Volumetric Fraction Of Nanoparticles Research Articles

Convective flow of ethylene glycol‐silver Jeffery nanofluid in a Hele‐Shaw cell with an influence of external magnetic field

AbstractThis effort investigates the arrival of magnetothermal convection of ethylene glycol‐silver Jeffrey nanofluid in a Hele‐Shaw cell utilizing the linear stability concept. The model practiced for the Jeffrey nanofluid includes the impacts of Brownian movement and thermophoresis. The norms for both marginal and overstable modes of convections are developed analytically. The impact of magnetic Chandrasekhar number , magnetic Prandtl number , Jeffrey parameter , Hele‐Shaw number , and a variety of nanofluid parameters such as the volumetric fraction of nanoparticles , nanoparticle Rayleigh number , adjusted diffusive ratio , and Lewis number on the beginning of convective motion are investigated, and results are illustrated graphically. It is observed that the overstable approach of convection is probable below the certain threshold estimate of the magnetic Prandtl number . This threshold estimate of the magnetic Prandtl number upturns with a rise in the rate of , , and , while it drops with a surge in the nanofluid parameters. The system was found to be more stable by decreasing the Hele‐Shaw number , the Jeffery parameter , and nanofluid parameters, while it was unstable by decreasing the magnetic Chandrasekhar number and the magnetic Prandtl number .

Magneto-Nanofluid Flow via Mixed Convection Inside E-Shaped Square Chamber

Nanofluids play a crucial role in the augmentation of heat transfer in several energy systems. They exhibit better thermal conductivity and physical strength compared to normal fluids. Here, we conduct an evaluative investigation of the magnetized flow of water–copper nanofluid and its heat transport inside a symmetrical E-shaped square chamber via mixed convective impact with a heated corner. The chamber was constructed symmetrically with an inclined magnetic field strength, and the upper surface of the chamber was isolated and set to move at a fixed velocity. The heated corner was set at a fixed hot temperature in both the left and lower directions. The right side was maintained at a fixed cold temperature, while the remaining portions of the left and lower parts were isolated. The investigation was implemented computationally, solving each of the energy and Navier–Stokes models via the application of a symmetrical finite volume method. The following topics have been addressed in this study: the consequences of the magnetic field, the volumetric fraction of nanoparticles, the heat generation–absorption parameters, and the effects of heat-source length and Richardson number on the fluid comportment and heat transport. The outputs of this symmetric study enabled us to arrive at the following derivation: the magnetic field reduces the fluid circulation inside the E-shaped square chamber. The augmentation of the Richardson number leads to an increase in the heat transfer. Moreover, the decrease in heat generation coefficient lowers the nanofluid temperature and weakens the flow fields.

FEM solution to quadratic convective and radiative flow of Ag-MgO/H2O hybrid nanofluid over a rotating cone with Hall current: Optimization using Response Surface Methodology

The nonlinear buoyancy-induced (quadratic convection) flow of water conveying hybrid nanoparticles (25 nm Ag and 40 nm MgO) around a revolving cone surface subjected to quadratic radiative heat transfer is studied, taking into deliberation of Hall current, and thermal jump condition. The quadratic form of Boussinesq approximation (QBA) with quadratic Rosseland thermal radiation (QRTR) is employed to model the problem. Esfe models for thermal conductivity and dynamic viscosity with a volumetric fraction of nanoparticles (50% MgO and 50% Ag) are used. The effective medium correlations for heat capacitance, thermal expansion factor, and density of Ag-MgO/water hybrid nanofluid are used. The governing equations are solved by using the Finite element method (FEM). The effects of parameters on the shear stress and heat transport of the system are scrutinized using the friction factors and Nusselt number through two-dimensional contour and three-dimensional surface plots. The friction factor and the heat transport rate are optimized using the Response Surface Method (RSM) and the optimal level of intensity of the magnetic field, radiation, and thermal slip is determined. Because of the influence of hybrid nanoparticles, the heat transport rate is observed to be the highest. When compared to Linear Rosseland Thermal Radiation (LRTR), the Nusselt number for QRTR is found to be the highest. Furthermore, at a low level of Ts and a high level of Ha and Rd, maximum heat transport (2.42951) and minimum shear stress (1.07598) are achieved with a desirability of 0.797.

