Ohmic Effects Research Articles

Three‐Dimensional Fluid Flow Over an Elastic Sheet Stretched Nonlinearly in Two Lateral Directions

AbstractPresent research work explores the three‐dimensional nanofluid flow across a horizontal surface with bi‐directional deviation of velocity in power‐law index n. Porosity, the ohmic effect with other parameters, thermophoresis, Prandtl number, Schmidt number, and Brownian motion in the flow geometry are taken into consideration. Dimensional nonlinear formulations are changed into dimensionless expressions by employing the appropriate similarity transformation. Utilizing shooting procedure and the fourth‐fifth‐order Runge–Kutta integration approach, the numerical result has been achieved, and velocity, temperature, and concentration profiles are presented through graphs to illustrate the findings. The current outcome has numerous industrial applications, including the production of paper, metal extrusion, and optical fiber. The major findings of the present research are good agreement compared to the data that are accessible in the limiting instance compared with the earlier results.

Experimental Investigation of Temperature Homogeneity and Peak Temperature in a Battery Pack of Cylindrical Li-ion Cells Under Free and Forced Convection

Electrical vehicles (EVs) are emerging as a suitable replacement for conventional IC engine-based automobiles because of their environmental friendliness. An EV is powered by a rechargeable battery pack usually made of Lithium-ion batteries and these batteries generate heat during their operation cycle due to exothermic reactions and ohmic effect. Thermal management of batteries is important for their safe operation and optimum lifespan. In this paper, a comparative analysis of temperature homogeneity, peak temperature and average temperature of battery pack is presented between free and forced convection-based Battery Thermal Management System (BTMS). Cells that are at higher temperature than average temperature of battery pack are more liable to fail earlier as compared to other cells of pack. Present research focuses on finding such critical cells in a battery pack consisting of twelve lithium-ion batteries. The battery pack is discharged at three different rates: 1C, 2C and 3C, and temperature of each cell is measured at regular intervals during the discharge process. The experimental results from present study revealed that free convection is better at maintaining temperature homogeneity, but peak temperatures were above 50 ̊C. Forced convection based BTMS was able to keep peak temperatures below 50˚C at 1C discharge rate but temperature homogeneity was not maintained within ideal limits of 5˚C. At higher discharge rates, the performance of both free convection and forced convection based BTMS is not within acceptable limits. Critical cells were identified to get better insight into limitations of conventional cooling systems so that better layout of battery module and better alternative methods of battery pack cooling can be developed.

Quantitative Correction of Ohmic Effects on Square Wave Voltammetry for High-Concentration Soluble-Soluble Redox Reactions in Molten Salts

Molten salts are of particular interest for a variety of industrial applications. As such, accurate characterization of species’ concentrations within the molten salt media is critical to ensure a well-controlled unit operation. Although electroanalytical tools are properly suited for precise in situ monitoring in these systems, uncompensated ohmic resistance R Ω can lead to erroneous, technique-dependent results. Using numerical simulations applied to a model system, this work will first illustrate then quantify the extent to which R Ω attenuates square wave voltammograms. This approach allows for post-experiment correction that leads to converging results across voltammetric techniques and facilitates accurate predictions of species’ concentrations.

Electrochemically activated persulfate combined with tannic acid significantly improved sludge-dewatering performance: Sludge floc weight structure, Fe(II)/Fe(III), and organic component conversion

Sludge-dewatering effect is a key factor in sludge disposal. In this study, the conditioning system of electrochemically activated persulfate combined with tannic acid (EF-PDS/TA) was used to improve sludge-dewatering performance. Results showed that the sludge water content (Wc) and Specific resistance to filtration (SRF) decreased by 29.4 % and 93.3 %, respectively, under the optimal operating conditions, which significantly improved the sludge-dewatering effect. Through research, we found that SO4•− and ·OH were the main factors promoting the improvement in sludge-dewatering performance. After the reaction, the physicochemical properties of the sludge changed significantly, and the floc structure effectively cracked. Further analysis of Fe2+/Fe3+ conversion, EEM and FTIR showed that in the process of sludge conditioning, on the basis of EF promoting Fe2+/Fe3+ conversion through electron transfer between cathode and anode plates, TA addition further improved the conversion efficiency of Fe2+/Fe3+. The conversion rate was as high as 90 %, which improved the oxidation ability of sludge. The thermal energy generated by the EF ohmic heat effect can promote the complexation and precipitation of proteins in EPS by TA, and the energy can be effectively utilized. Moreover, EF and TA exerted a synergistic effect in promoting Fe2+/Fe3+ conversion and protein cleavage. Finally, the economic cost of the combined conditioning system was calculated, and the practical application value of the conditioning system was evaluated. The findings laid a theoretical foundation for further research in the field of advanced sludge oxidation.

