Extraordinary Thermal Conductivity Research Articles

Extraordinary thermal conductivity for carbon nanotube encapsulated linear carbon chain

Carbyne is a sp1 linear carbon chain (LCC) with characteristics of strong chemical reactivity and extreme instability under environmental conditions, which has become an obstacle to the application of LCC with high thermal and electrical conductivity. Utilizing CNT as a container to store LCC is one of the most feasible ways to realize LCC applications. However, current research of LCC encapsulated in CNT (LCC@CNT) focuses on its preparation and lacks of in-depth exploration of the intrinsic heat transfer mechanism. This paper reports the high axis thermal conductivity of LCC@CNT, explore the thermal transport enhancement degree of LCC@CNT under a wide temperature range and multiple diameters, and analyzed the underling mechanism through crucial thermal parameters and phonon theory. When LCC is loaded in CNT, the axial thermal conductivity of CNT is further increased by 15 %. Moreover, LCC@CNT shows the lower sensitivity diameter than pristine CNT. This work is expected to provide data support for the application of LCC, the lower production standard of CNT, and also attempt the higher efficient one-dimensional thermal energy transfer micro devices.

Extreme in-plane thermal conductivity anisotropy in Rhenium-based dichalcogenides

Anisotropies in thermal conductivity are important for thermal management in a variety of applications, but also provide insight on the physics of nanoscale heat transfer. As materials are discovered with more extreme transport properties, it is interesting to ask what the limits are for how dissimilar the thermal conductivity can be along different directions in a crystal. Here we report on the thermal properties of rhenium-based transition metal dichalcogenides (TMDs), specifically rhenium disulfide (ReS2) and rhenium diselenide (ReSe2), highlighting their extraordinary thermal conductivity anisotropy. Along the basal crystal plane of ReS2, a maximum of 169±11 W mK−1 is detected along the b-axis and a minimum of 53±4 W mK−1 perpendicular to it. For ReSe2, the maximum and minimum values of 116±3 W mK−1 and 27±1 W mK−1 are found to lie 60° and 150° away from the b-axis, along the polarization direction of some of the principal Raman modes. These measurements demonstrate a remarkable anisotropy of 3.2 × and 4.3 × in the conductivity within the crystal basal planes, respectively. The through-plane thermal conductivities, recorded at 0.66±0.01 W mK−1 for ReS2 and 2.31±0.01 W mK−1 for ReSe2, highlight the impact of their layered structures, contributing to notably high in-plane to through-plane thermal conductivity ratios of 256 × for ReS2 and 50 × for ReSe2. This research demonstrates the unique thermal properties that these comparatively underexplored TMDs have, shedding light on the need for further exploration into the intricate thermal behavior of such materials, while underscoring their potential significance for future applications in the fields of semiconductor devices and nanotechnology.

Heat and mass transfer phenomenon and aligned entropy generation with simultaneous effect for magnetized ternary nanoparticles induced by ferro and nano-layer fluid flow of porous disk subject to motile microorganisms

This articles focus the dynamics of fluid conveying ternary solid particles, nano-layer, and magnetic field effects subject to porous disks. The magnetized ternary nanoparticles induced by Ferro and nano-layer are considered due to their unusual characteristics like extraordinary thermal conductivity, which are significant in advanced nanotechnology, heat exchangers, material sciences, and electronics. To avoid possible sedimentation of tiny particles, the motile microorganisms are also considered in the elaborated fluid problem. The main objective of this comprehensive study is the enhancement of heat transportation. In this study, we also investigate the physical dynamics of entropy generation, particularly emphasizing viscous dissipation related to joule heating effects. The mass transfer equation was employed to monitor the chemical interaction with diverse nanoparticles. The results of comparative and numerical validation agree well. The approach of stable and accurate numerical boundary value problem of fourth order code (bvp4c) is applied to solve the nonlinear system of ordinary differential equations. Many useful engineering results are summarized here, including the skin friction coefficient ( C f ) , Nusselt number (Nu), Sherwood number (Sh), and motile number (Nn). For both porous disks, several non-dimensional parameter effects are depicted graphically and tabulated. The results show that the increasing the number of nanolayer particles slows the rate of the temperature profile in both porous disks, associated with the expansion ratio, Reynolds number, and magnetic field number. Moreover, increasing the values of the density ratio number results in an increase in the flow of microorganisms profile in both porous disks. Increasing the values of the diffusivity parameters and the temperature difference enhances the flow of entropy generation.

