Nanoparticles Mass Flux Research Articles

Characteristics of Flow Boiling Heat Transfer and Pressure Drop of MWCNT–R123 Nanorefrigerant: Experimental Investigations and Correlations

ABSTRACTIn the present work, the flow boiling heat transfer characteristics and pressure drop are experimentally investigated using multiwalled carbon nanotube (MWCNT)–R123-based nanofluids flowing inside a horizontal circular tube. The effects of particle concentration, mass flux, and vapor quality on the heat transfer coefficient (HTC) and pressure drop of MWCNT–R123-based nanofluid are analyzed. Results show that flow boiling HTC and frictional pressure drop increased with nanoparticle concentration, mass flux, and vapor quality as expected. The effects of nanoparticles on the flow boiling HTC and pressure drop are quantitatively analyzed by introducing a nanoparticle impact factor. A modified correlation for predicting the flow boiling HTC of nanorefrigerants is proposed, and the proposed correlation predicts 95% of the points with a deviation of ±20%. In addition, frictional pressure drop can be predicted using the Müller-Steinhagen and Heck correlation with a mean absolute error of 13.07% if the thermophysical properties of nanofluids are substituted.

On three-dimensional boundary layer flow of Sisko nanofluid with magnetic field effects

This article models the effects of magnetic field and nanoparticles in the three-dimensional flow of Sisko fluid. The flow is caused by a bidirectional stretching surface. Effects of Brownian motion and thermophoresis in the nanofluid model are considered. Sisko fluid is assumed electrically conducted through a constant applied magnetic field. Mathematical formulation in boundary layer regime is presented for a low magnetic Reynolds number. Newly constructed boundary condition subject to zero nanoparticles mass flux at the surface is employed. Nonlinear differential systems are solved for the convergent solutions. Effects of various physical parameters are studied and discussed. Numerical values of skin friction coefficients and Nusselt number are tabulated and analyzed. It is observed that the effects of Brownian motion and thermophoresis parameters on the nanoparticles concentration distribution are quite opposite. Further the temperature and nanoparticles concentration distributions are enhanced for the larger values of magnetic parameter.

On magnetohydrodynamic flow of second grade nanofluid over a nonlinear stretching sheet

This research article addresses the magnetohydrodynamic (MHD) flow of second grade nanofluid over a nonlinear stretching sheet. Heat and mass transfer aspects are investigated through the thermophoresis and Brownian motion effects. Second grade fluid is assumed electrically conducting through a non-uniform applied magnetic field. Mathematical formulation is developed subject to small magnetic Reynolds number and boundary layer assumptions. Newly constructed condition having zero mass flux of nanoparticles at the boundary is incorporated. Transformations have been invoked for the reduction of partial differential systems into the set of nonlinear ordinary differential systems. The governing nonlinear systems have been solved for local behavior. Graphical results of different influential parameters are studied and discussed in detail. Computations for skin friction coefficient and local Nusselt number have been carried out. It is observed that the effects of thermophoresis parameter on the temperature and nanoparticles concentration distributions are qualitatively similar. The temperature and nanoparticles concentration distributions are enhanced for the larger magnetic parameter.

MHD boundary layer flow of a power-law nanofluid with new mass flux condition

An analysis is carried out to study the magnetohydrodynamic MHD boundary layer flow of power-law nanofluid over a non-linear stretching sheet. In the presence of a transverse magnetic field, the flow is generated due to non-linear stretching sheet. By using similarity transformations, the governing boundary layer equations are reduced into a system of ordinary differential equations. A recently proposed boundary condition requiring zero nanoparticle mass flux is employed in the flow analysis of power-law fluid. The reduced coupled differential equations are then solved numerically by the shooting method. The variations of dimensionless temperature and nanoparticle concentration with various parameters are graphed and discussed in detail. Numerical values of physical quantities such as the skin-friction coefficient and the reduced local Nusselt number are computed in tabular form.

ナノ流体で満たされた多孔質体における粒子機械分散の数値解

Substantial heat transfer enhancement is possible using a passage filled with a nanofluid saturated metal foam, because of its high specific surface area, high thermal conductivity and comparatively low pressure drop. In addition to the Brownian diffusion and thermophoresis associated with nanofluids, one must fully understand both thermal dispersion and particle mechanical dispersion, so as to elucidate their combined effects on the heat transfer enhancement mechanism. Microscopic numerical calculations were conducted using a numerical model describing a structural unit of a passage filled with nanofluid saturated metal foam. The results were integrated over a local control volume, to evaluate the mechanical dispersion terms, purely from the theoretical basis. The present study reveals that the effect of the particle volume fraction on the thermal dispersion correlation is only minor, so that the correlations obtained for the base fluid can be used universally. On the other hand, the nanoparticle mass flux is found rather sensitive to the interstitial heat transfer rate from the metal to nanofluid, since it increases with the interstitial heat transfer rate.