Fluorinated aggregated nanocarbon with high discharge voltage as cathode materials for alkali-metal primary batteries.

Due to its exceptionally high theoretical energy density, fluorinated carbon has been recognized as a strong contender for the cathode material in lithium primary batteries particularly valued in aerospace and related industries. However, CF x cathode with high F/C ratio, which enables higher energy density, often suffer from inadequate rate capability and are unable to satisfy escalating demand. Furthermore, their intrinsic low discharge voltage imposes constraints on their applicability. In this study, a novel and high F/C ratio fluorinated carbon nanomaterials (FNC) enriched with semi-ionic C-F bonds is synthesized at a lower fluorination temperature, using aggregated nanocarbon as the precursor. The increased presence semi-ionic C-F bonds of the FNC enhances conductivity, thereby ameliorating ohmic polarization effects during initial discharge. In addition, the spherical shape and aggregated configuration of FNC facilitate the diffusion of Li+ to abundant active sites through continuous paths. Consequently, the FNC exhibits high discharge voltage of 3.15V at 0.01C and superior rate capability in lithium primary batteries. At a high rate of 20C, power density of 33,694Wkg-1 and energy density of 1,250Wh kg-1 are achieved. Moreover, FNC also demonstrates notable electrochemical performance in sodium/potassium-CF x primary batteries. This new-type alkali-metal/CF x primary batteries exhibit outstanding rate capability, rendering them with vast potential in high-power applications.

Improving the accessibility of phytonutrients in Chlorella vulgaris through ohmic heating

The application of electric fields, coupled with its attendant ohmic heating effect, might represent a novel approach to process microalgae biomass. When exposed to temperatures above 70 °C, depending on the duration of exposure, significant effects were observed in the release of intracellular compounds from Chlorella vulgaris cells. The most significant effects were observed when they were treated at 90 °C with a constant electric field of 225 V.cm−1, resulting in a protein concentration of 108.52 ± 9.18 mg.L−1. This technology offers the advantage of achieving an extremely rapid heating rate, minimizing the risk of compound degradation due to thermal effects. Additionally, some effects on the cellular structure of microalgae were identified, which can enhance the extraction of biomolecules and metabolites, thereby promoting their digestibility as a food product.

Transport characteristics of gas in an alkaline water electrolyser with the addition of baffles: Analysis of mechanism and performance

The adhesion of gases to the electrodes is a major reason for reductions in energy efficiency, and hinders the production of hydrogen in alkaline water electrolysis (AWE). The development of an effective solution to this problem will be crucial for the design and optimization of AWE. In this paper, we present a novel structure for an electrolyser in which baffles are inserted into the channel. The flow process of the electrolyte and the electrochemical reactions in the electrolyser with the new structure are simulated, and the effects of the added baffles on the distribution of the gas phase production and the efficiency of energy conversion are analysed. Several important structural parameters are considered, such as the angle, number and length of the baffles, and corresponding numerical calculations are performed. In order to carry out a comprehensive evaluation of the performance of each electrolyser, the energy efficiency of AWE is evaluated and the current effect, ohmic overvoltage effect and bubble overvoltage effect caused by gas adhesion are quantitatively investigated. The results show that the flow of the electrolyte can be divided into three phases when baffles are added to the channel of the electrolyser, and that the baffles play a crucial role in both the transition phase and the full development phase. The maximum reduction in gas coverage at the electrodes reaches 60% and the maximum increase in energy efficiency reaches more than 3.0% with the addition of baffles. The addition of baffles has significant effects on the current and ohmic overpotential, and the balance between the gas coverage and ohmic overpotential can allow the maximum energy efficiency of the AWE to be achieved.