Coupled Effects of Lorentz Force, Radiation, and Dissipation on the Dynamics of a Hybrid Nanofluid over an Exponential Stretching Sheet

The flow and heat transfer induced by an exponentially shrinking sheet with hybrid nanoparticles are investigated comprehensively in this paper. Nanoparticles are considered due to their unusual characteristics such as extraordinary thermal conductivity, which is significant in advanced nanotechnology, heat exchangers, material sciences, and electronics. The main objective of this research is to enhance heat transportation. The flow model is first transformed and simplified to a system of ordinary differential equations utilizing non-dimensional quantities and similarity functions. Then, the desired system is solved with the help of the Runge–Kutta numerical method and the shooting technique in MATLAB script. The results show that a stronger porosity parameter raises the temperature while diminishing the velocity. Additionally, they emphasize that augmentations in the magnetic parameter, Eckert number, radiation parameter, and the volume fractions of titanium dioxide and silver nanoparticles are all proportional to the temperature profile.

Numerical study of convective heat transfer and particle distribution subject to magneto-static field in a square cavity

Magnetic nanoparticle suspension has been applied in a variety of energy transport systems due to its excellent flowing characteristics and extraordinary thermal conductivity, and it has proven to significantly influence the sustainable development of energy and the environment. This work aims to focus on the thermal, fluidic properties of the magnetic nanofluid while also considering the coupling factors of magnetic field, thermal exchange, fluidity and nanoparticle concentration. Firstly, the simulation results of velocity and temperature distribution will be validated using the finite element method, which is in accordance with previous results of natural convection in a square cavity. The analysis model of developed magneto-hydrodynamics heat transfer will then be constructed with the explanation of entropy and concentration distribution. In comparison to natural convection, the magnetic field-enhanced method is able to break through the limit of thermal exchange efficiency. In addition, when the magnetic field is increased to 30 kA/m, the thermodynamic force is replaced by magnetic volumetric force and this plays a role in the heat transfer of the cavity, while the average Nusselt numbers increase by 17% in comparison to natural convection performance (Ra = 105). Entropy generation increases as magnetic field strength increases as a result of the enhancement to circulation and temperature gradient in the nanofluid. This work utilises an advanced strategy for the convection performance of magnetic nanofluid and analyses the multi-physical field.

Impact of magnetized non-linear radiative flow on 3D chemically reactive sutterby nanofluid capturing heat sink/source aspects

A recent advancement in fluid dynamics is the consideration of nanofluids which has an extraordinary thermal conductivity characteristics and upsurge heat transfer in fluids. This paper examines the heat and mass transfer properties of a steady 3D movement of a sutterby nanomaterial on a bidirectional stretching plane. Nanoparticle mass flow and convective boundary conditions are deliberated. In addition, the effect of heat generation/absorption and non-linear thermal radiation is explored. Moreover, the latest proposed model of the nanofluid has been pondered which involves controlling the nanoparticle volume element at the wall submissively relatively than dynamically. We introduced a similarity transformation to change the equations of boundary layer to a self-similar system after that processed analytically with the help of the bvp4c scheme. The outcomes of several control parameters on heat and mass transfer properties are shown among graphs then scrutinized. The systematic outputs of the Nusselt number are premeditated via tables. We observed that by increasing the estimates of the Lewis number (Le) indicates a reduction in the concentration field as well as the thickness of the equivalent boundary layer. Similarly, it is seen that the concentration field decreases rapidly according to the Brownian motion parameter as compared to the Lewis number (Le).