Magnetic Field Effect on Heat and Momentum of Fractional Maxwell Nanofluid within a Channel by Power Law Kernel Using Finite Difference Method

The mathematical model of physical problems interprets physical phenomena closely. This research work is focused on numerical solution of a nonlinear mathematical model of fractional Maxwell nanofluid with the finite difference element method. Addition of nanoparticles in base fluids such as water, sodium alginate, kerosene oil, and engine oil is observed, and velocity profile and heat transfer energy profile of solutions are investigated. The finite difference method involving the discretization of time and distance parameters is applied for numerical results by using the Caputo time fractional operator. These results are plotted against different physical parameters under the effects of magnetic field. These results depicts that a slight decrease occurs for velocity for a high value of Reynolds number, while a small value of Re provides more dominant effects on velocity and temperature profile. It is observed that fractional parameters α and β show inverse behavior against u(y, t) and θ(y, t). An increase in volumetric fraction of nanoparticles in base fluids decreases the temperature profile of fractional Maxwell nanofluids. Using mathematical software of MAPLE, codes are developed and executed to obtain these results.

Entropy generation of MHD natural convection heat transfer in a heated incinerator using hybrid-nanoliquid

The present study explores magnetic hybrid-nanoliquid (Al2O3–Cu/H2O) natural convection in a heated incinerator shaped cavity by using the lattice Boltzmann method (LBM). Numerical results are presented in the form temperature contours, stream function and local entropy generation. Complex interaction between various physical phenomena characterizing this problem including the natural convection and the magnetic field has been observed. Influences of Rayleigh number (Ra = 103–106), volumetric fraction of nanoparticles (ϕ= 0–0.04), and Hartmann number (Ha = 0–90) are clarified in details through graphical portraits. Results depict that the average Nusselt number (Num) and average entropy generation (Sgen,A) increases with an increase of the Rayleigh number while are decreased by applying a magnetic field. In addition, it is found that the average Nusselt number (Num) increases with the rise of volumetric fraction of nanoparticles for all Rayleigh and Hartmann numbers. Conversely, an opposite effect is obtained by an increase in volumetric fraction of nanoparticles on the average entropy generation (Sgen,A). Finally, the numerical results demonstrate that the effect of Lorentz force is reduced when the heat transfer regime conduction is considered.

A novel application of Lobatto IIIA solver for numerical treatment of mixed convection nanofluidic model

The objective of the current investigation is to examine the influence of variable viscosity and transverse magnetic field on mixed convection fluid model through stretching sheet based on copper and silver nanoparticles by exploiting the strength of numerical computing via Lobatto IIIA solver. The nonlinear partial differential equations are changed into ordinary differential equations by means of similarity transformations procedure. A renewed finite difference based Lobatto IIIA method is incorporated to solve the fluidic system numerically. Vogel's model is considered to observe the influence of variable viscosity and applied oblique magnetic field with mixed convection along with temperature dependent viscosity. Graphical and numerical illustrations are presented to visualize the behavior of different sundry parameters of interest on velocity and temperature. Outcomes reflect that volumetric fraction of nanoparticles causes to increase the thermal conductivity of the fluid and the temperature enhances due to blade type copper nanoparticles. The convergence analysis on the accuracy to solve the problem is investigated viably though the residual errors with different tolerances to prove the worth of the solver. The temperature of the fluid accelerates due the blade type nanoparticles of copper and skin friction coefficient is reduced due to enhancement of Grashof Number.

