Water-based Carbon Nanotubes Research Articles

Impact of induced magnetic field on Darcy–Forchheimer nanofluid flows comprising carbon nanotubes with homogeneous-heterogeneous reactions

The appealing traits of carbon nanotubes (CNTs) encompassing mechanical and chemical steadiness, exceptional electrical and thermal conductivities, lightweight, and physiochemical reliability make them desired materials in engineering gadgets. Considering such stimulating characteristics of carbon nanotubes, our goal in the current study is to scrutinize the comparative analysis of Darcy–Forchheimer nanofluid flows containing CNTs of both types of multi and single-wall carbon nanotubes (MWCNTs, SWCNTs) immersed into two different base fluids over a stretched surface. The originality of the model being presented is the implementation of the induced magnetic field that triggers the electric conductivity of carbon nanotubes. Moreover, the envisioned model is also analyzed with homogeneous-heterogeneous (h-h) chemical reactions and heat source/sink. The second-order slip constraint is assumed at the boundary of the surface. The transmuted high-nonlinearity ordinary differential equations (ODEs) are attained from the governing set of equations via similarity transformations. The bvp4c scheme is engaged to get the numerical results. The influence of different parameters is depicted via graphs. For both CNTs, the rate of heat flux and the surface drag coefficient are calculated using tables. It is highlighted that an increase in liquid velocity is witnessed for a varied counts volume fraction of nanoparticles. Also, Single-wall water-based carbon nanotube fluid has comparatively stronger effects on concentration than the multi-walled carbon nanotubes in water-based liquid. The analysis also indicates that the rate of heat flux and the surface drag coefficient are augmented for both SWCNTs and MWCNTs for different physical parameters. The said model is also validated by comparing it with a published result.

Chemically reactive water-based carbon nanotubes flow saturated in Darcy-Forchheimer porous media coupled with entropy generation

This investigation described the features of magnetized water-based carbon nanotubes in slip flow saturated through Darcy-Forchheimer porous space. Cattaneo and Christov heat diffusion relation is used for the modeling of energy equation. Chemical reaction and heat generation influences are accounted. The entropy generation (EG) volumetric rate relation is modeled. The Fehlberg numerical scheme is implemented for the construction of the solutions. The results revealed that the EG is augmented in the presence of magnetic field and porosity parameter but decays against solid volume fraction of nanoparticles for both SWCNTs (single-wall carbon nanotubes) and MWCNTs (multi-wall carbon nanotubes).

Study of thermal convection in chemically reactive carbon nanotube suspension saturated in anisotropic porous enclosure

This study aims to investigate the influence of chemical reactions and anisotropic porous material on the convective instability, heat and mass transfer rate of water-based carbon nanotube suspension. Flow governing dynamics are modeled using the modified Brinkman–Buongiorno model. The effects of pertinent flow characterizing parameters such as chemical reaction parameter, porosity parameter, mechanical anisotropy parameter and thermal anisotropy parameter on the threshold of convection, heat and mass transport rate are discussed and compared for three types of enclosures: shallow, square and tall. The study concludes that nanoliquid suspended with single-walled carbon nanotubes has higher heat and mass transfer capability than the multi-walled carbon nanotubes when saturated in a tall porous enclosure and also tall enclosure allows the convection to set in earlier. Anisotropic effect and destructive chemical reaction delay the starting of convection. Further, it is observed that the heat transfer rate decreases with the chemical reaction parameter.

Nonlinear radiation effects on water-based nanofluid containing CNTs subject to heat source/ sink past a wedge

In this paper, a two-dimensional and incompressible laminar flow comprised of water-based carbon nanotubes over convectively heated moving wedge under the magnetic field and nonlinear radiation and heat production/ absorption is investigated. The base nanofluid (water) contains single wall carbon nanotubes (SWCNTs) and multiple walls carbon nanotubes (MWCNTs). In order to convert the dimensional nonlinear partial differential equations in nondimensional nonlinear ordinary differential form, an adequate set of similarity variables had been used. These set of equations and boundary conditions are evaluated by the implementation of RKF-45 (Runge–Kutta–Fehlberg fourth-fifth) order scheme. The influence of several physical parameters on particular nanoparticle’s volume friction, temperature and velocity ratio parameter, heat source/ sink parameter, nonlinear radiative constraint, exponent constant, magnetic factor, Eckert and Biot numbers is studied. An opposite behavior of volume fraction and velocity ratio parameters on velocity and energy profiles is achieved.