Extraordinary thermal conductivity of polyvinyl alcohol composite by aligning densified carbon fiber via magnetic field

Extraordinary thermal conductivity of polyvinyl alcohol composite by aligning densified carbon fiber via magnetic field

High-Performance Ionanofluids from Subzipped Carbon Nanotube Networks

Investments in the transfer and storage of thermal energy along with renewable energy sources strengthen health and economic infrastructure. These factors intensify energy diversification and the more rapid post-COVID recovery of economies. Ionanofluids (INFs) composed of long multiwalled carbon nanotubes (MWCNTs) rich in sp2-hybridized atoms and ionic liquids (ILs) display excellent thermal conductivity enhancement with respect to the pure IL, high thermal stability, and attractive rheology. However, the influence of the morphology, physicochemistry of nanoparticles and the IL-nanostructure interactions on the mechanism of heat transfer and rheological properties of INFs remain unidentified. Here, we show that intertube nanolayer coalescence, supported by 1D geometry assembly, leads to the subzipping of MWCNT bundles and formation of thermal bridges toward 3D networks in the whole INF volume. We identified stable networks of straight and bent MWCNTs separated by a layer of ions at the junctions. We found that the interactions between the ultrasonication-induced breaking nanotubes and the cations were covalent in nature. Furthermore, we found that the ionic layer imposed by close MWCNT surfaces favored enrichment of the cis conformer of the bis(trifluoromethylsulfonyl)imide anion. Our results demonstrate how the molecular perfection of the MWCNT structure with its supramolecular arrangement affects the extraordinary thermal conductivity enhancement of INFs. Thus, we gave the realistic description of the interactions at the IL-CNT interface with its (super)structure and chemistry as well as the molecular structure of the continuous phase. We anticipate our results to be a starting point for more complex studies on the supramolecular zipping mechanism. For example, ionically functionalized MWCNTs toward polyionic systems─of projected and controlled nanolayers─could enable the design of even more efficient heat-transfer fluids and miniaturization of flexible electronics.

Enhancement of heat transfer considering Joule heating and variable conductivity in magneto Maxwell nanofluid

The heat conversation medium temperately regulates the heat exploitation effectiveness of solar energy. Nanofluids, a kind of functioning fluids with extraordinary thermal conductivity and strong light concentration, have been scrutinized and functionalized to progress the exploitation of solar energy. In recent times the current progress examines the nanofluids with the consideration of thermal sources as it can raise the heat transportation amount. Here, the purpose is to explore the thermal properties of Joule heating and thermal conductivity in magnetite Maxwell nanofluid. The concept of heat sink/source and chemical reaction are also studied. The achieved ordinary differential equations have been solved via homotopic algorithm. The enactment of functioning variables is examined. For Eckert number and variable conductivity factors, the Maxwell temperature field has analogous tendencies. The fluid concentration inflates for thermophoretic factor; however, slows down for the Brownian motion factor. The Brownian and thermophoretic factors decay for Nusselt number. Additionally, the excellent results have been achieved accompanied with possible existing prose precisely.

Morphology of Hybrid MHD Nanofluid Flow through Orthogonal Coaxial Porous Disks

In this article, we study the novel features of morphological effects for hybrid nanofluid flow subject to expanding/contracting geometry. The nanoparticles are incorporated due to their extraordinary thermal conductivity and innovative work for hybrid nanofluids, which are assembled of aluminum oxides, Al2O3 metallic oxides, and metallic copper Cu. Cu nanoparticles demonstrate very strong catalytic activity, while Al2O3 nanoparticles perform well as an electrical insulator. The governing partial differential equations of the elaborated model are transformed into a system of nonlinear ordinary differential equations with the use of similarity variables, and these equations are numerically solved through a shooting technique based on the Runge–Kutta method. We develop a hybrid correlation for thermophysical properties based on a single-phase approach. A favorable comparison between shape and size factors for metallic and metallic-oxide nanoparticles is discussed via tables and figures. Moreover, the effect of embedding flow factors on concentration, velocity, and temperature is shaped in line with parametric studies, such as the permeable Reynolds number, nanoparticle volume fractions, and expansion/contraction parameters. The fluid velocity, temperature, and concentration are demonstrated in the presence of hybrid nanoparticles and are discussed in detail, while physical parameters such as the shear stress, flow of heat, and mass transfer at the lower and upper disks are demonstrated in a table. The hybrid nanoparticles show significant results as compared to the nanofluids. If we increase the nanoparticle volume fraction, this increases the thermal performance for an injection/suction case as well. The above collaborative research provides a strong foundation in the field of biomedical equipment and for the development of nanotechnology-oriented computers.

