Joule Heating Effect Research Articles

Joule heating and Soret effects on an electro-osmotic viscoelastic fluid flow considering the generalized Phan-Thien–Tanner model

This work analyzes the non-isothermal electro-osmotic fluid flow in a microchannel considering the Soret effect and temperature-dependent properties. The constitutive equation that models the fluid rheology corresponds to the generalized Phan-Thien–Tanner (gPTT) model. Temperature and pressure gradients are induced due to the interaction between an ionized fluid and the electrical field imposed at the microchannel's ends, resulting in Joule heating. The temperature-dependent physical properties of the fluid modify the ionic distribution in the electric double layer and its thickness change along the microchannel walls. The generalized Phan-Thien–Tanner (gPTT) model is used as a constitutive equation that describes the fluid rheology, where the trace-stress tensor is based on the Mittag–Leffler function, which represents the destruction of physical junctions and entanglements in the Lodge–Yamamoto network of viscoelastic fluids, through the inclusion of two fitting parameters: α and β. The gPTT model allows better fitting and flexibility to experimental data and a wider range of variation in the description of rheological responses of complex fluids. The hydrodynamics and thermodiffusion obtained through the gPTT model are compared against that using the linear form of the Phan-Thien–Tanner model (lPTT).

Joule Heating and Viscous Dissipation Effects on a Stretching/Shrinking Cannel Filled by Micropolar Hybrid Nanofluid in Presence Thermal/Solar Radiation

The main goal for this research is to investigate the effect of two composed hybrid nanoparticle materials in heat transfer with account several parameters and in two cases. In addition, exploring how the micropolar hybrid nanofluid (Cu–TiO2) behaves in a shrinking and expansion of the channel. The model considers external factors such as magnetic fields, heat radiation, and solar radiation. The boundary layer approach has been utilized to create transformations that pout the equations of the system in the dimensionless form. The shooting method has been combined with the fourth-order Runge-Kutta-Gill to numerically solve the modified ordinary differential equations. The impacts of the nanoparticles transport on the heat transfer and fluid flow are addressed, and the results are compared to the case of pure water. The velocity, isotherms, angular-velocity, and concentration distributions, are given in tables or graphs. It was found that the effect of heat on the hybrid nanofluids is directly proportional to its velocity and angular velocity. For mass fraction of the two nanofluids φ1 and φ2, the velocity profile f′(η) has a comparable influence for both hybrid nanofluid and nanofluid. The larger quantity of the factors φ1, φ2, M and Q enhance the temperature. For M, φ1 and φ2, the angular velocity profile g(η) has a comparable influence for both hybrid and magnetic parameter. The absorption parameter storing the radiation energy and augmentation of the solar irradiance immersion capacity leads to a greater heat transfer.

Unsteady mixed convective MHD boundary stagnation point nanofluid flow with multi-slip effects, variable wall temperature and porosity phenomenon

This research highlights the physical significance of nanoparticle in magnetohydrodynamics (MHD) stagnation point flow (SPF) over a stretchable surface with porosity effect and boundary slip phenomenon. The nanoliquid and its advanced thermal activity are shown extra auspicious results when the flow is considered over a permeable (porous) medium. In addition, the nanoparticles of radius size play an important role in the thermal performance of nanofluid. In this work, copper is accounted as a nanoparticle and water as a base fluid. Nanomanufacturing, surface engineering, coatings, nanofabrication and tribology are some of the important and special mechanical characteristics of nanoparticles [D. Guo, G. Xie and J. Luo, J. Phys. D, Appl. Phys. 47, 013001 (2014)]. The flow is electrically conducted in the presence of applied magnetic field. Mixed convection, Joule heating and viscous dissipation effects are accounted in the mathematical modeling. Appropriate similarity variables are used to convert the couple governing system of PDEs into ordinary ones and results are computed through bvp4c via shooting concept. From the obtained results, it is divulged that the velocity field increases against higher estimations of unsteady parameter, while it declines versus larger magnetic parameter and radius of nanoparticles. The engineering interest like skin friction and Nusselt number is mathematically calculated and results are computed in a tabular form, and their obtained outcomes show that the magnitude of skin friction rises against unsteadiness parameter and radius of nanoparticles. This study is an extended work of [Verma et al. Chem. Eng. J. Adv. 12, 100366 (2022)] with some extra flow assumptions like MHD, SPF, Joule heating, heat generation/absorption and viscous dissipation. Obtained results are compared with [Grubka and Bobba J. Heat Transf. 107, 248 (1985)], Verma et al. [Chem. Eng. J. Adv. 12, 100366 (2022)] and [Elbashbeshy and Emam Therm. Sci. 15, 477 (2011)] found 100% accuracy with them. The most important result of the conducted study is that the skin friction coefficient immensely augments subject to larger estimations of radius of nanoparticles when permeability of porosity is less.