Synergistic effect between ohmic contacts and localized surface plasmon resonance for enhancing CO2 photoreduction of BiOBr

The fast recombination rate of photogenerated carrier and short electron lifetime are the main factors affecting the CO2 reduction performance of BiOBr (BOB). The utilization of ohmic contacts and the localised surface plasmon resonance (LSPR) effect of metals can effectively solve the above problems. However, one mean alone is not ideal for improving the photocatalytic performance of BOB. Therefore, in this work, we reduced the metal Bi to the surface of BOB in an attempt to form a synergistic effect of ohmic contact and LSPR effect. DFT calculations confirm the ohmic contact between Bi and BOB. Meanwhile, electrochemical tests show that Bi/BOB-2 has a higher photocurrent density (1.1 μA/cm2), suggesting that the ohmic contact achieves ultrafast electron transfer from BOB to Bi under light. While the UV–Vis diffuse reflectance spectroscopy results show resonance absorption peaks from the LSPR effect of Bi, the TRPL results show that Bi/BOB-2 has a longer τave (3.05 ns), implying that longer-lived hot electrons are generated on the Bi surface. The synergistic effect of the two contributes to the efficient CO2 to CO transition on the catalyst surface. As a result, Bi/BOB-2 exhibites a 4.37-fold higher CO generation rate (11.45 μmolg-1 h−1) than that of pure BOB (2.62 μmolg-1 h−1) under light. This study provides a new blueprint for the design of BiOBr-based materials for efficient photocatalytic reduction of CO2.

Ferromagnetic and ohmic effects on nanofluid flow via permeability rotative disk: significant interparticle radial and nanoparticle radius

The significance of interparticle spacing and nanoparticle radius for the case of single-phase nanofluid flow has often been neglected. Tremendous applications of this phenomenon can be witnessed in different fields, especially in electron microscopes, heat exchange processes, and many others. This research highlights this vital aspect of Ohmic heating in nanofluid flow over a spinning disk. To ensure the novelty, a ferromagnetic nanoparticle (Manganese ferrite) has been incorporated to examine interparticle spacing and particle radius to explore the features of heat transfer. The ferromagnetic nanofluids are vital in carriers for drug delivery systems, in cancer treatment, design of systems for hyperthermia therapy, in microfluidic devices used for chemical synthesis, etc. The quantiles of dimensional equations are converted into dimensionless ones by adopting similarity transformations and to solve highly coupled nonlinear equations numerically, built-in bvp5c MATLAB tool is utilized. The effect of a few revealed factors, the velocity and temperature distributions, are examined via visualization. Furthermore, streamlined plots are also visualized. The outcomes produced showed excellent agreement with those made in the literature in the same direction by assuming some exceptional cases on different gradients. Further, the outstanding results are reported as; the permeability of the surface produces the suction velocity, and the enhanced suction velocity attenuates the fluid velocity in either of the case of pure and nanofluid. The increase in thermal radiation boosts up the heat transfer rate whereas the augmentation in the Eckert number retards it significantly.

Hall and ohmic heating effects on radiative flow of viscoelastic nanofluids over a convective rotating rigid/stretched disk

In this article, the impacts of the Hall current on the 3D forced convection and heat transfer due to the rotation of a disk are examined. The disk's surface is considered to be rigid or stretched and the non-Newtonian viscoelastic nanofluids are assumed to be the working suspension. The convective boundary conditions together with passively control of the nanoparticles are imposed to the disk's surface. Several important influences are considered such as Ohmic heating, thermal radiation, heat generation/absorption and Arrhenius energy. The transformed governing equations are solved numerically using the shooting technique with 4th order Runge-Kutta method. The major findings revealed that the Hall current parameter enhances the radial velocity in both rigid and stretched surface while the tangential velocity has lower features. Also, the viscoelastic nanofluid parameter causes lower behaviors of tangential velocity and nanofluid temperatures. The considered range of the Hall parameter causes an increase in the heat transfer rate by 1.73%.