Activation Energy Performance through Magnetized Hybrid Fe3O4–PP Nanofluids Flow with Impact of the Cluster Interfacial Nanolayer

The current work investigated the mass and heat transfer of the MHD hybrid nanofluid flow subject to the impact of activation energy and cluster interfacial nanolayer. The heat transport processes related to the interfacial nanolayer between nanoparticles and base fluids enhanced the base fluid’s thermal conductivity. The tiny particles of Fe3O4 and PPy were considered due to the extraordinary thermal conductivity which is of remarkable significance in nanotechnology, electronic devices, and modern shaped heat exchangers. Using the similarity approach, the governing higher-order nonlinear coupled partial differential equation was reduced to a system of ordinary differential equations (ODEs). Fe3O4–PPy hybrid nanoparticles have a considerable influence on thermal performance, and when compared to non-interfacial nanolayer thermal conductivity, the interfacial nanolayer thermal conductivity model produced substantial findings. The increase in nanolayer thickness from level 1 to level 5 had a significant influence on thermal performance improvement. Further, the heat and mass transfer rate was enhanced with higher input values of interfacial nanolayer thickness.

The numerical simulation of nanoparticle size and thermal radiation with the magnetic field effect based on tangent hyperbolic nanofluid flow

Tiny particles have extraordinary thermal conductivity due to their unusual characteristics, making them crucial in materials science, nanotechnology, heat exchangers, and electronics. When there is the inclusion of thermal radiation, a heat source, and a convective boundary, magnetohydrodynamic (MHD) micropolar, tangent hyperbolic flow for water-based Al2O3 nanofluid over a stretching sheet, this work intends to investigate the significance of a nanoparticle's radius. The mathematically described ordinary differential system is created by transforming a set of partial differential equations via similarity transformations. The bvp4c approach is used to solve the problem numerically (MATLAB built-in function). In this comprehensive study, the main objective is to improve heat transformation under the impact of various parameters. The velocity profiles, temperature distribution, micro-rotation distribution, and the local skin friction factor, along with the rate of heat transfer, have been displayed with several physical parameters. It is observed that the variation in velocity and the temperature profiles is the cause of increasing the size of the nanoparticles and the involving parameters that caused an increase in the rate of heat transfer. Graphs and tables have then been used to demonstrate the consequences of these physical parameters. The enhancement in the radius of nanoparticles causes a decrease in the skin friction factor, thermal layer, and micro-rotation. As the Biot number increased, the thermal layer became thicker. The impact of influential parameters on physical quantities is illustrated using three-dimensional graphs.

Rotating Flow and Heat Transfer of Single-Wall Carbon Nanotube and Multi-Wall Carbon Nanotube Hybrid Nanofluid with Base Fluid Water over a Stretching Sheet

In this article, numerical simulations of the rotational flow of water-based magnetohydrodynamic (MHD) nanofluid containing single-wall carbon nanotube (SWCNT) and hybrid nanofluid containing single- and multiple-wall carbon nanotube (SWCNT-MWCNT) over a stretching sheet are performed. The primary goal is to improve thermal transport efficiency due to CNTs extraordinary thermal conductivity. The 3D governing equations for microorganism concentration, energy, momentum, concentration, and mass conservation are transformed into 1D ordinary differentiation via similarity transformations. In a MATLAB environment, the resultant system of equations (ODEs) are then solved using Runge–Kutta fourth order with the shooting process. Tables and graphs were used to show the results of physical parameters. According to our findings, enhancing the rotational parameter λ and the magnetic field M reduce the base fluid velocity along the x-axis, and on the other hand, the opposite tendency is shown along the y-axis. Furthermore, the velocities, temperature, and microorganism concentration profiles of hybrid nanofluid (SWCNT−MWCNT/H2O) are found to be higher than those of mono nanofluid (H2O+SWCNT), while the concentration profile is found to be lower.