Effect of fabrication method on the physical properties of carbon-nanotube/silicone-rubber nanocomposite in high-voltage insulators

Effects of fog condensation and fine dust on the high-voltage insulator surface are harmful. The insulator housing material (silicone rubber) must be changed in order to allow a controlled leakage current to flow on the surface and causes Joule heating effect. Accordingly, surface temperature of the insulator is increased and fog condensation on the insulator surface is prevented. For this purpose, silicone rubber - multiwalled carbon nanotubes (MWCNT) nanocomposites (SRCNT) were prepared using two different processes: a solution-blending (SB) method and a dry-state of melt-blending (MB) method. Field Emission Scanning Electron Microscopy (FESEM) images indicated that the MWCNT dispersion in silicone rubber matrix of SRCNT samples produced by SB method is much better than that of MB method. Fourier Transform Infrared (FTIR) spectroscopy determined the possibility of a greater reduction in hydrophobicity properties in the sample prepared by the SB method compared to the sample made by the MB method, and the contact angle measurements confirmed this expectation. Furthermore, in a same MWCNT concentration, the electrical conductivity of SRCNT samples prepared by SB method are greater than those produced by MB method. Results showed that MB is a high efficient method for producing the SRCNT in a large amount.

An unsteady instigated induced magnetic field’s influence on the axisymmetric stagnation point flow of various shaped copper and silver nanomaterials submerged in ethylene glycol over an unsteady radial stretching sheet

The axisymmetric stagnation point flow of brick and blade-shaped Silver and Copper nanoparticles immersed in an ethylene glycol base fluid under the influence of an induced magnetic field over an unsteady radial stretching surface is investigated in this study. The unsteady phenomenon is considered because most flow issues in practice are unsteady. The fundamental laws of mass, momentum, and energy conservation are used to present the physical model. Heat transmission is also examined under the effects of magnetohydrodynamics, Joule heating, viscous dissipation, and convective boundary conditions to give a realistic physical investigation. Scaling analysis transforms the flow-governing issue into a collection of higher-order nonlinear ODEs. These are, then, solved numerically using the fourth-order Runge–Kutta and shooting techniques. Moreover, the numerical technique is validated by calculating residual error. It is concluded that, compared to the Ag–EG nanofluid, the Cu–EG nanofluid had the highest IMF, lowest temperature, minimum surface drag, and maximum heat flux, making it the ideal choice for creating a radial module.