Numerical Study of Shell and Tube Heat Exchanger Performance Enhancement Using Nanofluids and Baffling Technique

The aim of this work is to investigate the forced convective heat transfer phenomena and fluid flows of water-based Al2O3 nanofluids in the baffled shell and tubes heat exchanger (STHE). Water as a hot fluid flows in the side of the tubes, and Al2O3 nanofluids as cooling fluid flow in the shell side. Numerical investigations have been carried out based on the continuity, momentum, and energy equations which are solved by using the finite element method with the help of the COMSOL 5.4 CFD software. The obtained results were presented by average Nusselt number, streamlines, isotherms, and various physical parameters which are a volumetric fraction of nanoparticles (1%? Cv ?3%). The results are found that the heat transfer increases with the rise of inlet velocity and volume fraction. In addition, the presence of baffles inside tubular heat exchangers can create a better mixture of fluids which is augmenting heat transfer execution. The choice of these parameters is important to get the maximum improvement of heat transfer with minimum entropy consumption.

Thermal performance analysis of a 1–5 TEMA E shell and coil heat exchanger operating with SWCNT–water nanofluid with varied nanoparticle concentration

Single-walled carbon nanotube–water nanofluids were tested in a 1–5 TEMA E shell and coil heat exchanger. Cold nanofluid, flowing inside the coil, was heated by hot water flowing in the shell side. Volumetric fraction of nanoparticles, inlet temperature of nanofluid, and mass flow rate of nanofluids ranged from 0 to 0.21%, 2.3 to 23.4 °C, and 40 to 90 g/s, respectively. For a given Reynolds number, at the coil side, pure base fluid (φ = 0%) performed better than low-concentration nanofluid samples (φ = 0.035% and 0.053%) and was nearly equivalent to the nanofluid of highest concentration, φ = 0.21%. The thermal conductivity enhancement factor of the nanofluid ranged from 0 to 0.2 and to 0.45, at inlet temperatures of 30 °C and 50 °C, respectively. It is believed to work in favor of a better performance of the nanofluid samples. On the other hand, the unusual (literature-wise) low temperature of the nanofluid further amplified the enhancement of the nanofluid viscosity, with a reduction effect on the Reynolds number. Besides, other thermal resistances of the heat exchanger work toward an attenuation of the enhancement effect that nanoparticles may have in the heat exchanger performance.

MHD Heat Transfer in W-Shaped Inclined Cavity Containing a Porous Medium Saturated with Ag/Al2O3 Hybrid Nanofluid in the Presence of Uniform Heat Generation/Absorption

In this paper, a 2D numerical study of natural convection heat transfer in a W-shaped inclined enclosure with a variable aspect ratio was performed. The enclosure contained a porous medium saturated with Ag/Al2O3 hybrid nanofluid in the presence of uniform heat generation or absorption under the effect of a uniform magnetic field. The vertical walls of the enclosure were heated differentially; however, the top and bottom walls were kept insulated. The governing equations were solved with numerical simulation software COMSOL Multiphysics which is based on the finite element method. The results showed that the convection heat transfer was improved with the increase of the aspect ratio; the average Nusselt number reached a maximum for an aspect ratio (AR) = 0.7 and the effect of the inclination was practically negligible for an aspect ratio of AR = 0.7. The maximum heat transfer performance was obtained for an inclination of ω = 15 and the minimum is obtained for ω = 30 . The addition of composite nanoparticles ameliorated the convection heat transfer performance. This effect was proportional to the increase of Rayleigh and Darcy numbers, the aspect ratio and the fraction of Ag in the volumetric fraction of nanoparticles.

Thermal performance analysis of a parabolic trough collector using water-based green-synthesized nanofluids