STEADY DOUBLE-DIFFUSIVE MIXED CONVECTION BOUNDARY LAYER FLOW PAST A VERTICAL FLAT PLATE EMBEDDED IN A POROUS MEDIUM FILLED BY A NANOFLUID USING BUONGIORNO'S MODEL

The steady double-diffusive mixed convection boundary layer flow past a vertical flat plate embedded in a porous medium filled by a nanofluid is investigated numerically. Using a similarity transformation, the partial differential equations are transformed into ordinary differential equations before being solved numerically by a shooting method and Maple software. The effects of the mixed convection parameter on the flow and heat transfer characteristics are investigated. The results show that it is possible to obtain dual solutions for the opposing flow, while for the assisting flow, the solution is unique. The local Nusselt number, the local Sherwood number, and the local nanoparticle mass flux increase as the mixed convection parameter increases.

Impact of magnetic field in three-dimensional flow of an Oldroyd-B nanofluid

This study explores the three-dimensional boundary layer flow of an Oldroyd-B nanofluid. Flow is induced by a bidirectional stretching surface. Brownian motion and thermophoresis effects are considered. Fluid is electrically conducted in the presence of an applied magnetic field. Newly proposed boundary condition requiring zero nanoparticle mass flux at the boundary is employed. The governing nonlinear boundary layer equations through appropriate transformations are reduced into the nonlinear ordinary differential systems. The resulting nonlinear system has been solved for the velocities, temperature and nanoparticle concentration expressions. The contributions of various interesting parameters are studied graphically. The local Nusselt number is tabulated and discussed.

Three-Dimensional Flow of Jeffrey Nanofluid with a New Mass Flux Condition

AbstractThe three-dimensional (3D) boundary layer flow of Jeffrey nanofluid subject to the convective boundary condition is analyzed. The flow is induced by a bidirectional stretching surface. Effects of thermophoresis and Brownian motion are considered. Newly developed boundary condition with the zero nanoparticles mass flux is employed. Mathematical modeling is made under boundary layer approach. Similarity variables are used to convert the governing partial differential equations into the nonlinear ordinary differential equations. The resulting nonlinear ordinary differential equations have been solved for the velocities, temperature, and nanoparticles concentration. Graphs are plotted to examine the influence of various physical parameters on the dimensionless temperature and nanoparticles concentration distributions. Numerical values of local Nusselt number are tabulated and discussed. It is found that the effects of the Biot number on the temperature and nanoparticles concentration are quite similar...

FLOW REVERSAL OF FULLY DEVELOPED MIXED CONVECTION OF NANOFLUIDS IN A VERTICAL CHANNEL FILLED WITH POROUS MEDIUM

The present analysis is concerning the criteria for the onset of flow reversal of the fully developed flow mixed convection of nanofluids in a vertical channel filled with porous medium. The governing equations and the critical values of the buoyancy force are solved and calculated numerically via dsolve package in MAPLE. It was found that the critical values of mixed con- vection parameter for the occurrence of reversed flow decreases with increasing temperature difference ratio and increases with increasing nanoparticles mass flux.

Three-dimensional boundary layer flow of Maxwell nanofluid: mathematical model

The present research explores the three-dimensional boundary layer flow of the Maxwell nanofluid. The flow is generated by a bidirectional stretching surface. The mathematical formulation is carried out through a boundary layer approach with the heat source/sink, the Brownian motion, and the thermophoresis effects. The newly developed boundary conditions requiring zero nanoparticle mass flux at the boundary are employed in the flow analysis for the Maxwell fluid. The governing nonlinear boundary layer equations through appropriate transformations are reduced to the coupled nonlinear ordinary differential system. The resulting nonlinear system is solved. Graphs are plotted to examine the effects of various interesting parameters on the non-dimensional velocities, temperature, and concentration fields. The values of the local Nusselt number are computed and examined numerically.

Interaction of magnetic field in flow of Maxwell nanofluid with convective effect

Magnetohydrodynamic (MHD) three-dimensional flow of Maxwell nanofluid subject to the convective boundary condition is investigated. The flow is generated by a bidirectional stretching surface. Thermophoresis and Brownian motion effects are present. Fluid is electrically conducted in the presence of a constant applied magnetic field. Unlike the previous cases even in the absence of nanoparticles, the correct formulation for the flow of Maxwell fluid in the presence of a magnetic field is established. Newly proposed boundary condition with the zero nanoparticles mass flux at the boundary is employed. The governing nonlinear boundary layer equations through appropriate transformations are reduced in the nonlinear ordinary differential system. The resulting nonlinear system has been solved for the velocities, temperature and nanoparticles concentration distributions. Convergence of the constructed solutions is verified. Effects of emerging parameters on the temperature and nanoparticles concentration are plotted and discussed. Numerical values of local Nusselt number are computed and analyzed. It is observed that the effects of magnetic parameter and the Biot number on the temperature and nanoparticles concentration are quite similar. Both the temperature and nanoparticles concentration are enhanced for the increasing value of magnetic parameter and Biot number.