Viscous dissipation and Joule heating effects on hydro-thermal power law nanofluid through annular duct

This study presents a mathematical model along with numerical simulation to investigate the viscous dissipation and Joule heating effects on electrically conducting magnetohydrodynamics (MHD) forced convection non-Newtonian power law nanofluid flow through annular sector duct. Hydro-thermal power law nanofluid flow through annular sector duct is not investigated in the presence of Joule heating and viscous dissipation effects. The consideration of Joule heating and viscous dissipation effects makes it very much novel in its own right. The main objective of this work is to explore the Joule heating and viscous dissipation effects on hydro-thermal power law nanofluid. Both Copper, Cu/Titanium oxide, TiO2 nanoparticles with base fluid water have been taken as a power law model. Numerically simulation is carried out for viscous, incompressible and steady laminar fully developed fluid flow with constant properties, by using the finite volume method (FVM) and strongly implicit procedure (SIP). It has been observed that viscous dissipation effect on temperature profiles is enhanced in the absence of magnetic field/at lower value of Ha, however, when nanoparticles’ concentration is increased, the effect of magnetic field slightly decreases. Furthermore, by adding Cu nanoparticles from 0% to 5%, we observe the increment in average Nusselt number, Nu up to 16.01% and 16.07% in pseudo-plastic and dilatant fluids, respectively, at [Formula: see text].

Critical Review on the Mechanisms of Fe2+ Regeneration in the Electro-Fenton Process: Fundamentals and Boosting Strategies

This review presents an exhaustive overview on the mechanisms of Fe3+ cathodic reduction within the context of the electro-Fenton (EF) process. Different strategies developed to improve the reduction rate are discussed, dividing them into two categories that regard the mechanistic feature that is promoted: electron transfer control and mass transport control. Boosting the Fe3+ conversion to Fe2+ via electron transfer control includes: (i) the formation of a series of active sites in both carbon- and metal-based materials and (ii) the use of other emerging strategies such as single-atom catalysis or confinement effects. Concerning the enhancement of Fe2+ regeneration by mass transport control, the main routes involve the application of magnetic fields, pulse electrolysis, interfacial Joule heating effects, and photoirradiation. Finally, challenges are singled out, and future prospects are described. This review aims to clarify the Fe3+/Fe2+ cycling process in the EF process, eventually providing essential ideas for smart design of highly effective systems for wastewater treatment and valorization at an industrial scale.

Prediction of PV cell parameters at different temperatures via ML algorithms and comparative performance analysis in Multiphysics environment

As the world moves towards renewable resources to meet the heaping power demand, the dependence on Photo Voltaic (PV) panel-based power generation has globally touched 1000TWh in 2021. These panels made up of different materials, such as Germanium (Ge), Silicon (Si), Indium Phosphide (InP), and Gallium Arsenide (GaAs), work in wider applications ranging from earth to space. But in real-time environmental conditions, these materials exhibit only 11 to 15 % efficiency, mainly due to thermal loss and exposure to variable irradiation and temperature conditions. Thus, in the current research, the PV cell/panel is modeled in an experimentally validated Multiphysics environment at temperatures from – 45 0C to + 51 0C using Ge, Si, InP, and GaAs as materials.The efficiency of the PV cell/panel is estimated in the current research based on the thermal losses within the material, the width of the bandgap, and the thickness of the cell. To analyze the thermal losses, joule heat generation of PV cell/panels made of all different materials is obtained. It is observed that at ambient temperature, although the GaAs and InP have an energy bandgap of 1.42 eV and 1.34 eV, respectively, the joule heating effect is minimum (3.95KW/m3 - InP, 5.05KW/m3- GaAs) when compared to Si (61KW/m3) and Ge (234KW/m3). But InP showed lower efficiency due to the thickness of the cell, which prevents the penetration of photons deeper into the inner layers. Further, in this research, the effect of real-time temperature conditions is obtained for all the PV panels by modeling them at −45 °C, 0 °C, 25 °C, and 51 °C. Parameters such as short circuit current (Isc), open circuit voltage (Voc), Fill Factor (FF), and maximum power (Pmax) are enumerated along with the efficiency. For a faster parametric analysis at all possible real-time temperature conditions in Indian climatic scenario, in this research, an ML based prediction model is developed using Kernel Ridge Regression (KRR), Polynomial Regression (PR), Linear Regression (LR), and Support Vector Regression (SVR). It is observed that, the KRR algorithm can give faster (in few seconds), effective, and error-free prediction (92.23% of accuracy). The prediction results are validated with the Multiphysics environment, data sheet, and experimental data.