The parabolic trough collector (PTC) is one of the most advanced solar concentrating technology available. The study employed experimental synthesis and numerical modeling to present possible solutions to the challenges of nanofluids application in solar collectors. A green alternative of using nanoparticles synthesized from green bio-matter (Olive leaf extract OLE) and agricultural waste (barley husk BH) is proposed. The synthesized nanoparticles were characterized using analytical and morphological techniques and were found to be efficient corrosion inhibitor, non-toxic and cheap to produce when compared to the conventional ones. The study presents an innovative thermal performance evaluation of a parabolic trough collector operating with green-synthesized nanofluids: water/BH-SiO2 and water/OLE-TiO2. The model of the PTC was developed on the engineering equation solver (EES) and validated using the experimental results of the Sandia National Laboratory (SNL), AZTRAK platform LS-2 test. The results of the analysis show that a 0.073% mean enhancement in the thermal efficiency is observed with the use of water/BH-SiO2 nanofluids and 0.077% mean enhancement with the use of water/OLE-TiO2 nanofluids. The heat transfer performance of the nanofluids shows a mean enhancement in heat transfer coefficient of 128% and 138% for water/OLE-TiO2 and water/BH-SiO2 nanofluids respectively. The mean variation in pressure losses between the nanofluids and base fluid was also observed to be less than 14.85% at a 3% volumetric fraction of nanoparticles.

Numerical Analysis of the Unsteady Natural Convection MHD Couette Nanofluid Flow in the Presence of Thermal Radiation Using Single and Two-Phase Nanofluid Models for Cu–Water Nanofluids

The unsteady Couette nanofluid flow with heat transfer is investigated numerically for copper–water nanofluids under the combined effects of thermal radiation and a uniform transverse magnetic field with variable thermo-physical properties, in the case where the flow is established vertically between two parallel plates, so that one of them has an accelerated motion. The homogeneous single-phase model (i.e., Tiwari and Das’s nanofluid model) and the two-phase mixture model (i.e., Buongiorno’s nanofluid model) are utilized in this study together with Corcione’s model to further investigate and clarify the differences between those models and evaluate the validity of the single-phase model for studying the unsteady natural convection MHD Couette nanofluid flow with thermal radiation. In this investigation, we assume that the studied nanofluid is electrically conducting and has a Newtonian rheological behavior. The nonlinear dynamical system of partial differential equations are solved numerically by means of the Gear–Chebyshev–Gauss–Lobatto collocation technique for zero nanoparticles mass flux and no-slip impermeable conditions at the isothermal vertical plates. In a special case, the present numerical solution is also validated analytically and numerically with the earlier available results. For both nanofluid models, the effects of major parameters on the dimensionless velocity, temperature and volumetric fraction of nanoparticles are analysed via representative profiles, whereas the skin friction factor and the heat transfer rate are estimated numerically and discussed through tabular illustrations.

Zero and nonzero normal fluxes of thermal radiative boundary layer flow of nanofluid over a radially stretched surface

The axisymmetric flow of a nanoparticles-saturated-fluid with existence of thermic radiation over a stretched sheet is investigated. The effects of zero (passive control) as well as nonzero fluxes (active control) of nanoparticles on the plate towards distributions of temperature and volumetric fraction of nanoparticles are investigated together comparatively. Through the supposition of boundary layer, the Navier-Stokes equations are simplified hence converted into non-dimensional form by similarity transformation. A shooting technique is engaged to deal with the emerging nonlinear system of ordinary differential equations numerically in MATLAB software. Several distributions of velocity, thermal energy and volumetric fraction of nanoparticles under zero/nonzero normal flux are graphically demonstrated. The impact of the parameters towards the reduced coefficient of skin friction, and are investigated too. The presence of thermic radiation under consideration of both zero and nonzero normal fluxes have significant effects on the intensification of the flow heat transfer. Thermophoresis enhances the heat conductivity performance in the case of zero fluxes of nanoparticles.

Numerical analysis of Al2O3/water nano-fluids natural convection and entropy generation in enclosures

The aim of this work is to analyze the natural convection phenomena and entropy generation of water-based Al 2 O 3 nanofluids in square enclosure. The simulated domain corresponds to a square cavity heated from below and cooled from the top. The left and right walls are heated up to a height H = (3/4 W) and are adiabatic in the remaining part (1- H ). Numerical investigations have been carried out based on coupled partial differential equations of momentum and energy which are solved using finite volume method. The effective thermal conductivity of the nanofluid was expressed by the Maxwell-Garnetts model however the dynamic viscosity was calculated according to the Brinkman formula. The obtained results were presented by average Nusselt number, streamlines, isotherms and entropy generation with various pertinent parameters, namely, Rayleigh number (10 0 ≤ Ra ≤ 10 6 ), volumetric fraction of nanoparticles (1% ≤ ϕ ≤ 4% ). It was found that the heat transfer increases with the increase of Rayleigh number and volume fraction. The choice of these parameters is important to obtain maximum enhancement of heat transfer with minimum entropy generation.