Multifunctional sandwich materials with ROTIS structure for improved thermal and electrical properties in construction application

There is still a lot of research space and market demand for lightweight, heat-insulating, and EMI-shielding construction materials. This paper develops and compares the thermal insulation, ohmic heating effect, and EMI shielding properties of a kind of multifunctional sandwich material with “ROTIS” and “FLAT” structures. The ROTIS-structured sample exhibits slightly higher thermal conductivity than the FLAT-structured sample, owing to its lower volume porosity and higher plated copper content per unit area. Since ROTIS technology allows for a significant increase in the thickness of thinner raw materials, this structure allows for an increase in the thermal insulation of thinner materials. Also, samples with ROTIS structures have a better ohmic heating effect than samples with FLAT structures. This is because the active layer has more plated copper content per unit area, while the insulation layer has less thermal resistance. Unsatisfactorily, the samples with the ROTIS structure show lower electromagnetic shielding effectiveness at 1-1.5 GHz, which is mainly due to their reduced volume porosity. In conclusion, this research develops sandwich materials with the ROTIS structure that exhibit excellent thermal insulation, electromagnetic shielding, and ohmic heating properties, making them suitable for use as building materials in demanding indoor temperatures and electromagnetic environments.

Computational Investigation of Brownian Motion and Thermophoresis Effect on Blood-Based Casson Nanofluid on a Non-linearly Stretching Sheet with Ohmic and Viscous Dissipation Effects

Computational Investigation of Brownian Motion and Thermophoresis Effect on Blood-Based Casson Nanofluid on a Non-linearly Stretching Sheet with Ohmic and Viscous Dissipation Effects

Formula omitted]-soliton asymptotic analysis on the Gerdjikov–Ivanov equation for the Alfvén waves in a plasma

Gerdjikov–Ivanov equation describes the propagation of the weakly nonlinear and dispersive Alfvén waves along the ambient electromagnetic field in a partially ionized plasma in the presence of the Hall, ambipolar, and Ohmic effects. With respect to the transverse components of the electromagnetic field to the lowest order, N solitons in the determinant form are derived and analyzed via the asymptotic analysis on the basis of an existing binary DT and an existing Lax pair, where N is a positive integer. Without loss of generality, expressions of the N asymptotic solitons in the determinant form are obtained, from which we can obtain the amplitudes, positions, velocities and phase shifts of the N asymptotic solitons. Those results reveal that the interaction among the N solitons is elastic. When N=3, we graphically illustrate the elastic interaction among the three solitons. This work may provide a physical mechanism for the generations and interactions of the Alfvén solitons in the magnetized plasmas.

Mechanism and Kinetics of the Phase Formation and Dissolution of NaxWO3 on a Pt Electrode in a Na2WO4-WO3 Melt.

A comprehensive study concerning the phase formation mechanism and growth/dissolution kinetics of sodium tungsten bronze crystals during the electrolysis of a 0.8Na2WO4-0.2WO3 melt was carried out. The regularities of deposit formation on a Pt(111) working electrode were investigated experimentally using cyclic voltammetry, chronoamperometry, scanning electron microscopy, and X-ray diffraction analysis. Models have been developed to calculate the current response during the formation, growth and dissolution of a two-phase deposit consisting of NaxWO3 and metallic tungsten or two oxide tungsten bronzes with different sodium content. These models consider mass transfer to the electrode and nuclei; chemical and electrochemical reactions with the participation of polytungstate ions, Na+, Na0, and O2-; as well as the ohmic drop effect. The approach was proposed to describe the dissolution of an NaxWO3 crystal with a nonuniform sodium distribution. The fitting of cyclic voltammograms was performed using the Levenberg-Marquardt algorithm. The NaxWO3 formation/growth/dissolution mechanism was determined. Concentration profiles and diffusion coefficients of [WnO3n]-, reaction rate constants, number density of nuclei, and time dependencies of crystal size were calculated. The proposed approaches and models can be used in other systems for the cyclic voltammogram analysis and study of the mechanism and kinetics of electrode processes complicated by phase formation; parallel and sequential electrochemical and chemical reactions; as well as the formation of a deposit characterized by a nonuniform phase and/or chemical composition.