Thermosolutal Marangoni stagnation point GO–MoS2/water hybrid nanofluid over a stretching sheet with the inclined magnetic field

The graphene oxide–molybdenum disulfide (GO–MoS2) exhibited the performance of photocatalytics under solar light radiation and the problem is more significant during Marangoni convection. In this scenario, the thermosolutal Marangoni stagnation point flow over a stretching sheet where the GO–MoS2 nanoparticles are embedded in a base fluid water are taken into consideration. The inclined magnetic field with the Joule heating effect, thermal radiation, chemical reaction and Soret and Dufour effect is introduced in the system. The leading equations are simplified by applying the proper similarity transformation and then solved numerically with the help of the MATLAB bvp4c routine. The impact of several parameters on the velocity, temperature and concentration with other physical properties such as skin friction, local Nusselt number and local Sherwood number has been displayed. Moreover, the results of this paper demonstrate a brief equivalency between nanofluid and hybrid nanofluid. It is experimented that the Marangoni effect arises due to a fluctuation in temperature as well as a chemical reaction. Surface tension refers to mean temperature and mean concentration restricts the fluid velocity. GO–MoS2 exhibits the increase in antimicrobial effects with enhancement in the glutathione oxidation and it is also used for DNA detection. The impact of GO and MoS2 in the flow of hybrid nanofluid shows significance with a huge application in medical science.

Optically pumped wavelength-tunable lasing from a GaN beam cavity with an integrated Joule heater pivoted on Si

Dynamically tunable laser sources are highly promising for realizing visionary concepts of integrated photonic circuits and other applications. In this paper, a GaN-based laser with an integrated PN junction heater on Si is fabricated. The photoluminescence properties of the GaN beam cavity are controlled by temperature, and the Joule heater provides electrically driven regulation of temperature. These two features of the cavity make it possible to realize convenient tuning of the lasing properties. The multi-functional GaN beam cavity achieves optically pumped lasing with a single mode near 362.4 nm with a high Q-factor of 1394. The temperature of this device increases by 0–5 °C under the Joule heating effect. Then, electrical control of the lasing mode is demonstrated. The lasing resonant peak shows a continuous redshift of about 0.5 nm and the device also exhibits dynamic switching of its lasing mode. The lasing modulation can be ascribed to temperature-induced reduction of the bandgap. Our work may be of benefit for external optical modulation in future chip-based optoelectronic devices.

Heat transfer and hydromagnetic electroosmotic Von Kármán swirling flow from a rotating porous disc to a permeable medium with viscous heating and Joule dissipation

AbstractMagnetohydrodynamic flow and heat transfer in an ionic viscous fluid in a porous medium induced by a stretching spinning disc and modulated by electroosmosis under an axial magnetic field and radial electrical field is presented in this study. The effects of convective wall boundary conditions, Joule heating and viscous dissipation are incorporated. The governing partial differential conservation equations are transformed into a system of self‐similar coupled, nonlinear ordinary differential equations with associated boundary conditions. The Matlab bvp4c solver featuring a shooting technique and the fourth‐order Runge–Kutta–Fehlberg method are used to numerically solve the governing dimensionless boundary value problem. Multivariate analysis is also performed to examine the thermal characteristics. An increase in rotation parameter induces a reduction in the radial velocity, whereas it elevates the tangential velocity. Greater electrical field parameter strongly damps the radial velocity whereas it slightly decreases the tangential velocity. Increasing magnetic parameter also damps both the radial and tangential velocities. An increment in electroosmotic parameter substantially decelerates the radial flow but has a weak effect on the tangential velocity field. Increasing permeability parameter (inversely proportional to permeability) markedly damps both radial and tangential velocities. The pressure gradient is initially enhanced near the disk surface but reduced further from the disk surface with increasing magnetic parameter and electrical field parameter, whereas the opposite effect is produced with increasing Joule dissipation. Increasing magnetic and rotational parameters generate a strong heating effect and boost temperature and thermal boundary layer thickness. Nusselt number is boosted with increasing Brinkman number (viscous heating effect) and Reynolds number. The simulations are relevant to electromagnetic coating flows, bioreactors and electrochemical sensing technologies in medicine.