Experimental investigation on forced convective heat transfer coefficient of a nano fluid

Nano fluids are used in broad range of engineering applications due to their improved thermo-physical properties such as thermal conductivity, thermal diffusivity, viscosity and convective heat transfer coefficient. In this paper Al2O3Nano fluid has been prepared by using sonicator and the size of nanoparticle is 28 nm diameters. The property changes of Nano fluids depend on the volumetric fraction of nanoparticles, shape and size of the nanomaterial. This paper presents an experimental investigation on forced convective heat transfer coefficient of a Nano fluid flowing in a single pass and multi tubes counter flow shell and tube heat exchanger under turbulent flow condition. In this we are taking different volume concentrations (0.1%, 0.2%, 0.3% and 0.4%). The results observed the heat transfer performance and characteristics of an Al203/water Nano fluid estimated.Heat transfer coefficient for forced convection is higher than the water at the same flow velocity and inlet temperatures of both hot and cold fluid conditions. The other properties of the Nano fluid such as its thermal conductivity, specific heat, density, and viscosity, tube diameter also calculated.

Transient behavior analysis of the melting of nanoparticle-enhanced phase change material inside a rectangular latent heat storage unit

Melting of Paraffin Wax (P116) dispersed with Al2O3 nanoparticles in a rectangular latent heat storage unit (LHSU) is numerically investigated. The storage unit consists of a number of vertical and identical plates of nanoparticle-enhanced phase change material (NEPCM) separated by rectangular channels through which a heat transfer fluid flows (HTF: Water). A two-dimensional mathematical model is considered to numerically investigate the heat and flow characteristics of the LHSU. The heat transfer and fluid flow during the melting process were formulated using the enthalpy-porosity method. The finite difference forms of the governing equations are obtained using the finite volume approach. The numerical model has been validated by experimental, theoretical and numerical results available in the literature. The effects of the aspect ratio of NEPCM slabs, volumetric fraction of nanoparticles, Reynolds number and Rayleigh number on the flow characteristics and thermal performance of the storage unit were investigated. A correlation including all these investigated control parameters has been developed to predict the time required for the complete melting of NEPCM.

Natural convection and entropy generation in a cubical cavity with twin adiabatic blocks filled by aluminum oxide–water nanofluid

ABSTRACTA finite volume-based three-dimensional numerical simulation on natural convection and entropy generation in a cubical cavity filled with a nanofluid of aluminum oxide–water is presented by vorticity–vector potential formalism. The blocks are adiabatic and the vertical walls are differentially heated unidirectionally. The variables considered are Ra, volumetric fraction of aluminum oxide particles, and block size. The results for fluid flow with a single-phase model are elucidated with iso-surfaces of temperature, Nusselt number, and Bejan number. The local entropy generated was due to friction surges when the volumetric fraction of nanoparticles was increased. The average Nusselt number rose with the increase in Ra and volumetric fraction of solid particles and declined with the increase in block size.

Thermal instability in a rotating nanofluid layer: A revised model

Abstract In this paper, the analysis of thermal instability of rotating nanofluid layer is revised with a physically more realistic boundary condition on the nanoparticle volumetric fraction i.e. the nanoparticle flux is assumed to be zero rather than prescribing the nanoparticle volumetric fraction on the rigid impermeable boundaries. This shows that the nanoparticle fraction value at the boundary adjusts accordingly. In this respect, the present model is more realistic physically than those of the previous investigations. The numerical computations are presented for water-based nanofluids with alumina and copper nanoparticles. For Alumina-water nanofluid, zero flux nanoparticle boundary condition has more destabilizing effect than the constant nanoparticle boundary conditions, while reverse for copper–water nanofluid. The effect of rotation is found to have a stabilizing effect. Further, volumetric fraction of nanoparticles ϕ 0 ∗ , the Lewis number L e , the density ratio R ρ and modified diffusivity ratio N A are found to destabilize the system.