Heat and mass transport in an electrically conducting nanofluid flow over two-dimensional geometries

Engineering equipment in medicine, chemical and power engineering, electronics, and other human endeavours use nanofluids. The ability to improve mass and heat transport because of the low concentration of nanoparticles is the primary driver behind the vast array of nanofluid applications. Thus, the famous problems of viscous, incompressible, Newtonian, and 2-D laminar flow are revisited to investigate the mass and heat transmission rates for water-based carbon nanotubes (CNTs) with variable magnetic fields and external pressure gradients. Flow cases considered with varying pressure gradients are the flows upon a flat plate, flow in a planar diverging and converging channel, flow over a wedge, and plane stagnation flows, which are investigated. The impressions of thermophoresis and Brownian motion parameters are examined through the Buongiorno model. Using the Görtler transformation, the leading boundary layer (BL) equations are converted into dimensionless forms of ordinary differential equations (ODEs). Runge-Kutta Fehlberg Method (RKF45) is operated to tackle the ensuing ODEs to find the mass, heat, and skin friction rates. It has been found that the rates of shear stress, mass, and heat transport slow down with an escalating magnetic field. Although mass transport rates are decreased, shear stress and heat transport (HT) rates escalate due to the solid volume portion of carbon nanotubes. Furthermore, the pressure gradient parameter facilitates faster heat and shear stress transmission rates.

Thermal performance of the seal oil cooler of the RFCC MCB Pump by using CNT-water nanofluids

In this article, the water-based Carbon nanotube (CNT) nanofluid in various CNT concentrations was used in an industrial shell and tube cooler as a cooling fluid. The heat transfer factors have been analyzed, such as Reynolds number, Nusselt number, overall heat transfer coefficient, and heat transfer rate. The cooling fluid flows on the tube side, and the hot fluid flows on the shell side. The CNT concentrations were 0.0055%, 0.055%, 0.111% and 0.278% volume fraction. The results represented that the heat transfer properties increased with CNT volume fraction as 0.278 CNT volume fraction enhanced the Nusselt number and the convection heat transfer coefficient about 47% and 59.3%, respectively, for example. Likewise, heat transfer was enhanced with the increment of the nanofluid mass flow rate for all the CNT volume concentrations.

An Optimal Investigation of Convective Fluid Flow Suspended by Carbon Nanotubes and Thermal Radiation Impact

This study is focused towards analyzing the heat and flow movement among two stretching rotating disks inside water-based carbon nanotubes. The idea of thermal boundary conditions and heat convection is used and the system is expressed in partial differential equations. Using the similarity techniques, the model is successfully converted to a nonlinear ordinary differential equation. A familiar collocation method is used to simulate the outcomes of the governed system while the method is validated through a set of tables and assessed with existing literature. The physical aspects of the proposed model have been studied in detail and assisted via graphical diagrams against the variation of different parameters. It is found that the multiple-wall carbon nanotubes intensify the system quickly and improve the rate of heat transmission. It is also noted that the proposed method is in excellent in agreement with already published studies and can be extended for other physical problems. Moreover, when values of Re parameter increase, a drop is noted in the magnitude of radial velocity near the faces of the disks. It is very clear from the tabular comparison that collocation scheme is in good agreement with already published studies and homotopic solutions.

Comparative analysis of the CNTs nano fluid flow between the two gyrating disks

Nanofluids play a prominent role in the development of various electronic structures and technological devices. Herein, we devise new and efficient techniques for overcoming the problems faced by the base fluids. This article describes water-based carbon nanotubes, including two major types of single-wall carbon nanotubes (SWCNT) and multi-wall carbon nanotubes (MWCNT). A mathematical model is considered for unsteady three-dimensional CNTs nanofluids flow with a uniform magnetic field between two revolving disks. The basic equations of the modeled flow problem are solved by the BVPh 2.0 package which is implemented using the Optimal Homotopy Analysis Method (OHAM). It has been observed that by stretching the top disk while keeping the lower disk stationary, the rotation aspect is reduced, whilst radial velocity near the top disk significantly increases. Moreover, The higher the values of unsteadiness parameter, the more accurate the temperature profile.