A Mathematical Study for Three-Dimensional Boundary Layer Flow of Jeffrey Nanofluid

Abstract In this article we investigated the characteristics of Brownian motion and thermophoresis in the magnetohydrodynamic (MHD) three-dimensional boundary layer flow of an incompressible Jeffrey fluid. The flow is generated by a bidirectional stretching surface. Fluid is electrically conducting in the presence of a constant applied magnetic field. Mathematical formulation of the considered flow problem is made through the boundary layer analysis. A newly proposed boundary condition requiring zero nanoparticle mass flux is employed in the flow analysis of Jeffrey fluid. The governing nonlinear boundary layer equations are reduced into the nonlinear ordinary differential systems through appropriate transformations. The resulting systems have been solved for the velocities, temperature, and nanoparticle concentration expressions. The contributions of various interesting parameters are studied graphically. The values of the Nusselt number are computed and examined.

Magnetohydrodynamic three-dimensional flow of viscoelastic nanofluid in the presence of nonlinear thermal radiation

Magnetohydrodynamic (MHD) three-dimensional flow of couple stress nanofluid in the presence of thermophoresis and Brownian motion effects is analyzed. Energy equation subject to nonlinear thermal radiation is taken into account. The flow is generated by a bidirectional stretching surface. Fluid is electrically conducting in the presence of a constant applied magnetic field. The induced magnetic field is neglected for a small magnetic Reynolds number. Mathematical formulation is performed using boundary layer analysis. Newly proposed boundary condition requiring zero nanoparticle mass flux is employed. The governing nonlinear mathematical problems are first converted into dimensionless expressions and then solved for the series solutions of velocities, temperature and nanoparticles concentration. Convergence of the constructed solutions is verified. Effects of emerging parameters on the temperature and nanoparticles concentration are plotted and discussed. Skin friction coefficients and Nusselt number are also computed and analyzed. It is found that the thermal boundary layer thickness is an increasing function of radiative effect.

Analytical and numerical solutions for axisymmetric flow of nanofluid due to non-linearly stretching sheet

This article reports the laminar axisymmetric flow of nanofluid over a non-linearly stretching sheet. The model used for nanofluid contains the simultaneous effects of Brownian motion and thermophoretic diffusion of nanoparticles. The recently proposed boundary condition is considered which requires the mass flux of nanoparticles at the wall to be zero. Analytic solutions of the arising boundary value problem are obtained by optimal homotopy analysis method. Moreover the numerical solutions are computed by Keller–Box method. Both the solutions are found in excellent agreement. The behavior of Brownian motion on the fluid temperature and wall heat transfer rate is insignificant. Further the nanoparticle volume fraction distribution is found to be negative near the vicinity of the stretching sheet.

Natural Convection Boundary Layer Flow over a Horizontal Plate Embedded in a Porous Medium Saturated with a Nanofluid: Case of Variable Thermophysical Properties

There is a rising interest in application of nanofluids in porous media. As such, this paper is aimed at numerically investigating convective boundary layer flow over a plate embedded in a porous medium filled with nanofluid. Influence of multifarious boundary layers’ applications namely concentration boundary layer of nanoparticles and thermal ones on thermal conductivity and dynamic viscosity of the nanofluid is studied. A new enhanced boundary condition, zero mass flux of nanoparticles through the surface, is adopted to calculate the volume fraction of nanoparticles on the surface. Furthermore, the effect of different practical non-dimensional parameters such as Brownian motion, thermophoresis, Lewis number, and buoyancy ratio on the hydrodynamic, thermal, and concentration boundary layers is investigated. It is revealed that an increase in buoyancy ratio culminates in temperature rise and velocity reduction. The results also show that as the dimensionless Lewis number increases, the fraction of nanoparticles at the sheet soars; on the other hand, the variation of Lewis number does not have considerable effect on the thermal and hydrodynamic boundary layers. Moreover, introducing an enhancement ratio as a criterion to examine the variation of thermal convective coefficient reveals that this value is a decreasing function of buoyancy ratio parameter. In some cases, the value of enhancement ratio becomes less than unity as the buoyancy ratio gets stronger.

Mixed-Convection Flow of Nanofluids and Regular Fluids in Vertical Porous Media with Viscous Heating

In this article, the problem of combined forced and natural convection in a vertical porous channel for both regular fluids and nanofluids has been solved by perturbation and numerical methods, taking into account the influences of viscous heating and inertial force. In this regard, various types of viscous dissipation models, including the Darcy model, the power of drag force model, and the clear fluid compatible model, were considered to account for viscous heating. In addition, the mass flux of nanoparticles was also considered in terms of Brownian and thermophoresis mechanisms. The velocity and temperature distributions of both the regular fluid and nanofluid and the Nusselt number values were determined by considering isothermal boundary conditions in terms of Grashof, Reynolds, Forchheimer, Brinkman, and Darcy numbers. Moreover, the results of the numerical method were validated against those predicted by the perturbation method for small values of the Forchheimer drag term and the Brinkman number. In addition, the results obtained for both the nanofluid and the regular fluid were compared in terms of dimensionless parameters such as Brinkman number, Forchheimer drag term, pressure drop, Grashof-to-Reynolds-number ratio, Darcy number, and nanoparticle mass flux. The predicted results clearly indicate that the presence of nanoparticles enhances the Nusselt number values significantly.