Natural convection in an inclined rectangular enclosure filled by CuO–H2O nanofluid, with sinusoidal temperature distribution

A two-dimensional steady laminar natural convection in an inclined rectangular enclosure filled with CuO–water nanofluid is investigated numerically. The horizontal walls are thermally insulated and the left vertical side wall is heated by a spatial temperature distribution. Mass Conservation, momentum, and energy equations are solved numerically by the finite volume element method using the SIMPLER algorithm for pressure–velocity coupling. This study has been carried out for the pertinent parameters in the following ranges: inclination angle ω = 0°–90°, the volumetric fraction of nanoparticles between 0 and 4% and aspect ratio (Ar = 0.25, 0.5, 1 and 2). These simulations are performed at constant Rayleigh and Prandtl numbers, they are fixed at Ra = 105and Pr = 7.02. The results are presented in the form of streamlines, isotherms and Nusselt numbers. The heat transfer increases first, then decreases with increasing the inclination of the enclosure for aspect ratio (Ar ≥ 1) and increases with increasing the inclination angle for Ar < 1. The rate of heat transfer increases with increasing of volume fraction of nanoparticles.The subject of this paper is to study the effect of nanoparticles on heat transfer, together with the effect of the tilt angle and the aspect ratio.

Effect of a Magnetic Field on Natural Convection in a Nanofluid-Filled Enclosure with a Linearly Heated Wall Using LBM

In this paper, effect of a magnetic field on natural convection flow in a nanofluid-filled enclosure with a linearly heated wall has been analyzed with a new attitude to Lattice Boltzmann method. The cavity is filled with water and nanoparticles of Cu in the presence of the magnetic field. This study has been carried out for the pertinent parameters in the following ranges: the Rayleigh number of base fluid, Ra = 103–105, the volumetric fraction of nanoparticles between 0 and 15 % with interval 5 %. The Hartmann number varied from Ha = 0 to 90 with interval 30, while magnetic field is considered at the direction of the cavity horizontal. Results show that the heat transfer decreases by increment of Hartmann number for various Rayleigh numbers. Heat transfer increases with growth of the volume fractions, but this growth is various for different Rayleigh numbers. The magnetic field augments the effect of nanoparticles at high Rayleigh numbers (Ra = 105), while the effect declines in the presence of the magnetic field for low Rayleigh numbers (Ra = 103 and 104).

Lattice Boltzmann simulation of natural convection in nanofluid-filled 2D long enclosures at presence of magnetic field

In this paper, the effects of a magnetic field on natural convection flow in filled long enclosures with Cu/water nanofluid have been analyzed by lattice Boltzmann method. This study has been carried out for the pertinent parameters in the following ranges: the Rayleigh number of base fluid, Ra = 103–105, the volumetric fraction of nanoparticles between 0 and 6 %, the aspect ratio of the enclosure between A = 0.5 and 2. The Hartmann number has been varied from Ha = 0 to 90 with interval 30 while the magnetic field is considered at inclination angles of θ = 0°, 30°, 60° and 90°. Results show that the heat transfer decreases by the increment of Hartmann number for various Rayleigh numbers and the aspect ratios. Heat transfer decreases with the growth of the aspect ratio but this growth causes the effect of the nanoparticles to increase. The magnetic field augments the effect of the nanoparticles at high Rayleigh numbers (Ra = 105). The effect of the nanoparticles rises for high Hartmann numbers when the aspect ratio increases. The rise in the magnetic field inclination improves heat transfer at aspect ratio of A = 0.5.