Intelligent supervised learning for viscous fluid submerged in water based carbon nanotubes with irreversibility concept

This article examined the Silver based Di‑hydrogen carbon nanotubes flow model (SDH-CNTFM) between two stretchable coaxially disks by utilizing the Method of Levenberg Marquardt with Back-propagated Neural Networks (MLM-BPNN). Here the base liquid is silver (Ag) and the nanoparticles are SWCNTs and MWCNTs (single and multiwall carbon nanotubes). The governing PDEs for SDH-CNTFM are transformed into ODEs by utilizing similarity transformation. Energy equations are developed through heat generation and viscous dissipation joule heating. Also calculated the total entropy optimization. Flow parameters velocity, entropy optimization, temperature, Nusselt number and Bejan number are discussed for both single and multi-walls carbon nanotubes (SWCNTs and MWCNTs) graphically and in Tabular form. The reference dataset is calculated through implementation of Optimal Homotopy Analysis method (OHAM) for variants of SDH-CNTFM. For the variation of different parameters this reference dataset is utilized in MATLAB to clarify the solution and error analysis plots. Moreover, the approximated solution is assessed through adopting training/testing/validation procedure and comparing it with standard solution which is endorsed by performance study based on MSE convergence, error histogram and regression studies. Heat transfer rate and surface drag force are discussed for both SWCNTs and MWCNTs numerically by using different flow parameters. From obtained outcomes, it is observed that entropy rate boosts up for higher approximation of nanoparticles of volume friction and Brickman number (Br) which is controlled due to the minimization of Brickman number.

Thermal Absorption Performance Evaluation of Water-Based Nanofluids (CNTs, Cu, and Al2O3) for Solar Thermal Harvesting

For solar thermal harvesting, an experimental study was performed on the thermal absorption performance of water-based carbon nanotubes (CNTs), Cu, and Al2O3 nanofluids using a halogen lamp-based thermal radiation system. The effect of nanoparticle concentrations (0.01 wt.%, 0.1 wt.%, and 1 wt.%) on the nanofluid dispersion, stability, and thermal absorption characteristics was investigated, and a comparative analysis was performed for each type of nanofluid. All types of nanofluids increased the absorbance and electrical conductivity with increasing nanoparticle concentration, which contributed to improving the thermal absorption performance of nanofluids. The results showed that the thermal absorption performance was high in the order of carbon-based nanofluids (CNTs), metal-based nanofluids (Cu), and oxide-based nanofluids (Al2O3). In CNTs nanofluids, the thermal absorption performance expressed the time reduction rate, which was 12.8%, 16.3%, and 16.4% at 0.01 wt.%, 0.1 wt.%, and 1 wt.% test cases, respectively. Therefore, the 0.1 wt.%-CNTs nanofluid is more economical and appropriate. However, in Al2O3 nanofluids, the time reduction rate of the 1 wt.% nanofluid was significantly higher than that of the 0.01 wt.% and 0.1 wt.% nanofluids. In Cu nanofluids, unlike CNTs and Al2O3 nanofluids, the time reduction rate constantly increased as the nanoparticle concentration increased.

Effects of aligned magnetic field on heat transfer of water-based carbon nanotubes nanofluid over a stretching sheet with homogeneous–heterogeneous reactions

The present analysis deals with the heat transfer of chemically reactive magnetic-nanofluid over a stretching surface by considering the aligned magnetic field in a porous medium under the influence of nonlinear thermal radiation, variable thermal conductivity and suction. An isothermal model of homogeneous–heterogeneous reactions is used to regulate the solute concentration profile. It is assumed that the water-based nanofluid is composed of single and multi-walled carbon nanotubes. By applying a suitable set of similarity transformations, the system of partial differential equations is first transformed into a system of nonlinear ordinary differential equations before being solved numerically. The impact of various pertinent parameters on the velocity, temperature, concentration, skin friction and local Nusselt number coefficient is discussed. It is found that the increase in the rate of heterogeneous and homogeneous reactions retards nanoparticle concentration distribution. The existence of variable thermal conductivity and an inclined magnetic field realise a decrease in heat transfer.