Significance of the Coriolis Force on the Dynamics of Carreau–Yasuda Rotating Nanofluid Subject to Darcy–Forchheimer and Gyrotactic Microorganisms

In this study, the significance of the Coriolis force on the dynamics of Carreau—Yasuda flow toward a continuously stretched surface subject to the Darcy–Forchheimer law is investigated. The nanoparticles are incorporated due to their unusual characteristics (e.g., extraordinary thermal conductivity), which are significant in heat exchangers and advanced nanotechnology. To avoid possible sedimentation of tiny particles, the gyrotactic microorganisms must be incorporated. The goal of this research was to find out the dynamics of three-dimensional rotational flow for nanofluids under the influence of Darcy–Forchheimer with the thermophoresis effect and motile microorganisms. The equations governing mass, momentum, and energy equations are formalized using partial derivatives, which may subsequently be transformed into dimensionless differential shapes using the personifications of apposite similarity transformations. The MATLAB application bvp4c was used in conjunction with a shooting technique to solve a nonlinear mathematical model based on ordinary differential equations. It was observed that the base fluid velocities decreased against higher input of rotation and porosity parameters; moreover, the Brownian motion and thermophoresis increased the temperature profile.

Impact of surface catalyst and variable diffusion coefficients on a comparative appraisal of hybrid and nanofluid flows

A comparison of the hybrid and nanofluid flows performance amidst two spinning disks accompanying variable thermal conductivity and viscosity is appraised in this study. The hybrid nanofluid is comprised of single-wall-multiwall carbon nanotubes/water combination and a simple nanofluid consists of single-wall carbon nanotubes (multiwall carbon nanotubes)/water amalgamation. The selection of carbon nanotubes is based on their matchless characteristics including lightweight, extraordinary thermal conductivity attributes, and stability. The envisaged model is supported with catalysis on the surface to influence the homogeneous-heterogeneous reactions and trigger the process in a relatively lesser time. The cases of clockwise and anticlockwise rotation for both disks are undertaken. The numerical MATLAB-based bvp4c technique is betrothed. The graphical illustrations depicting the association of the prominent parameters with the allied profiles are given with logical arguments. The fallouts revealed that the hybrid nanofluids are more effective than the simple nanofluids as far as thermal efficiency is concerned. It is also heeded that the rate of mass transfer is proliferated for the surface catalyzed parameter. A comparison table in a limiting case is also supplemented to jazz up the justification of the presented model.

Crystal Growth, Thermal and Spectral Properties of Er: LGGG Crystal.

A high-quality Er3+-doped (Gd1−xLux)3Ga5O12 (Er: LGGG) laser crystal with a size of Φ 36 × 45 mm3 was successfully grown by the Czochralski (Cz) method for the first time. The effective segregation coefficient of Er3+ was determined to be 0.97, close to 1, and, thus, the uniform high-quality Er: LGGG crystal can be grown. In addition, the thermal and spectroscopic properties of Er: LGGG were investigated. Based on the measured characteristics, the Er: LGGG crystal has a huge potential for use in the 3.0 µm mid-infrared laser because of its outstanding optical quality, extraordinary thermal conductivity and stable structure.

Significance of bioconvection and mass transpiration for MHD micropolar Maxwell nanofluid flow over an extending sheet*

Motivated by several practical submissions, the current modeling addresses the theoretical and numerical aspects of Maxwell micropolar nanofluids with diluted homogeneous diffusion of nanoparticles and gyrotactic microorganisms. Nanoparticles are considered due to extraordinary thermal conductivity, which are very useful in modern technology, electronics, heat exchangers, and material sciences. Further, gyrotactic microorganisms are incorporated to avoid possible sedimentation. The similarity variables are used to transform the flow equations into corresponding non-dimensional ODEs, furthermore these ODEs are transmuted into linear form by adopting shooting technique. The graphical and numerical results are utilized by computational software Matlab with Runge–Kutta order 4 method. Numerical and graphical consequences of velocity, micro-rotation, temperature, concentration and motile density profiles are displayed. As uplifting values of magnetic parameter, a twisting behavior is observed on micro-rotational profile but velocity profile is diminishing. The motile density profile is decline when Lewis and Peclet numbers are boosted. Temperature distribution increased for larger values of Brownian motion, Rayleigh number, and thermophoresis parameters.