Homogenization of residual stress in the raceway of cold rolled M50 bearing ring via electromagnetic shocking treatment

The uneven residual stress caused by cold rolling on the raceway seriously affect the distortion and performance of bearing rings. Here, a novel strategy of electromagnetic shocking treatment (EST) was proposed to regulate the distribution of residual stress in the raceway of cold rolled M50 bearing ring. The results indicate that the distribution of residual stress and local micro-strain along the raceway of the cold rolled ring become more homogenized after EST, leading to the homogenization of hardness along the whole cross section. In addition, attributed to the ‘targeted’ regulation effect of EST without joule heat effect, the distribution of small angle grain boundaries and the texture also become uniform along the raceway.

Structural conductive carbon nanotube nanocomposites for stretchable electronics

Carbon nanotube (CNT) nanocomposites have been widely used for electronic devices because of their high conductivity and ease of processing. However, these nanocomposites have limited functionality because of their rigid intrinsic mechanical properties. In this study, we fabricated a stretchable serpentine structure using a CNT nanocomposite with a carboxymethyl cellulose binder. For a flexible mold, a polydimethylsiloxane (PDMS) was cast by the stretchable serpentine structure fabricated by a 3D printer. The CNT nanocomposite slurry was squeegeed into the serpentine-patterned PDMS mold. Fourier-transform infra-red spectroscopy and scanning electron microscopy were used to analyze the material properties of the nanocomposites with 15–45 wt% CNTs. We analyzed the serpentine grid structure using current-voltage curves, strain resistance values, and the Joule heating effect. Next, we developed the structural CNT nanocomposite electrode (SCNE) that was insulated by PDMS, and induced a skin-warming effect by Joule heating. Furthermore, light emitting diodes (LEDs) were implanted in series into a T-shaped linear SCNE, which had greater stretchability. The nine LEDs embedded in the SCNE were successfully operated by applying 20 V during the bending of the structure. Finally, the serpentine-shaped linear SCNEs with serially-implanted LEDs were programmed to light the LEDs in unison with the beat of a song.

Rheological impact on thermofluidic transport characteristics of generalized Maxwell fluids through a soft nanopore

The time-dependent electroosmotic flow (EOF) and heat transfer characteristic of a generalized Maxwell fluid through the polyelectrolyte layer (PEL) grafted nanopore are investigated while considering different permittivity between the PEL and electrolyte solution. The ion partitioning effects arise due to the different permittivity among these regions. Taking the ion partitioning effects, the analytic solution for the induced potential is established within and outside the PEL from the modified Poisson–Boltzmann equation assuming the Debye–Hückel approximation for a low surface charge. The Cauchy momentum equation with a suitable constitutive equation for fractional Maxwell fluids is derived, and the corresponding analytic solution is presented to provide the axial fluid flow distribution in the full domain. The energy fluxes that have major contributions to the energy equation mainly depend on axial conduction, convection due to electrolyte transport, and Joule heating effects for the external electric field. The analytical solutions of the energy equation for hydro-dynamically fully developed flow with constant thermophysical properties are presented to provide the temperature distribution considering constant heat flux at the nanopore wall. The influence of several important factors for characterizing heat transfer behavior is investigated in the present study. The maximum fluid velocity occurs when the permittivity between the PEL and electrolyte region is the same. The increasing values of fluid velocity imply higher convective heat transfer and make the Nusselt number higher. This study makes a conscious effort toward highlighting the modality controlling the heat transfer characteristics for the ion partitioning effects.