Arrhenius activation energy effect in thermally viscous dissipative flow of micropolar material with gyrotactic microorganisms

The rheology of micropolar material with heat energy transport features is fully progressive, which allows considerable industrial and engineering applications. In this study, numerical analysis is presented to examine the micro-rotation characteristics of magnetized micropolar fluid flow towards the stagnation point region on a porous shrinking surface with gyrotactic microorganisms. To describe the convective energy transport features, Arrehenius activation energy, thermal radiation, Ohmic, and viscous dissipation effects are taken into consideration. The governing equations are converted into ordinary differential equations using appropriate similarity variables. The physical features of flow constraints are displayed and explained for velocity, thermal and solutal distributions, microorganism profile, as well as friction drag, couple stress, and energy transport rate. The results revealed that suction strength contributes to the increment of friction drag, couple stress, and energy transport rate, but the boosted values of the micropolar parameter lower the values of these physical quantities. For a specific range of the shrinking parameter, analysis confirmed the persistence of non-uniqueness solutions. Further, the microorganism profile declines as the bioconvection Lewis number and the bioconvection Peclet number increases. Additionally, according to time-dependent stability analysis, only the upper branch of solutions is physically stable, while the lower branch is not physically.

Modeling Strategies Based on Multiple Neural Network Systems Applied for a Monopolar and Bipolar Electrocoagulation

The objective of this research was to evaluate the efficiency of an electrocoagulation system using iron and aluminum electrodes, arranged in both monopolar and bipolar arrangements, for the removal of acid red 18 dye. Experimental and modeling approaches were employed to investigate the system’s performance. The effects of operating parameters: including initial pH (3–9), current density (0.4–5.6 mA cm−2), charge passed (2.16–21.6 C cm−2), and initial dye concentration (50–300 mg l−1) were studied. The results demonstrated that an increase in electric current intensity and passed charge enhanced the removal of COD and dye. However, to minimize energy consumption, these parameters were optimized for different dye concentrations. The monopolar arrangement exhibited favorable performance for the both electrodes, primarily due to reduced ohmic drop effect, although the iron electrode generated sludge with better settling characteristics. The monopolar iron electrode consumed the least energy (38.3 kWh kg−1 COD). Experimental evaluation was conducted to assess the influence of key electrolysis process parameters on dye and COD removal. Additionally, neural network models, employing radial basis function and multilayer perceptron approaches, were utilized to predict system outputs based on initial characteristics (COD and dye) and operation conditions. The neural network models provided accurate predictions, offering practical insights for experimental applications.

Radiative magneto-cross Eyring-Powell flow with activation energy past porous stretching wedge considering suction/injection and ohmic heating effect

A semi-numeric study is presented to explore the nonlinear, radiative, mixed convective boundary layer flow of non-Newtonian Eyring-Powell fluid (EPF) over a porous stretching wedge in the existence of suction/injection, viscous dissipation, activated energy, and ohmic heating. The governing coupled partial differential equations (PDEs) in the flow regime are transformed into coupled ordinary differential equations (ODEs) under suitable boundary conditions (BCs). Computations are performed for variations of various pertinent parameters on velocity, temperature distribution, surface drag force, and heat transfer rate number. It is noted that with increasing Eyring Powell parameter velocity increases for stretching parameter greater than free stream velocity, but decreases when wedge stretches slowly than free stream velocity. An increase in the local non-Newtonian fluid parameter decreases velocity when the wedge stretches faster as compared to free stream velocity. However, velocity increases when the wedge stretches faster. Temperature velocity decreases for both cases of wedge stretches faster or slower as the local non-Newtonian fluid parameter increases. Similar behavior is seen in the case of Eyring Powell parameter. Increasing heat generation or absorption decreases the momentum as well as thermal boundary layer thickness. When the suction/injection parameter is enhanced the velocity shows a declines behavior for both the cases of stretching parameter as it increases. Temperature profiles decline as the mass transfer parameter is enhanced for both the case's velocity ratio parameters, respectively. Excellent agreement is achieved with the differential transform method and numerical result.