Irreversibility analysis of carbon nanotubes subject to rotating frame

This article interprets the chemically reactive flow of water-based carbon nanotubes subject to rotating frame. Homogeneous-heterogeneous reactions are considered. Heat transfer is studied in presence of heat generation/absorption and viscous dissipation. Flow in porous space is investigated through nonlinear Darcy-Forchheimer expression. Carbon nanotubes of two types (namely single wall SWCNTs and multi wall MWCNTs) are utilized. Optimal solutions are obtained through optimal homotopy analysis method (OHAM). Roles of sundry variables on flow fields, physical quantities and entropy generation rate are interpreted. It is witnessed that rate of entropy generation increases through homogeneous and heterogeneous reaction parameters.

Entropy generation and heat transfer analysis for ferrofluid flow between two rotating disks with variable conductivity

Present model analyze the flow and heat transfer of water-based carbon nanotubes (CNTs) [Formula: see text] ferrofluid flow between two radially stretchable rotating disks in the presence of a uniform magnetic field. A study for entropy generation analysis is carried out to measure the irreversibility of the system. Using similarity transformation, the governing equations in the model are transformed into a set of nonlinear coupled differential equations in non-dimensional form. The nonlinear coupled differential equations are solved numerically through the finite element method. Variable viscosity, variable thermal conductivity, thermal radiation, and volume concentration have a crucial role in heat transfer enhancement. The results for the entropy generation rate, velocity distributions, and temperature distribution are graphically presented in the presence of physical and geometrical parameters of the flow. Increasing the values of ferromagnetic interaction number, Reynolds number, and temperature-dependent viscosity enhances the skin friction coefficients on the surface and wall of the lower disk. The local heat transfer rate near the lower disk is reduced in the presence of Harman number, Reynolds number, and Prandtl number. The ferrohydrodynamic flow between two rotating disks might be useful to optimize the use of hybrid nanofluid for liquid seals in rotating machinery.

Unsteady free convection flow of water-based carbon nanotubes due to non-coaxial rotations of moving disk

ABSTRACT Nanofluid is one of the significant developments for having an efficient heat transport process. Its implementation in a non-coaxial rotating system has benefited from designing a mixer machine with two stirrer blades, cooling fan, and jet engines. This study analytically investigates the free convection of unsteady non-coaxial rotating nanofluid flow through a moving disk. The suspension of single-wall or multi-wall carbon nanotubes in water is known as the nanofluid in this study. The fluid motion is affected by the effects of rotation and buoyancy forces. Using suitable dimensionless variables, the dimensional coupled partial differential of momentum and energy equations along with their initial and moving boundary conditions are converted into the dimensionless form. The expressions for temperature and velocity profiles are obtained by solving governing equations using Laplace transform method. The validity of obtained solution is confirmed by having a good agreement when comparing present results with the published result. The results show that the insertion of CNTs particles into the rotating water causes the temperature and velocity profiles to increase. The amount of heat transferred by SWCNTs is greater than MWCNTs. Increasing CNTs particles has descended both primary and secondary skin friction but increase Nusselt number. Further analysis with the help of pictorial discussion for the fluid flows and heat transfer under the influences of nanoparticle volume fraction, Grashof number, the amplitude of disk, and time is carried out.

Dual nature solutions of water-based carbon nanotubes along a shrinking surface in the presence of thermal radiation and viscous dissipation

The current analysis is performed to find the dual nature solutions of MHD (magnetohydrodynamic) water-based carbon nanotubes (CNTs) over a shrinking sheet. This phenomenon contains other important effects such as: laminar, incompressible, porous media, thermal radiation and viscous dissipation. The sheet is shrinking along x-axis and fluid is dealing for the boundary domain. The governing partial differential equations are transformed to nonlinear system of ordinary differential equation by using appropriate similarity transformations. This mathematical model is solved and obtained the closed form dual nature solutions in special hyper geometric function. Results of velocity, temperature, skin friction and Nusselt number are plotted against variation of different emerging parameters.

Consequence of exponential heat generation on non-Darcy-Forchheimer flow of water based carbon nanotubes driven by a curved stretching sheet

The present article comprises the study on the influence of exponential space based heat generation on the non-Darcy-Forchheimer flow of carbon nanotubes (CNTs). The flow is considered over a curved stretching sheet. Similarity variables are used to reduce the flow descriptive nonlinear partial derivative equations to simple equations. Simplified equations are then solved by the exploiting Runge-Kutta-Fehlberg fourth- and fifth-order methods. Obtained numerical solutions are shown in graphs and tables. Comparison between single and multi-walled CNTs has been established through the tabulated values and plotted graphs. It is concluded that the heat source parameter plays a prime role in enhancement of temperature, and the curvature parameter has adverse impact on velocity and temperature panels. Both the inertial parameter and inverse-Darcy number affect the fluid velocity.