Numerical treatment of hybrid water based nanofluid flow with effect of dissipation and Joule heating over a shrinking surface: Stability analysis

In the current work, the steady flow of magnetohydrodynamic of Cu-Al2O3/water hybrid nanofluid was investigated along with Joule heating and viscous dissipation effect across a porous shrinking sheet. Using an appropriate similarity transformation, the governing partial differential equations (PDEs) are transformed into ordinary differential equations (ODEs). The system of ODEs is solved using the bvp4c function in MATLAB. The present findings are numerically and visually compared to the available literature, and excellent agreements are discovered. The impacts of several new physical governing factors on velocity and temperature profiles, while the variation of heat transfer and skin friction, are visually shown and explicated hypothetically. In addition, the findings demonstrate the presence of duality within a limited range of suction parameters. Increasing the solid volume fraction ϕCu increases the values of f′′(0) for an initial solution and reduces them for an unstable solution. The investigation of the temporal stability of the solutions concludes that the first solution is stable only. The values of smallest eigenvalues values (γ>0) are positive for first solution indicated the stability of solution while the values of smallest eigenvalues values (γ<0) are negative for second solution indicates the instability of solution. The quantitative outcomes are in Table 4. The concentration of Al2O3 and Cu is almost 20% (0.01≤ϕAl2O3≤0.2 and 0.01≤ϕCu≤0.2).

Numerical and artificial neural network modelling of magnetorheological radiative hybrid nanofluid flow with Joule heating effects

In the current investigation, the radiative hybrid nanofluid flow through microchannel (HNF-MC) is investigated with the mathematical computational software MATHEMATICA with an innovative employment of intelligent computing solver based on Levenberg-Marquardt backpropagation neural networks (LMBNN). The effects of viscous dissipation, magnetohydrodynamics and velocity slip are considered. The heat transfer phenomenon is studied under the considerations of both convection and velocity slip phenomena. The governing dimensional equations are nondimensionalized with appropriate physical quantities. The data collection for proposed LMBNN is generated through different scenarios of HNF-MC model with sundry parameters via MATHEMATICA. To predict the multi-layer perceptron (MLP) values, the artificial neural network (ANN) has been developed. To obtain the approximate solutions for HNF-MC in various scenarios and for the processes of training, testing and validation are set. Later, for assurance of accuracy of the model the results are matched with given data sets. The error (ERR) and mean square error (MSE) are analysed. According to the current investigation, ANN is the best effective and accurate, and conveniently applicable for simulating the motion of hybrid nanofluid (water-CNT based nanofluid) through the parallel microchannel. It is concluded that, the stronger magnetic field declines the velocity and temperature profiles due to Lorentz forces.

Numerical inspection of two-dimensional MHD mixed bioconvective flows of radiating Maxwell nanofluids nearby a convectively heated vertical surface

The non-homogeneous aspect and dynamical feature of a radiating mixture of an upper-convected Maxwell nanofluid and gyrotactic motile microorganisms are revealed numerically in this investigation during its two-dimensional mixed convective motion nearby a convectively heated vertical surface and a uniform magnetic field source. Based on relevant physical and mathematical backgrounds, the conservation laws (i.e. equations of continuity, momentum, heat balance, solid nanoparticles’ concentration, and gyrotactic motile microorganisms’ concentration) monitoring the present flow problem are derived appropriately in the form of partial differential equations. By making use of specific transformations and rearrangements, these differential equations are converted thereafter into a gigantic structure of first-order ordinary differential equations. By executing computationally an appropriate bvp4c subroutine, the resulting boundary layer equations are handled accordingly for well-defined physical constraints. Afterward, the computing unitless characteristics (i.e. velocity, temperature, solid nanoparticles’ concentration, gyrotactic motile microorganisms’ concentration, skin friction coefficient, Nusselt's number, Sherwood's number, and motile microorganisms’ transfer rate) are discussed exhaustively via graphical and tabular illustrations. As prominent outcomes, it is demonstrated that Joule's heating effect and Lorentz's forces exhibit an enhancing influence on the heat and mass transport phenomena within the nanofluidic medium with a dissimilar dynamical impact.

