated with both the Equation of State of Seawater 1980 and Thermodynamic Equation of Seawater 2010 equations of state of seawater. Thus, to ensure accurate measurements in locations of very high frazil concentration, the entrainment of frazil needs to be prevented, which is not possible with methods currently available, or corrected for. An example for such a correction is given and could be modified to be applicable to other particles, for example, sediment.

Clinical Effects of Sacubitril/Valsartan Combined with Dapagliflozin in Patients with Diabetes and ST-segment Elevation Myocardial Infarction

Objectives: This study was aimed at observing the clinical effects of sacubitril/valsartan combined with dapagliflozin on cardiac function and ventricular remodeling in patients with type 2 diabetes and ST-segment elevation myocardial infarction (STEMI). Methods: Between May 2019 and May 2022, we retrospectively analyzed 57 patients with diabetes and STEMI receiving percutaneous coronary intervention: 32 patients receiving sacubitril/valsartan and dapagliflozin tablets comprised the observation group and 25 patients receiving angiotensin converting enzyme inhibition (ACEI) or angiotensin receptor blockers ARB) in combination with other hypoglycemic drugs comprised the control group. We compared the left ventricular end diastolic diameter (LVEDD), right ventricular end diastolic diameter (RVEDD), left ventricular ejection fraction (LVEF), N-terminal pro-B-type natriuretic peptide (NT-pro BNP), and noninvasive hemodynamic parameters at baseline and 3–6 months after treatment between the groups. Results: Before treatment, the parameters were similar between the observation group and control group. However, after 3−6 months of treatment, serum NT-pro BNP levels showed a greater decline in the observation group than the control group. Moreover, the LVEDD and LVEF improved more substantially in the observation group than the control group (P<0.05). RVEDD did not markedly change after treatment (P>0.05). After treatment, in the observation group, the cardiac index (CI) and cardiac output (CO) were significantly higher, and the thoracic fluid conduction (TFC) and systemic vascular resistance index (SVRI) were significantly lower, than those in the control group (P<0.05). Conclusions: Sacubitril/valsartan combination with dapagliflozin exerted better effects than ACEI or ARB with other hypoglycemic drugs in improving cardiac function and ventricular remodeling in patients with diabetes and STEMI.

Local and Global Mild Solution for Gravitational Effects of the Time Fractional Navier–Stokes Equations

The gravitational effect is a physical phenomenon that explains the motion of a conductive fluid flowing under the impact of an exterior gravitational force. In this paper, we work on the Navier–Stokes equations (NSES) of the fluid flowing under the impact of an exterior gravitational force inclined at an angle of 45∘ with A time-fractional derivative of order β∈(0,1). To encourage anomalous diffusion in fractal media, we apply these equations. In Hδ,r, we prove the existence and uniqueness of local and global mild solutions. Additionally, we provide moderate local solutions in Jr. Additionally, we establish the regularity and existence of classical solutions to these equations in Jr.