The function of nanoparticle’s diameter and Darcy-Forchheimer flow over a cylinder with effect of magnetic field and thermal radiation

In engineering and industry, the function of vitality and mass diffusivity because of heat and density gradients plays an important role. The heat and mass transfer rate depends on the tendency of the magnetic field, nature of heat source, thermal radiation, and the variance of concentration of nanofluid. In this study, the significance of variation in nanoparticle’s diameter, dissipation of energy, and mass flux due to the temperature gradient in the convective radiation dynamics of the fluid, heat source, and the Darcy-Forchheimer model over a cylinder has discussed. The basic formulation constituted in the form of coupled non-linear PDEs that has transformed into higher-order ODEs by using peculiar similarity functions. Tiny particles are considered due to their unusual characteristics like extraordinary thermal conductivity, which are significant in advanced nanotechnology, heat exchangers, material sciences, and electronics. The main objective of this comprehensive study is the enhancement of heat transformation. It is observed that if the energy diffusion is relatively higher in intensity due to the concentration gradient, a substantial reduction in temperature distribution throughout the domain is probable in response to increasing copper nanoparticle’s diameter. The concentration gradient leads to a reduction in the viscidness of water-base nanofluids, which leads to an increase in velocity. The convergence of numerical technique is noticed for optimum meshing and the accuracy of the presented results are verified with their exactness to the results as existing in the relevant studies.

Transient rotating nanofluid flow over a Riga plate with gyrotactic micro-organisms, binary chemical reaction and non-Fourier heat flux

Bioconvection for rotational flow is conceived to provide stability to improved thermal transportation for nanofluid flow over Riga plate design. Nanoparticles are considered due to their unusual characteristics like extraordinary thermal conductivity, which are significant in heat exchangers, advanced nanotechnology, electronics, and material sciences. Cattaneo–Christov theory and activation energy are incorporated. The unsteady three dimensional partially differentiate formulation is simplified in the form of two independent coordinates (ζ,η). For steady-state solution (ζ=1), Galerkin discretization in used to employ finite element simulation in MATLAB environment. The unsteady parameter rotating parameter, thermophoresis, and Brownian motion parameter escalated the nanofluid temperature field. Modified electromagnetic parameter MH accelerated the primary flow velocity and activation energy augmented the volume fraction of nanoparticles in the boundary layer region. The larger modified Hartmaan number MH reduces the coefficient of skin friction in primary direction but the magnitude of coefficient of skin friction in secondary direction is augmented. The local Nusselt number Rex1/2Nux is directly proportional to MH but it is inversely related to β. The higher values of Brownian motion and thermophoresis boosted the temperature. An excellent accord among the present and previously existing solutions is establishes the validity of the current findings.

Insight into the dynamics of fluid conveying tiny particles over a rotating surface subject to Cattaneo–Christov heat transfer, Coriolis force, and Arrhenius activation energy

This article addressees the dynamics of fluid conveying tinny particles and Coriolis force effects on transient rotational flow toward a continuously stretching sheet. Tiny particles are considered due to their unusual characteristics like extraordinary thermal conductivity, which are significant in advanced nanotechnology, heat exchangers, material sciences, and electronics. The main objective of this comprehensive study is the enhancement of heat transportation. The governing equations in three dimensional form are transmuted in to dimensionless two-dimensional form with implementation of suitable scaling transformations. The variational finite element procedure is harnessed and coded in Matlab script to obtain numerical solution of the coupled non-linear partial differential problem. It is observed that higher inputs of the parameters for magnetic force and rotational fluid cause to slow the primary as well as secondary velocities, but the thermophoresis and Brownian motion raise the temperature. However, thermal relaxation parameter reduces the nanofluid temperature. The velocities for viscosity constant case are faster than that for the variable viscosity, but temperature and species concentration depict opposite behavior.