Design of a low-voltage dielectrophoresis lab-on-the chip to separate tumor and blood cells

In this paper, we design and propose a compact label-free microfluidic lab-on-a-chip device to separate circulating tumor cells (CTCs) from red blood cells (RBCs) at low voltage to minimize cell damage. With the aim of developing a mm-long device to perform cell separation, we used 3D finite element simulation modeling and investigated separation efficiency for different electrode configurations, electrode shapes, and channel heights. Our results show that configuring the electrodes as two arrays, consisting of only five pairs of top and bottom planar electrodes shifted relative to each other and energized with ± 6 V at 70 kHz, generates sufficient non-uniform electric fields to separate CTCs and RBCs in a 2 mm long channel. The advantage of the proposed design is the simplicity of the electrode arrangement and that the electrodes do not cover the central part of the channel, thus allowing for brightfield imaging of the channel. In addition, the low voltage needed and the 50 µm high channel reduce the Joule heating effect and improve the device's separation and throughput efficiency. We suggest that the proposed design would be effective for separating CTCs and RBCs and, thus, used as a device for the early detection of CTCs.

Effect of Pulsed Current-Assisted Tension on the Mechanical Behavior and Local Strain of Nickel-Based Superalloy Sheet

Electrically assisted (EA) forming is a plastic forming technique under the coupling action of multiple energy fields, such as force field, temperature field, and electric field. It is suitable for the forming of difficult-to-deform materials such as nickel-based superalloys. In this paper, uniaxial tensile tests on nickel-based superalloy sheets were carried out using the pulsed current assisted with different parameters. The experimental results show that the flow stress of the material decreased with the increase in the current density under a high-frequency pulsed current, and the Joule heating effect explains the flow stress drop. In the pulsed current application process, the different types of Portevin-Le Chatelier phenomena appeared with the increase in the current density. The decrease in elongation assisted by the pulsed current was explained by analyzing the inhomogeneity of the maximum Joule heating temperature distribution. In addition, the digital image correlation (DIC) analysis was used to analyze the local strain behavior of the pulsed current-assisted tensile process. Under the application of a high-frequency pulse current, the specimen exerted an inhomogeneous temperature increase and local hot pressing stress, which resulted in the inhomogeneous distribution of the local strain.

Generation of atmospheric pressure air diffuse discharge plasma in oxygen enriched working gas with floating electrode

In this work, a floating electrode is employed to generate a stable large-area diffuse discharge plasma under an open oxygen-rich environment. The discharge image and the optical emission spectra of the N2(C-B), (B-X), N2(B-A), and O(3p–3s, 777 nm) are measured to analyze the morphological and optical characteristics of the discharge. The effects of applied voltage, gas flow rate, and electrode gap on the reactive species, vibrational temperature and rotational temperature are investigated, and the discharge mode is discussed by simulating the electrostatic field before the breakdown. It is found that the changes of applied voltage and electrode gap causes the transition of the discharge modes among corona mode, diffuse discharge mode and spark mode. It is shown that the floating electrode can inhibit the transition from discharge to spark mode to a certain extent, which is conducive to maintaining the stability of discharge. As is vividly illustrated in this study, the increase of applied voltage or the decrease of electrode gap contributes to the generation of more active particles, such as N2(C) and (B). Furthermore, the Joule heating effect becomes more evident with the increased applied voltage when the electrode gap is 15 and 20 mm. Moreover, as the applied voltage increases, the vibrational temperature increases at the electrode gap of 25 mm.