Influence of plasma inhomogeneity and ohmic heating on the nonlinear absorption of intense laser pulse in collisional magnetized plasma

AbstractThe nonlinear absorption in the interaction of an intense laser pulse with a collisional magnetized plasma is studied by considering the effects of plasma inhomogeneity, ohmic heating, and ponderomotive force. For this purpose, we obtain the plasma electron density, the effective dielectric permittivity, and the wave equation using the Maxwell and hydrodynamic equations and solve this equation by the Runge–Kutta numerical method. The results are shown that by increasing the plasma inhomogeneity, the inverse bremsstrahlung absorption coefficient is increased, and also the density ramp parameter and its sign can affect more the absorption coefficient than the temperature ramp parameter . However, when the initial electron density and temperature increase, the laser field amplitude and the absorption coefficient are increased and the spatial damping rate of the laser pulse becomes highly peaked inside the plasma. It is shown by increasing laser pulse energy, the nonlinear bremsstrahlung absorption coefficient is decreased significantly. The results also indicate that by increasing the external magnetic field, the dielectric permittivity is decreased while the laser energy spatial damping, and the absorption coefficient are increased. Moreover, it is found that by considering the ohmic heating effect, the electrons absorb further energy from the fields and consequently the nonlinear absorption is increased.

Insight into the role of graphene quantum dots on the boosted photocatalytic H2 production performance of a covalent organic framework

The photocatalytic activity of covalent organic frameworks (COFs) to evolve hydrogen (H2) triggered by visible light has been promising, but the separation and migration efficiency of photogenerated electron-hole pairs still have to be improved. In the study, we designed and synthesized a kind of graphene quantum dots (GQDs) modified β-ketoenamine-linked COF composite (GQDs/COF) by an in-situ method to improve its photocatalytic H2 evolution for the first time. The resulting 0.44% GQDs/TpPa-1-COF shows a rate of H2 production of 487 μmol g−1h−1 with the illumination of visible light, outperforming those of bare TpPa-1-COF by 2.9 times. It is found that the GQDs serve as a photosensitizer that effectively enhances the optical absorption ability. Moreover, GQDs serve as a means of collecting photoinduced electrons as for preventing the subsequent recombination of carriers excited by visible light. Furthermore, the Ohmic contact effect between the TpPa-1-COF and GQDs facilitates the highly efficient migration of photoinduced electrons, which has been demonstrated by the density functional theory (DFT) calculation results. Overall, this work provides a novel strategy to design COF-based composites and gives some insight into the role of GQDs on enhanced photocatalytic activity.

Darcy-Forchheimer mangetized flow based on differential type nanoliquid capturing Ohmic dissipation effects

Hydromagnetic nanoliquid establish an extraordinary category of nanoliquids that unveil both liquid and magnetic attributes. The interest in the utilization of hydromagnetic nanoliquids as a heat transporting medium stem from a likelihood of regulating its flow along with heat transportation process subjected to an externally imposed magnetic field. This analysis reports the hydromagnetic nanoliquid impact on differential type (second-grade) liquid from a convectively heated extending surface. The well-known Darcy-Forchheimer aspect capturing porosity characteristics is introduced for nonlinear analysis. Robin conditions elaborating heat-mass transportation effect are considered. In addition, Ohmic dissipation and suction/injection aspects are also a part of this research. Mathematical analysis is done by implementing the basic relations of fluid mechanics. The modeled physical problem is simplified through order analysis. The resulting systems (partial differential expressions) are rendered to the ordinary ones by utilizing the apposite variables. Convergent solutions are constructed employing homotopy algorithm. Pictorial and numeric result are addressed comprehensively to elaborate the nature of sundry parameters against physical quantities. The velocity profile is suppressed with increasing Hartmann number (magnetic parameter) whereas it is enhanced with increment in material parameter (second-grade). With the elevation in thermophoresis parameter, temperature and concentration of nanoparticles are accelerated.