Thermal exploration of radial porous fin fully wetted with SWCNTs and MWCNTs along with temperature-dependent internal heat generation

The numerical examination of radiation and natural convection in a porous radial fin along with varying internal heat generation with respect to temperature is carried out in the current study. The aim of this study is to scrutinize the heat transfer phenomenon in fin wetted with water-based carbon nanotubes like single-walled carbon nanotubes and multiwalled carbon nanotubes. In the proposed work, the Darcy’s model is employed for the analysis. The modeled equations are nondimensionalized and solved by utilizing Runge–Kutta–Fehlberg method. The impact of relevant parameters on the heat transfer rate is comprehensively explored with an aid of graphs. Here, multiwalled carbon nanotube–water shows better heat transfer from surface of fin compared to single-walled carbon nanotube–water.

Effects of volume fraction on water-based carbon nanotubes flow in a right-angle trapezoidal cavity: FEM based analysis

The purpose of the current study is to investigate the effects of water-based single-walled carbon nanotubes on free convection in a partially heated right trapezoidal cavity. The bottom wall of the cavity is heated while the side walls are kept cold, and the top wall is adiabatic. The governing dimensionless partial differential equations are solved with selected dimensionless boundary conditions via finite element scheme. The effects of the heating domain, the volume fraction of carbon nanotubes, Rayleigh and Hartmann numbers on the streamlines, isotherms, dimensionless horizontal and vertical velocities, dimensionless temperature and the local Nusselt number along the heating element are investigated numerically. The strength of streamlines decreases with increasing values of volume fraction of CNTs and Hartmann number while an enhanced behavior is noted for higher values of Rayleigh number and increasing the length of the heating element. The isotherms confirm the transfer of heat from bottom to side cold walls. It is demonstrated that the local Nusselt number attains the maximum values around the edges of the heating element and then decreases. Furthermore, the heating domain and the carbon nanotubes enhance the local Nusselt number along the heated surface.

Darcy–Forchheimer flow of carbon nanotubes subject to heat flux boundary condition

Flow of water-based carbon nanotubes past an exponentially stretching curved surface is modeled. Analysis is carried out for imposed flux condition and heat generation/absorption. Darcy–Forchheimer expression is used to characterize the flow in porous space. Carbon nanotubes of two types (recognized as SWCNT and MWCNT) are utilized. Adequate transformations correspond to system of coupled differential equations. The resulting nonlinear system is solved by NDSolve technique. Influences of various pertinent variables for quantities of interest are examined. Our results reveal that temperature against volume fraction of nanoparticles is enhanced.

Natural convection of water-based carbon nanotubes in a partially heated rectangular fin-shaped cavity with an inner cylindrical obstacle

This study investigates the heat augmentation and hydromagnetic flow of water-based carbon nanotubes (CNTs) inside a partially heated rectangular fin-shaped cavity. A thin heated rod is placed within the cavity to create a resistance or to provide a source for heat transfer. The obstacle is tested for the heated case, while the right side of the horizontal tip is tested for three different temperatures (adiabatic, cold, and heated). The left vertical side of the cavity is partially heated with temperature Th, and the rest of the sides are kept cold at temperature Tc except the right tip. Two different thermal boundary conditions (prescribed temperature and adiabatic) are employed on the fin tip. The CNTs and water are assumed to be in thermal equilibrium with no-slip velocity. The magnetic field and thermal radiation are introduced in the momentum and energy equations, respectively. The governing equations are obtained in dimensionless form by means of dimensionless variables. The numerical computation is performed via the finite element method using the Galerkin approach. The substantial effects of emerging parameters on the streamlines, isotherms, dimensionless velocities, and temperature are reported graphically and discussed. In the case of a cold or adiabatic fin-tip, a drop to minimum is found in the dimensionless temperature. The components of velocity are perceived maximum at a vertical corner while minimum at the horizontal corner. It is demonstrated that the local Nusselt numbers are increased by introducing both solid volume fraction of CNTs and radiation effects, while the Nusselt number noticed maximum at the corners.